[Lldb-commits] [lldb] [clang] Reland "[clang][DebugInfo] Emit global variable definitions for static data members with constant initializers" (PR #71780)
Michael Buch via lldb-commits
lldb-commits at lists.llvm.org
Wed Nov 8 23:03:42 PST 2023
https://github.com/Michael137 created https://github.com/llvm/llvm-project/pull/71780
This patch relands https://github.com/llvm/llvm-project/pull/70639
It was reverted because under certain conditions we triggered an assertion
in `DIBuilder`. Specifically, in the original patch we called `EmitGlobalVariable`
at the end of `CGDebugInfo::finalize`, after all the temporary `DIType`s have
been uniqued. With limited debug-info such temporary nodes would be created
more frequently, leaving us with non-uniqued nodes by the time we got to
`DIBuilder::finalize`; this violated its pre-condition and caused
assertions to trigger.
To fix this, the latest iteration of the patch moves `EmitGlobalVariable` to the
beginning of `CGDebugInfo::finalize`. Now, when we create a temporary
`DIType` node as a result of emitting a variable definition, it will get uniqued
in time. A test-case was added for this scenario.
Original commit message:
"""
When an LLDB user asks for the value of a static data member, LLDB starts
by searching the Names accelerator table for the corresponding variable
definition DIE. For static data members with out-of-class definitions that
works fine, because those get represented as global variables with a location
and making them eligible to be added to the Names table. However, in-class
definitions won’t get indexed because we usually don't emit global variables
for them. So in DWARF we end up with a single `DW_TAG_member` that
usually holds the constant initializer. But we don't get a corresponding
CU-level `DW_TAG_variable` like we do for out-of-class definitions.
To make it more convenient for debuggers to get to the value of inline static data
members, this patch makes sure we emit definitions for static variables with
constant initializers the same way we do for other static variables. This also aligns
Clang closer to GCC, which produces CU-level definitions for inline statics and also
emits these into `.debug_pubnames`.
The implementation keeps track of newly created static data members.
Then in `CGDebugInfo::finalize`, we emit a global `DW_TAG_variable` with a
`DW_AT_const_value` for any of those declarations that didn't end up with a
definition in the `DeclCache`.
The newly emitted `DW_TAG_variable` will look as follows:
```
0x0000007b: DW_TAG_structure_type
DW_AT_calling_convention (DW_CC_pass_by_value)
DW_AT_name ("Foo")
...
0x0000008d: DW_TAG_member
DW_AT_name ("i")
DW_AT_type (0x00000062 "const int")
DW_AT_external (true)
DW_AT_declaration (true)
DW_AT_const_value (4)
Newly added
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
0x0000009a: DW_TAG_variable
DW_AT_specification (0x0000008d "i")
DW_AT_const_value (4)
DW_AT_linkage_name ("_ZN2t2IiE1iIfEE")
```
This patch also drops the `DW_AT_const_value` off of the declaration since we
now always have it on the definition. This ensures that the `DWARFParallelLinker`
can type-merge class with static members where we couldn't attach the constant
on the declaration in some CUs.
"""
Dependent changes:
* https://github.com/llvm/llvm-project/pull/71004
* https://github.com/llvm/llvm-project/pull/70641
>From e5bc858c35b479d29174c9945c6c67f4d2dc085b Mon Sep 17 00:00:00 2001
From: Michael Buch <michaelbuch12 at gmail.com>
Date: Thu, 9 Nov 2023 01:13:21 +0000
Subject: [PATCH] Reland "[clang][DebugInfo] Emit global variable definitions
for static data members with constant initializers"
---
clang/lib/CodeGen/CGDebugInfo.cpp | 58 +++++++++++++++----
clang/lib/CodeGen/CGDebugInfo.h | 6 ++
clang/test/CodeGenCXX/debug-info-class.cpp | 13 +++--
.../CodeGenCXX/debug-info-static-member.cpp | 52 ++++++++++-------
.../TestConstStaticIntegralMember.py | 7 ++-
.../lldb-dap/variables/TestDAP_variables.py | 9 +--
