[clang] d2a9df2 - [TBAA] Handle bitfields when generating !tbaa.struct metadata. (#82922)
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cfe-commits at lists.llvm.org
Tue Feb 27 12:09:57 PST 2024
Author: Florian Hahn
Date: 2024-02-27T20:09:54Z
New Revision: d2a9df2c8ffd21fd52fbd8199a191d10078f41af
URL: https://github.com/llvm/llvm-project/commit/d2a9df2c8ffd21fd52fbd8199a191d10078f41af
DIFF: https://github.com/llvm/llvm-project/commit/d2a9df2c8ffd21fd52fbd8199a191d10078f41af.diff
LOG: [TBAA] Handle bitfields when generating !tbaa.struct metadata. (#82922)
At the moment, clang generates what I believe are incorrect !tbaa.struct
fields for named bitfields. At the moment, the base type size is used
for named bifields (e.g. sizeof(int)) instead of the bifield width per
field. This results in overalpping fields in !tbaa.struct metadata.
This causes incorrect results when extracting individual copied fields
from !tbaa.struct as in added in dc85719d5.
This patch fixes that by skipping by combining adjacent bitfields
in fields with correct sizes.
Fixes https://github.com/llvm/llvm-project/issues/82586
Added:
Modified:
clang/lib/CodeGen/CodeGenModule.cpp
clang/lib/CodeGen/CodeGenTBAA.cpp
clang/lib/CodeGen/CodeGenTBAA.h
clang/test/CodeGen/tbaa-struct.cpp
Removed:
################################################################################
diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index 1550b000a89a3d..d16d12fac8b03c 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -397,8 +397,8 @@ CodeGenModule::CodeGenModule(ASTContext &C,
// Enable TBAA unless it's suppressed. ThreadSanitizer needs TBAA even at O0.
if (LangOpts.Sanitize.has(SanitizerKind::Thread) ||
(!CodeGenOpts.RelaxedAliasing && CodeGenOpts.OptimizationLevel > 0))
- TBAA.reset(new CodeGenTBAA(Context, TheModule, CodeGenOpts, getLangOpts(),
- getCXXABI().getMangleContext()));
+ TBAA.reset(new CodeGenTBAA(Context, getTypes(), TheModule, CodeGenOpts,
+ getLangOpts(), getCXXABI().getMangleContext()));
// If debug info or coverage generation is enabled, create the CGDebugInfo
// object.
diff --git a/clang/lib/CodeGen/CodeGenTBAA.cpp b/clang/lib/CodeGen/CodeGenTBAA.cpp
index dc288bc3f6157a..8a081612193978 100644
--- a/clang/lib/CodeGen/CodeGenTBAA.cpp
+++ b/clang/lib/CodeGen/CodeGenTBAA.cpp
@@ -15,6 +15,8 @@
//===----------------------------------------------------------------------===//
#include "CodeGenTBAA.h"
+#include "CGRecordLayout.h"
+#include "CodeGenTypes.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/Attr.h"
#include "clang/AST/Mangle.h"
@@ -26,16 +28,16 @@
#include "llvm/IR/Metadata.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/Type.h"
+#include "llvm/Support/Debug.h"
using namespace clang;
using namespace CodeGen;
-CodeGenTBAA::CodeGenTBAA(ASTContext &Ctx, llvm::Module &M,
- const CodeGenOptions &CGO,
+CodeGenTBAA::CodeGenTBAA(ASTContext &Ctx, CodeGenTypes &CGTypes,
+ llvm::Module &M, const CodeGenOptions &CGO,
const LangOptions &Features, MangleContext &MContext)
- : Context(Ctx), Module(M), CodeGenOpts(CGO),
- Features(Features), MContext(MContext), MDHelper(M.getContext()),
- Root(nullptr), Char(nullptr)
-{}
+ : Context(Ctx), CGTypes(CGTypes), Module(M), CodeGenOpts(CGO),
+ Features(Features), MContext(MContext), MDHelper(M.getContext()),
+ Root(nullptr), Char(nullptr) {}
CodeGenTBAA::~CodeGenTBAA() {
}
@@ -294,14 +296,34 @@ CodeGenTBAA::CollectFields(uint64_t BaseOffset,
return false;
const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
+ const CGRecordLayout &CGRL = CGTypes.getCGRecordLayout(RD);
unsigned idx = 0;
- for (RecordDecl::field_iterator i = RD->field_begin(),
- e = RD->field_end(); i != e; ++i, ++idx) {
- if ((*i)->isZeroSize(Context) || (*i)->isUnnamedBitfield())
+ for (RecordDecl::field_iterator i = RD->field_begin(), e = RD->field_end();
+ i != e; ++i, ++idx) {
+ if ((*i)->isZeroSize(Context))
continue;
- uint64_t Offset = BaseOffset +
- Layout.getFieldOffset(idx) / Context.getCharWidth();
+
+ uint64_t Offset =
+ BaseOffset + Layout.getFieldOffset(idx) / Context.getCharWidth();
+
+ // Create a single field for consecutive named bitfields using char as
+ // base type.
