[clang][DebugInfo] Revert to attaching DW_AT_const_value on static member declarations #73626
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…mber declarations In llvm#71780 we started emitting definitions for all static data-members with constant initialisers, even if they were constants (i.e., didn't have a location). We also dropped the DW_AT_const_value from the declaration to help resolve inconsistencies during type merging in the DWARFParallelLinker. However, for static data members that do have locations, we wouldn't emit a DW_AT_const_value on it, assuming that the consumer knows how to read the value using the location. This broke some consumers that really wanted to find a DW_AT_const_value. Ultimately we want to attach a DW_AT_const_value to definitions that have a location too. But to fix consumers broken by said change, this patch adds the constant back onto the declaration.
llvmbot
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FYI @petrhosek |
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@llvm/pr-subscribers-clang @llvm/pr-subscribers-debuginfo Author: Michael Buch (Michael137) ChangesIn #71780 we started emitting definitions for all static data-members with constant initialisers, even if they were constants (i.e., didn't have a location). We also dropped the DW_AT_const_value from the declaration to help resolve inconsistencies during type merging in the DWARFParallelLinker. However, for static data members that do have locations, we wouldn't emit a DW_AT_const_value on it, assuming that the consumer knows how to read the value using the location. This broke some consumers that really wanted to find a DW_AT_const_value. Ultimately we want to attach a DW_AT_const_value to definitions that have a location too. But to fix consumers broken by said change, this patch adds the constant back onto the declaration. Full diff: https://github.com/llvm/llvm-project/pull/73626.diff 3 Files Affected:
diff --git a/clang/lib/CodeGen/CGDebugInfo.cpp b/clang/lib/CodeGen/CGDebugInfo.cpp
index 0b52d99ad07f164..5d9d5d1792450c3 100644
--- a/clang/lib/CodeGen/CGDebugInfo.cpp
+++ b/clang/lib/CodeGen/CGDebugInfo.cpp
@@ -1678,14 +1678,26 @@ CGDebugInfo::CreateRecordStaticField(const VarDecl *Var, llvm::DIType *RecordTy,
unsigned LineNumber = getLineNumber(Var->getLocation());
StringRef VName = Var->getName();
+ // FIXME: to avoid complications with type merging we should
+ // emit the constant on the definition instead of the declaration.
+ 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 Tag = CGM.getCodeGenOpts().DwarfVersion >= 5
? llvm::dwarf::DW_TAG_variable
: llvm::dwarf::DW_TAG_member;
auto Align = getDeclAlignIfRequired(Var, CGM.getContext());
- llvm::DIDerivedType *GV =
- DBuilder.createStaticMemberType(RecordTy, VName, VUnit, LineNumber, VTy,
- Flags, /* Val */ nullptr, Tag, Align);
+ llvm::DIDerivedType *GV = DBuilder.createStaticMemberType(
+ RecordTy, VName, VUnit, LineNumber, VTy, Flags, C, Tag, Align);
StaticDataMemberCache[Var->getCanonicalDecl()].reset(GV);
StaticDataMemberDefinitionsToEmit.push_back(Var->getCanonicalDecl());
return GV;
diff --git a/clang/test/CodeGenCXX/debug-info-static-inline-member.cpp b/clang/test/CodeGenCXX/debug-info-static-inline-member.cpp
index f2d4d9408a8297a..d3b6a363c5bd8f2 100644
--- a/clang/test/CodeGenCXX/debug-info-static-inline-member.cpp
+++ b/clang/test/CodeGenCXX/debug-info-static-inline-member.cpp
@@ -49,19 +49,19 @@ int main() {
// CHECK: ![[INT_DECL]] = !DIDerivedType(tag: DW_TAG_member, name: "cexpr_int_with_addr",
// CHECK-SAME: flags: DIFlagStaticMember
-// CHECK-NOT: extraData:
+// CHECK-SAME: extraData: i32 25
// CHECK: ![[INT_DECL2:[0-9]+]] = !DIDerivedType(tag: DW_TAG_member, name: "cexpr_int2",
// CHECK-SAME: flags: DIFlagStaticMember
-// CHECK-NOT: extraData:
+// CHECK-SAME: extraData: i32 26
// CHECK: ![[FLOAT_DECL:[0-9]+]] = !DIDerivedType(tag: DW_TAG_member, name: "cexpr_float",
// CHECK-SAME: flags: DIFlagStaticMember
-// CHECK-NOT: extraData:
+// CHECK-SAME: extraData: float
// CHECK: ![[ENUM_DECL:[0-9]+]] = !DIDerivedType(tag: DW_TAG_member, name: "cexpr_enum",
// CHECK-SAME: flags: DIFlagStaticMember
-// CHECK-NOT: extraData:
+// CHECK-SAME: extraData: i32 -1
// CHECK: ![[EMPTY_DECL:[0-9]+]] = !DIDerivedType(tag: DW_TAG_member, name: "cexpr_struct_with_addr",
// CHECK-SAME: flags: DIFlagStaticMember
@@ -69,15 +69,15 @@ int main() {
// CHECK: ![[IENUM_DECL:[0-9]+]] = !DIDerivedType(tag: DW_TAG_member, name: "inline_enum",
// CHECK-SAME: flags: DIFlagStaticMember
-// CHECK-NOT: extraData:
+// CHECK-SAME: extraData: i32 -1
// CHECK: ![[EMPTY_TEMPLATED_DECL:[0-9]+]] = !DIDerivedType(tag: DW_TAG_member, name: "empty_templated",
// CHECK-SAME: flags: DIFlagStaticMember
