r346542 - Fix a nondeterminism in the debug info for VLA size expressions.
Adrian Prantl via cfe-commits
cfe-commits at lists.llvm.org
Fri Nov 9 11:17:56 PST 2018
Author: adrian
Date: Fri Nov 9 11:17:56 2018
New Revision: 346542
URL: http://llvm.org/viewvc/llvm-project?rev=346542&view=rev
Log:
Fix a nondeterminism in the debug info for VLA size expressions.
The artificial variable describing the array size is supposed to be
called "__vla_expr", but this was implemented by retrieving the name
of the associated alloca, which isn't a reliable source for the name,
since nonassert compilers may drop names from LLVM IR.
rdar://problem/45924808
Modified:
cfe/trunk/lib/CodeGen/CGDecl.cpp
cfe/trunk/lib/CodeGen/CodeGenFunction.h
cfe/trunk/test/CodeGen/debug-info-vla.c
cfe/trunk/test/CodeGenCXX/debug-info-vla.cpp
Modified: cfe/trunk/lib/CodeGen/CGDecl.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGDecl.cpp?rev=346542&r1=346541&r2=346542&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CGDecl.cpp (original)
+++ cfe/trunk/lib/CodeGen/CGDecl.cpp Fri Nov 9 11:17:56 2018
@@ -1066,6 +1066,7 @@ void CodeGenFunction::EmitAndRegisterVar
// For each dimension stores its QualType and corresponding
// size-expression Value.
SmallVector<CodeGenFunction::VlaSizePair, 4> Dimensions;
+ SmallVector<IdentifierInfo *, 4> VLAExprNames;
// Break down the array into individual dimensions.
QualType Type1D = D.getType();
@@ -1074,8 +1075,14 @@ void CodeGenFunction::EmitAndRegisterVar
if (auto *C = dyn_cast<llvm::ConstantInt>(VlaSize.NumElts))
Dimensions.emplace_back(C, Type1D.getUnqualifiedType());
else {
- auto SizeExprAddr = CreateDefaultAlignTempAlloca(
- VlaSize.NumElts->getType(), "__vla_expr");
+ // Generate a locally unique name for the size expression.
+ Twine Name = Twine("__vla_expr") + Twine(VLAExprCounter++);
+ SmallString<12> Buffer;
+ StringRef NameRef = Name.toStringRef(Buffer);
+ auto &Ident = getContext().Idents.getOwn(NameRef);
+ VLAExprNames.push_back(&Ident);
+ auto SizeExprAddr =
+ CreateDefaultAlignTempAlloca(VlaSize.NumElts->getType(), NameRef);
Builder.CreateStore(VlaSize.NumElts, SizeExprAddr);
Dimensions.emplace_back(SizeExprAddr.getPointer(),
Type1D.getUnqualifiedType());
@@ -1089,20 +1096,20 @@ void CodeGenFunction::EmitAndRegisterVar
// Register each dimension's size-expression with a DILocalVariable,
// so that it can be used by CGDebugInfo when instantiating a DISubrange
// to describe this array.
+ unsigned NameIdx = 0;
for (auto &VlaSize : Dimensions) {
llvm::Metadata *MD;
if (auto *C = dyn_cast<llvm::ConstantInt>(VlaSize.NumElts))
MD = llvm::ConstantAsMetadata::get(C);
else {
// Create an artificial VarDecl to generate debug info for.
- IdentifierInfo &NameIdent = getContext().Idents.getOwn(
- cast<llvm::AllocaInst>(VlaSize.NumElts)->getName());
+ IdentifierInfo *NameIdent = VLAExprNames[NameIdx++];
auto VlaExprTy = VlaSize.NumElts->getType()->getPointerElementType();
auto QT = getContext().getIntTypeForBitwidth(
VlaExprTy->getScalarSizeInBits(), false);
auto *ArtificialDecl = VarDecl::Create(
getContext(), const_cast<DeclContext *>(D.getDeclContext()),
- D.getLocation(), D.getLocation(), &NameIdent, QT,
+ D.getLocation(), D.getLocation(), NameIdent, QT,
getContext().CreateTypeSourceInfo(QT), SC_Auto);
ArtificialDecl->setImplicit();
Modified: cfe/trunk/lib/CodeGen/CodeGenFunction.h
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CodeGenFunction.h?rev=346542&r1=346541&r2=346542&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CodeGenFunction.h (original)
+++ cfe/trunk/lib/CodeGen/CodeGenFunction.h Fri Nov 9 11:17:56 2018
@@ -1197,6 +1197,8 @@ public:
private:
CGDebugInfo *DebugInfo;
+ /// Used to create unique names for artificial VLA size debug info variables.
+ unsigned VLAExprCounter = 0;
bool DisableDebugInfo = false;
/// DidCallStackSave - Whether llvm.stacksave has been called. Used to avoid
Modified: cfe/trunk/test/CodeGen/debug-info-vla.c
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGen/debug-info-vla.c?rev=346542&r1=346541&r2=346542&view=diff
==============================================================================
--- cfe/trunk/test/CodeGen/debug-info-vla.c (original)
+++ cfe/trunk/test/CodeGen/debug-info-vla.c Fri Nov 9 11:17:56 2018
@@ -2,9 +2,9 @@
void testVLAwithSize(int s)
{
-// CHECK-DAG: dbg.declare({{.*}} %__vla_expr, metadata ![[VLAEXPR:[0-9]+]]
+// CHECK-DAG: dbg.declare({{.*}} %__vla_expr0, metadata ![[VLAEXPR:[0-9]+]]
// CHECK-DAG: dbg.declare({{.*}} %vla, metadata ![[VAR:[0-9]+]]
-// CHECK-DAG: ![[VLAEXPR]] = !DILocalVariable(name: "__vla_expr", {{.*}} flags: DIFlagArtificial
+// CHECK-DAG: ![[VLAEXPR]] = !DILocalVariable(name: "__vla_expr0", {{.*}} flags: DIFlagArtificial
// CHECK-DAG: ![[VAR]] = !DILocalVariable(name: "vla",{{.*}} line: [[@LINE+2]]
// CHECK-DAG: !DISubrange(count: ![[VLAEXPR]])
int vla[s];
Modified: cfe/trunk/test/CodeGenCXX/debug-info-vla.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenCXX/debug-info-vla.cpp?rev=346542&r1=346541&r2=346542&view=diff
==============================================================================
--- cfe/trunk/test/CodeGenCXX/debug-info-vla.cpp (original)
+++ cfe/trunk/test/CodeGenCXX/debug-info-vla.cpp Fri Nov 9 11:17:56 2018
@@ -13,7 +13,7 @@ int (*fp)(int[][*]) = nullptr;
// CHECK: [[ELEM_TYPE]] = !{[[NOCOUNT:.*]]}
// CHECK: [[NOCOUNT]] = !DISubrange(count: -1)
//
-// CHECK: [[VAR:![0-9]+]] = !DILocalVariable(name: "__vla_expr", {{.*}}flags: DIFlagArtificial
+// CHECK: [[VAR:![0-9]+]] = !DILocalVariable(name: "__vla_expr0", {{.*}}flags: DIFlagArtificial
// CHECK: !DICompositeType(tag: DW_TAG_array_type,
// CHECK-NOT: size:
// CHECK-SAME: elements: [[ELEM_TYPE:![0-9]+]]
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