Add unit tagging to InstBlockId (#6259)

Co-authored-by: Dana Jansens <danakj@orodu.net>

toolchain/base/block_value_store.h

@@ -30,8 +30,9 @@ class BlockValueStore : public Yaml::Printable<BlockValueStore<IdT, ElementT>> {
   using RefType = llvm::MutableArrayRef<ElementT>;
   using ConstRefType = llvm::ArrayRef<ElementT>;
 
-  explicit BlockValueStore(llvm::BumpPtrAllocator& allocator)
-      : allocator_(&allocator) {
+  explicit BlockValueStore(llvm::BumpPtrAllocator& allocator,
+                           IdTag tag = IdTag())
+      : allocator_(&allocator), values_(tag) {
     auto empty = RefType();
     auto empty_val = canonical_blocks_.Insert(
         empty, [&] { return values_.Add(empty); }, KeyContext(this));
@@ -107,6 +108,8 @@ class BlockValueStore : public Yaml::Printable<BlockValueStore<IdT, ElementT>> {
 
   auto size() const -> int { return values_.size(); }
 
+  auto GetRawIndex(IdT id) const -> int { return values_.GetRawIndex(id); }
+
  protected:
   // Allocates a copy of the given data using our slab allocator.
   auto AllocateCopy(ConstRefType data) -> RefType {

toolchain/base/value_store.h

@@ -44,7 +44,11 @@ struct IdTag {
          // doesn't collide with anything else (though with the
          // second-highest-bit-tagging this might not be needed).
         id_tag_(llvm::reverseBits((((id_index + 1) << 1) | 1) << 1)),
-        initial_reserved_ids_(initial_reserved_ids) {}
+        initial_reserved_ids_(initial_reserved_ids) {
+    CARBON_CHECK(
+        id_index != -1,
+        "IdTag should be default constructed if no tagging id is available.");
+  }
 
   auto Apply(int32_t index) const -> int32_t {
     if (index < initial_reserved_ids_) {

toolchain/check/testdata/basics/raw_sem_ir/builtins.carbon

@@ -75,6 +75,6 @@
 // CHECK:STDOUT:     exports:         {}
 // CHECK:STDOUT:     imports:         {}
 // CHECK:STDOUT:     global_init:     {}
-// CHECK:STDOUT:     inst_block00000004:
+// CHECK:STDOUT:     inst_block60000004:
 // CHECK:STDOUT:       0:               inst0000000E
 // CHECK:STDOUT: ...

toolchain/check/testdata/basics/raw_sem_ir/cpp_interop.carbon

@@ -63,13 +63,13 @@ fn G(x: Cpp.X) {
 // CHECK:STDOUT:   cpp_global_vars:
 // CHECK:STDOUT:     cpp_global_var00000000: {key: {entity_name_id: entity_name60000003}, clang_decl_id: clang_decl_id00000007}
 // CHECK:STDOUT:   functions:
-// CHECK:STDOUT:     function60000000: {name: name00000001, parent_scope: name_scope00000000, call_params_id: inst_block00000006, body: [inst_block00000009]}
+// CHECK:STDOUT:     function60000000: {name: name00000001, parent_scope: name_scope00000000, call_params_id: inst_block60000006, body: [inst_block60000009]}
 // CHECK:STDOUT:     function60000001: {name: name00000004, parent_scope: name_scope60000001, call_params_id: inst_block_empty}
 // CHECK:STDOUT:     function60000002: {name: name00000007, parent_scope: name_scope60000001, call_params_id: inst_block_empty}
-// CHECK:STDOUT:     function60000003: {name: name00000004, parent_scope: name_scope60000001, call_params_id: inst_block0000000D}
-// CHECK:STDOUT:     function60000004: {name: name00000007, parent_scope: name_scope60000001, call_params_id: inst_block00000012}
+// CHECK:STDOUT:     function60000003: {name: name00000004, parent_scope: name_scope60000001, call_params_id: inst_block6000000D}
+// CHECK:STDOUT:     function60000004: {name: name00000007, parent_scope: name_scope60000001, call_params_id: inst_block60000012}
 // CHECK:STDOUT:   classes:
-// CHECK:STDOUT:     class60000000:   {name: name00000003, parent_scope: name_scope60000001, self_type_id: type(inst60000013), inheritance_kind: Base, is_dynamic: 0, scope_id: name_scope60000002, body_block_id: inst_block0000000A, adapt_id: inst<none>, base_id: inst<none>, complete_type_witness_id: inst60000024, vtable_decl_id: inst<none>}}
+// CHECK:STDOUT:     class60000000:   {name: name00000003, parent_scope: name_scope60000001, self_type_id: type(inst60000013), inheritance_kind: Base, is_dynamic: 0, scope_id: name_scope60000002, body_block_id: inst_block6000000A, adapt_id: inst<none>, base_id: inst<none>, complete_type_witness_id: inst60000024, vtable_decl_id: inst<none>}}
 // CHECK:STDOUT:   generics:        {}
 // CHECK:STDOUT:   specifics:       {}
 // CHECK:STDOUT:   struct_type_fields:
@@ -136,8 +136,8 @@ fn G(x: Cpp.X) {
 // CHECK:STDOUT:     inst60000017:    {kind: BindingPattern, arg0: entity_name60000000, type: type(inst60000016)}
 // CHECK:STDOUT:     inst60000018:    {kind: ValueParamPattern, arg0: inst60000017, arg1: call_param0, type: type(inst60000016)}
 // CHECK:STDOUT:     inst60000019:    {kind: ValueParam, arg0: call_param0, arg1: name00000002, type: type(inst60000013)}
-// CHECK:STDOUT:     inst6000001A:    {kind: SpliceBlock, arg0: inst_block00000004, arg1: inst60000014, type: type(TypeType)}
-// CHECK:STDOUT:     inst6000001B:    {kind: FunctionDecl, arg0: function60000000, arg1: inst_block00000008, type: type(inst6000001C)}
+// CHECK:STDOUT:     inst6000001A:    {kind: SpliceBlock, arg0: inst_block60000004, arg1: inst60000014, type: type(TypeType)}
+// CHECK:STDOUT:     inst6000001B:    {kind: FunctionDecl, arg0: function60000000, arg1: inst_block60000008, type: type(inst6000001C)}
 // CHECK:STDOUT:     inst6000001C:    {kind: FunctionType, arg0: function60000000, arg1: specific<none>, type: type(TypeType)}
 // CHECK:STDOUT:     inst6000001D:    {kind: TupleType, arg0: inst_block_empty, type: type(TypeType)}
 // CHECK:STDOUT:     inst6000001E:    {kind: StructValue, arg0: inst_block_empty, type: type(inst6000001C)}
@@ -168,7 +168,7 @@ fn G(x: Cpp.X) {
 // CHECK:STDOUT:     inst60000037:    {kind: BindingPattern, arg0: entity_name60000001, type: type(inst60000016)}
 // CHECK:STDOUT:     inst60000038:    {kind: ValueParamPattern, arg0: inst60000037, arg1: call_param0, type: type(inst60000016)}
 // CHECK:STDOUT:     inst60000039:    {kind: ValueParam, arg0: call_param0, arg1: name00000002, type: type(inst60000013)}
-// CHECK:STDOUT:     inst6000003A:    {kind: FunctionDecl, arg0: function60000003, arg1: inst_block0000000F, type: type(inst6000003B)}
+// CHECK:STDOUT:     inst6000003A:    {kind: FunctionDecl, arg0: function60000003, arg1: inst_block6000000F, type: type(inst6000003B)}
 // CHECK:STDOUT:     inst6000003B:    {kind: FunctionType, arg0: function60000003, arg1: specific<none>, type: type(TypeType)}
 // CHECK:STDOUT:     inst6000003C:    {kind: StructValue, arg0: inst_block_empty, type: type(inst6000003B)}
 // CHECK:STDOUT:     inst6000003D:    {kind: BindName, arg0: entity_name60000002, arg1: inst60000041, type: type(inst6000001F)}
@@ -176,26 +176,26 @@ fn G(x: Cpp.X) {
 // CHECK:STDOUT:     inst6000003F:    {kind: BindingPattern, arg0: entity_name60000002, type: type(inst6000003E)}
 // CHECK:STDOUT:     inst60000040:    {kind: ValueParamPattern, arg0: inst6000003F, arg1: call_param0, type: type(inst6000003E)}
 // CHECK:STDOUT:     inst60000041:    {kind: ValueParam, arg0: call_param0, arg1: name00000002, type: type(inst6000001F)}
-// CHECK:STDOUT:     inst60000042:    {kind: FunctionDecl, arg0: function60000004, arg1: inst_block00000014, type: type(inst60000043)}
+// CHECK:STDOUT:     inst60000042:    {kind: FunctionDecl, arg0: function60000004, arg1: inst_block60000014, type: type(inst60000043)}
 // CHECK:STDOUT:     inst60000043:    {kind: FunctionType, arg0: function60000004, arg1: specific<none>, type: type(TypeType)}
 // CHECK:STDOUT:     inst60000044:    {kind: StructValue, arg0: inst_block_empty, type: type(inst60000043)}
 // CHECK:STDOUT:     inst60000045:    {kind: ValueAsRef, arg0: inst60000035, type: type(inst60000013)}
 // CHECK:STDOUT:     inst60000046:    {kind: AddrOf, arg0: inst60000045, type: type(inst6000001F)}
-// CHECK:STDOUT:     inst60000047:    {kind: Call, arg0: inst60000042, arg1: inst_block00000016, type: type(inst6000001D)}
+// CHECK:STDOUT:     inst60000047:    {kind: Call, arg0: inst60000042, arg1: inst_block60000016, type: type(inst6000001D)}
 // CHECK:STDOUT:     inst60000048:    {kind: NameRef, arg0: name00000000, arg1: inst60000010, type: type(inst(NamespaceType))}
 // CHECK:STDOUT:     inst60000049:    {kind: NameRef, arg0: name00000004, arg1: inst60000029, type: type(inst60000028)}
 // CHECK:STDOUT:     inst6000004A:    {kind: NameRef, arg0: name00000000, arg1: inst60000010, type: type(inst(NamespaceType))}
 // CHECK:STDOUT:     inst6000004B:    {kind: VarStorage, arg0: inst6000004D, type: type(inst6000001F)}
 // CHECK:STDOUT:     inst6000004C:    {kind: BindingPattern, arg0: entity_name60000003, type: type(inst6000003E)}
 // CHECK:STDOUT:     inst6000004D:    {kind: VarPattern, arg0: inst6000004C, type: type(inst6000003E)}
-// CHECK:STDOUT:     inst6000004E:    {kind: NameBindingDecl, arg0: inst_block00000017}
+// CHECK:STDOUT:     inst6000004E:    {kind: NameBindingDecl, arg0: inst_block60000017}
 // CHECK:STDOUT:     inst6000004F:    {kind: NameRef, arg0: name00000005, arg1: inst6000004B, type: type(inst6000001F)}
 // CHECK:STDOUT:     inst60000050:    {kind: BindValue, arg0: inst6000004F, type: type(inst6000001F)}
 // CHECK:STDOUT:     inst60000051:    {kind: Deref, arg0: inst60000050, type: type(inst60000013)}
 // CHECK:STDOUT:     inst60000052:    {kind: BindValue, arg0: inst60000051, type: type(inst60000013)}
 // CHECK:STDOUT:     inst60000053:    {kind: ValueAsRef, arg0: inst60000052, type: type(inst60000013)}
 // CHECK:STDOUT:     inst60000054:    {kind: AddrOf, arg0: inst60000053, type: type(inst6000001F)}
-// CHECK:STDOUT:     inst60000055:    {kind: Call, arg0: inst60000042, arg1: inst_block00000019, type: type(inst6000001D)}
+// CHECK:STDOUT:     inst60000055:    {kind: Call, arg0: inst60000042, arg1: inst_block60000019, type: type(inst6000001D)}
 // CHECK:STDOUT:     inst60000056:    {kind: Return}
 // CHECK:STDOUT:   constant_values:
 // CHECK:STDOUT:     values:
@@ -282,21 +282,21 @@ fn G(x: Cpp.X) {
 // CHECK:STDOUT:       7:               inst6000004E
 // CHECK:STDOUT:       8:               inst6000004B
 // CHECK:STDOUT:     global_init:     {}
-// CHECK:STDOUT:     inst_block00000004:
+// CHECK:STDOUT:     inst_block60000004:
 // CHECK:STDOUT:       0:               inst60000011
 // CHECK:STDOUT:       1:               inst60000014
-// CHECK:STDOUT:     inst_block00000005:
+// CHECK:STDOUT:     inst_block60000005:
 // CHECK:STDOUT:       0:               inst60000018
-// CHECK:STDOUT:     inst_block00000006:
+// CHECK:STDOUT:     inst_block60000006:
 // CHECK:STDOUT:       0:               inst60000019
-// CHECK:STDOUT:     inst_block00000007:
+// CHECK:STDOUT:     inst_block60000007:
 // CHECK:STDOUT:       0:               inst60000017
 // CHECK:STDOUT:       1:               inst60000018
-// CHECK:STDOUT:     inst_block00000008:
+// CHECK:STDOUT:     inst_block60000008:
 // CHECK:STDOUT:       0:               inst60000019
 // CHECK:STDOUT:       1:               inst6000001A
 // CHECK:STDOUT:       2:               inst60000015
-// CHECK:STDOUT:     inst_block00000009:
+// CHECK:STDOUT:     inst_block60000009:
 // CHECK:STDOUT:       0:               inst60000027
 // CHECK:STDOUT:       1:               inst6000002B
 // CHECK:STDOUT:       2:               inst60000032
@@ -317,44 +317,44 @@ fn G(x: Cpp.X) {
 // CHECK:STDOUT:       17:              inst60000054
 // CHECK:STDOUT:       18:              inst60000055
 // CHECK:STDOUT:       19:              inst60000056
-// CHECK:STDOUT:     inst_block0000000A:
+// CHECK:STDOUT:     inst_block6000000A:
 // CHECK:STDOUT:       0:               inst60000021
 // CHECK:STDOUT:       1:               inst60000022
 // CHECK:STDOUT:       2:               inst60000024
-// CHECK:STDOUT:     inst_block0000000B: {}
-// CHECK:STDOUT:     inst_block0000000C:
+// CHECK:STDOUT:     inst_block6000000B: {}
+// CHECK:STDOUT:     inst_block6000000C:
 // CHECK:STDOUT:       0:               inst60000038
-// CHECK:STDOUT:     inst_block0000000D:
+// CHECK:STDOUT:     inst_block6000000D:
 // CHECK:STDOUT:       0:               inst60000039
-// CHECK:STDOUT:     inst_block0000000E:
+// CHECK:STDOUT:     inst_block6000000E:
 // CHECK:STDOUT:       0:               inst60000037
 // CHECK:STDOUT:       1:               inst60000038
-// CHECK:STDOUT:     inst_block0000000F:
+// CHECK:STDOUT:     inst_block6000000F:
 // CHECK:STDOUT:       0:               inst60000039
 // CHECK:STDOUT:       1:               inst60000036
-// CHECK:STDOUT:     inst_block00000010: {}
-// CHECK:STDOUT:     inst_block00000011:
+// CHECK:STDOUT:     inst_block60000010: {}
+// CHECK:STDOUT:     inst_block60000011:
 // CHECK:STDOUT:       0:               inst60000040
-// CHECK:STDOUT:     inst_block00000012:
+// CHECK:STDOUT:     inst_block60000012:
 // CHECK:STDOUT:       0:               inst60000041
-// CHECK:STDOUT:     inst_block00000013:
+// CHECK:STDOUT:     inst_block60000013:
 // CHECK:STDOUT:       0:               inst6000003F
 // CHECK:STDOUT:       1:               inst60000040
-// CHECK:STDOUT:     inst_block00000014:
+// CHECK:STDOUT:     inst_block60000014:
 // CHECK:STDOUT:       0:               inst60000041
 // CHECK:STDOUT:       1:               inst6000003D
-// CHECK:STDOUT:     inst_block00000015:
+// CHECK:STDOUT:     inst_block60000015:
 // CHECK:STDOUT:       0:               inst60000035
-// CHECK:STDOUT:     inst_block00000016:
+// CHECK:STDOUT:     inst_block60000016:
 // CHECK:STDOUT:       0:               inst60000046
-// CHECK:STDOUT:     inst_block00000017:
+// CHECK:STDOUT:     inst_block60000017:
 // CHECK:STDOUT:       0:               inst6000004C
 // CHECK:STDOUT:       1:               inst6000004D
-// CHECK:STDOUT:     inst_block00000018:
+// CHECK:STDOUT:     inst_block60000018:
 // CHECK:STDOUT:       0:               inst60000052
-// CHECK:STDOUT:     inst_block00000019:
+// CHECK:STDOUT:     inst_block60000019:
 // CHECK:STDOUT:       0:               inst60000054
-// CHECK:STDOUT:     inst_block0000001A:
+// CHECK:STDOUT:     inst_block6000001A:
 // CHECK:STDOUT:       0:               inst0000000E
 // CHECK:STDOUT:       1:               inst6000000F
 // CHECK:STDOUT:       2:               inst6000001B

