[clang][DebugInfo] Improve heuristic to determine whether to evaluate a static variable's initializer #72974
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@llvm/pr-subscribers-debuginfo @llvm/pr-subscribers-clang-codegen Author: Michael Buch (Michael137) ChangesThis patch extracts the logic to evaluate a C++ static data-member's constant initializer such that it can be used by an upcoming patch. It also makes the check for whether we are dealing with a constant initializer more robust/idiomatic, which revealed a bug in the Full diff: https://github.com/llvm/llvm-project/pull/72974.diff 2 Files Affected:
diff --git a/clang/lib/CodeGen/CGDebugInfo.cpp b/clang/lib/CodeGen/CGDebugInfo.cpp
index 0b52d99ad07f164..4c7c7d68b4271e3 100644
--- a/clang/lib/CodeGen/CGDebugInfo.cpp
+++ b/clang/lib/CodeGen/CGDebugInfo.cpp
@@ -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),
@@ -5596,14 +5619,11 @@ 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;
diff --git a/clang/test/CodeGenCXX/debug-info-static-inline-member.cpp b/clang/test/CodeGenCXX/debug-info-static-inline-member.cpp
index f2d4d9408a8297a..6ba98373d33ada8 100644
--- a/clang/test/CodeGenCXX/debug-info-static-inline-member.cpp
+++ b/clang/test/CodeGenCXX/debug-info-static-inline-member.cpp
@@ -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:
@@ -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:
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@llvm/pr-subscribers-clang Author: Michael Buch (Michael137) ChangesThis patch extracts the logic to evaluate a C++ static data-member's constant initializer such that it can be used by an upcoming patch. It also makes the check for whether we are dealing with a constant initializer more robust/idiomatic, which revealed a bug in the Full diff: https://github.com/llvm/llvm-project/pull/72974.diff 2 Files Affected:
diff --git a/clang/lib/CodeGen/CGDebugInfo.cpp b/clang/lib/CodeGen/CGDebugInfo.cpp
index 0b52d99ad07f164..4c7c7d68b4271e3 100644
--- a/clang/lib/CodeGen/CGDebugInfo.cpp
+++ b/clang/lib/CodeGen/CGDebugInfo.cpp
@@ -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),
@@ -5596,14 +5619,11 @@ 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;
diff --git a/clang/test/CodeGenCXX/debug-info-static-inline-member.cpp b/clang/test/CodeGenCXX/debug-info-static-inline-member.cpp
index f2d4d9408a8297a..6ba98373d33ada8 100644
--- a/clang/test/CodeGenCXX/debug-info-static-inline-member.cpp
+++ b/clang/test/CodeGenCXX/debug-info-static-inline-member.cpp
@@ -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:
@@ -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:
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This patch extracts the logic to evaluate a C++ static data-member's constant initializer such that it can be used by an upcoming patch. It also makes the check for whether we are dealing with a constant initializer more robust/idiomatic, which revealed a bug in the `debug-info-static-inline-member` test.
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Nov 29, 2023
Michael137
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Nov 30, 2023
…fo-static-inline-member The check for this was removed in llvm#72974 This patch removes the member from the source itself since it was confusing FileCheck
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Test fix in flight... |
Michael137
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that referenced
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Nov 30, 2023
…fo-static-inline-member The check for this was removed in #72974 This patch removes the member from the source itself since it was confusing FileCheck
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This patch extracts the logic to evaluate a C++ static data-member's constant initializer. This logic will be re-used in an upcoming patch.
It also makes the check for whether we are dealing with a constant initializer more robust/idiomatic, which revealed a bug in the
debug-info-static-inline-membertest (which existed since its introduction in #71780)Test changes
debug-info-static-member.cpp:const_bas part of thepatch series in
638a8393615e911b729d5662096f60ef49f1c65e.The check for
isUsableAsConstantExpressionadded in the current patchdoesn't support constant inline floats (since they are neither constexpr nor
integrals). This isn't a regression since before said patch series
we wouldn't ever emit the definition for
const_banyway. Nowwe just don't do it for
inline const floats. This is consistent withGCC's behaviour starting with C++11.
debug-info-static-inline-member:a
DW_AT_const_valuefor a non-const static.