Debug Info: Represent local anonymous unions as anonymous unions
and as artificial local variables in the debug info.
This is a follow-up to r236059. We can't get rid of the local variables
entirely because the gdb buildbot depends on them, but we can mark them
as artificial while still emitting the correct debug info. As I learned
from review comments other compilers also follow this model.
A paired commit in LLVM temporarily relaxes the debug info verifier to
not check the integrity of DW_OP_bit_pieces of artificial variables.
rdar://problem/20730771
llvm-svn: 236125
diff --git a/clang/lib/CodeGen/CGDebugInfo.cpp b/clang/lib/CodeGen/CGDebugInfo.cpp
index cbb4f85..3a9b4c7 100644
--- a/clang/lib/CodeGen/CGDebugInfo.cpp
+++ b/clang/lib/CodeGen/CGDebugInfo.cpp
@@ -2839,6 +2839,13 @@
// all union fields.
const RecordDecl *RD = cast<RecordDecl>(RT->getDecl());
if (RD->isUnion() && RD->isAnonymousStructOrUnion()) {
+ // GDB has trouble finding local variables in anonymous unions, so we emit
+ // artifical local variables for each of the members.
+ //
+ // FIXME: Remove this code as soon as GDB supports this.
+ // The debug info verifier in LLVM operates based on the assumption that a
+ // variable has the same size as its storage and we had to disable the check
+ // for artificial variables.
for (const auto *Field : RD->fields()) {
llvm::DIType *FieldTy = getOrCreateType(Field->getType(), Unit);
StringRef FieldName = Field->getName();
@@ -2850,14 +2857,14 @@
// Use VarDecl's Tag, Scope and Line number.
auto *D = DBuilder.createLocalVariable(
Tag, Scope, FieldName, Unit, Line, FieldTy,
- CGM.getLangOpts().Optimize, Flags, ArgNo);
+ CGM.getLangOpts().Optimize, Flags | llvm::DINode::FlagArtificial,
+ ArgNo);
// Insert an llvm.dbg.declare into the current block.
DBuilder.insertDeclare(Storage, D, DBuilder.createExpression(Expr),
llvm::DebugLoc::get(Line, Column, Scope),
Builder.GetInsertBlock());
}
- return;
}
}
diff --git a/clang/test/CodeGenCXX/debug-info-anon-union-vars.cpp b/clang/test/CodeGenCXX/debug-info-anon-union-vars.cpp
index cfc7bc8..ad3b6d4 100644
--- a/clang/test/CodeGenCXX/debug-info-anon-union-vars.cpp
+++ b/clang/test/CodeGenCXX/debug-info-anon-union-vars.cpp
@@ -21,8 +21,26 @@
return (c == 1);
}
+void foo() {
+ union {
+ int i;
+ char c;
+ };
+ i = 8;
+}
+
// CHECK: [[FILE:.*]] = !DIFile(filename: "{{.*}}debug-info-anon-union-vars.cpp",
// CHECK: !DIGlobalVariable(name: "c",{{.*}} file: [[FILE]], line: 6,{{.*}} isLocal: true, isDefinition: true
// CHECK: !DIGlobalVariable(name: "d",{{.*}} file: [[FILE]], line: 6,{{.*}} isLocal: true, isDefinition: true
// CHECK: !DIGlobalVariable(name: "a",{{.*}} file: [[FILE]], line: 6,{{.*}} isLocal: true, isDefinition: true
// CHECK: !DIGlobalVariable(name: "b",{{.*}} file: [[FILE]], line: 6,{{.*}} isLocal: true, isDefinition: true
+// CHECK: !DILocalVariable(tag: DW_TAG_auto_variable, name: "i", {{.*}}, flags: DIFlagArtificial
+// CHECK: !DILocalVariable(tag: DW_TAG_auto_variable, name: "c", {{.*}}, flags: DIFlagArtificial
+// CHECK: !DILocalVariable(
+// CHECK-NOT: name:
+// CHECK: type: ![[UNION:[0-9]+]]
+// CHECK: ![[UNION]] = !DICompositeType(tag: DW_TAG_union_type,
+// CHECK-NOT: name:
+// CHECK: elements
+// CHECK: !DIDerivedType(tag: DW_TAG_member, name: "i", scope: ![[UNION]],
+// CHECK: !DIDerivedType(tag: DW_TAG_member, name: "c", scope: ![[UNION]],