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Reuse LLVM global constants. (#5273)

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Reuse LLVM global constants: do not generate a new llvm::Global constant
for a pointer to a global constant for the same Carbon const_inst_id,
reuse already generated one.
This commit is contained in:
Alina Sbirlea
2025-04-09 16:36:42 +00:00
committed by GitHub
parent 20444c0103
commit 694a329bdd
3 changed files with 10 additions and 10 deletions
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toolchain/lower/file_context.cpp
+7 -4
View File
@@ -154,9 +154,9 @@ auto FileContext::GetGlobal(SemIR::InstId inst_id,
return const_value;
}
// If we want a pointer to the constant, materialize a global to hold it.
// TODO: We could reuse the same global if the constant is used more than
// once.
if (auto result = global_variables().Lookup(const_inst_id)) {
return result.value();
}
// Include both the name of the constant, if any, and the point of use in
// the name of the variable.
@@ -177,10 +177,13 @@ auto FileContext::GetGlobal(SemIR::InstId inst_id,
}
llvm::StringRef sep = (use_name[0] == '.') ? "" : ".";
return new llvm::GlobalVariable(
auto* global_variable = new llvm::GlobalVariable(
llvm_module(), GetType(sem_ir().GetPointeeType(value_rep.type_id)),
/*isConstant=*/true, llvm::GlobalVariable::InternalLinkage, const_value,
const_name + sep + use_name);
global_variables_.Insert(const_inst_id, global_variable);
return global_variable;
}
auto FileContext::GetOrCreateFunction(SemIR::FunctionId function_id,
toolchain/lower/testdata/class/virtual.carbon
Vendored
+2 -4
View File
@@ -110,8 +110,6 @@ fn Use() {
// CHECK:STDOUT: @"_CIntermediate.Classes.$vtable" = external unnamed_addr constant ptr
// CHECK:STDOUT: @"_CDerived.Classes.$vtable" = external unnamed_addr constant ptr
// CHECK:STDOUT: @Base.val.loc7_3.2 = internal constant {} zeroinitializer
// CHECK:STDOUT: @Base.val.loc8_44.6 = internal constant {} zeroinitializer
// CHECK:STDOUT: @Base.val.loc9_48.6 = internal constant {} zeroinitializer
// CHECK:STDOUT:
// CHECK:STDOUT: define void @_CCreate.Create() !dbg !4 {
// CHECK:STDOUT: entry:
@@ -125,13 +123,13 @@ fn Use() {
// CHECK:STDOUT: %.loc8_44.2.vptr = getelementptr inbounds nuw { ptr, {} }, ptr %i.var, i32 0, i32 0, !dbg !8
// CHECK:STDOUT: store ptr @"_CIntermediate.Classes.$vtable", ptr %.loc8_44.2.vptr, align 8, !dbg !8
// CHECK:STDOUT: %.loc8_44.5.base = getelementptr inbounds nuw { ptr, {} }, ptr %i.var, i32 0, i32 1, !dbg !8
// CHECK:STDOUT: call void @llvm.memcpy.p0.p0.i64(ptr align 1 %.loc8_44.5.base, ptr align 1 @Base.val.loc8_44.6, i64 0, i1 false), !dbg !8
// CHECK:STDOUT: call void @llvm.memcpy.p0.p0.i64(ptr align 1 %.loc8_44.5.base, ptr align 1 @Base.val.loc7_3.2, i64 0, i1 false), !dbg !8
// CHECK:STDOUT: call void @llvm.lifetime.start.p0(i64 8, ptr %d.var), !dbg !7
// CHECK:STDOUT: %.loc9_49.2.base = getelementptr inbounds nuw { { ptr, {} } }, ptr %d.var, i32 0, i32 0, !dbg !9
// CHECK:STDOUT: %.loc9_48.2.vptr = getelementptr inbounds nuw { ptr, {} }, ptr %.loc9_49.2.base, i32 0, i32 0, !dbg !10
// CHECK:STDOUT: store ptr @"_CDerived.Classes.$vtable", ptr %.loc9_48.2.vptr, align 8, !dbg !10
// CHECK:STDOUT: %.loc9_48.5.base = getelementptr inbounds nuw { ptr, {} }, ptr %.loc9_49.2.base, i32 0, i32 1, !dbg !10
// CHECK:STDOUT: call void @llvm.memcpy.p0.p0.i64(ptr align 1 %.loc9_48.5.base, ptr align 1 @Base.val.loc9_48.6, i64 0, i1 false), !dbg !10
// CHECK:STDOUT: call void @llvm.memcpy.p0.p0.i64(ptr align 1 %.loc9_48.5.base, ptr align 1 @Base.val.loc7_3.2, i64 0, i1 false), !dbg !10
// CHECK:STDOUT: call void @llvm.lifetime.start.p0(i64 8, ptr %d2.var), !dbg !7
// CHECK:STDOUT: ret void, !dbg !11
// CHECK:STDOUT: }
toolchain/lower/testdata/global/class_with_fun.carbon
Vendored
+1 -2
View File
@@ -20,7 +20,6 @@ var a: A = {};
// CHECK:STDOUT:
// CHECK:STDOUT: @a = internal global {} zeroinitializer
// CHECK:STDOUT: @A.val.loc13_12 = internal constant {} zeroinitializer
// CHECK:STDOUT: @A.val.loc16_1 = internal constant {} zeroinitializer
// CHECK:STDOUT: @llvm.global_ctors = appending global [1 x { i32, ptr, ptr }] [{ i32, ptr, ptr } { i32 0, ptr @_C__global_init.Main, ptr null }]
// CHECK:STDOUT:
// CHECK:STDOUT: define void @_Cret_a.Main(ptr sret({}) %return) !dbg !4 {
@@ -31,7 +30,7 @@ var a: A = {};
// CHECK:STDOUT:
// CHECK:STDOUT: define void @_C__global_init.Main() !dbg !8 {
// CHECK:STDOUT: entry:
// CHECK:STDOUT: call void @llvm.memcpy.p0.p0.i64(ptr align 1 @a, ptr align 1 @A.val.loc16_1, i64 0, i1 false), !dbg !9
// CHECK:STDOUT: call void @llvm.memcpy.p0.p0.i64(ptr align 1 @a, ptr align 1 @A.val.loc13_12, i64 0, i1 false), !dbg !9
// CHECK:STDOUT: ret void, !dbg !10
// CHECK:STDOUT: }
// CHECK:STDOUT: