https://github.com/nikic created
https://github.com/llvm/llvm-project/pull/144720
Verify that the alignments specified by clang TargetInfo match the alignments
specified by LLVM data layout, which will hopefully prevent accidental
mismatches in the future.
This currently contains opt-outs for a lot of existing mismatches.
I'm also skipping the verification if options like `-malign-double` are used,
or a language that mandates sizes/alignments that differ from C.
The verification happens in CodeGen, as we can't have an IR dependency in Basic.
>From c4082c425c8100913c0bf0334875d015f9bcfc9a Mon Sep 17 00:00:00 2001
From: Nikita Popov <npo...@redhat.com>
Date: Wed, 18 Jun 2025 14:48:19 +0200
Subject: [PATCH] [Clang] Verify data layout consistency
Verify that the alignments specified by clang TargetInfo match
the alignments specified by LLVM data layout, which will hopefully
prevent accidental mismatches in the future.
This currently contains opt-outs for a lot of existing mismatches.
I'm also skipping the verification if options like `-malign-double`
are used, or a language that mandates sizes/alignments that differ
from C.
---
clang/lib/CodeGen/CodeGenModule.cpp | 73 +++++++++++++++++++++++++++++
1 file changed, 73 insertions(+)
diff --git a/clang/lib/CodeGen/CodeGenModule.cpp
b/clang/lib/CodeGen/CodeGenModule.cpp
index c27168e4c4bfe..aabc872e22df1 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -332,6 +332,76 @@ const TargetCodeGenInfo
&CodeGenModule::getTargetCodeGenInfo() {
return *TheTargetCodeGenInfo;
}
+static void checkDataLayoutConsistency(const TargetInfo &Target,
+ llvm::LLVMContext &Context,
+ const LangOptions &Opts) {
+#ifndef NDEBUG
+ // Don't verify non-standard ABI configurations.
+ if (Opts.AlignDouble || Opts.OpenCL || Opts.HLSL)
+ return;
+
+ llvm::Triple Triple = Target.getTriple();
+ llvm::DataLayout DL(Target.getDataLayoutString());
+ auto Check = [&](const char *Name, llvm::Type *Ty, unsigned Alignment) {
+ llvm::Align DLAlign = DL.getABITypeAlign(Ty);
+ llvm::Align ClangAlign(Alignment / 8);
+ if (DLAlign != ClangAlign) {
+ llvm::errs() << "For target " << Triple.str() << " type " << Name
+ << " mapping to " << *Ty << " has data layout alignment "
+ << DLAlign.value() << " while clang specifies "
+ << ClangAlign.value() << "\n";
+ abort();
+ }
+ };
+
+ Check("bool", llvm::Type::getIntNTy(Context, Target.BoolWidth),
+ Target.BoolAlign);
+ Check("short", llvm::Type::getIntNTy(Context, Target.ShortWidth),
+ Target.ShortAlign);
+ // FIXME: M68k specifies incorrect wrong int and long alignments in Clang
+ // and incorrect long long alignment in both LLVM and Clang.
+ if (Triple.getArch() != llvm::Triple::m68k) {
+ Check("int", llvm::Type::getIntNTy(Context, Target.IntWidth),
+ Target.IntAlign);
+ Check("long", llvm::Type::getIntNTy(Context, Target.LongWidth),
+ Target.LongAlign);
+ Check("long long", llvm::Type::getIntNTy(Context, Target.LongLongWidth),
+ Target.LongLongAlign);
+ }
+ // FIXME: There are int128 alignment mismatches on multiple targets.
+ if (Target.hasInt128Type() && !Target.getTargetOpts().ForceEnableInt128 &&
+ !Triple.isAMDGPU() && !Triple.isSPIRV() &&
+ Triple.getArch() != llvm::Triple::ve)
+ Check("__int128", llvm::Type::getIntNTy(Context, 128), Target.Int128Align);
+
+ if (Target.hasFloat16Type())
+ Check("half", llvm::Type::getFloatingPointTy(Context, *Target.HalfFormat),
+ Target.HalfAlign);
+ if (Target.hasBFloat16Type())
+ Check("bfloat", llvm::Type::getBFloatTy(Context), Target.BFloat16Align);
+ Check("float", llvm::Type::getFloatingPointTy(Context, *Target.FloatFormat),
+ Target.FloatAlign);
+ // FIXME: AIX specifies wrong double alignment in DataLayout
+ if (!Triple.isOSAIX()) {
+ Check("double",
+ llvm::Type::getFloatingPointTy(Context, *Target.DoubleFormat),
+ Target.DoubleAlign);
+ Check("long double",
+ llvm::Type::getFloatingPointTy(Context, *Target.LongDoubleFormat),
+ Target.LongDoubleAlign);
+ }
+ // FIXME: Wasm has a mismatch in f128 alignment between Clang and LLVM.
+ if (Target.hasFloat128Type() && !Triple.isWasm())
+ Check("__float128", llvm::Type::getFP128Ty(Context), Target.Float128Align);
+ if (Target.hasIbm128Type())
+ Check("__ibm128", llvm::Type::getPPC_FP128Ty(Context), Target.Ibm128Align);
+
+ // FIXME: Clang specifies incorrect pointer alignment for m68k.
+ if (Triple.getArch() != llvm::Triple::m68k)
+ Check("void*", llvm::PointerType::getUnqual(Context), Target.PointerAlign);
+#endif
+}
+
CodeGenModule::CodeGenModule(ASTContext &C,
IntrusiveRefCntPtr<llvm::vfs::FileSystem> FS,
const HeaderSearchOptions &HSO,
@@ -458,6 +528,9 @@ CodeGenModule::CodeGenModule(ASTContext &C,
if (Context.getTargetInfo().getTriple().getArch() == llvm::Triple::x86)
getModule().addModuleFlag(llvm::Module::Error, "NumRegisterParameters",
CodeGenOpts.NumRegisterParameters);
+
+ if (!Context.getAuxTargetInfo())
+ checkDataLayoutConsistency(Context.getTargetInfo(), LLVMContext, LangOpts);
}
CodeGenModule::~CodeGenModule() {}
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