https://github.com/jhuber6 created https://github.com/llvm/llvm-project/pull/175076
Summary: We support variadic functions in AMDGPU / NVPTX via an LLVM-IR pass. This patch applies the same handling here to support them on this target. I am unsure what the ABI should look like here, I have mostly copied the one we use for NVPTX where it's basically a struct layout with natural alignment. This wastes some space, which is why AMDGPU does not pad them. Additionally, this required allowing the SPIRV_FUNC calling convention. I'm assuming this is compatible with the C calling convention in IR, but I will need someone to confirm that for me. >From ffa2dca186ac3f8d742c06d00da1fe8b4bcaadd5 Mon Sep 17 00:00:00 2001 From: Joseph Huber <[email protected]> Date: Thu, 8 Jan 2026 15:48:20 -0600 Subject: [PATCH] [SPIR-V] Enable variadic function lowering for the SPIR-V target Summary: We support variadic functions in AMDGPU / NVPTX via an LLVM-IR pass. This patch applies the same handling here to support them on this target. I am unsure what the ABI should look like here, I have mostly copied the one we use for NVPTX where it's basically a struct layout with natural alignment. This wastes some space, which is why AMDGPU does not pad them. Additionally, this required allowing the SPIRV_FUNC calling convention. I'm assuming this is compatible with the C calling convention in IR, but I will need someone to confirm that for me. --- clang/lib/CodeGen/Targets/SPIR.cpp | 15 ++ clang/test/CodeGenSPIRV/Builtins/variadic.c | 31 ++++ llvm/lib/Target/SPIRV/SPIRVGlobalRegistry.cpp | 6 - llvm/lib/Target/SPIRV/SPIRVTargetMachine.cpp | 2 + llvm/lib/Transforms/IPO/ExpandVariadics.cpp | 38 ++++- .../SPIRV/function/variadics-lowering.ll | 135 ++++++++++++++++++ 6 files changed, 219 insertions(+), 8 deletions(-) create mode 100644 clang/test/CodeGenSPIRV/Builtins/variadic.c create mode 100644 llvm/test/CodeGen/SPIRV/function/variadics-lowering.ll diff --git a/clang/lib/CodeGen/Targets/SPIR.cpp b/clang/lib/CodeGen/Targets/SPIR.cpp index 6c6c4794bba49..ba90ab3e67053 100644 --- a/clang/lib/CodeGen/Targets/SPIR.cpp +++ b/clang/lib/CodeGen/Targets/SPIR.cpp @@ -36,6 +36,8 @@ class SPIRVABIInfo : public CommonSPIRABIInfo { public: SPIRVABIInfo(CodeGenTypes &CGT) : CommonSPIRABIInfo(CGT) {} void computeInfo(CGFunctionInfo &FI) const override; + RValue EmitVAArg(CodeGenFunction &CGF, Address VAListAddr, QualType Ty, + AggValueSlot Slot) const override; private: ABIArgInfo classifyKernelArgumentType(QualType Ty) const; @@ -207,6 +209,11 @@ void SPIRVABIInfo::computeInfo(CGFunctionInfo &FI) const { // arguments handling. llvm::CallingConv::ID CC = FI.getCallingConvention(); + for (auto &&[ArgumentsCount, I] : llvm::enumerate(FI.arguments())) + I.info = ArgumentsCount < FI.getNumRequiredArgs() + ? classifyArgumentType(I.type) + : ABIArgInfo::getDirect(); + if (!getCXXABI().classifyReturnType(FI)) FI.getReturnInfo() = classifyReturnType(FI.getReturnType()); @@ -219,6 +226,14 @@ void SPIRVABIInfo::computeInfo(CGFunctionInfo &FI) const { } } +RValue SPIRVABIInfo::EmitVAArg(CodeGenFunction &CGF, Address VAListAddr, + QualType Ty, AggValueSlot Slot) const { + return emitVoidPtrVAArg(CGF, VAListAddr, Ty, /*IsIndirect=*/false, + getContext().getTypeInfoInChars(Ty), + CharUnits::fromQuantity(1), + /*AllowHigherAlign=*/true, Slot); +} + unsigned AMDGCNSPIRVABIInfo::numRegsForType(QualType Ty) const { // This duplicates the AMDGPUABI computation. unsigned NumRegs = 0; diff --git a/clang/test/CodeGenSPIRV/Builtins/variadic.c b/clang/test/CodeGenSPIRV/Builtins/variadic.c new file mode 100644 index 0000000000000..64915a3f0a8ae --- /dev/null +++ b/clang/test/CodeGenSPIRV/Builtins/variadic.c @@ -0,0 +1,31 @@ +// RUN: %clang_cc1 -triple spirv64 -emit-llvm -o - %s | FileCheck %s + +extern void varargs_simple(int, ...); + +void foo() { + char c = '\x1'; + short s = 1; + int i = 1; + long l = 1; + float f = 1.f; + double d = 1.; + varargs_simple(0, c, s, i, l, f, d); + + struct {int x; char c; int y;} a = {1, '\x1', 1}; + varargs_simple(0, a); + + typedef int __attribute__((ext_vector_type(4))) int4; + int4 v = {1, 1, 1, 1}; + varargs_simple(0, v); + + struct {char c, d;} t; + varargs_simple(0, t, t, 0, t); +} + +typedef struct {long x; long y;} S; +extern void varargs_complex(S, S, ...); + +void bar() { + S s = {1l, 1l}; + varargs_complex(s, s, 1, 1l, 1.0); +} diff --git a/llvm/lib/Target/SPIRV/SPIRVGlobalRegistry.cpp b/llvm/lib/Target/SPIRV/SPIRVGlobalRegistry.cpp index 9a2b0771e4dc0..adaf34b897ab3 100644 --- a/llvm/lib/Target/SPIRV/SPIRVGlobalRegistry.cpp +++ b/llvm/lib/Target/SPIRV/SPIRVGlobalRegistry.cpp @@ -1020,12 +1020,6 @@ SPIRVType *SPIRVGlobalRegistry::getOpTypeFunction( const FunctionType *Ty, SPIRVType *RetType, const SmallVectorImpl<SPIRVType *> &ArgTypes, MachineIRBuilder &MIRBuilder) { - if (Ty->isVarArg()) { - Function &Fn = MIRBuilder.getMF().getFunction(); - Ty->getContext().diagnose(DiagnosticInfoUnsupported( - Fn, "SPIR-V does not support variadic functions", - MIRBuilder.getDebugLoc())); - } return createOpType(MIRBuilder, [&](MachineIRBuilder &MIRBuilder) { auto MIB = MIRBuilder.buildInstr(SPIRV::OpTypeFunction) .addDef(createTypeVReg(MIRBuilder)) diff --git a/llvm/lib/Target/SPIRV/SPIRVTargetMachine.cpp b/llvm/lib/Target/SPIRV/SPIRVTargetMachine.cpp index 10038753f4a75..4769d6a92eba4 100644 --- a/llvm/lib/Target/SPIRV/SPIRVTargetMachine.cpp +++ b/llvm/lib/Target/SPIRV/SPIRVTargetMachine.cpp @@ -33,6 +33,7 @@ #include "llvm/Passes/PassBuilder.h" #include "llvm/Support/Compiler.h" #include "llvm/Target/TargetOptions.h" +#include "llvm/Transforms/IPO/ExpandVariadics.h" #include "llvm/Transforms/Scalar.h" #include "llvm/Transforms/Utils.h" #include <optional> @@ -178,6 +179,7 @@ void SPIRVPassConfig::addIRPasses() { addPass(createSPIRVRegularizerPass()); addPass(createSPIRVPrepareFunctionsPass(TM)); addPass(createSPIRVPrepareGlobalsPass()); + addPass(createExpandVariadicsPass(ExpandVariadicsMode::Lowering)); } void SPIRVPassConfig::addISelPrepare() { diff --git a/llvm/lib/Transforms/IPO/ExpandVariadics.cpp b/llvm/lib/Transforms/IPO/ExpandVariadics.cpp index 4863d6ba789a8..6a92a0dca4d37 100644 --- a/llvm/lib/Transforms/IPO/ExpandVariadics.cpp +++ b/llvm/lib/Transforms/IPO/ExpandVariadics.cpp @@ -230,7 +230,8 @@ class ExpandVariadics : public ModulePass { F->hasFnAttribute(Attribute::Naked)) return false; - if (F->getCallingConv() != CallingConv::C) + if (F->getCallingConv() != CallingConv::C && + F->getCallingConv() != CallingConv::SPIR_FUNC) return false; if (rewriteABI()) @@ -249,7 +250,8 @@ class ExpandVariadics : public ModulePass { return false; } - if (CI->getCallingConv() != CallingConv::C) + if (CI->getCallingConv() != CallingConv::C && + CI->getCallingConv() != CallingConv::SPIR_FUNC) return false; return true; @@ -940,6 +942,33 @@ struct NVPTX final : public VariadicABIInfo { } }; +struct SPIRV final : public VariadicABIInfo { + + bool enableForTarget() override { return true; } + + bool vaListPassedInSSARegister() override { return true; } + + Type *vaListType(LLVMContext &Ctx) override { + return PointerType::getUnqual(Ctx); + } + + Type *vaListParameterType(Module &M) override { + return PointerType::getUnqual(M.getContext()); + } + + Value *initializeVaList(Module &M, LLVMContext &Ctx, IRBuilder<> &Builder, + AllocaInst *, Value *Buffer) override { + return Builder.CreateAddrSpaceCast(Buffer, vaListParameterType(M)); + } + + VAArgSlotInfo slotInfo(const DataLayout &DL, Type *Parameter) override { + // Expects natural alignment in all cases. The variadic call ABI will handle + // promoting types to their appropriate size and alignment. + Align A = DL.getABITypeAlign(Parameter); + return {A, false}; + } +}; + struct Wasm final : public VariadicABIInfo { bool enableForTarget() override { @@ -995,6 +1024,11 @@ std::unique_ptr<VariadicABIInfo> VariadicABIInfo::create(const Triple &T) { return std::make_unique<NVPTX>(); } + case Triple::spirv: + case Triple::spirv64: { + return std::make_unique<SPIRV>(); + } + default: return {}; } diff --git a/llvm/test/CodeGen/SPIRV/function/variadics-lowering.ll b/llvm/test/CodeGen/SPIRV/function/variadics-lowering.ll