https://github.com/koachan created https://github.com/llvm/llvm-project/pull/155829
This coerces 9 to 16-byte C structs that are 16-byte aligned as an i128 in LLVM IR. Additionally, since i128 values will be lowered as split i64 pairs in the backend, correctly set the alignment of such arguments as 16 bytes. This should make clang compliant with the ABI specification and fix https://github.com/llvm/llvm-project/issues/144709. >From a8707a6452b77b75603dc780213835f6e5e4b582 Mon Sep 17 00:00:00 2001 From: Koakuma <koac...@protonmail.com> Date: Thu, 28 Aug 2025 19:48:38 +0700 Subject: [PATCH 1/2] [clang][SPARC] Pass 16-aligned 16-byte structs as i128 in CC This coerces 16-byte C structs that are 16-byte aligned as an i128 in LLVM IR. Additionally, since i128 values will be lowered as split i64 pairs in the backend, correctly set the alignment of such arguments as 16 bytes. This should make it compliant with the ABI specification and fix https://github.com/llvm/llvm-project/issues/144709. --- clang/lib/CodeGen/Targets/Sparc.cpp | 11 ++++++++--- clang/test/CodeGen/sparcv9-abi.c | 9 +++++++++ llvm/lib/Target/Sparc/SparcISelLowering.cpp | 3 ++- llvm/test/CodeGen/SPARC/64abi.ll | 15 ++++++++++++++- 4 files changed, 33 insertions(+), 5 deletions(-) diff --git a/clang/lib/CodeGen/Targets/Sparc.cpp b/clang/lib/CodeGen/Targets/Sparc.cpp index 5f3c15d106eb6..300b5fdf35e37 100644 --- a/clang/lib/CodeGen/Targets/Sparc.cpp +++ b/clang/lib/CodeGen/Targets/Sparc.cpp @@ -228,6 +228,7 @@ SparcV9ABIInfo::classifyType(QualType Ty, unsigned SizeLimit) const { return ABIArgInfo::getIgnore(); uint64_t Size = getContext().getTypeSize(Ty); + unsigned Alignment = getContext().getTypeAlign(Ty); // Anything too big to fit in registers is passed with an explicit indirect // pointer / sret pointer. @@ -275,10 +276,14 @@ SparcV9ABIInfo::classifyType(QualType Ty, unsigned SizeLimit) const { // Try to use the original type for coercion. llvm::Type *CoerceTy = CB.isUsableType(StrTy) ? StrTy : CB.getType(); + // We use a pair of i64 for 16-byte aggregate with 8-byte alignment. + // For 16-byte aggregates with 16-byte alignment, we use i128. + llvm::Type *WideTy = llvm::Type::getIntNTy(getVMContext(), 128); + bool UseI128 = (Size == 128) && (Alignment == 128); + if (CB.InReg) - return ABIArgInfo::getDirectInReg(CoerceTy); - else - return ABIArgInfo::getDirect(CoerceTy); + return ABIArgInfo::getDirectInReg(UseI128 ? WideTy : CoerceTy); + return ABIArgInfo::getDirect(UseI128 ? WideTy : CoerceTy); } RValue SparcV9ABIInfo::EmitVAArg(CodeGenFunction &CGF, Address VAListAddr, diff --git a/clang/test/CodeGen/sparcv9-abi.c b/clang/test/CodeGen/sparcv9-abi.c index 5a3d64fd37889..9819d07425274 100644 --- a/clang/test/CodeGen/sparcv9-abi.c +++ b/clang/test/CodeGen/sparcv9-abi.c @@ -25,12 +25,21 @@ long double f_ld(long double x) { return x; } struct empty {}; struct emptyarr { struct empty a[10]; }; +// 16-byte structs with 16-byte alignment gets passed as if i128. +struct align16 { _Alignas(16) int x; }; + // CHECK-LABEL: define{{.*}} i64 @f_empty(i64 %x.coerce) struct empty f_empty(struct empty x) { return x; } // CHECK-LABEL: define{{.*}} i64 @f_emptyarr(i64 %x.coerce) struct empty f_emptyarr(struct emptyarr x) { return x.a[0]; } +// CHECK-LABEL: define{{.