toolchain/check/testdata/basics/raw_sem_ir/multifile.carbon

@@ -40,7 +40,7 @@ fn B() {
 // CHECK:STDOUT:   entity_names:    {}
 // CHECK:STDOUT:   cpp_global_vars: {}
 // CHECK:STDOUT:   functions:
-// CHECK:STDOUT:     function60000000: {name: name00000000, parent_scope: name_scope00000000, call_params_id: inst_block_empty, body: [inst_block00000005]}
+// CHECK:STDOUT:     function60000000: {name: name00000000, parent_scope: name_scope00000000, call_params_id: inst_block_empty, body: [inst_block60000005]}
 // CHECK:STDOUT:   classes:         {}
 // CHECK:STDOUT:   generics:        {}
 // CHECK:STDOUT:   specifics:       {}
@@ -78,10 +78,10 @@ fn B() {
 // CHECK:STDOUT:       0:               inst6000000F
 // CHECK:STDOUT:     imports:         {}
 // CHECK:STDOUT:     global_init:     {}
-// CHECK:STDOUT:     inst_block00000004: {}
-// CHECK:STDOUT:     inst_block00000005:
+// CHECK:STDOUT:     inst_block60000004: {}
+// CHECK:STDOUT:     inst_block60000005:
 // CHECK:STDOUT:       0:               inst60000013
-// CHECK:STDOUT:     inst_block00000006:
+// CHECK:STDOUT:     inst_block60000006:
 // CHECK:STDOUT:       0:               inst0000000E
 // CHECK:STDOUT:       1:               inst6000000F
 // CHECK:STDOUT: ...
@@ -103,7 +103,7 @@ fn B() {
 // CHECK:STDOUT:     entity_name50000000: {name: name00000001, parent_scope: name_scope50000001, index: -1, is_template: 0}
 // CHECK:STDOUT:   cpp_global_vars: {}
 // CHECK:STDOUT:   functions:
-// CHECK:STDOUT:     function50000000: {name: name00000000, parent_scope: name_scope00000000, call_params_id: inst_block_empty, body: [inst_block00000005]}
+// CHECK:STDOUT:     function50000000: {name: name00000000, parent_scope: name_scope00000000, call_params_id: inst_block_empty, body: [inst_block50000005]}
 // CHECK:STDOUT:     function50000001: {name: name00000001, parent_scope: name_scope50000001}
 // CHECK:STDOUT:   classes:         {}
 // CHECK:STDOUT:   generics:        {}
@@ -161,13 +161,13 @@ fn B() {
 // CHECK:STDOUT:       1:               inst50000016
 // CHECK:STDOUT:       2:               inst50000017
 // CHECK:STDOUT:     global_init:     {}
-// CHECK:STDOUT:     inst_block00000004: {}
-// CHECK:STDOUT:     inst_block00000005:
+// CHECK:STDOUT:     inst_block50000004: {}
+// CHECK:STDOUT:     inst_block50000005:
 // CHECK:STDOUT:       0:               inst50000015
 // CHECK:STDOUT:       1:               inst5000001A
 // CHECK:STDOUT:       2:               inst5000001B
 // CHECK:STDOUT:       3:               inst5000001C
-// CHECK:STDOUT:     inst_block00000006:
+// CHECK:STDOUT:     inst_block50000006:
 // CHECK:STDOUT:       0:               inst0000000E
 // CHECK:STDOUT:       1:               inst5000000F
 // CHECK:STDOUT:       2:               inst50000011

toolchain/check/testdata/basics/raw_sem_ir/multifile_with_textual_ir.carbon

@@ -40,7 +40,7 @@ fn B() {
 // CHECK:STDOUT:   entity_names:    {}
 // CHECK:STDOUT:   cpp_global_vars: {}
 // CHECK:STDOUT:   functions:
-// CHECK:STDOUT:     function60000000: {name: name00000000, parent_scope: name_scope00000000, call_params_id: inst_block_empty, body: [inst_block00000005]}
+// CHECK:STDOUT:     function60000000: {name: name00000000, parent_scope: name_scope00000000, call_params_id: inst_block_empty, body: [inst_block60000005]}
 // CHECK:STDOUT:   classes:         {}
 // CHECK:STDOUT:   generics:        {}
 // CHECK:STDOUT:   specifics:       {}
@@ -78,10 +78,10 @@ fn B() {
 // CHECK:STDOUT:       0:               inst6000000F
 // CHECK:STDOUT:     imports:         {}
 // CHECK:STDOUT:     global_init:     {}
-// CHECK:STDOUT:     inst_block00000004: {}
-// CHECK:STDOUT:     inst_block00000005:
+// CHECK:STDOUT:     inst_block60000004: {}
+// CHECK:STDOUT:     inst_block60000005:
 // CHECK:STDOUT:       0:               inst60000013
-// CHECK:STDOUT:     inst_block00000006:
+// CHECK:STDOUT:     inst_block60000006:
 // CHECK:STDOUT:       0:               inst0000000E
 // CHECK:STDOUT:       1:               inst6000000F
 // CHECK:STDOUT: ...
@@ -122,7 +122,7 @@ fn B() {
 // CHECK:STDOUT:     entity_name50000000: {name: name00000001, parent_scope: name_scope50000001, index: -1, is_template: 0}
 // CHECK:STDOUT:   cpp_global_vars: {}
 // CHECK:STDOUT:   functions:
-// CHECK:STDOUT:     function50000000: {name: name00000000, parent_scope: name_scope00000000, call_params_id: inst_block_empty, body: [inst_block00000005]}
+// CHECK:STDOUT:     function50000000: {name: name00000000, parent_scope: name_scope00000000, call_params_id: inst_block_empty, body: [inst_block50000005]}
 // CHECK:STDOUT:     function50000001: {name: name00000001, parent_scope: name_scope50000001}
 // CHECK:STDOUT:   classes:         {}
 // CHECK:STDOUT:   generics:        {}
@@ -180,13 +180,13 @@ fn B() {
 // CHECK:STDOUT:       1:               inst50000016
 // CHECK:STDOUT:       2:               inst50000017
 // CHECK:STDOUT:     global_init:     {}
-// CHECK:STDOUT:     inst_block00000004: {}
-// CHECK:STDOUT:     inst_block00000005:
+// CHECK:STDOUT:     inst_block50000004: {}
+// CHECK:STDOUT:     inst_block50000005:
 // CHECK:STDOUT:       0:               inst50000015
 // CHECK:STDOUT:       1:               inst5000001A
 // CHECK:STDOUT:       2:               inst5000001B
 // CHECK:STDOUT:       3:               inst5000001C
-// CHECK:STDOUT:     inst_block00000006:
+// CHECK:STDOUT:     inst_block50000006:
 // CHECK:STDOUT:       0:               inst0000000E
 // CHECK:STDOUT:       1:               inst5000000F
 // CHECK:STDOUT:       2:               inst50000011