6 files changed, 103 insertions(+), 42 deletions(-)
diff --git a/clang/lib/CodeGen/CGDebugInfo.cpp b/clang/lib/CodeGen/CGDebugInfo.cpp
index 84a166d3ac3659c..245f7516640d098 100644
--- a/clang/lib/CodeGen/CGDebugInfo.cpp
+++ b/clang/lib/CodeGen/CGDebugInfo.cpp
@@ -1677,22 +1677,13 @@ CGDebugInfo::CreateRecordStaticField(const VarDecl *Var, llvm::DIType *RecordTy,
unsigned LineNumber = getLineNumber(Var->getLocation());
StringRef VName = Var->getName();
- llvm::Constant *C = nullptr;
- if (Var->getInit()) {
- const APValue *Value = Var->evaluateValue();
- if (Value) {
- if (Value->isInt())
- C = llvm::ConstantInt::get(CGM.getLLVMContext(), Value->getInt());
- if (Value->isFloat())
- C = llvm::ConstantFP::get(CGM.getLLVMContext(), Value->getFloat());
- }
- }
llvm::DINode::DIFlags Flags = getAccessFlag(Var->getAccess(), RD);
auto Align = getDeclAlignIfRequired(Var, CGM.getContext());
llvm::DIDerivedType *GV = DBuilder.createStaticMemberType(
- RecordTy, VName, VUnit, LineNumber, VTy, Flags, C, Align);
+ RecordTy, VName, VUnit, LineNumber, VTy, Flags, /* Val */ nullptr, Align);
StaticDataMemberCache[Var->getCanonicalDecl()].reset(GV);
+ StaticDataMemberDefinitionsToEmit.push_back(Var->getCanonicalDecl());
return GV;
}
@@ -5596,6 +5587,39 @@ void CGDebugInfo::EmitGlobalVariable(const ValueDecl *VD, const APValue &Init) {
TemplateParameters, Align));
}
+void CGDebugInfo::EmitGlobalVariable(const VarDecl *VD) {
+ assert(VD->hasInit());
+ assert(CGM.getCodeGenOpts().hasReducedDebugInfo());
+ if (VD->hasAttr<NoDebugAttr>())
+ return;
+
+ auto &GV = DeclCache[VD];
+ if (GV)
+ return;
+
+ auto const *InitVal = VD->evaluateValue();
+ if (!InitVal)
+ return;
+
+ llvm::DIFile *Unit = nullptr;
+ llvm::DIScope *DContext = nullptr;
+ unsigned LineNo;
+ StringRef DeclName, LinkageName;
+ QualType T;
+ llvm::MDTuple *TemplateParameters = nullptr;
+ collectVarDeclProps(VD, Unit, LineNo, T, DeclName, LinkageName,
+ TemplateParameters, DContext);
+
+ auto Align = getDeclAlignIfRequired(VD, CGM.getContext());
+ llvm::DINodeArray Annotations = CollectBTFDeclTagAnnotations(VD);
+ llvm::DIExpression *InitExpr = createConstantValueExpression(VD, *InitVal);
+
+ GV.reset(DBuilder.createGlobalVariableExpression(
+ TheCU, DeclName, LinkageName, Unit, LineNo, getOrCreateType(T, Unit),
+ true, true, InitExpr, getOrCreateStaticDataMemberDeclarationOrNull(VD),
+ TemplateParameters, Align, Annotations));
+}
+
void CGDebugInfo::EmitExternalVariable(llvm::GlobalVariable *Var,
const VarDecl *D) {
assert(CGM.getCodeGenOpts().hasReducedDebugInfo());
@@ -5800,6 +5824,18 @@ void CGDebugInfo::setDwoId(uint64_t Signature) {
}
void CGDebugInfo::finalize() {
+ for (auto const *VD : StaticDataMemberDefinitionsToEmit) {
+ assert(VD->isStaticDataMember());
+
+ if (DeclCache.contains(VD))
+ continue;
+
+ if (!VD->hasInit())
+ continue;
+
+ EmitGlobalVariable(VD);
+ }
+
// Creating types might create further types - invalidating the current
// element and the size(), so don't cache/reference them.
for (size_t i = 0; i != ObjCInterfaceCache.size(); ++i) {
diff --git a/clang/lib/CodeGen/CGDebugInfo.h b/clang/lib/CodeGen/CGDebugInfo.h
index 7b60e94555d0608..3e4c133b7f2b9f1 100644
--- a/clang/lib/CodeGen/CGDebugInfo.h
+++ b/clang/lib/CodeGen/CGDebugInfo.h
@@ -161,6 +161,9 @@ class CGDebugInfo {
llvm::DenseMap<const Decl *, llvm::TypedTrackingMDRef<llvm::DIDerivedType>>
StaticDataMemberCache;
+ /// Keeps track of static data members for which we should emit a definition.
+ std::vector<const VarDecl *> StaticDataMemberDefinitionsToEmit;
+
using ParamDecl2StmtTy = llvm::DenseMap<const ParmVarDecl *, const Stmt *>;
using Param2DILocTy =
llvm::DenseMap<const ParmVarDecl *, llvm::DILocalVariable *>;
@@ -526,6 +529,9 @@ class CGDebugInfo {
/// Emit a constant global variable's debug info.
void EmitGlobalVariable(const ValueDecl *VD, const APValue &Init);
+ /// Emit debug-info for a variable with a constant initializer.
+ void EmitGlobalVariable(const VarDecl *VD);
+
/// Emit information about an external variable.
void EmitExternalVariable(llvm::GlobalVariable *GV, const VarDecl *Decl);
diff --git a/clang/test/CodeGenCXX/debug-info-class.cpp b/clang/test/CodeGenCXX/debug-info-class.cpp
index ef84b91b67821a9..a3111cd7c3640a0 100644
--- a/clang/test/CodeGenCXX/debug-info-class.cpp
+++ b/clang/test/CodeGenCXX/debug-info-class.cpp
@@ -116,11 +116,19 @@ int main(int argc, char **argv) {
// CHECK-SAME: DIFlagFwdDecl
// CHECK-NOT: identifier:
// CHECK-SAME: ){{$}}
+
+// CHECK: !DIGlobalVariableExpression(var: ![[HDR_VAR:[0-9]+]], expr: !DIExpression(DW_OP_constu, 52, DW_OP_stack_value))
+// CHECK: ![[HDR_VAR]] = distinct !DIGlobalVariable(name: "HdrSize",
+// CHECK-SAME: isLocal: true, isDefinition: true, declaration: ![[HDR_VAR_DECL:[0-9]+]])
+// CHECK: ![[INT:[0-9]+]] = !DIBasicType(name: "int"
+// CHECK: ![[HDR_VAR_DECL]] = !DIDerivedType(tag: DW_TAG_member, name: "HdrSize"
+
+// CHECK: !DICompositeType(tag: DW_TAG_structure_type, name: "A"
+
// CHECK: !DICompositeType(tag: DW_TAG_structure_type, name: "I"
// CHECK-NOT: DIFlagFwdDecl
// CHECK-SAME: ){{$}}
-// CHECK: ![[INT:[0-9]+]] = !DIBasicType(name: "int"
// CHECK: !DICompositeType(tag: DW_TAG_structure_type, name: "foo"
// CHECK: !DICompositeType(tag: DW_TAG_class_type, name: "bar"
// CHECK: !DICompositeType(tag: DW_TAG_union_type, name: "baz"
@@ -186,8 +194,5 @@ int main(int argc, char **argv) {
// CHECK: [[G_INNER_I]] = !DIDerivedType(tag: DW_TAG_member, name: "j"
// CHECK-SAME: baseType: ![[INT]]
-// CHECK: !DICompositeType(tag: DW_TAG_structure_type, name: "A"
-// CHECK: !DIDerivedType(tag: DW_TAG_member, name: "HdrSize"
-//
// CHECK: ![[EXCEPTLOC]] = !DILocation(line: 100,
// CHECK: ![[RETLOC]] = !DILocation(line: 99,
diff --git a/clang/test/CodeGenCXX/debug-info-static-member.cpp b/clang/test/CodeGenCXX/debug-info-static-member.cpp
index 260a3afdd6524f3..578995801c6400b 100644
--- a/clang/test/CodeGenCXX/debug-info-static-member.cpp
+++ b/clang/test/CodeGenCXX/debug-info-static-member.cpp
@@ -63,19 +63,19 @@ int C::a = 4;
// CHECK-NOT: offset:
// CHECK-SAME: flags: DIFlagStaticMember)
//
-// CHECK: !DIDerivedType(tag: DW_TAG_member, name: "const_a"
-// CHECK-NOT: size:
-// CHECK-NOT: align:
-// CHECK-NOT: offset:
-// CHECK-SAME: flags: DIFlagStaticMember,
-// CHECK-SAME: extraData: i1 true)
-
-// CHECK: !DIDerivedType(tag: DW_TAG_member, name: "const_b"
-// CHECK-NOT: size:
-// CHECK-NOT: align:
-// CHECK-NOT: offset:
-// CHECK-SAME: flags: DIFlagProtected | DIFlagStaticMember,
-// CHECK-SAME: extraData: float 0x{{.*}})
+// CHECK: ![[CONST_A_DECL:[0-9]+]] = !DIDerivedType(tag: DW_TAG_member, name: "const_a"
+// CHECK-NOT: size:
+// CHECK-NOT: align:
+// CHECK-NOT: offset:
+// CHECK-SAME: flags: DIFlagStaticMember
+// CHECK-NOT: extraData:
+
+// CHECK: ![[CONST_B_DECL:[0-9]+]] = !DIDerivedType(tag: DW_TAG_member, name: "const_b"
+// CHECK-NOT: size:
+// CHECK-NOT: align:
+// CHECK-NOT: offset:
+// CHECK-SAME: flags: DIFlagProtected | DIFlagStaticMember
+// CHECK-NOT: extraData:
// CHECK: ![[DECL_C:[0-9]+]] = !DIDerivedType(tag: DW_TAG_member, name: "c"
// CHECK-NOT: size:
@@ -83,12 +83,12 @@ int C::a = 4;
// CHECK-NOT: offset:
// CHECK-SAME: flags: DIFlagPublic | DIFlagStaticMember)
