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[clang][DebugInfo] Attach DW_AT_const_value to static data-member definitions if available #72730

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[clang][DebugInfo] Attach DW_AT_const_value to static data-member definitions if available #72730

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6dcb09d
[clang][DebugInfo][NFC] Create evaluateConstantInitializer helper fun…
Michael137 Nov 18, 2023
fcc6e19
fixup! clang-format
Michael137 Nov 18, 2023
148ab17
[clang][DebugInfo] Attach DW_AT_const_value to static data-member def…
Michael137 Nov 18, 2023
d654d67
fixup! make helper static
Michael137 Nov 18, 2023
e21fb80
fixup! add braces to adhere to llvm-code style
Michael137 Nov 18, 2023
c5a6f0e
fixup! use getAnyInitializer instead of canonical decl
Michael137 Nov 20, 2023
6677a50
fixup! fix tests
Michael137 Nov 20, 2023
3e5ed7b
fixup! clarify function comment
Michael137 Nov 20, 2023
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39 changes: 33 additions & 6 deletions clang/lib/CodeGen/CGDebugInfo.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -69,6 +69,29 @@ static uint32_t getDeclAlignIfRequired(const Decl *D, const ASTContext &Ctx) {
return D->hasAttr<AlignedAttr>() ? D->getMaxAlignment() : 0;
}

/// Given a VarDecl corresponding to either the definition or
/// declaration of a C++ static data member, if it has a constant
/// initializer and is evaluatable, return the evaluated value.
/// Returns std::nullopt otherwise.
static std::optional<APValue>
evaluateConstantInitializer(const clang::VarDecl *VD,
const clang::ASTContext &Ctx) {
assert(VD != nullptr);

if (!VD->isStaticDataMember())
return std::nullopt;

if (!VD->isUsableInConstantExpressions(Ctx))
return std::nullopt;

auto const *InitExpr = VD->getAnyInitializer();
Expr::EvalResult Result;
if (!InitExpr->EvaluateAsConstantExpr(Result, Ctx))
return std::nullopt;

return Result.Val;
}

CGDebugInfo::CGDebugInfo(CodeGenModule &CGM)
: CGM(CGM), DebugKind(CGM.getCodeGenOpts().getDebugInfo()),
DebugTypeExtRefs(CGM.getCodeGenOpts().DebugTypeExtRefs),
Expand Down Expand Up @@ -5503,11 +5526,18 @@ void CGDebugInfo::EmitGlobalVariable(llvm::GlobalVariable *Var,
}
AppendAddressSpaceXDeref(AddressSpace, Expr);

llvm::DIExpression *E = nullptr;
if (Expr.empty()) {
if (const auto InitVal = evaluateConstantInitializer(D, CGM.getContext()))
E = createConstantValueExpression(D, *InitVal);
} else {
E = DBuilder.createExpression(Expr);
}

llvm::DINodeArray Annotations = CollectBTFDeclTagAnnotations(D);
GVE = DBuilder.createGlobalVariableExpression(
DContext, DeclName, LinkageName, Unit, LineNo, getOrCreateType(T, Unit),
Var->hasLocalLinkage(), true,
Expr.empty() ? nullptr : DBuilder.createExpression(Expr),
Var->hasLocalLinkage(), true, E,
getOrCreateStaticDataMemberDeclarationOrNull(D), TemplateParameters,
Align, Annotations);
Var->addDebugInfo(GVE);
Expand Down Expand Up @@ -5596,14 +5626,11 @@ void CGDebugInfo::EmitGlobalVariable(const VarDecl *VD) {
if (VD->hasAttr<NoDebugAttr>())
return;

if (!VD->hasInit())
return;

const auto CacheIt = DeclCache.find(VD);
if (CacheIt != DeclCache.end())
return;

auto const *InitVal = VD->evaluateValue();
const auto InitVal = evaluateConstantInitializer(VD, CGM.getContext());
if (!InitVal)
return;

Expand Down
11 changes: 1 addition & 10 deletions clang/test/CodeGenCXX/debug-info-static-inline-member.cpp
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Expand Up @@ -43,7 +43,7 @@ int main() {
// CHECK: @{{.*}}cexpr_struct_with_addr{{.*}} =
// CHECK-SAME !dbg ![[EMPTY_GLOBAL:[0-9]+]]

// CHECK: !DIGlobalVariableExpression(var: ![[INT_VAR:[0-9]+]], expr: !DIExpression())
// CHECK: !DIGlobalVariableExpression(var: ![[INT_VAR:[0-9]+]], expr: !DIExpression(DW_OP_constu, 25, DW_OP_stack_value))
// CHECK: ![[INT_VAR]] = distinct !DIGlobalVariable(name: "cexpr_int_with_addr", linkageName:
// CHECK-SAME: isLocal: false, isDefinition: true, declaration: ![[INT_DECL:[0-9]+]])

Expand All @@ -67,10 +67,6 @@ int main() {
// CHECK-SAME: flags: DIFlagStaticMember
// CHECK-NOT: extraData:

// CHECK: ![[IENUM_DECL:[0-9]+]] = !DIDerivedType(tag: DW_TAG_member, name: "inline_enum",
// CHECK-SAME: flags: DIFlagStaticMember
// CHECK-NOT: extraData:

// CHECK: ![[EMPTY_TEMPLATED_DECL:[0-9]+]] = !DIDerivedType(tag: DW_TAG_member, name: "empty_templated",
// CHECK-SAME: flags: DIFlagStaticMember
// CHECK-NOT: extraData:
Expand Down Expand Up @@ -98,11 +94,6 @@ int main() {
// CHECK-NOT: linkageName:
// CHECK-SAME: isLocal: true, isDefinition: true, declaration: ![[ENUM_DECL]])