toolchain/check/testdata/basics/raw_sem_ir/one_file.carbon

@@ -296,7 +296,7 @@ fn Foo[T:! type](p: T*) -> (T*, ()) {
 // CHECK:STDOUT:     entity_name6000003D: {name: name00000006, parent_scope: name_scope<none>, index: 2, is_template: 0}
 // CHECK:STDOUT:   cpp_global_vars: {}
 // CHECK:STDOUT:   functions:
-// CHECK:STDOUT:     function60000000: {name: name00000000, parent_scope: name_scope00000000, call_params_id: inst_block0000000D, return_slot_pattern: inst60000030, body: [inst_block00000014]}
+// CHECK:STDOUT:     function60000000: {name: name00000000, parent_scope: name_scope00000000, call_params_id: inst_block6000000D, return_slot_pattern: inst60000030, body: [inst_block60000014]}
 // CHECK:STDOUT:     function60000001: {name: name00000004, parent_scope: name_scope60000002, return_slot_pattern: inst60000055}
 // CHECK:STDOUT:     function60000002: {name: name00000004, parent_scope: name_scope60000003, return_slot_pattern: inst60000073}
 // CHECK:STDOUT:     function60000003: {name: name00000004, parent_scope: name_scope60000008, return_slot_pattern: inst600000AA}
@@ -304,42 +304,42 @@ fn Foo[T:! type](p: T*) -> (T*, ()) {
 // CHECK:STDOUT:     function60000005: {name: name00000004, parent_scope: name_scope6000000C, return_slot_pattern: inst60000111}
 // CHECK:STDOUT:   classes:         {}
 // CHECK:STDOUT:   generics:
-// CHECK:STDOUT:     generic60000000: {decl: inst60000035, bindings: inst_block00000010}
-// CHECK:STDOUT:     generic60000001: {decl: inst6000004F, bindings: inst_block00000018}
-// CHECK:STDOUT:     generic60000002: {decl: inst6000005E, bindings: inst_block0000001D}
-// CHECK:STDOUT:     generic60000003: {decl: inst6000006E, bindings: inst_block00000024}
-// CHECK:STDOUT:     generic60000004: {decl: inst6000009B, bindings: inst_block0000002E}
-// CHECK:STDOUT:     generic60000005: {decl: inst600000A6, bindings: inst_block00000034}
-// CHECK:STDOUT:     generic60000006: {decl: inst600000BD, bindings: inst_block0000003B}
-// CHECK:STDOUT:     generic60000007: {decl: inst600000D0, bindings: inst_block00000043}
-// CHECK:STDOUT:     generic60000008: {decl: inst600000F5, bindings: inst_block00000051}
-// CHECK:STDOUT:     generic60000009: {decl: inst6000010C, bindings: inst_block00000059}
+// CHECK:STDOUT:     generic60000000: {decl: inst60000035, bindings: inst_block60000010}
+// CHECK:STDOUT:     generic60000001: {decl: inst6000004F, bindings: inst_block60000018}
+// CHECK:STDOUT:     generic60000002: {decl: inst6000005E, bindings: inst_block6000001D}
+// CHECK:STDOUT:     generic60000003: {decl: inst6000006E, bindings: inst_block60000024}
+// CHECK:STDOUT:     generic60000004: {decl: inst6000009B, bindings: inst_block6000002E}
+// CHECK:STDOUT:     generic60000005: {decl: inst600000A6, bindings: inst_block60000034}
+// CHECK:STDOUT:     generic60000006: {decl: inst600000BD, bindings: inst_block6000003B}
+// CHECK:STDOUT:     generic60000007: {decl: inst600000D0, bindings: inst_block60000043}
+// CHECK:STDOUT:     generic60000008: {decl: inst600000F5, bindings: inst_block60000051}
+// CHECK:STDOUT:     generic60000009: {decl: inst6000010C, bindings: inst_block60000059}
 // CHECK:STDOUT:   specifics:
-// CHECK:STDOUT:     specific60000000: {generic: generic60000000, args: inst_block00000011}
-// CHECK:STDOUT:     specific60000001: {generic: generic60000001, args: inst_block0000001A}
-// CHECK:STDOUT:     specific60000002: {generic: generic60000002, args: inst_block0000001F}
-// CHECK:STDOUT:     specific60000003: {generic: generic60000002, args: inst_block00000020}
-// CHECK:STDOUT:     specific60000004: {generic: generic60000003, args: inst_block0000001F}
-// CHECK:STDOUT:     specific60000005: {generic: generic60000001, args: inst_block0000001F}
-// CHECK:STDOUT:     specific60000006: {generic: generic60000001, args: inst_block00000029}
-// CHECK:STDOUT:     specific60000007: {generic: generic60000004, args: inst_block00000011}
-// CHECK:STDOUT:     specific60000008: {generic: generic60000004, args: inst_block00000030}
-// CHECK:STDOUT:     specific60000009: {generic: generic60000005, args: inst_block00000011}
-// CHECK:STDOUT:     specific6000000A: {generic: generic60000006, args: inst_block0000003D}
-// CHECK:STDOUT:     specific6000000B: {generic: generic60000006, args: inst_block0000003F}
-// CHECK:STDOUT:     specific6000000C: {generic: generic60000007, args: inst_block0000003D}
-// CHECK:STDOUT:     specific6000000D: {generic: generic60000001, args: inst_block00000049}
-// CHECK:STDOUT:     specific6000000E: {generic: generic60000001, args: inst_block0000004A}
-// CHECK:STDOUT:     specific6000000F: {generic: generic60000001, args: inst_block0000004B}
-// CHECK:STDOUT:     specific60000010: {generic: generic60000008, args: inst_block00000053}
-// CHECK:STDOUT:     specific60000011: {generic: generic60000008, args: inst_block00000055}
-// CHECK:STDOUT:     specific60000012: {generic: generic60000009, args: inst_block00000053}
-// CHECK:STDOUT:     specific60000013: {generic: generic60000001, args: inst_block0000005F}
-// CHECK:STDOUT:     specific60000014: {generic: generic60000001, args: inst_block00000060}
-// CHECK:STDOUT:     specific60000015: {generic: generic60000001, args: inst_block00000061}
-// CHECK:STDOUT:     specific60000016: {generic: generic60000001, args: inst_block00000062}
-// CHECK:STDOUT:     specific60000017: {generic: generic60000001, args: inst_block00000069}
-// CHECK:STDOUT:     specific60000018: {generic: generic60000001, args: inst_block0000006B}
+// CHECK:STDOUT:     specific60000000: {generic: generic60000000, args: inst_block60000011}
+// CHECK:STDOUT:     specific60000001: {generic: generic60000001, args: inst_block6000001A}
+// CHECK:STDOUT:     specific60000002: {generic: generic60000002, args: inst_block6000001F}
+// CHECK:STDOUT:     specific60000003: {generic: generic60000002, args: inst_block60000020}
+// CHECK:STDOUT:     specific60000004: {generic: generic60000003, args: inst_block6000001F}
+// CHECK:STDOUT:     specific60000005: {generic: generic60000001, args: inst_block6000001F}
+// CHECK:STDOUT:     specific60000006: {generic: generic60000001, args: inst_block60000029}
+// CHECK:STDOUT:     specific60000007: {generic: generic60000004, args: inst_block60000011}
+// CHECK:STDOUT:     specific60000008: {generic: generic60000004, args: inst_block60000030}
+// CHECK:STDOUT:     specific60000009: {generic: generic60000005, args: inst_block60000011}
+// CHECK:STDOUT:     specific6000000A: {generic: generic60000006, args: inst_block6000003D}
+// CHECK:STDOUT:     specific6000000B: {generic: generic60000006, args: inst_block6000003F}
+// CHECK:STDOUT:     specific6000000C: {generic: generic60000007, args: inst_block6000003D}
+// CHECK:STDOUT:     specific6000000D: {generic: generic60000001, args: inst_block60000049}
+// CHECK:STDOUT:     specific6000000E: {generic: generic60000001, args: inst_block6000004A}
+// CHECK:STDOUT:     specific6000000F: {generic: generic60000001, args: inst_block6000004B}
+// CHECK:STDOUT:     specific60000010: {generic: generic60000008, args: inst_block60000053}
+// CHECK:STDOUT:     specific60000011: {generic: generic60000008, args: inst_block60000055}
+// CHECK:STDOUT:     specific60000012: {generic: generic60000009, args: inst_block60000053}
+// CHECK:STDOUT:     specific60000013: {generic: generic60000001, args: inst_block6000005F}
+// CHECK:STDOUT:     specific60000014: {generic: generic60000001, args: inst_block60000060}
+// CHECK:STDOUT:     specific60000015: {generic: generic60000001, args: inst_block60000061}
+// CHECK:STDOUT:     specific60000016: {generic: generic60000001, args: inst_block60000062}
+// CHECK:STDOUT:     specific60000017: {generic: generic60000001, args: inst_block60000069}
+// CHECK:STDOUT:     specific60000018: {generic: generic60000001, args: inst_block6000006B}
 // CHECK:STDOUT:   struct_type_fields:
 // CHECK:STDOUT:     struct_type_fields00000000: {}
 // CHECK:STDOUT:   types:
@@ -404,22 +404,22 @@ fn Foo[T:! type](p: T*) -> (T*, ()) {
 // CHECK:STDOUT:     inst60000023:    {kind: PointerType, arg0: inst60000022, type: type(TypeType)}
 // CHECK:STDOUT:     inst60000024:    {kind: TupleType, arg0: inst_block_empty, type: type(TypeType)}
 // CHECK:STDOUT:     inst60000025:    {kind: TupleLiteral, arg0: inst_block_empty, type: type(inst60000024)}
-// CHECK:STDOUT:     inst60000026:    {kind: TupleType, arg0: inst_block00000009, type: type(TypeType)}
-// CHECK:STDOUT:     inst60000027:    {kind: TupleLiteral, arg0: inst_block00000008, type: type(inst60000026)}
+// CHECK:STDOUT:     inst60000026:    {kind: TupleType, arg0: inst_block60000009, type: type(TypeType)}
+// CHECK:STDOUT:     inst60000027:    {kind: TupleLiteral, arg0: inst_block60000008, type: type(inst60000026)}
 // CHECK:STDOUT:     inst60000028:    {kind: PointerType, arg0: inst60000026, type: type(TypeType)}
 // CHECK:STDOUT:     inst60000029:    {kind: Converted, arg0: inst60000025, arg1: inst60000024, type: type(TypeType)}
-// CHECK:STDOUT:     inst6000002A:    {kind: TupleType, arg0: inst_block0000000B, type: type(TypeType)}
+// CHECK:STDOUT:     inst6000002A:    {kind: TupleType, arg0: inst_block6000000B, type: type(TypeType)}
 // CHECK:STDOUT:     inst6000002B:    {kind: Converted, arg0: inst60000027, arg1: inst6000002A, type: type(TypeType)}
-// CHECK:STDOUT:     inst6000002C:    {kind: TupleType, arg0: inst_block0000000C, type: type(TypeType)}
+// CHECK:STDOUT:     inst6000002C:    {kind: TupleType, arg0: inst_block6000000C, type: type(TypeType)}
 // CHECK:STDOUT:     inst6000002D:    {kind: PatternType, arg0: inst6000002A, type: type(TypeType)}
 // CHECK:STDOUT:     inst6000002E:    {kind: ReturnSlotPattern, arg0: inst6000002B, type: type(symbolic_constant0000000A)}
 // CHECK:STDOUT:     inst6000002F:    {kind: PatternType, arg0: inst6000002C, type: type(TypeType)}
 // CHECK:STDOUT:     inst60000030:    {kind: OutParamPattern, arg0: inst6000002E, arg1: call_param1, type: type(symbolic_constant0000000A)}
 // CHECK:STDOUT:     inst60000031:    {kind: ValueParam, arg0: call_param0, arg1: name00000002, type: type(symbolic_constant00000004)}
