[clang] 53a24c3 - [clang][DebugInfo] Improve heuristic to determine whether to evaluate a static variable's initializer (#72974)
via cfe-commits
cfe-commits at lists.llvm.org
Thu Nov 30 02:41:30 PST 2023
Author: Michael Buch
Date: 2023-11-30T10:41:24Z
New Revision: 53a24c33f09b81b8f009afbabd05f7086db3f288
URL: https://github.com/llvm/llvm-project/commit/53a24c33f09b81b8f009afbabd05f7086db3f288
DIFF: https://github.com/llvm/llvm-project/commit/53a24c33f09b81b8f009afbabd05f7086db3f288.diff
LOG: [clang][DebugInfo] Improve heuristic to determine whether to evaluate a static variable's initializer (#72974)
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-member` test (which existed since its
introduction in https://github.com/llvm/llvm-project/pull/71780)
**Test changes**
* `debug-info-static-member.cpp`:
* We added the check for `const_b` as part of the
patch series in `638a8393615e911b729d5662096f60ef49f1c65e`.
The check for `isUsableAsConstantExpression` added in the current patch
doesn'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_b` anyway. Now
we just don't do it for `inline const float`s. This is consistent with
GCC's behaviour starting with C++11.
* `debug-info-static-inline-member`:
* This was just a bug which is now fixed. We shouldn't emit
a `DW_AT_const_value` for a non-const static.
Added:
Modified:
clang/lib/CodeGen/CGDebugInfo.cpp
clang/test/CodeGenCXX/debug-info-static-inline-member.cpp
clang/test/CodeGenCXX/debug-info-static-member.cpp
Removed:
################################################################################
diff --git a/clang/lib/CodeGen/CGDebugInfo.cpp b/clang/lib/CodeGen/CGDebugInfo.cpp
index f1f4a1b79b7bcf4..602e325e560f98d 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),
@@ -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;
diff --git a/clang/test/CodeGenCXX/debug-info-static-inline-member.cpp b/clang/test/CodeGenCXX/debug-info-static-inline-member.cpp
index d3b6a363c5bd8f2..1a1547a687f9188 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-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
@@ -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:
diff --git a/clang/test/CodeGenCXX/debug-info-static-member.cpp b/clang/test/CodeGenCXX/debug-info-static-member.cpp
index 096bfa0271e0e3d..a111dc84b6e665a 100644
--- a/clang/test/CodeGenCXX/debug-info-static-member.cpp
+++ b/clang/test/CodeGenCXX/debug-info-static-member.cpp
@@ -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]+]]
@@ -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"
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