// CHECK: !DIGlobalVariableExpression(var: ![[IENUM_VAR:[0-9]+]], expr: !DIExpression(DW_OP_constu, {{.*}}, DW_OP_stack_value))
// CHECK: ![[IENUM_VAR]] = distinct !DIGlobalVariable(name: "inline_enum"
// CHECK-NOT: linkageName:
// CHECK-SAME: isLocal: true, isDefinition: true, declaration: ![[IENUM_DECL]])

// CHECK: !DIGlobalVariableExpression(var: ![[EMPTY_TEMPLATED_VAR:[0-9]+]], expr: !DIExpression(DW_OP_constu, 1, DW_OP_stack_value))
// CHECK: ![[EMPTY_TEMPLATED_VAR]] = distinct !DIGlobalVariable(name: "empty_templated"
// CHECK-NOT: linkageName:
Expand Down
14 changes: 7 additions & 7 deletions clang/test/CodeGenCXX/debug-info-static-member.cpp
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@@ -1,8 +1,8 @@
// RUN: %clangxx -target x86_64-unknown-unknown -g -gdwarf-4 %s -emit-llvm -S -o - | FileCheck --check-prefixes=CHECK,DWARF4,NOT-MS %s
// RUN: %clangxx -target x86_64-unknown-unknown -g -gdwarf-4 %s -emit-llvm -S -o - | FileCheck --check-prefixes=CHECK,DWARF4,CPP11,NOT-MS %s
// RUN: %clangxx -target x86_64-unknown-unknown -g -gdwarf-4 -std=c++98 %s -emit-llvm -S -o - | FileCheck --check-prefixes=CHECK,DWARF4,NOT-MS %s
// RUN: %clangxx -target x86_64-unknown-unknown -g -gdwarf-4 -std=c++11 %s -emit-llvm -S -o - | FileCheck --check-prefixes=CHECK,DWARF4,NOT-MS %s
// RUN: %clangxx -target x86_64-unknown-unknown -g -gdwarf-5 -std=c++11 %s -emit-llvm -S -o - | FileCheck --check-prefixes=CHECK,DWARF5 %s
// RUN: %clangxx -target x86_64-windows-msvc -g -gdwarf-4 %s -emit-llvm -S -o - | FileCheck --check-prefixes=CHECK,DWARF4 %s
// RUN: %clangxx -target x86_64-unknown-unknown -g -gdwarf-4 -std=c++11 %s -emit-llvm -S -o - | FileCheck --check-prefixes=CHECK,DWARF4,CPP11,NOT-MS %s
// RUN: %clangxx -target x86_64-unknown-unknown -g -gdwarf-5 -std=c++11 %s -emit-llvm -S -o - | FileCheck --check-prefixes=CHECK,DWARF5,CPP11 %s
// RUN: %clangxx -target x86_64-windows-msvc -g -gdwarf-4 %s -emit-llvm -S -o - | FileCheck --check-prefixes=CHECK,DWARF4,CPP11 %s
// PR14471

// CHECK: @{{.*}}a{{.*}} = dso_local global i32 4, align 4, !dbg [[A:![0-9]+]]
Expand Down Expand Up @@ -171,9 +171,9 @@ int y::z;
// CHECK: ![[CONST_A_VAR]] = distinct !DIGlobalVariable(name: "const_a"
// CHECK-SAME: isLocal: true, isDefinition: true, declaration: ![[CONST_A_DECL]])

// CHECK: !DIGlobalVariableExpression(var: ![[CONST_B_VAR:[0-9]+]], expr: !DIExpression(DW_OP_constu, {{.*}}, DW_OP_stack_value))
// CHECK: ![[CONST_B_VAR]] = distinct !DIGlobalVariable(name: "const_b"
// CHECK-SAME: isLocal: true, isDefinition: true, declaration: ![[CONST_B_DECL]])
// CPP11: !DIGlobalVariableExpression(var: ![[CONST_B_VAR:[0-9]+]], expr: !DIExpression(DW_OP_constu, {{.*}}, DW_OP_stack_value))
// CPP11: ![[CONST_B_VAR]] = distinct !DIGlobalVariable(name: "const_b"
// CPP11-SAME: isLocal: true, isDefinition: true, declaration: ![[CONST_B_DECL]])

// CHECK: !DIGlobalVariableExpression(var: ![[CONST_C_VAR:[0-9]+]], expr: !DIExpression(DW_OP_constu, 18, DW_OP_stack_value))
// CHECK: ![[CONST_C_VAR]] = distinct !DIGlobalVariable(name: "const_c"
Expand Down
2 changes: 1 addition & 1 deletion clang/test/CodeGenCXX/inline-dllexport-member.cpp
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Expand Up @@ -7,7 +7,7 @@ struct __declspec(dllexport) s {
static const unsigned int ui = 0;
};

// CHECK: [[UI]] = !DIGlobalVariableExpression(var: [[UIV:.*]], expr: !DIExpression())
// CHECK: [[UI]] = !DIGlobalVariableExpression(var: [[UIV:.*]], expr: !DIExpression(DW_OP_constu, 0, DW_OP_stack_value))
// CHECK: [[UIV]] = distinct !DIGlobalVariable(name: "ui", linkageName: "?ui@s@@2IB", scope: ![[SCOPE:[0-9]+]],
// CHECK: ![[SCOPE]] = distinct !DICompileUnit(