-// CHECK:STDOUT:     inst60000032:    {kind: SpliceBlock, arg0: inst_block00000006, arg1: inst6000001A, type: type(TypeType)}
+// CHECK:STDOUT:     inst60000032:    {kind: SpliceBlock, arg0: inst_block60000006, arg1: inst6000001A, type: type(TypeType)}
 // CHECK:STDOUT:     inst60000033:    {kind: OutParam, arg0: call_param1, arg1: name(ReturnSlot), type: type(symbolic_constant00000008)}
 // CHECK:STDOUT:     inst60000034:    {kind: ReturnSlot, arg0: inst6000002A, arg1: inst60000033, type: type(symbolic_constant00000008)}
-// CHECK:STDOUT:     inst60000035:    {kind: FunctionDecl, arg0: function60000000, arg1: inst_block0000000F, type: type(inst60000036)}
+// CHECK:STDOUT:     inst60000035:    {kind: FunctionDecl, arg0: function60000000, arg1: inst_block6000000F, type: type(inst60000036)}
 // CHECK:STDOUT:     inst60000036:    {kind: FunctionType, arg0: function60000000, arg1: specific<none>, type: type(TypeType)}
 // CHECK:STDOUT:     inst60000037:    {kind: StructValue, arg0: inst_block_empty, type: type(inst60000036)}
 // CHECK:STDOUT:     inst60000038:    {kind: PointerType, arg0: inst6000002A, type: type(TypeType)}
@@ -431,7 +431,7 @@ fn Foo[T:! type](p: T*) -> (T*, ()) {
 // CHECK:STDOUT:     inst6000003E:    {kind: RequireCompleteType, arg0: inst6000001C, type: type(inst(WitnessType))}
 // CHECK:STDOUT:     inst6000003F:    {kind: NameRef, arg0: name00000002, arg1: inst6000001D, type: type(symbolic_constant00000004)}
 // CHECK:STDOUT:     inst60000040:    {kind: TupleLiteral, arg0: inst_block_empty, type: type(inst60000024)}
-// CHECK:STDOUT:     inst60000041:    {kind: TupleLiteral, arg0: inst_block00000015, type: type(symbolic_constant00000008)}
+// CHECK:STDOUT:     inst60000041:    {kind: TupleLiteral, arg0: inst_block60000015, type: type(symbolic_constant00000008)}
 // CHECK:STDOUT:     inst60000042:    {kind: RequireCompleteType, arg0: inst6000002A, type: type(inst(WitnessType))}
 // CHECK:STDOUT:     inst60000043:    {kind: TupleAccess, arg0: inst60000034, arg1: element0, type: type(symbolic_constant00000004)}
 // CHECK:STDOUT:     inst60000044:    {kind: RequireCompleteType, arg0: inst6000001B, type: type(inst(WitnessType))}
@@ -470,7 +470,7 @@ fn Foo[T:! type](p: T*) -> (T*, ()) {
 // CHECK:STDOUT:     inst60000065:    {kind: ImportRefLoaded, arg0: import_ir_inst00000013, arg1: entity_name<none>, type: type(TypeType)}
 // CHECK:STDOUT:     inst60000066:    {kind: ImportRefLoaded, arg0: import_ir_inst00000014, arg1: entity_name<none>, type: type(TypeType)}
 // CHECK:STDOUT:     inst60000067:    {kind: ImportRefUnloaded, arg0: import_ir_inst00000015, arg1: entity_name<none>}
-// CHECK:STDOUT:     inst60000068:    {kind: ImplWitnessTable, arg0: inst_block0000001E, arg1: impl60000000}
+// CHECK:STDOUT:     inst60000068:    {kind: ImplWitnessTable, arg0: inst_block6000001E, arg1: impl60000000}
 // CHECK:STDOUT:     inst60000069:    {kind: ImplWitness, arg0: inst60000068, arg1: specific60000002, type: type(inst(WitnessType))}
 // CHECK:STDOUT:     inst6000006A:    {kind: BindSymbolicName, arg0: entity_name60000001, arg1: inst<none>, type: type(inst60000047)}
 // CHECK:STDOUT:     inst6000006B:    {kind: SymbolicBindingType, arg0: entity_name60000001, arg1: inst6000006A, type: type(TypeType)}
@@ -527,7 +527,7 @@ fn Foo[T:! type](p: T*) -> (T*, ()) {
 // CHECK:STDOUT:     inst6000009E:    {kind: ImportRefLoaded, arg0: import_ir_inst00000041, arg1: entity_name<none>, type: type(TypeType)}
 // CHECK:STDOUT:     inst6000009F:    {kind: ImportRefLoaded, arg0: import_ir_inst00000042, arg1: entity_name<none>, type: type(TypeType)}
 // CHECK:STDOUT:     inst600000A0:    {kind: ImportRefUnloaded, arg0: import_ir_inst00000043, arg1: entity_name<none>}
-// CHECK:STDOUT:     inst600000A1:    {kind: ImplWitnessTable, arg0: inst_block0000002F, arg1: impl60000005}
+// CHECK:STDOUT:     inst600000A1:    {kind: ImplWitnessTable, arg0: inst_block6000002F, arg1: impl60000005}
 // CHECK:STDOUT:     inst600000A2:    {kind: ImplWitness, arg0: inst600000A1, arg1: specific60000007, type: type(inst(WitnessType))}
 // CHECK:STDOUT:     inst600000A3:    {kind: BindSymbolicName, arg0: entity_name60000001, arg1: inst<none>, type: type(TypeType)}
 // CHECK:STDOUT:     inst600000A4:    {kind: PointerType, arg0: inst600000A3, type: type(TypeType)}
@@ -558,7 +558,7 @@ fn Foo[T:! type](p: T*) -> (T*, ()) {
 // CHECK:STDOUT:     inst600000BD:    {kind: ImplDecl, arg0: impl60000008, arg1: inst_block_empty}
 // CHECK:STDOUT:     inst600000BE:    {kind: BindSymbolicName, arg0: entity_name6000001A, arg1: inst<none>, type: type(inst60000047)}
 // CHECK:STDOUT:     inst600000BF:    {kind: SymbolicBindingType, arg0: entity_name6000001A, arg1: inst600000BE, type: type(TypeType)}
-// CHECK:STDOUT:     inst600000C0:    {kind: TupleType, arg0: inst_block00000039, type: type(TypeType)}
+// CHECK:STDOUT:     inst600000C0:    {kind: TupleType, arg0: inst_block60000039, type: type(TypeType)}
 // CHECK:STDOUT:     inst600000C1:    {kind: SymbolicBindingPattern, arg0: entity_name6000001C, type: type(inst60000062)}
 // CHECK:STDOUT:     inst600000C2:    {kind: SymbolicBindingPattern, arg0: entity_name6000001D, type: type(inst60000062)}
 // CHECK:STDOUT:     inst600000C3:    {kind: ImportRefLoaded, arg0: import_ir_inst00000060, arg1: entity_name<none>, type: type(inst60000047)}
@@ -566,13 +566,13 @@ fn Foo[T:! type](p: T*) -> (T*, ()) {
 // CHECK:STDOUT:     inst600000C5:    {kind: ImportRefLoaded, arg0: import_ir_inst00000062, arg1: entity_name<none>, type: type(TypeType)}
 // CHECK:STDOUT:     inst600000C6:    {kind: ImportRefLoaded, arg0: import_ir_inst00000063, arg1: entity_name<none>, type: type(TypeType)}
 // CHECK:STDOUT:     inst600000C7:    {kind: ImportRefUnloaded, arg0: import_ir_inst00000064, arg1: entity_name<none>}
-// CHECK:STDOUT:     inst600000C8:    {kind: ImplWitnessTable, arg0: inst_block0000003C, arg1: impl60000008}
+// CHECK:STDOUT:     inst600000C8:    {kind: ImplWitnessTable, arg0: inst_block6000003C, arg1: impl60000008}
 // CHECK:STDOUT:     inst600000C9:    {kind: ImplWitness, arg0: inst600000C8, arg1: specific6000000A, type: type(inst(WitnessType))}
 // CHECK:STDOUT:     inst600000CA:    {kind: BindSymbolicName, arg0: entity_name60000001, arg1: inst<none>, type: type(inst60000047)}
 // CHECK:STDOUT:     inst600000CB:    {kind: BindSymbolicName, arg0: entity_name6000001A, arg1: inst<none>, type: type(inst60000047)}
 // CHECK:STDOUT:     inst600000CC:    {kind: SymbolicBindingType, arg0: entity_name60000001, arg1: inst600000CA, type: type(TypeType)}
 // CHECK:STDOUT:     inst600000CD:    {kind: SymbolicBindingType, arg0: entity_name6000001A, arg1: inst600000CB, type: type(TypeType)}
-// CHECK:STDOUT:     inst600000CE:    {kind: TupleType, arg0: inst_block0000003E, type: type(TypeType)}
+// CHECK:STDOUT:     inst600000CE:    {kind: TupleType, arg0: inst_block6000003E, type: type(TypeType)}
 // CHECK:STDOUT:     inst600000CF:    {kind: ImplWitness, arg0: inst600000C8, arg1: specific6000000B, type: type(inst(WitnessType))}
 // CHECK:STDOUT:     inst600000D0:    {kind: FunctionDecl, arg0: function60000004, arg1: inst_block_empty, type: type(symbolic_constant00000072)}
 // CHECK:STDOUT:     inst600000D1:    {kind: FunctionType, arg0: function60000004, arg1: specific6000000A, type: type(TypeType)}
@@ -590,7 +590,7 @@ fn Foo[T:! type](p: T*) -> (T*, ()) {
 // CHECK:STDOUT:     inst600000DD:    {kind: SymbolicBindingType, arg0: entity_name60000001, arg1: inst600000DC, type: type(TypeType)}
 // CHECK:STDOUT:     inst600000DE:    {kind: BindSymbolicName, arg0: entity_name6000001A, arg1: inst<none>, type: type(inst60000047)}
 // CHECK:STDOUT:     inst600000DF:    {kind: SymbolicBindingType, arg0: entity_name6000001A, arg1: inst600000DE, type: type(TypeType)}
-// CHECK:STDOUT:     inst600000E0:    {kind: TupleType, arg0: inst_block00000046, type: type(TypeType)}
+// CHECK:STDOUT:     inst600000E0:    {kind: TupleType, arg0: inst_block60000046, type: type(TypeType)}
 // CHECK:STDOUT:     inst600000E1:    {kind: PatternType, arg0: inst600000E0, type: type(TypeType)}
 // CHECK:STDOUT:     inst600000E2:    {kind: RequireCompleteType, arg0: inst600000C0, type: type(inst(WitnessType))}
 // CHECK:STDOUT:     inst600000E3:    {kind: RequireCompleteType, arg0: inst600000BF, type: type(inst(WitnessType))}
@@ -614,7 +614,7 @@ fn Foo[T:! type](p: T*) -> (T*, ()) {
 // CHECK:STDOUT:     inst600000F5:    {kind: ImplDecl, arg0: impl60000009, arg1: inst_block_empty}
 // CHECK:STDOUT:     inst600000F6:    {kind: BindSymbolicName, arg0: entity_name60000029, arg1: inst<none>, type: type(inst60000047)}
 // CHECK:STDOUT:     inst600000F7:    {kind: SymbolicBindingType, arg0: entity_name60000029, arg1: inst600000F6, type: type(TypeType)}
-// CHECK:STDOUT:     inst600000F8:    {kind: TupleType, arg0: inst_block0000004F, type: type(TypeType)}
+// CHECK:STDOUT:     inst600000F8:    {kind: TupleType, arg0: inst_block6000004F, type: type(TypeType)}
 // CHECK:STDOUT:     inst600000F9:    {kind: SymbolicBindingPattern, arg0: entity_name6000002B, type: type(inst60000062)}
 // CHECK:STDOUT:     inst600000FA:    {kind: SymbolicBindingPattern, arg0: entity_name6000002C, type: type(inst60000062)}
 // CHECK:STDOUT:     inst600000FB:    {kind: SymbolicBindingPattern, arg0: entity_name6000002D, type: type(inst60000062)}
@@ -624,7 +624,7 @@ fn Foo[T:! type](p: T*) -> (T*, ()) {
 // CHECK:STDOUT:     inst600000FF:    {kind: ImportRefLoaded, arg0: import_ir_inst0000008E, arg1: entity_name<none>, type: type(TypeType)}
 // CHECK:STDOUT:     inst60000100:    {kind: ImportRefLoaded, arg0: import_ir_inst0000008F, arg1: entity_name<none>, type: type(TypeType)}
 // CHECK:STDOUT:     inst60000101:    {kind: ImportRefUnloaded, arg0: import_ir_inst00000090, arg1: entity_name<none>}
-// CHECK:STDOUT:     inst60000102:    {kind: ImplWitnessTable, arg0: inst_block00000052, arg1: impl60000009}
+// CHECK:STDOUT:     inst60000102:    {kind: ImplWitnessTable, arg0: inst_block60000052, arg1: impl60000009}
 // CHECK:STDOUT:     inst60000103:    {kind: ImplWitness, arg0: inst60000102, arg1: specific60000010, type: type(inst(WitnessType))}
 // CHECK:STDOUT:     inst60000104:    {kind: BindSymbolicName, arg0: entity_name60000001, arg1: inst<none>, type: type(inst60000047)}
 // CHECK:STDOUT:     inst60000105:    {kind: BindSymbolicName, arg0: entity_name6000001A, arg1: inst<none>, type: type(inst60000047)}
@@ -632,7 +632,7 @@ fn Foo[T:! type](p: T*) -> (T*, ()) {
 // CHECK:STDOUT:     inst60000107:    {kind: SymbolicBindingType, arg0: entity_name60000001, arg1: inst60000104, type: type(TypeType)}
 // CHECK:STDOUT:     inst60000108:    {kind: SymbolicBindingType, arg0: entity_name6000001A, arg1: inst60000105, type: type(TypeType)}
 // CHECK:STDOUT:     inst60000109:    {kind: SymbolicBindingType, arg0: entity_name60000029, arg1: inst60000106, type: type(TypeType)}
-// CHECK:STDOUT:     inst6000010A:    {kind: TupleType, arg0: inst_block00000054, type: type(TypeType)}
+// CHECK:STDOUT:     inst6000010A:    {kind: TupleType, arg0: inst_block60000054, type: type(TypeType)}
 // CHECK:STDOUT:     inst6000010B:    {kind: ImplWitness, arg0: inst60000102, arg1: specific60000011, type: type(inst(WitnessType))}
 // CHECK:STDOUT:     inst6000010C:    {kind: FunctionDecl, arg0: function60000005, arg1: inst_block_empty, type: type(symbolic_constant000000BA)}
 // CHECK:STDOUT:     inst6000010D:    {kind: FunctionType, arg0: function60000005, arg1: specific60000010, type: type(TypeType)}
@@ -653,7 +653,7 @@ fn Foo[T:! type](p: T*) -> (T*, ()) {
 // CHECK:STDOUT:     inst6000011C:    {kind: SymbolicBindingType, arg0: entity_name6000001A, arg1: inst6000011B, type: type(TypeType)}
 // CHECK:STDOUT:     inst6000011D:    {kind: BindSymbolicName, arg0: entity_name60000029, arg1: inst<none>, type: type(inst60000047)}
 // CHECK:STDOUT:     inst6000011E:    {kind: SymbolicBindingType, arg0: entity_name60000029, arg1: inst6000011D, type: type(TypeType)}
-// CHECK:STDOUT:     inst6000011F:    {kind: TupleType, arg0: inst_block0000005C, type: type(TypeType)}
+// CHECK:STDOUT:     inst6000011F:    {kind: TupleType, arg0: inst_block6000005C, type: type(TypeType)}
 // CHECK:STDOUT:     inst60000120:    {kind: PatternType, arg0: inst6000011F, type: type(TypeType)}
 // CHECK:STDOUT:     inst60000121:    {kind: RequireCompleteType, arg0: inst600000F8, type: type(inst(WitnessType))}
 // CHECK:STDOUT:     inst60000122:    {kind: RequireCompleteType, arg0: inst600000F7, type: type(inst(WitnessType))}
@@ -680,11 +680,11 @@ fn Foo[T:! type](p: T*) -> (T*, ()) {
 // CHECK:STDOUT:     inst60000137:    {kind: PatternType, arg0: inst600000F7, type: type(TypeType)}
 // CHECK:STDOUT:     inst60000138:    {kind: LookupImplWitness, arg0: inst6000001B, arg1: specific_interface60000000, type: type(inst(WitnessType))}
 // CHECK:STDOUT:     inst60000139:    {kind: LookupImplWitness, arg0: inst6000001C, arg1: specific_interface60000000, type: type(inst(WitnessType))}
-// CHECK:STDOUT:     inst6000013A:    {kind: FacetValue, arg0: inst6000001B, arg1: inst_block00000067, type: type(inst60000047)}
+// CHECK:STDOUT:     inst6000013A:    {kind: FacetValue, arg0: inst6000001B, arg1: inst_block60000067, type: type(inst60000047)}
 // CHECK:STDOUT:     inst6000013B:    {kind: FunctionTypeWithSelfType, arg0: inst60000050, arg1: inst6000013A, type: type(TypeType)}
 // CHECK:STDOUT:     inst6000013C:    {kind: ImplWitnessAccess, arg0: inst60000138, arg1: element0, type: type(symbolic_constant00000100)}
 // CHECK:STDOUT:     inst6000013D:    {kind: ImplWitnessAccess, arg0: inst60000138, arg1: element0, type: type(symbolic_constant000000FD)}
-// CHECK:STDOUT:     inst6000013E:    {kind: FacetValue, arg0: inst6000001C, arg1: inst_block00000068, type: type(inst60000047)}
+// CHECK:STDOUT:     inst6000013E:    {kind: FacetValue, arg0: inst6000001C, arg1: inst_block60000068, type: type(inst60000047)}
 // CHECK:STDOUT:     inst6000013F:    {kind: FunctionTypeWithSelfType, arg0: inst60000050, arg1: inst6000013E, type: type(TypeType)}
 // CHECK:STDOUT:     inst60000140:    {kind: ImplWitnessAccess, arg0: inst60000139, arg1: element0, type: type(symbolic_constant00000100)}
 // CHECK:STDOUT:     inst60000141:    {kind: BoundMethod, arg0: inst6000003F, arg1: inst6000013C, type: type(inst(BoundMethodType))}
@@ -693,13 +693,13 @@ fn Foo[T:! type](p: T*) -> (T*, ()) {
 // CHECK:STDOUT:     inst60000144:    {kind: SpecificImplFunction, arg0: inst60000140, arg1: specific60000018, type: type(inst(SpecificFunctionType))}
 // CHECK:STDOUT:     inst60000145:    {kind: BoundMethod, arg0: inst6000003F, arg1: inst60000142, type: type(inst(BoundMethodType))}
 // CHECK:STDOUT:     inst60000146:    {kind: RequireCompleteType, arg0: inst6000001B, type: type(inst(WitnessType))}
-// CHECK:STDOUT:     inst60000147:    {kind: Call, arg0: inst60000145, arg1: inst_block0000006C, type: type(symbolic_constant00000004)}
+// CHECK:STDOUT:     inst60000147:    {kind: Call, arg0: inst60000145, arg1: inst_block6000006C, type: type(symbolic_constant00000004)}
 // CHECK:STDOUT:     inst60000148:    {kind: InitializeFrom, arg0: inst60000147, arg1: inst60000043, type: type(symbolic_constant00000004)}
 // CHECK:STDOUT:     inst60000149:    {kind: TupleAccess, arg0: inst60000034, arg1: element1, type: type(inst60000024)}
 // CHECK:STDOUT:     inst6000014A:    {kind: TupleInit, arg0: inst_block_empty, arg1: inst60000149, type: type(inst60000024)}
 // CHECK:STDOUT:     inst6000014B:    {kind: TupleValue, arg0: inst_block_empty, type: type(inst60000024)}
 // CHECK:STDOUT:     inst6000014C:    {kind: Converted, arg0: inst60000040, arg1: inst6000014A, type: type(inst60000024)}
-// CHECK:STDOUT:     inst6000014D:    {kind: TupleInit, arg0: inst_block0000006D, arg1: inst60000034, type: type(symbolic_constant00000008)}
+// CHECK:STDOUT:     inst6000014D:    {kind: TupleInit, arg0: inst_block6000006D, arg1: inst60000034, type: type(symbolic_constant00000008)}
 // CHECK:STDOUT:     inst6000014E:    {kind: Converted, arg0: inst60000041, arg1: inst6000014D, type: type(symbolic_constant00000008)}
 // CHECK:STDOUT:     inst6000014F:    {kind: ReturnExpr, arg0: inst6000014E, arg1: inst60000034}
 // CHECK:STDOUT:   constant_values:
@@ -1376,40 +1376,40 @@ fn Foo[T:! type](p: T*) -> (T*, ()) {
 // CHECK:STDOUT:       100:             inst60000115
 // CHECK:STDOUT:       101:             inst60000116
 // CHECK:STDOUT:     global_init:     {}
-// CHECK:STDOUT:     inst_block00000004:
+// CHECK:STDOUT:     inst_block60000004:
 // CHECK:STDOUT:       0:               inst60000012
-// CHECK:STDOUT:     inst_block00000005:
+// CHECK:STDOUT:     inst_block60000005:
 // CHECK:STDOUT:       0:               inst60000018
-// CHECK:STDOUT:     inst_block00000006:
+// CHECK:STDOUT:     inst_block60000006:
 // CHECK:STDOUT:       0:               inst60000019
 // CHECK:STDOUT:       1:               inst6000001A
-// CHECK:STDOUT:     inst_block00000007:
+// CHECK:STDOUT:     inst_block60000007:
 // CHECK:STDOUT:       0:               inst60000021
-// CHECK:STDOUT:     inst_block00000008:
+// CHECK:STDOUT:     inst_block60000008:
 // CHECK:STDOUT:       0:               inst60000023
 // CHECK:STDOUT:       1:               inst60000025
-// CHECK:STDOUT:     inst_block00000009:
+// CHECK:STDOUT:     inst_block60000009:
 // CHECK:STDOUT:       0:               inst(TypeType)
 // CHECK:STDOUT:       1:               inst60000024
-// CHECK:STDOUT:     inst_block0000000A:
+// CHECK:STDOUT:     inst_block6000000A:
 // CHECK:STDOUT:       0:               inst60000023
 // CHECK:STDOUT:       1:               inst60000029
-// CHECK:STDOUT:     inst_block0000000B:
+// CHECK:STDOUT:     inst_block6000000B:
 // CHECK:STDOUT:       0:               inst6000001B
 // CHECK:STDOUT:       1:               inst60000024
-// CHECK:STDOUT:     inst_block0000000C:
+// CHECK:STDOUT:     inst_block6000000C:
 // CHECK:STDOUT:       0:               inst6000001C
 // CHECK:STDOUT:       1:               inst60000024
-// CHECK:STDOUT:     inst_block0000000D:
+// CHECK:STDOUT:     inst_block6000000D:
 // CHECK:STDOUT:       0:               inst60000031
 // CHECK:STDOUT:       1:               inst60000033
-// CHECK:STDOUT:     inst_block0000000E:
+// CHECK:STDOUT:     inst_block6000000E:
 // CHECK:STDOUT:       0:               inst60000018
 // CHECK:STDOUT:       1:               inst6000001F
 // CHECK:STDOUT:       2:               inst60000021
 // CHECK:STDOUT:       3:               inst6000002E
 // CHECK:STDOUT:       4:               inst60000030
-// CHECK:STDOUT:     inst_block0000000F:
+// CHECK:STDOUT:     inst_block6000000F:
 // CHECK:STDOUT:       0:               inst60000022
 // CHECK:STDOUT:       1:               inst60000023
 // CHECK:STDOUT:       2:               inst60000025
@@ -1423,23 +1423,23 @@ fn Foo[T:! type](p: T*) -> (T*, ()) {
 // CHECK:STDOUT:       10:              inst6000001D
 // CHECK:STDOUT:       11:              inst60000033
 // CHECK:STDOUT:       12:              inst60000034
-// CHECK:STDOUT:     inst_block00000010:
+// CHECK:STDOUT:     inst_block60000010:
 // CHECK:STDOUT:       0:               inst60000014
-// CHECK:STDOUT:     inst_block00000011:
+// CHECK:STDOUT:     inst_block60000011:
 // CHECK:STDOUT:       0:               inst60000015
-// CHECK:STDOUT:     inst_block00000012:
+// CHECK:STDOUT:     inst_block60000012:
 // CHECK:STDOUT:       0:               inst60000016
 // CHECK:STDOUT:       1:               inst6000001C
 // CHECK:STDOUT:       2:               inst60000020
 // CHECK:STDOUT:       3:               inst6000002C
 // CHECK:STDOUT:       4:               inst6000002F
-// CHECK:STDOUT:     inst_block00000013:
+// CHECK:STDOUT:     inst_block60000013:
 // CHECK:STDOUT:       0:               inst60000015
 // CHECK:STDOUT:       1:               inst6000001B
 // CHECK:STDOUT:       2:               inst6000001E
 // CHECK:STDOUT:       3:               inst6000002A
 // CHECK:STDOUT:       4:               inst6000002D
-// CHECK:STDOUT:     inst_block00000014:
+// CHECK:STDOUT:     inst_block60000014:
 // CHECK:STDOUT:       0:               inst6000003F
 // CHECK:STDOUT:       1:               inst60000040
 // CHECK:STDOUT:       2:               inst60000041
@@ -1456,183 +1456,183 @@ fn Foo[T:! type](p: T*) -> (T*, ()) {