new file mode 100644 index 0000000000000..5ce4414c65ada --- /dev/null +++ b/llvm/test/CodeGen/SPIRV/function/variadics-lowering.ll @@ -0,0 +1,135 @@ +; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 6 +; RUN: opt -S -mtriple=spirv64-- --passes=expand-variadics --expand-variadics-override=lowering < %s | FileCheck %s + +%struct.S = type { i64, i64 } +%struct.anon = type { i32, i8, i32 } +%struct.anon.0 = type { i8, i8 } + +@__const.foo.a = private unnamed_addr addrspace(1) constant { i32, i8, [3 x i8], i32 } { i32 1, i8 1, [3 x i8] zeroinitializer, i32 1 }, align 4 +@__const.bar.s = private unnamed_addr addrspace(1) constant %struct.S { i64 1, i64 1 }, align 8 + +define spir_func void @foo() { +; CHECK-LABEL: define spir_func void @foo() { +; CHECK-NEXT: [[ENTRY:.*:]] +; CHECK-NEXT: [[C:%.*]] = alloca i8, align 1 +; CHECK-NEXT: [[S:%.*]] = alloca i16, align 2 +; CHECK-NEXT: [[I:%.*]] = alloca i32, align 4 +; CHECK-NEXT: [[L:%.*]] = alloca i64, align 8 +; CHECK-NEXT: [[F:%.*]] = alloca float, align 4 +; CHECK-NEXT: [[D:%.*]] = alloca double, align 8 +; CHECK-NEXT: [[A:%.*]] = alloca [[STRUCT_ANON:%.*]], align 4 +; CHECK-NEXT: [[V:%.*]] = alloca <4 x i32>, align 16 +; CHECK-NEXT: [[T:%.*]] = alloca [[STRUCT_ANON_0:%.*]], align 1 +; CHECK-NEXT: [[VARARG_BUFFER:%.*]] = alloca [[FOO_VARARG:%.*]], align 4 +; CHECK-NEXT: [[VARARG_BUFFER1:%.*]] = alloca [[FOO_VARARG_0:%.*]], align 16 +; CHECK-NEXT: [[VARARG_BUFFER2:%.*]] = alloca [[FOO_VARARG_1:%.*]], align 4 +; CHECK-NEXT: [[VARARG_BUFFER3:%.*]] = alloca [[FOO_VARARG_2:%.*]], align 8 +; CHECK-NEXT: [[VARARG_BUFFER4:%.*]] = alloca [[FOO_VARARG_3:%.*]], align 8 +; CHECK-NEXT: store i8 1, ptr [[C]], align 1 +; CHECK-NEXT: store i16 1, ptr [[S]], align 2 +; CHECK-NEXT: store i32 1, ptr [[I]], align 4 +; CHECK-NEXT: store i64 1, ptr [[L]], align 8 +; CHECK-NEXT: store float 1.000000e+00, ptr [[F]], align 4 +; CHECK-NEXT: store double 1.000000e+00, ptr [[D]], align 8 +; CHECK-NEXT: [[TMP0:%.*]] = load i8, ptr [[C]], align 1 +; CHECK-NEXT: [[CONV:%.*]] = sext i8 [[TMP0]] to i32 +; CHECK-NEXT: [[TMP1:%.*]] = load i16, ptr [[S]], align 2 +; CHECK-NEXT: [[CONV1:%.*]] = sext i16 [[TMP1]] to i32 +; CHECK-NEXT: [[TMP2:%.*]] = load i32, ptr [[I]], align 4 +; CHECK-NEXT: [[TMP3:%.*]] = load i64, ptr [[L]], align 8 +; CHECK-NEXT: [[TMP4:%.*]] = load float, ptr [[F]], align 4 +; CHECK-NEXT: [[CONV2:%.*]] = fpext float [[TMP4]] to double +; CHECK-NEXT: [[TMP5:%.*]] = load double, ptr [[D]], align 8 +; CHECK-NEXT: call void @llvm.lifetime.start.p0(ptr [[VARARG_BUFFER3]]) +; CHECK-NEXT: [[TMP13:%.*]] = getelementptr inbounds nuw [[FOO_VARARG_2]], ptr [[VARARG_BUFFER3]], i32 0, i32 0 +; CHECK-NEXT: store i32 [[CONV]], ptr [[TMP13]], align 4 +; CHECK-NEXT: [[TMP7:%.