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[clang][DebugInfo] Improve heuristic to determine whether to evaluate a static variable's initializer #72974

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Nov 30, 2023
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[clang][DebugInfo] Improve heuristic to determine whether to evaluate a static variable's initializer #72974

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0120962
[clang][DebugInfo] Create evaluateConstantInitializer helper function
Michael137 Nov 18, 2023
a5614db
Merge branch 'main' into inline-statics-support/clang/improve-initial…
Michael137 Nov 30, 2023
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28 changes: 24 additions & 4 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 @@ -5610,14 +5633,11 @@ 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
9 changes: 0 additions & 9 deletions clang/test/CodeGenCXX/debug-info-static-inline-member.cpp
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Expand Up @@ -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-SAME: extraData: i32 -1

// CHECK: ![[EMPTY_TEMPLATED_DECL:[0-9]+]] = !DIDerivedType(tag: DW_TAG_member, name: "empty_templated",
// CHECK-SAME: flags: DIFlagStaticMember
// CHECK-SAME: extraData: i32 1
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