 // CHECK:STDOUT:       13:              inst6000014D
 // CHECK:STDOUT:       14:              inst6000014E
 // CHECK:STDOUT:       15:              inst6000014F
-// CHECK:STDOUT:     inst_block00000015:
+// CHECK:STDOUT:     inst_block60000015:
 // CHECK:STDOUT:       0:               inst6000003F
 // CHECK:STDOUT:       1:               inst60000040
-// CHECK:STDOUT:     inst_block00000016:
+// CHECK:STDOUT:     inst_block60000016:
 // CHECK:STDOUT:       0:               inst6000004B
-// CHECK:STDOUT:     inst_block00000017:
+// CHECK:STDOUT:     inst_block60000017:
 // CHECK:STDOUT:       0:               inst60000057
-// CHECK:STDOUT:     inst_block00000018:
+// CHECK:STDOUT:     inst_block60000018:
 // CHECK:STDOUT:       0:               inst60000058
-// CHECK:STDOUT:     inst_block00000019:
+// CHECK:STDOUT:     inst_block60000019:
 // CHECK:STDOUT:       0:               inst60000059
 // CHECK:STDOUT:       1:               inst6000005A
 // CHECK:STDOUT:       2:               inst6000005B
-// CHECK:STDOUT:     inst_block0000001A:
+// CHECK:STDOUT:     inst_block6000001A:
 // CHECK:STDOUT:       0:               inst60000048
-// CHECK:STDOUT:     inst_block0000001B:
+// CHECK:STDOUT:     inst_block6000001B:
 // CHECK:STDOUT:       0:               inst60000048
 // CHECK:STDOUT:       1:               inst60000052
 // CHECK:STDOUT:       2:               inst60000053
-// CHECK:STDOUT:     inst_block0000001C:
+// CHECK:STDOUT:     inst_block6000001C:
 // CHECK:STDOUT:       0:               inst60000063
-// CHECK:STDOUT:     inst_block0000001D:
+// CHECK:STDOUT:     inst_block6000001D:
 // CHECK:STDOUT:       0:               inst60000064
-// CHECK:STDOUT:     inst_block0000001E:
+// CHECK:STDOUT:     inst_block6000001E:
 // CHECK:STDOUT:       0:               inst60000067
-// CHECK:STDOUT:     inst_block0000001F:
+// CHECK:STDOUT:     inst_block6000001F:
 // CHECK:STDOUT:       0:               inst6000005F
-// CHECK:STDOUT:     inst_block00000020:
+// CHECK:STDOUT:     inst_block60000020:
 // CHECK:STDOUT:       0:               inst6000006A
-// CHECK:STDOUT:     inst_block00000021:
+// CHECK:STDOUT:     inst_block60000021:
 // CHECK:STDOUT:       0:               inst6000006A
 // CHECK:STDOUT:       1:               inst6000006B
 // CHECK:STDOUT:       2:               inst6000006C
 // CHECK:STDOUT:       3:               inst6000006D
-// CHECK:STDOUT:     inst_block00000022:
+// CHECK:STDOUT:     inst_block60000022:
 // CHECK:STDOUT:       0:               inst6000005F
 // CHECK:STDOUT:       1:               inst60000060
 // CHECK:STDOUT:       2:               inst60000061
 // CHECK:STDOUT:       3:               inst60000069
-// CHECK:STDOUT:     inst_block00000023:
+// CHECK:STDOUT:     inst_block60000023:
 // CHECK:STDOUT:       0:               inst60000075
-// CHECK:STDOUT:     inst_block00000024:
+// CHECK:STDOUT:     inst_block60000024:
 // CHECK:STDOUT:       0:               inst60000076
-// CHECK:STDOUT:     inst_block00000025:
+// CHECK:STDOUT:     inst_block60000025:
 // CHECK:STDOUT:       0:               inst6000006A
-// CHECK:STDOUT:     inst_block00000026:
+// CHECK:STDOUT:     inst_block60000026:
 // CHECK:STDOUT:       0:               inst60000077
 // CHECK:STDOUT:       1:               inst60000078
-// CHECK:STDOUT:     inst_block00000027:
+// CHECK:STDOUT:     inst_block60000027:
 // CHECK:STDOUT:       0:               inst60000079
 // CHECK:STDOUT:       1:               inst6000007A
 // CHECK:STDOUT:       2:               inst6000007B
 // CHECK:STDOUT:       3:               inst6000007C
-// CHECK:STDOUT:     inst_block00000028:
+// CHECK:STDOUT:     inst_block60000028:
 // CHECK:STDOUT:       0:               inst6000005F
 // CHECK:STDOUT:       1:               inst60000060
 // CHECK:STDOUT:       2:               inst60000061
 // CHECK:STDOUT:       3:               inst60000071
-// CHECK:STDOUT:     inst_block00000029:
+// CHECK:STDOUT:     inst_block60000029:
 // CHECK:STDOUT:       0:               inst60000079
-// CHECK:STDOUT:     inst_block0000002A:
+// CHECK:STDOUT:     inst_block6000002A:
 // CHECK:STDOUT:       0:               inst60000083
 // CHECK:STDOUT:       1:               inst60000084
 // CHECK:STDOUT:       2:               inst60000085
 // CHECK:STDOUT:       3:               inst60000086
 // CHECK:STDOUT:       4:               inst60000087
 // CHECK:STDOUT:       5:               inst60000088
-// CHECK:STDOUT:     inst_block0000002B:
+// CHECK:STDOUT:     inst_block6000002B:
 // CHECK:STDOUT:       0:               inst6000005F
 // CHECK:STDOUT:       1:               inst60000060
 // CHECK:STDOUT:       2:               inst60000089
-// CHECK:STDOUT:     inst_block0000002C:
+// CHECK:STDOUT:     inst_block6000002C:
 // CHECK:STDOUT:       0:               inst6000006F
 // CHECK:STDOUT:       1:               inst60000070
-// CHECK:STDOUT:     inst_block0000002D:
+// CHECK:STDOUT:     inst_block6000002D:
 // CHECK:STDOUT:       0:               inst6000009C
-// CHECK:STDOUT:     inst_block0000002E:
+// CHECK:STDOUT:     inst_block6000002E:
 // CHECK:STDOUT:       0:               inst6000009D
-// CHECK:STDOUT:     inst_block0000002F:
+// CHECK:STDOUT:     inst_block6000002F:
 // CHECK:STDOUT:       0:               inst600000A0
-// CHECK:STDOUT:     inst_block00000030:
+// CHECK:STDOUT:     inst_block60000030:
 // CHECK:STDOUT:       0:               inst600000A3
-// CHECK:STDOUT:     inst_block00000031:
+// CHECK:STDOUT:     inst_block60000031:
 // CHECK:STDOUT:       0:               inst600000A3
 // CHECK:STDOUT:       1:               inst600000A4
 // CHECK:STDOUT:       2:               inst600000A5
-// CHECK:STDOUT:     inst_block00000032:
+// CHECK:STDOUT:     inst_block60000032:
 // CHECK:STDOUT:       0:               inst60000015
 // CHECK:STDOUT:       1:               inst6000001B
 // CHECK:STDOUT:       2:               inst600000A2
-// CHECK:STDOUT:     inst_block00000033:
+// CHECK:STDOUT:     inst_block60000033:
 // CHECK:STDOUT:       0:               inst600000AC
-// CHECK:STDOUT:     inst_block00000034:
+// CHECK:STDOUT:     inst_block60000034:
 // CHECK:STDOUT:       0:               inst600000AD
-// CHECK:STDOUT:     inst_block00000035:
+// CHECK:STDOUT:     inst_block60000035:
 // CHECK:STDOUT:       0:               inst600000A3
-// CHECK:STDOUT:     inst_block00000036:
+// CHECK:STDOUT:     inst_block60000036:
 // CHECK:STDOUT:       0:               inst600000AE
 // CHECK:STDOUT:       1:               inst600000AF
 // CHECK:STDOUT:       2:               inst600000B0
-// CHECK:STDOUT:     inst_block00000037:
+// CHECK:STDOUT:     inst_block60000037:
 // CHECK:STDOUT:       0:               inst600000B1
 // CHECK:STDOUT:       1:               inst600000B2
 // CHECK:STDOUT:       2:               inst600000B3
-// CHECK:STDOUT:     inst_block00000038:
+// CHECK:STDOUT:     inst_block60000038:
 // CHECK:STDOUT:       0:               inst60000015
 // CHECK:STDOUT:       1:               inst6000001B
 // CHECK:STDOUT:       2:               inst6000001E
-// CHECK:STDOUT:     inst_block00000039:
+// CHECK:STDOUT:     inst_block60000039:
 // CHECK:STDOUT:       0:               inst60000060
 // CHECK:STDOUT:       1:               inst600000BF
-// CHECK:STDOUT:     inst_block0000003A:
+// CHECK:STDOUT:     inst_block6000003A:
 // CHECK:STDOUT:       0:               inst600000C2
 // CHECK:STDOUT:       1:               inst600000C1
-// CHECK:STDOUT:     inst_block0000003B:
+// CHECK:STDOUT:     inst_block6000003B:
 // CHECK:STDOUT:       0:               inst600000C3
 // CHECK:STDOUT:       1:               inst600000C4
-// CHECK:STDOUT:     inst_block0000003C:
+// CHECK:STDOUT:     inst_block6000003C:
 // CHECK:STDOUT:       0:               inst600000C7
-// CHECK:STDOUT:     inst_block0000003D:
+// CHECK:STDOUT:     inst_block6000003D:
 // CHECK:STDOUT:       0:               inst6000005F
 // CHECK:STDOUT:       1:               inst600000BE
-// CHECK:STDOUT:     inst_block0000003E:
+// CHECK:STDOUT:     inst_block6000003E:
 // CHECK:STDOUT:       0:               inst600000CC
 // CHECK:STDOUT:       1:               inst600000CD
-// CHECK:STDOUT:     inst_block0000003F:
+// CHECK:STDOUT:     inst_block6000003F:
 // CHECK:STDOUT:       0:               inst600000CA
 // CHECK:STDOUT:       1:               inst600000CB
-// CHECK:STDOUT:     inst_block00000040:
+// CHECK:STDOUT:     inst_block60000040:
 // CHECK:STDOUT:       0:               inst600000CA
 // CHECK:STDOUT:       1:               inst600000CB
 // CHECK:STDOUT:       2:               inst600000CC
 // CHECK:STDOUT:       3:               inst600000CD
 // CHECK:STDOUT:       4:               inst600000CE
 // CHECK:STDOUT:       5:               inst600000CF
-// CHECK:STDOUT:     inst_block00000041:
+// CHECK:STDOUT:     inst_block60000041:
 // CHECK:STDOUT:       0:               inst6000005F
 // CHECK:STDOUT:       1:               inst600000BE
 // CHECK:STDOUT:       2:               inst60000060
 // CHECK:STDOUT:       3:               inst600000BF
 // CHECK:STDOUT:       4:               inst600000C0
 // CHECK:STDOUT:       5:               inst600000C9
-// CHECK:STDOUT:     inst_block00000042:
+// CHECK:STDOUT:     inst_block60000042:
 // CHECK:STDOUT:       0:               inst600000D7
-// CHECK:STDOUT:     inst_block00000043:
+// CHECK:STDOUT:     inst_block60000043:
 // CHECK:STDOUT:       0:               inst600000D8
 // CHECK:STDOUT:       1:               inst600000D9
-// CHECK:STDOUT:     inst_block00000044:
+// CHECK:STDOUT:     inst_block60000044:
 // CHECK:STDOUT:       0:               inst600000CA
 // CHECK:STDOUT:       1:               inst600000CB
-// CHECK:STDOUT:     inst_block00000045:
+// CHECK:STDOUT:     inst_block60000045:
 // CHECK:STDOUT:       0:               inst600000DA
 // CHECK:STDOUT:       1:               inst600000DB
-// CHECK:STDOUT:     inst_block00000046:
+// CHECK:STDOUT:     inst_block60000046:
 // CHECK:STDOUT:       0:               inst600000DD
 // CHECK:STDOUT:       1:               inst600000DF
-// CHECK:STDOUT:     inst_block00000047:
+// CHECK:STDOUT:     inst_block60000047:
 // CHECK:STDOUT:       0:               inst600000DC
 // CHECK:STDOUT:       1:               inst600000DD
 // CHECK:STDOUT:       2:               inst600000DE
 // CHECK:STDOUT:       3:               inst600000DF
 // CHECK:STDOUT:       4:               inst600000E0
 // CHECK:STDOUT:       5:               inst600000E1
-// CHECK:STDOUT:     inst_block00000048:
+// CHECK:STDOUT:     inst_block60000048:
 // CHECK:STDOUT:       0:               inst6000005F
 // CHECK:STDOUT:       1:               inst60000060
 // CHECK:STDOUT:       2:               inst600000BE
 // CHECK:STDOUT:       3:               inst600000BF
 // CHECK:STDOUT:       4:               inst600000C0
 // CHECK:STDOUT:       5:               inst600000D3
-// CHECK:STDOUT:     inst_block00000049:
+// CHECK:STDOUT:     inst_block60000049:
 // CHECK:STDOUT:       0:               inst600000BE
-// CHECK:STDOUT:     inst_block0000004A:
+// CHECK:STDOUT:     inst_block6000004A:
 // CHECK:STDOUT:       0:               inst600000DC
-// CHECK:STDOUT:     inst_block0000004B:
+// CHECK:STDOUT:     inst_block6000004B:
 // CHECK:STDOUT:       0:               inst600000DE
-// CHECK:STDOUT:     inst_block0000004C:
+// CHECK:STDOUT:     inst_block6000004C:
 // CHECK:STDOUT:       0:               inst600000E8
 // CHECK:STDOUT:       1:               inst600000E9
 // CHECK:STDOUT:       2:               inst600000EA
@@ -1644,40 +1644,40 @@ fn Foo[T:! type](p: T*) -> (T*, ()) {
 // CHECK:STDOUT:       8:               inst600000F0
 // CHECK:STDOUT:       9:               inst600000F1
 // CHECK:STDOUT:       10:              inst600000F2
-// CHECK:STDOUT:     inst_block0000004D:
+// CHECK:STDOUT:     inst_block6000004D:
 // CHECK:STDOUT:       0:               inst600000BE
 // CHECK:STDOUT:       1:               inst600000BF
 // CHECK:STDOUT:       2:               inst600000F3
-// CHECK:STDOUT:     inst_block0000004E:
+// CHECK:STDOUT:     inst_block6000004E:
 // CHECK:STDOUT:       0:               inst600000D1
 // CHECK:STDOUT:       1:               inst600000D2
-// CHECK:STDOUT:     inst_block0000004F:
+// CHECK:STDOUT:     inst_block6000004F:
 // CHECK:STDOUT:       0:               inst60000060
 // CHECK:STDOUT:       1:               inst600000BF
 // CHECK:STDOUT:       2:               inst600000F7
-// CHECK:STDOUT:     inst_block00000050:
+// CHECK:STDOUT:     inst_block60000050:
 // CHECK:STDOUT:       0:               inst600000FB
 // CHECK:STDOUT:       1:               inst600000FA
 // CHECK:STDOUT:       2:               inst600000F9
-// CHECK:STDOUT:     inst_block00000051:
+// CHECK:STDOUT:     inst_block60000051:
 // CHECK:STDOUT:       0:               inst600000FC
 // CHECK:STDOUT:       1:               inst600000FD
 // CHECK:STDOUT:       2:               inst600000FE
-// CHECK:STDOUT:     inst_block00000052:
+// CHECK:STDOUT:     inst_block60000052:
 // CHECK:STDOUT:       0:               inst60000101
-// CHECK:STDOUT:     inst_block00000053:
+// CHECK:STDOUT:     inst_block60000053:
 // CHECK:STDOUT:       0:               inst6000005F
 // CHECK:STDOUT:       1:               inst600000BE
 // CHECK:STDOUT:       2:               inst600000F6
-// CHECK:STDOUT:     inst_block00000054:
+// CHECK:STDOUT:     inst_block60000054:
 // CHECK:STDOUT:       0:               inst60000107
 // CHECK:STDOUT:       1:               inst60000108
 // CHECK:STDOUT:       2:               inst60000109
-// CHECK:STDOUT:     inst_block00000055:
+// CHECK:STDOUT:     inst_block60000055:
 // CHECK:STDOUT:       0:               inst60000104
 // CHECK:STDOUT:       1:               inst60000105
 // CHECK:STDOUT:       2:               inst60000106
-// CHECK:STDOUT:     inst_block00000056:
+// CHECK:STDOUT:     inst_block60000056:
 // CHECK:STDOUT:       0:               inst60000104
 // CHECK:STDOUT:       1:               inst60000105
 // CHECK:STDOUT:       2:               inst60000106
@@ -1686,7 +1686,7 @@ fn Foo[T:! type](p: T*) -> (T*, ()) {
 // CHECK:STDOUT:       5:               inst60000109
 // CHECK:STDOUT:       6:               inst6000010A
 // CHECK:STDOUT:       7:               inst6000010B
-// CHECK:STDOUT:     inst_block00000057:
+// CHECK:STDOUT:     inst_block60000057:
 // CHECK:STDOUT:       0:               inst6000005F
 // CHECK:STDOUT:       1:               inst600000BE
 // CHECK:STDOUT:       2:               inst600000F6
@@ -1695,24 +1695,24 @@ fn Foo[T:! type](p: T*) -> (T*, ()) {
 // CHECK:STDOUT:       5:               inst600000F7
 // CHECK:STDOUT:       6:               inst600000F8
 // CHECK:STDOUT:       7:               inst60000103
-// CHECK:STDOUT:     inst_block00000058:
+// CHECK:STDOUT:     inst_block60000058:
 // CHECK:STDOUT:       0:               inst60000113
-// CHECK:STDOUT:     inst_block00000059:
+// CHECK:STDOUT:     inst_block60000059:
 // CHECK:STDOUT:       0:               inst60000114
 // CHECK:STDOUT:       1:               inst60000115
 // CHECK:STDOUT:       2:               inst60000116
-// CHECK:STDOUT:     inst_block0000005A:
+// CHECK:STDOUT:     inst_block6000005A:
 // CHECK:STDOUT:       0:               inst60000104
 // CHECK:STDOUT:       1:               inst60000105
 // CHECK:STDOUT:       2:               inst60000106
-// CHECK:STDOUT:     inst_block0000005B:
+// CHECK:STDOUT:     inst_block6000005B:
 // CHECK:STDOUT:       0:               inst60000117
 // CHECK:STDOUT:       1:               inst60000118
-// CHECK:STDOUT:     inst_block0000005C:
+// CHECK:STDOUT:     inst_block6000005C:
 // CHECK:STDOUT:       0:               inst6000011A
 // CHECK:STDOUT:       1:               inst6000011C
 // CHECK:STDOUT:       2:               inst6000011E
-// CHECK:STDOUT:     inst_block0000005D:
+// CHECK:STDOUT:     inst_block6000005D:
 // CHECK:STDOUT:       0:               inst60000119
 // CHECK:STDOUT:       1:               inst6000011A
 // CHECK:STDOUT:       2:               inst6000011B
@@ -1721,7 +1721,7 @@ fn Foo[T:! type](p: T*) -> (T*, ()) {
 // CHECK:STDOUT:       5:               inst6000011E
 // CHECK:STDOUT:       6:               inst6000011F
 // CHECK:STDOUT:       7:               inst60000120
-// CHECK:STDOUT:     inst_block0000005E:
+// CHECK:STDOUT:     inst_block6000005E:
 // CHECK:STDOUT:       0:               inst6000005F
 // CHECK:STDOUT:       1:               inst60000060
 // CHECK:STDOUT:       2:               inst600000BE
@@ -1730,15 +1730,15 @@ fn Foo[T:! type](p: T*) -> (T*, ()) {
 // CHECK:STDOUT:       5:               inst600000F7
 // CHECK:STDOUT:       6:               inst600000F8
 // CHECK:STDOUT:       7:               inst6000010F
-// CHECK:STDOUT:     inst_block0000005F:
+// CHECK:STDOUT:     inst_block6000005F:
 // CHECK:STDOUT:       0:               inst600000F6
-// CHECK:STDOUT:     inst_block00000060:
+// CHECK:STDOUT:     inst_block60000060:
 // CHECK:STDOUT:       0:               inst60000119
-// CHECK:STDOUT:     inst_block00000061:
+// CHECK:STDOUT:     inst_block60000061:
 // CHECK:STDOUT:       0:               inst6000011B
-// CHECK:STDOUT:     inst_block00000062:
+// CHECK:STDOUT:     inst_block60000062:
 // CHECK:STDOUT:       0:               inst6000011D
-// CHECK:STDOUT:     inst_block00000063:
+// CHECK:STDOUT:     inst_block60000063:
 // CHECK:STDOUT:       0:               inst60000127
 // CHECK:STDOUT:       1:               inst60000128
 // CHECK:STDOUT:       2:               inst60000129
@@ -1755,35 +1755,35 @@ fn Foo[T:! type](p: T*) -> (T*, ()) {
 // CHECK:STDOUT:       13:              inst60000134
 // CHECK:STDOUT:       14:              inst60000135
 // CHECK:STDOUT:       15:              inst60000136
-// CHECK:STDOUT:     inst_block00000064:
+// CHECK:STDOUT:     inst_block60000064:
 // CHECK:STDOUT:       0:               inst600000F6
 // CHECK:STDOUT:       1:               inst600000F7
 // CHECK:STDOUT:       2:               inst60000137
-// CHECK:STDOUT:     inst_block00000065:
+// CHECK:STDOUT:     inst_block60000065:
 // CHECK:STDOUT:       0:               inst6000010D
 // CHECK:STDOUT:       1:               inst6000010E
-// CHECK:STDOUT:     inst_block00000066:
+// CHECK:STDOUT:     inst_block60000066:
 // CHECK:STDOUT:       0:               inst600000A7
 // CHECK:STDOUT:       1:               inst600000A8
 // CHECK:STDOUT:       2:               inst6000003D
-// CHECK:STDOUT:     inst_block00000067:
+// CHECK:STDOUT:     inst_block60000067:
 // CHECK:STDOUT:       0:               inst60000138
-// CHECK:STDOUT:     inst_block00000068:
+// CHECK:STDOUT:     inst_block60000068:
 // CHECK:STDOUT:       0:               inst60000139
-// CHECK:STDOUT:     inst_block00000069:
+// CHECK:STDOUT:     inst_block60000069:
 // CHECK:STDOUT:       0:               inst6000013A
-// CHECK:STDOUT:     inst_block0000006A:
+// CHECK:STDOUT:     inst_block6000006A:
 // CHECK:STDOUT:       0:               inst6000013A
 // CHECK:STDOUT:       1:               inst6000001B
 // CHECK:STDOUT:       2:               inst6000001E
-// CHECK:STDOUT:     inst_block0000006B:
+// CHECK:STDOUT:     inst_block6000006B:
 // CHECK:STDOUT:       0:               inst6000013E
-// CHECK:STDOUT:     inst_block0000006C:
+// CHECK:STDOUT:     inst_block6000006C:
 // CHECK:STDOUT:       0:               inst6000003F
-// CHECK:STDOUT:     inst_block0000006D:
+// CHECK:STDOUT:     inst_block6000006D:
 // CHECK:STDOUT:       0:               inst60000148
 // CHECK:STDOUT:       1:               inst6000014C
-// CHECK:STDOUT:     inst_block0000006E:
+// CHECK:STDOUT:     inst_block6000006E:
 // CHECK:STDOUT:       0:               inst6000003B
 // CHECK:STDOUT:       1:               inst6000003E
 // CHECK:STDOUT:       2:               inst60000139
@@ -1791,7 +1791,7 @@ fn Foo[T:! type](p: T*) -> (T*, ()) {
 // CHECK:STDOUT:       4:               inst6000013F
 // CHECK:STDOUT:       5:               inst60000140
 // CHECK:STDOUT:       6:               inst60000144
-// CHECK:STDOUT:     inst_block0000006F:
+// CHECK:STDOUT:     inst_block6000006F:
 // CHECK:STDOUT:       0:               inst0000000E
 // CHECK:STDOUT:       1:               inst6000000F
 // CHECK:STDOUT:       2:               inst60000035