//
-// CHECK: !DIDerivedType(tag: DW_TAG_member, name: "const_c"
-// CHECK-NOT: size:
-// CHECK-NOT: align:
-// CHECK-NOT: offset:
-// CHECK-SAME: flags: DIFlagPublic | DIFlagStaticMember,
-// CHECK-SAME: extraData: i32 18)
+// CHECK: ![[CONST_C_DECL:[0-9]+]] = !DIDerivedType(tag: DW_TAG_member, name: "const_c"
+// CHECK-NOT: size:
+// CHECK-NOT: align:
+// CHECK-NOT: offset:
+// CHECK-SAME: flags: DIFlagPublic | DIFlagStaticMember
+// CHECK-NOT: extraData:
//
// CHECK: !DIDerivedType(tag: DW_TAG_member, name: "x_a"
// CHECK-SAME: flags: DIFlagPublic | DIFlagStaticMember)
@@ -144,7 +144,7 @@ struct V {
// const_va is not emitted for MS targets.
// NOT-MS: !DIDerivedType(tag: DW_TAG_member, name: "const_va",
// NOT-MS-SAME: line: [[@LINE-5]]
-// NOT-MS-SAME: extraData: i32 42
+// NOT-MS-NOT: extraData:
const int V::const_va;
namespace x {
@@ -156,3 +156,15 @@ struct y {
};
int y::z;
}
+
+// CHECK: !DIGlobalVariableExpression(var: ![[CONST_A_VAR:[0-9]+]], expr: !DIExpression(DW_OP_constu, 1, DW_OP_stack_value))
+// 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]])
+
+// 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"
+// CHECK-SAME: isLocal: true, isDefinition: true, declaration: ![[CONST_C_DECL]])
diff --git a/lldb/test/API/lang/cpp/const_static_integral_member/TestConstStaticIntegralMember.py b/lldb/test/API/lang/cpp/const_static_integral_member/TestConstStaticIntegralMember.py
index 530191e8a37ba1b..78ea23ac8f70610 100644
--- a/lldb/test/API/lang/cpp/const_static_integral_member/TestConstStaticIntegralMember.py
+++ b/lldb/test/API/lang/cpp/const_static_integral_member/TestConstStaticIntegralMember.py
@@ -102,9 +102,10 @@ def test(self):
# it does not crash.
self.expect("image lookup -t A")
- # dsymutil strips the debug info for classes that only have const static
- # data members without a definition namespace scope.
- @expectedFailureAll(debug_info=["dsym"])
+ # For debug-info produced by older versions of clang, dsymutil strips the
+ # debug info for classes that only have const static data members without
+ # definitions.
+ @expectedFailureAll(compiler=["clang"], compiler_version=["<", "18.0"])
def test_class_with_only_const_static(self):
self.build()
lldbutil.run_to_source_breakpoint(
diff --git a/lldb/test/API/tools/lldb-dap/variables/TestDAP_variables.py b/lldb/test/API/tools/lldb-dap/variables/TestDAP_variables.py
index 11d9bf18db7a6e1..d2a21ad3cd1d44f 100644
--- a/lldb/test/API/tools/lldb-dap/variables/TestDAP_variables.py
+++ b/lldb/test/API/tools/lldb-dap/variables/TestDAP_variables.py
@@ -87,10 +87,11 @@ def verify_values(self, verify_dict, actual, varref_dict=None, expression=None):
def verify_variables(self, verify_dict, variables, varref_dict=None):
for variable in variables:
name = variable["name"]
- self.assertIn(
- name, verify_dict, 'variable "%s" in verify dictionary' % (name)
- )
- self.verify_values(verify_dict[name], variable, varref_dict)
+ if not name.startswith("std::"):
+ self.assertIn(
+ name, verify_dict, 'variable "%s" in verify dictionary' % (name)
+ )
+ self.verify_values(verify_dict[name], variable, varref_dict)
def darwin_dwarf_missing_obj(self, initCommands):
self.build(debug_info="dwarf")
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