[clang] [clang] Strict aliasing warning ala GCC [PR50066] (PR #74155)
Vlad Serebrennikov via cfe-commits
cfe-commits at lists.llvm.org
Wed Dec 6 05:07:07 PST 2023
================
@@ -498,3 +498,137 @@ CodeGenTBAA::mergeTBAAInfoForMemoryTransfer(TBAAAccessInfo DestInfo,
// access type regardless of their base types.
return TBAAAccessInfo::getMayAliasInfo();
}
+
+// Determine the aliasing kind bit-converting from type Src to type Dst.
+CodeGenTBAA::AliasingKind CodeGenTBAA::getAliasingKind(QualType &Dst,
+ QualType &Src) {
+ assert(!Src->isVoidType() && !Dst->isVoidType());
+ if (TypeHasMayAlias(Src) || TypeHasMayAlias(Dst))
+ return AK_Ok;
+
+ Src = QualType{Src->getBaseElementTypeUnsafe(), 0};
+ Dst = QualType{Dst->getBaseElementTypeUnsafe(), 0};
+
+ auto *SrcDecl = Src->getAsRecordDecl();
+ auto *DstDecl = Dst->getAsRecordDecl();
+
+ const llvm::MDNode *AnyTBAA = getChar();
+ const llvm::MDNode *SrcTBAA = nullptr;
+ const llvm::MDNode *DstTBAA = nullptr;
+
+ if (!SrcDecl) {
+ SrcTBAA = getTypeInfo(Src);
+ if (!SrcTBAA || SrcTBAA == AnyTBAA)
----------------
Endilll wrote:
Are you sure `signed char` is allowed to alias everything, like `char` and `unsigned char`? It's not there in the strict aliasing rule.
https://github.com/llvm/llvm-project/pull/74155
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