-// CHECK-NOT: extraData:
+// CHECK-SAME: extraData: i32 1
// CHECK: ![[TEMPLATE_DECL:[0-9]+]] = !DIDerivedType(tag: DW_TAG_member, name: "cexpr_template",
// CHECK-SAME: flags: DIFlagStaticMember
-// CHECK-NOT: extraData:
+// CHECK-SAME: extraData: i32 1
// CHECK: !DIGlobalVariableExpression(var: ![[EMPTY_VAR:[0-9]+]], expr: !DIExpression())
// CHECK: ![[EMPTY_VAR]] = distinct !DIGlobalVariable(name: "cexpr_struct_with_addr", linkageName:
diff --git a/clang/test/CodeGenCXX/debug-info-static-member.cpp b/clang/test/CodeGenCXX/debug-info-static-member.cpp
index a2d25e98ed1cb62..096bfa0271e0e3d 100644
--- a/clang/test/CodeGenCXX/debug-info-static-member.cpp
+++ b/clang/test/CodeGenCXX/debug-info-static-member.cpp
@@ -74,7 +74,7 @@ int C::a = 4;
// CHECK-NOT: align:
// CHECK-NOT: offset:
// CHECK-SAME: flags: DIFlagStaticMember
-// CHECK-NOT: extraData:
+// CHECK-SAME: extraData: i1 true
// DWARF4: ![[CONST_B_DECL:[0-9]+]] = !DIDerivedType(tag: DW_TAG_member, name: "const_b"
// DWARF5: ![[CONST_B_DECL:[0-9]+]] = !DIDerivedType(tag: DW_TAG_variable, name: "const_b"
@@ -82,7 +82,7 @@ int C::a = 4;
// CHECK-NOT: align:
// CHECK-NOT: offset:
// CHECK-SAME: flags: DIFlagProtected | DIFlagStaticMember
-// CHECK-NOT: extraData:
+// CHECK-SAME: extraData: float
// DWARF4: ![[DECL_C:[0-9]+]] = !DIDerivedType(tag: DW_TAG_member, name: "c"
// DWARF5: ![[DECL_C:[0-9]+]] = !DIDerivedType(tag: DW_TAG_variable, name: "c"
@@ -97,7 +97,7 @@ int C::a = 4;
// CHECK-NOT: align:
// CHECK-NOT: offset:
// CHECK-SAME: flags: DIFlagPublic | DIFlagStaticMember
-// CHECK-NOT: extraData:
+// CHECK-SAME: extraData: i32 18
//
// DWARF4: !DIDerivedType(tag: DW_TAG_member, name: "x_a"
// DWARF5: !DIDerivedType(tag: DW_TAG_variable, name: "x_a"
@@ -154,7 +154,7 @@ 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-NOT: extraData:
+// NOT-MS-SAME: extraData: i32 42
const int V::const_va;
namespace x {
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jryans
approved these changes
Nov 28, 2023
|
I do wonder how feasible it would be for the downstream tests to be adjusted to look at the |
As I mentioned on the other thread, the point is not to have to read the value from the process-under-debug. This is not efficient in a remote-debugging scenario. |
Ah that's fair, missed your comment on the other thread |
|
Looks like LLDB linux buildbot isn't happy, checking... |
Michael137
added a commit
to Michael137/llvm-project
that referenced
this pull request
Nov 28, 2023
… of global variables In llvm#73626 we started attaching `DW_AT_const_value`s on a static data-member's declaration again. In DWARFv5, those static members are represented with a `DW_TAG_variable`. When LLDB builds the `ManualDWARFIndex`, it simply iterates over all DIEs in a CU and puts *any* `DW_TAG_variable` with a constant or location into the index. So when using the manual index, we can end up having 2 entries for a static data member in the index. This caused a test failure on Linux (where DWARFv5 is the default and the tests use the manual index). This patch loosens the restriction that we find exactly 1 variable.
Fix in #73707 |
felipepiovezan
pushed a commit
that referenced
this pull request
Nov 29, 2023
… of global variables (#73707) In #73626 we started attaching `DW_AT_const_value`s on a static data-member's declaration again. In DWARFv5, those static members are represented with a `DW_TAG_variable`. When LLDB builds the `ManualDWARFIndex`, it simply iterates over all DIEs in a CU and puts *any* `DW_TAG_variable` with a constant or location into the index. So when using the manual index, we can end up having 2 entries for a static data member in the index, one for the declaration and one for the definition. This caused a test failure on Linux (where DWARFv5 is the default and the tests use the manual index). This patch loosens the restriction that we find exactly 1 variable.
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In #71780 we started emitting definitions for all static data-members with constant initialisers, even if they were constants (i.e., didn't have a location). We also dropped the DW_AT_const_value from the declaration to help resolve inconsistencies during type merging in the DWARFParallelLinker. However, for static data members that do have locations, we wouldn't emit a DW_AT_const_value on it, assuming that the consumer knows how to read the value using the location. This broke some consumers that really wanted to find a DW_AT_const_value. Ultimately we want to attach a DW_AT_const_value to definitions that have a location too. But to fix consumers broken by said change, this patch adds the constant back onto the declaration. This is what we used to do prior to #71780