+ if ((*i)->isBitField()) {
+ const CGBitFieldInfo &Info = CGRL.getBitFieldInfo(*i);
+ if (Info.Offset != 0)
+ continue;
+ unsigned CurrentBitFieldSize = Info.StorageSize;
+ uint64_t Size =
+ llvm::divideCeil(CurrentBitFieldSize, Context.getCharWidth());
+ llvm::MDNode *TBAAType = getChar();
+ llvm::MDNode *TBAATag =
+ getAccessTagInfo(TBAAAccessInfo(TBAAType, Size));
+ Fields.push_back(
+ llvm::MDBuilder::TBAAStructField(Offset, Size, TBAATag));
+ continue;
+ }
+
QualType FieldQTy = i->getType();
if (!CollectFields(Offset, FieldQTy, Fields,
MayAlias || TypeHasMayAlias(FieldQTy)))
diff --git a/clang/lib/CodeGen/CodeGenTBAA.h b/clang/lib/CodeGen/CodeGenTBAA.h
index a65963596fe9de..aa6da2731a4163 100644
--- a/clang/lib/CodeGen/CodeGenTBAA.h
+++ b/clang/lib/CodeGen/CodeGenTBAA.h
@@ -29,6 +29,7 @@ namespace clang {
class Type;
namespace CodeGen {
+class CodeGenTypes;
// TBAAAccessKind - A kind of TBAA memory access descriptor.
enum class TBAAAccessKind : unsigned {
@@ -115,6 +116,7 @@ struct TBAAAccessInfo {
/// while lowering AST types to LLVM types.
class CodeGenTBAA {
ASTContext &Context;
+ CodeGenTypes &CGTypes;
llvm::Module &Module;
const CodeGenOptions &CodeGenOpts;
const LangOptions &Features;
@@ -167,8 +169,9 @@ class CodeGenTBAA {
llvm::MDNode *getBaseTypeInfoHelper(const Type *Ty);
public:
- CodeGenTBAA(ASTContext &Ctx, llvm::Module &M, const CodeGenOptions &CGO,
- const LangOptions &Features, MangleContext &MContext);
+ CodeGenTBAA(ASTContext &Ctx, CodeGenTypes &CGTypes, llvm::Module &M,
+ const CodeGenOptions &CGO, const LangOptions &Features,
+ MangleContext &MContext);
~CodeGenTBAA();
/// getTypeInfo - Get metadata used to describe accesses to objects of the
diff --git a/clang/test/CodeGen/tbaa-struct.cpp b/clang/test/CodeGen/tbaa-struct.cpp
index 28c7d396121af4..883c982be26c8f 100644
--- a/clang/test/CodeGen/tbaa-struct.cpp
+++ b/clang/test/CodeGen/tbaa-struct.cpp
@@ -162,11 +162,11 @@ void copy10(NamedBitfields3 *a1, NamedBitfields3 *a2) {
// CHECK-OLD: [[TS3]] = !{i64 0, i64 8, !{{.*}}, i64 0, i64 2, !{{.*}}, i64 4, i64 8, !{{.*}}}
// CHECK-OLD: [[TS4]] = !{i64 0, i64 1, [[TAG_CHAR]], i64 1, i64 1, [[TAG_CHAR]], i64 2, i64 1, [[TAG_CHAR]]}
// CHECK-OLD: [[TS5]] = !{i64 0, i64 1, [[TAG_CHAR]], i64 4, i64 1, [[TAG_CHAR]], i64 5, i64 1, [[TAG_CHAR]]}
-// CHECK-OLD: [[TS6]] = !{i64 0, i64 4, [[TAG_INT]], i64 1, i64 4, [[TAG_INT]], i64 2, i64 1, [[TAG_CHAR]], i64 8, i64 8, [[TAG_DOUBLE:!.+]]}
+// CHECK-OLD: [[TS6]] = !{i64 0, i64 2, [[TAG_CHAR]], i64 2, i64 1, [[TAG_CHAR]], i64 8, i64 8, [[TAG_DOUBLE:!.+]]}
// CHECK-OLD: [[TAG_DOUBLE]] = !{[[DOUBLE:!.+]], [[DOUBLE]], i64 0}
// CHECK-OLD [[DOUBLE]] = !{!"double", [[CHAR]], i64 0}
-// CHECK-OLD: [[TS7]] = !{i64 0, i64 1, [[TAG_CHAR]], i64 1, i64 1, [[TAG_CHAR]], i64 2, i64 1, [[TAG_CHAR]], i64 3, i64 4, [[TAG_INT]], i64 3, i64 4, [[TAG_INT]], i64 4, i64 1, [[TAG_CHAR]], i64 8, i64 8, [[TAG_DOUBLE]], i64 16, i64 4, [[TAG_INT]]}
-// CHECK-OLD: [[TS8]] = !{i64 1, i64 4, [[TAG_INT]], i64 2, i64 4, [[TAG_INT]], i64 8, i64 8, [[TAG_DOUBLE]]}
+// CHECK-OLD: [[TS7]] = !{i64 0, i64 1, [[TAG_CHAR]], i64 1, i64 1, [[TAG_CHAR]], i64 2, i64 1, [[TAG_CHAR]], i64 3, i64 1, [[TAG_CHAR]], i64 4, i64 1, [[TAG_CHAR]], i64 8, i64 8, [[TAG_DOUBLE]], i64 16, i64 1, [[TAG_CHAR]]}
+// CHECK-OLD: [[TS8]] = !{i64 0, i64 4, [[TAG_CHAR]], i64 8, i64 8, [[TAG_DOUBLE]]}
// CHECK-NEW-DAG: [[TYPE_char:!.*]] = !{{{.*}}, i64 1, !"omnipotent char"}
// CHECK-NEW-DAG: [[TAG_char]] = !{[[TYPE_char]], [[TYPE_char]], i64 0, i64 0}
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