*}} void @f_aligncaller(i128 %a.coerce) +void f_aligncallee(int pad, struct align16 a); +void f_aligncaller(struct align16 a) { + f_aligncallee(0, a); +} + // CHECK-LABEL: define{{.*}} i64 @f_emptyvar(i32 noundef zeroext %count, ...) long f_emptyvar(unsigned count, ...) { long ret; diff --git a/llvm/lib/Target/Sparc/SparcISelLowering.cpp b/llvm/lib/Target/Sparc/SparcISelLowering.cpp index d01218f573dc2..e5ed9d267afed 100644 --- a/llvm/lib/Target/Sparc/SparcISelLowering.cpp +++ b/llvm/lib/Target/Sparc/SparcISelLowering.cpp @@ -115,7 +115,8 @@ static bool Analyze_CC_Sparc64_Full(bool IsReturn, unsigned &ValNo, MVT &ValVT, // Stack space is allocated for all arguments starting from [%fp+BIAS+128]. unsigned size = (LocVT == MVT::f128) ? 16 : 8; - Align alignment = (LocVT == MVT::f128) ? Align(16) : Align(8); + Align alignment = + (LocVT == MVT::f128 || ArgFlags.isSplit()) ? Align(16) : Align(8); unsigned Offset = State.AllocateStack(size, alignment); unsigned Reg = 0; diff --git a/llvm/test/CodeGen/SPARC/64abi.ll b/llvm/test/CodeGen/SPARC/64abi.ll index 6485a7f13e8d5..dc8c9af4a5185 100644 --- a/llvm/test/CodeGen/SPARC/64abi.ll +++ b/llvm/test/CodeGen/SPARC/64abi.ll @@ -473,8 +473,8 @@ declare i64 @receive_fp128(i64 %a, ...) ; HARD-DAG: ldx [%sp+[[Offset0]]], %o2 ; HARD-DAG: ldx [%sp+[[Offset1]]], %o3 ; SOFT-DAG: mov %i0, %o0 -; SOFT-DAG: mov %i1, %o1 ; SOFT-DAG: mov %i2, %o2 +; SOFT-DAG: mov %i3, %o3 ; CHECK: call receive_fp128 define i64 @test_fp128_variable_args(i64 %a, fp128 %b) { entry: @@ -482,6 +482,19 @@ entry: ret i64 %0 } +declare i64 @receive_i128(i64 %a, i128 %b) + +; CHECK-LABEL: test_i128_args: +; CHECK: mov %i3, %o3 +; CHECK: mov %i2, %o2 +; CHECK: mov %i0, %o0 +; CHECK: call receive_i128 +define i64 @test_i128_args(i64 %a, i128 %b) { +entry: + %0 = call i64 @receive_i128(i64 %a, i128 %b) + ret i64 %0 +} + ; CHECK-LABEL: test_call_libfunc: ; HARD: st %f1, [%fp+[[Offset0:[0-9]+]]] ; HARD: fmovs %f3, %f1 >From 05f7e2b53693109818ccf789e4d059f8f3f5a79e Mon Sep 17 00:00:00 2001 From: Koakuma <koac...@protonmail.com> Date: Thu, 28 Aug 2025 20:06:10 +0700 Subject: [PATCH 2/2] Fix comment and size checks --- clang/lib/CodeGen/Targets/Sparc.cpp | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/clang/lib/CodeGen/Targets/Sparc.cpp b/clang/lib/CodeGen/Targets/Sparc.cpp index 300b5fdf35e37..b6c8fdcfe29b6 100644 --- a/clang/lib/CodeGen/Targets/Sparc.cpp +++ b/clang/lib/CodeGen/Targets/Sparc.cpp @@ -276,10 +276,10 @@ SparcV9ABIInfo::classifyType(QualType Ty, unsigned SizeLimit) const { // Try to use the original type for coercion. llvm::Type *CoerceTy = CB.isUsableType(StrTy) ? StrTy : CB.getType(); - // We use a pair of i64 for 16-byte aggregate with 8-byte alignment. - // For 16-byte aggregates with 16-byte alignment, we use i128. + // We use a pair of i64 for 9-16 byte aggregate with 8 byte alignment. + // For 9-16 byte aggregates with 16 byte alignment, we use i128. llvm::Type *WideTy = llvm::Type::getIntNTy(getVMContext(), 128); - bool UseI128 = (Size == 128) && (Alignment == 128); + bool UseI128 = (Size > 64) && (Size <= 128) && (Alignment == 128); if (CB.InReg) return ABIArgInfo::getDirectInReg(UseI128 ? WideTy : CoerceTy); _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