toolchain/check/testdata/basics/raw_sem_ir/one_file_with_textual_ir.carbon

@@ -31,7 +31,7 @@ fn Foo(n: ()) -> ((), ()) {
 // CHECK:STDOUT:     entity_name60000000: {name: name00000001, parent_scope: name_scope<none>, index: -1, is_template: 0}
 // CHECK:STDOUT:   cpp_global_vars: {}
 // CHECK:STDOUT:   functions:
-// CHECK:STDOUT:     function60000000: {name: name00000000, parent_scope: name_scope00000000, call_params_id: inst_block00000009, return_slot_pattern: inst60000020, body: [inst_block0000000C]}
+// CHECK:STDOUT:     function60000000: {name: name00000000, parent_scope: name_scope00000000, call_params_id: inst_block60000009, return_slot_pattern: inst60000020, body: [inst_block6000000C]}
 // CHECK:STDOUT:   classes:         {}
 // CHECK:STDOUT:   generics:        {}
 // CHECK:STDOUT:   specifics:       {}
@@ -63,8 +63,8 @@ fn Foo(n: ()) -> ((), ()) {
 // CHECK:STDOUT:     inst60000015:    {kind: ValueParamPattern, arg0: inst60000014, arg1: call_param0, type: type(inst60000013)}
 // CHECK:STDOUT:     inst60000016:    {kind: TupleLiteral, arg0: inst_block_empty, type: type(inst6000000F)}
 // CHECK:STDOUT:     inst60000017:    {kind: TupleLiteral, arg0: inst_block_empty, type: type(inst6000000F)}
-// CHECK:STDOUT:     inst60000018:    {kind: TupleType, arg0: inst_block00000007, type: type(TypeType)}
-// CHECK:STDOUT:     inst60000019:    {kind: TupleLiteral, arg0: inst_block00000006, type: type(inst60000018)}
+// CHECK:STDOUT:     inst60000018:    {kind: TupleType, arg0: inst_block60000007, type: type(TypeType)}
+// CHECK:STDOUT:     inst60000019:    {kind: TupleLiteral, arg0: inst_block60000006, type: type(inst60000018)}
 // CHECK:STDOUT:     inst6000001A:    {kind: PointerType, arg0: inst60000018, type: type(TypeType)}
 // CHECK:STDOUT:     inst6000001B:    {kind: Converted, arg0: inst60000016, arg1: inst6000000F, type: type(TypeType)}
 // CHECK:STDOUT:     inst6000001C:    {kind: Converted, arg0: inst60000017, arg1: inst6000000F, type: type(TypeType)}
@@ -73,24 +73,24 @@ fn Foo(n: ()) -> ((), ()) {
 // CHECK:STDOUT:     inst6000001F:    {kind: ReturnSlotPattern, arg0: inst6000001D, type: type(inst6000001E)}
 // CHECK:STDOUT:     inst60000020:    {kind: OutParamPattern, arg0: inst6000001F, arg1: call_param1, type: type(inst6000001E)}
 // CHECK:STDOUT:     inst60000021:    {kind: ValueParam, arg0: call_param0, arg1: name00000001, type: type(inst6000000F)}
-// CHECK:STDOUT:     inst60000022:    {kind: SpliceBlock, arg0: inst_block00000004, arg1: inst60000011, type: type(TypeType)}
+// CHECK:STDOUT:     inst60000022:    {kind: SpliceBlock, arg0: inst_block60000004, arg1: inst60000011, type: type(TypeType)}
 // CHECK:STDOUT:     inst60000023:    {kind: OutParam, arg0: call_param1, arg1: name(ReturnSlot), type: type(inst60000018)}
 // CHECK:STDOUT:     inst60000024:    {kind: ReturnSlot, arg0: inst60000018, arg1: inst60000023, type: type(inst60000018)}
-// CHECK:STDOUT:     inst60000025:    {kind: FunctionDecl, arg0: function60000000, arg1: inst_block0000000B, type: type(inst60000026)}
+// CHECK:STDOUT:     inst60000025:    {kind: FunctionDecl, arg0: function60000000, arg1: inst_block6000000B, type: type(inst60000026)}
 // CHECK:STDOUT:     inst60000026:    {kind: FunctionType, arg0: function60000000, arg1: specific<none>, type: type(TypeType)}
 // CHECK:STDOUT:     inst60000027:    {kind: StructValue, arg0: inst_block_empty, type: type(inst60000026)}
 // CHECK:STDOUT:     inst60000028:    {kind: NameRef, arg0: name00000001, arg1: inst60000012, type: type(inst6000000F)}
 // CHECK:STDOUT:     inst60000029:    {kind: TupleLiteral, arg0: inst_block_empty, type: type(inst6000000F)}
-// CHECK:STDOUT:     inst6000002A:    {kind: TupleLiteral, arg0: inst_block0000000D, type: type(inst60000018)}
+// CHECK:STDOUT:     inst6000002A:    {kind: TupleLiteral, arg0: inst_block6000000D, type: type(inst60000018)}
 // CHECK:STDOUT:     inst6000002B:    {kind: TupleAccess, arg0: inst60000024, arg1: element0, type: type(inst6000000F)}
-// CHECK:STDOUT:     inst6000002C:    {kind: TupleInit, arg0: inst_block0000000E, arg1: inst6000002B, type: type(inst6000000F)}
+// CHECK:STDOUT:     inst6000002C:    {kind: TupleInit, arg0: inst_block6000000E, arg1: inst6000002B, type: type(inst6000000F)}
 // CHECK:STDOUT:     inst6000002D:    {kind: TupleValue, arg0: inst_block_empty, type: type(inst6000000F)}
 // CHECK:STDOUT:     inst6000002E:    {kind: Converted, arg0: inst60000028, arg1: inst6000002C, type: type(inst6000000F)}
 // CHECK:STDOUT:     inst6000002F:    {kind: TupleAccess, arg0: inst60000024, arg1: element1, type: type(inst6000000F)}
 // CHECK:STDOUT:     inst60000030:    {kind: TupleInit, arg0: inst_block_empty, arg1: inst6000002F, type: type(inst6000000F)}
 // CHECK:STDOUT:     inst60000031:    {kind: Converted, arg0: inst60000029, arg1: inst60000030, type: type(inst6000000F)}
-// CHECK:STDOUT:     inst60000032:    {kind: TupleInit, arg0: inst_block0000000F, arg1: inst60000024, type: type(inst60000018)}
-// CHECK:STDOUT:     inst60000033:    {kind: TupleValue, arg0: inst_block00000010, type: type(inst60000018)}
+// CHECK:STDOUT:     inst60000032:    {kind: TupleInit, arg0: inst_block6000000F, arg1: inst60000024, type: type(inst60000018)}
+// CHECK:STDOUT:     inst60000033:    {kind: TupleValue, arg0: inst_block60000010, type: type(inst60000018)}
 // CHECK:STDOUT:     inst60000034:    {kind: Converted, arg0: inst6000002A, arg1: inst60000032, type: type(inst60000018)}
 // CHECK:STDOUT:     inst60000035:    {kind: ReturnExpr, arg0: inst60000034, arg1: inst60000024}
 // CHECK:STDOUT:   constant_values:
@@ -128,29 +128,29 @@ fn Foo(n: ()) -> ((), ()) {
 // CHECK:STDOUT:       0:               inst60000025
 // CHECK:STDOUT:     imports:         {}
 // CHECK:STDOUT:     global_init:     {}
-// CHECK:STDOUT:     inst_block00000004:
+// CHECK:STDOUT:     inst_block60000004:
 // CHECK:STDOUT:       0:               inst60000010
 // CHECK:STDOUT:       1:               inst60000011
-// CHECK:STDOUT:     inst_block00000005:
+// CHECK:STDOUT:     inst_block60000005:
 // CHECK:STDOUT:       0:               inst60000015
-// CHECK:STDOUT:     inst_block00000006:
+// CHECK:STDOUT:     inst_block60000006:
 // CHECK:STDOUT:       0:               inst60000016
 // CHECK:STDOUT:       1:               inst60000017
-// CHECK:STDOUT:     inst_block00000007:
+// CHECK:STDOUT:     inst_block60000007:
 // CHECK:STDOUT:       0:               inst6000000F
 // CHECK:STDOUT:       1:               inst6000000F
-// CHECK:STDOUT:     inst_block00000008:
+// CHECK:STDOUT:     inst_block60000008:
 // CHECK:STDOUT:       0:               inst6000001B
 // CHECK:STDOUT:       1:               inst6000001C
-// CHECK:STDOUT:     inst_block00000009:
+// CHECK:STDOUT:     inst_block60000009:
 // CHECK:STDOUT:       0:               inst60000021
 // CHECK:STDOUT:       1:               inst60000023
-// CHECK:STDOUT:     inst_block0000000A:
+// CHECK:STDOUT:     inst_block6000000A:
 // CHECK:STDOUT:       0:               inst60000014
 // CHECK:STDOUT:       1:               inst60000015
 // CHECK:STDOUT:       2:               inst6000001F
 // CHECK:STDOUT:       3:               inst60000020
-// CHECK:STDOUT:     inst_block0000000B:
+// CHECK:STDOUT:     inst_block6000000B:
 // CHECK:STDOUT:       0:               inst60000016
 // CHECK:STDOUT:       1:               inst60000017
 // CHECK:STDOUT:       2:               inst60000019
@@ -162,7 +162,7 @@ fn Foo(n: ()) -> ((), ()) {
 // CHECK:STDOUT:       8:               inst60000012
 // CHECK:STDOUT:       9:               inst60000023
 // CHECK:STDOUT:       10:              inst60000024
-// CHECK:STDOUT:     inst_block0000000C:
+// CHECK:STDOUT:     inst_block6000000C:
 // CHECK:STDOUT:       0:               inst60000028
 // CHECK:STDOUT:       1:               inst60000029
 // CHECK:STDOUT:       2:               inst6000002A
@@ -175,17 +175,17 @@ fn Foo(n: ()) -> ((), ()) {
 // CHECK:STDOUT:       9:               inst60000032
 // CHECK:STDOUT:       10:              inst60000034
 // CHECK:STDOUT:       11:              inst60000035
-// CHECK:STDOUT:     inst_block0000000D:
+// CHECK:STDOUT:     inst_block6000000D:
 // CHECK:STDOUT:       0:               inst60000028
 // CHECK:STDOUT:       1:               inst60000029
-// CHECK:STDOUT:     inst_block0000000E: {}
-// CHECK:STDOUT:     inst_block0000000F:
+// CHECK:STDOUT:     inst_block6000000E: {}
+// CHECK:STDOUT:     inst_block6000000F:
 // CHECK:STDOUT:       0:               inst6000002E
 // CHECK:STDOUT:       1:               inst60000031
-// CHECK:STDOUT:     inst_block00000010:
+// CHECK:STDOUT:     inst_block60000010:
 // CHECK:STDOUT:       0:               inst6000002D
 // CHECK:STDOUT:       1:               inst6000002D
-// CHECK:STDOUT:     inst_block00000011:
+// CHECK:STDOUT:     inst_block60000011:
 // CHECK:STDOUT:       0:               inst0000000E
 // CHECK:STDOUT:       1:               inst60000025
 // CHECK:STDOUT: ...

toolchain/driver/testdata/stdin.carbon

@@ -59,7 +59,7 @@
 // CHECK:STDOUT:     exports:         {}
 // CHECK:STDOUT:     imports:         {}
 // CHECK:STDOUT:     global_init:     {}
-// CHECK:STDOUT:     inst_block00000004:
+// CHECK:STDOUT:     inst_block60000004:
 // CHECK:STDOUT:       0:               inst0000000E
 // CHECK:STDOUT: ...
 // CHECK:STDOUT: --- -

toolchain/sem_ir/file.cpp

@@ -53,7 +53,7 @@ File::File(const Parse::Tree* parse_tree, CheckIRId check_ir_id,
       insts_(this, SingletonInstKinds.size() + 1),
       vtables_(check_ir_id),
       constant_values_(ConstantId::NotConstant, &insts_),
-      inst_blocks_(allocator_),
+      inst_blocks_(allocator_, check_ir_id),
       constants_(this) {
   // `type` and the error type are both complete & concrete types.
   types_.SetComplete(

toolchain/sem_ir/inst.h

@@ -674,8 +674,11 @@ class InstBlockStore : public BlockValueStore<InstBlockId, InstId> {
  public:
   using BaseType = BlockValueStore<InstBlockId, InstId>;
 
-  explicit InstBlockStore(llvm::BumpPtrAllocator& allocator)
-      : BaseType(allocator) {
+  explicit InstBlockStore(llvm::BumpPtrAllocator& allocator,
+                          CheckIRId check_ir_id = CheckIRId::None)
+      // 4 reserved ids for the
+      // `InstBlockId::{Empty,Exports,Imports,GlobalInit}` global ids.
+      : BaseType(allocator, IdTag(check_ir_id.index, 4)) {
     auto exports_id = AddPlaceholder();
     CARBON_CHECK(exports_id == InstBlockId::Exports);
     auto imports_id = AddPlaceholder();

toolchain/sem_ir/inst_namer.cpp

@@ -249,7 +249,8 @@ auto InstNamer::GetUnscopedLabelFor(InstBlockId block_id) const
   if (!block_id.has_value()) {
     return "";
   }
-  const auto& label_name = labels_[block_id.index].second;
+  const auto& label_name =
+      labels_[sem_ir_->inst_blocks().GetRawIndex(block_id)].second;
   return label_name ? label_name.GetFullName() : "";
 }
 
@@ -260,7 +261,8 @@ auto InstNamer::GetLabelFor(ScopeId scope_id, InstBlockId block_id) const
     return "!invalid";
   }
 
-  const auto& [label_scope, label_name] = labels_[block_id.index];
+  const auto& [label_scope, label_name] =
+      labels_[sem_ir_->inst_blocks().GetRawIndex(block_id)];
   if (!label_name) {
     // This should not happen in valid IR.
     RawStringOstream out;
@@ -374,7 +376,8 @@ auto InstNamer::Namespace::AllocateName(
 auto InstNamer::AddBlockLabel(
     ScopeId scope_id, InstBlockId block_id, std::string name,
     std::variant<LocId, uint64_t> loc_id_or_fingerprint) -> void {
-  if (!block_id.has_value() || labels_[block_id.index].second) {
+  if (!block_id.has_value() ||
+      labels_[sem_ir_->inst_blocks().GetRawIndex(block_id)].second) {
     return;
   }
 
@@ -386,7 +389,7 @@ auto InstNamer::AddBlockLabel(
     }
   }
 
-  labels_[block_id.index] = {
+  labels_[sem_ir_->inst_blocks().GetRawIndex(block_id)] = {
       scope_id, GetScopeInfo(scope_id).labels.AllocateName(
                     *this, loc_id_or_fingerprint, std::move(name))};
 }

toolchain/sem_ir/yaml_test.cpp

@@ -46,7 +46,8 @@ TEST(SemIRTest, Yaml) {
 
   // Matches the ID of an instruction. Instruction counts may change as various
   // support changes, so this code is only doing loose structural checks.
-  auto inst_block_id = Yaml::Scalar(MatchesRegex(R"(inst_block(\d+|_empty))"));
+  auto inst_block_id =
+      Yaml::Scalar(MatchesRegex(R"(inst_block([0-9A-F]+|_empty))"));
   auto inst_id = Yaml::Scalar(MatchesRegex(R"(inst[0-9A-F]+)"));
   auto constant_id =
       Yaml::Scalar(MatchesRegex(R"(concrete_constant\(inst[0-9A-F]+\))"));
@@ -98,11 +99,11 @@ TEST(SemIRTest, Yaml) {
               Pair("exports", Yaml::Mapping(Each(Pair(_, inst_id)))),
               Pair("imports", Yaml::Mapping(IsEmpty())),
               Pair("global_init", Yaml::Mapping(IsEmpty())),
-              Pair("inst_block00000004", Yaml::Mapping(Each(Pair(_, inst_id)))),
-              Pair("inst_block00000005", Yaml::Mapping(Each(Pair(_, inst_id)))),
-              Pair("inst_block00000006", Yaml::Mapping(Each(Pair(_, inst_id)))),
-              Pair("inst_block00000007", Yaml::Mapping(Each(Pair(_, inst_id)))),
-              Pair("inst_block00000008",
+              Pair("inst_block60000004", Yaml::Mapping(Each(Pair(_, inst_id)))),
+              Pair("inst_block60000005", Yaml::Mapping(Each(Pair(_, inst_id)))),
+              Pair("inst_block60000006", Yaml::Mapping(Each(Pair(_, inst_id)))),
+              Pair("inst_block60000007", Yaml::Mapping(Each(Pair(_, inst_id)))),
+              Pair("inst_block60000008",
                    Yaml::Mapping(Each(Pair(_, inst_id)))))))));
 
   auto root = Yaml::Sequence(ElementsAre(Yaml::Mapping(