*]] = getelementptr inbounds nuw [[FOO_VARARG_2]], ptr [[VARARG_BUFFER3]], i32 0, i32 1 +; CHECK-NEXT: store i32 [[CONV1]], ptr [[TMP7]], align 4 +; CHECK-NEXT: [[TMP8:%.*]] = getelementptr inbounds nuw [[FOO_VARARG_2]], ptr [[VARARG_BUFFER3]], i32 0, i32 2 +; CHECK-NEXT: store i32 [[TMP2]], ptr [[TMP8]], align 4 +; CHECK-NEXT: [[TMP9:%.*]] = getelementptr inbounds nuw [[FOO_VARARG_2]], ptr [[VARARG_BUFFER3]], i32 0, i32 4 +; CHECK-NEXT: store i64 [[TMP3]], ptr [[TMP9]], align 8 +; CHECK-NEXT: [[TMP10:%.*]] = getelementptr inbounds nuw [[FOO_VARARG_2]], ptr [[VARARG_BUFFER3]], i32 0, i32 5 +; CHECK-NEXT: store double [[CONV2]], ptr [[TMP10]], align 8 +; CHECK-NEXT: [[TMP11:%.*]] = getelementptr inbounds nuw [[FOO_VARARG_2]], ptr [[VARARG_BUFFER3]], i32 0, i32 6 +; CHECK-NEXT: store double [[TMP5]], ptr [[TMP11]], align 8 +; CHECK-NEXT: call spir_func void @varargs_simple(i32 0, ptr [[VARARG_BUFFER3]]) +; CHECK-NEXT: call void @llvm.lifetime.end.p0(ptr [[VARARG_BUFFER3]]) +; CHECK-NEXT: call void @llvm.memcpy.p0.p1.i64(ptr align 4 [[A]], ptr addrspace(1) align 4 @__const.foo.a, i64 12, i1 false) +; CHECK-NEXT: call void @llvm.lifetime.start.p0(ptr [[VARARG_BUFFER2]]) +; CHECK-NEXT: [[TMP12:%.*]] = getelementptr inbounds nuw [[FOO_VARARG_1]], ptr [[VARARG_BUFFER2]], i32 0, i32 0 +; CHECK-NEXT: call void @llvm.memcpy.p0.p0.i64(ptr [[TMP12]], ptr [[A]], i64 12, i1 false) +; CHECK-NEXT: call spir_func void @varargs_simple(i32 0, ptr [[VARARG_BUFFER2]]) +; CHECK-NEXT: call void @llvm.lifetime.end.p0(ptr [[VARARG_BUFFER2]]) +; CHECK-NEXT: store <4 x i32> splat (i32 1), ptr [[V]], align 16 +; CHECK-NEXT: [[TMP6:%.*]] = load <4 x i32>, ptr [[V]], align 16 +; CHECK-NEXT: call void @llvm.lifetime.start.p0(ptr [[VARARG_BUFFER1]]) +; CHECK-NEXT: [[TMP14:%.*]] = getelementptr inbounds nuw [[FOO_VARARG_0]], ptr [[VARARG_BUFFER1]], i32 0, i32 0 +; CHECK-NEXT: store <4 x i32> [[TMP6]], ptr [[TMP14]], align 16 +; CHECK-NEXT: call spir_func void @varargs_simple(i32 0, ptr [[VARARG_BUFFER1]]) +; CHECK-NEXT: call void @llvm.lifetime.end.p0(ptr [[VARARG_BUFFER1]]) +; CHECK-NEXT: call void @llvm.lifetime.start.p0(ptr [[VARARG_BUFFER]]) +; CHECK-NEXT: [[TMP15:%.*]] = getelementptr inbounds nuw [[FOO_VARARG]], ptr [[VARARG_BUFFER]], i32 0, i32 0 +; CHECK-NEXT: call void @llvm.memcpy.p0.p0.i64(ptr [[TMP15]], ptr [[T]], i64 2, i1 false) +; CHECK-NEXT: [[TMP16:%.*]] = getelementptr inbounds nuw [[FOO_VARARG]], ptr [[VARARG_BUFFER]], i32 0, i32 1 +; CHECK-NEXT: call void @llvm.memcpy.p0.p0.i64(ptr [[TMP16]], ptr [[T]], i64 2, i1 false) +; CHECK-NEXT: [[TMP17:%.*]] = getelementptr inbounds nuw [[FOO_VARARG]], ptr [[VARARG_BUFFER]], i32 0, i32 2 +; CHECK-NEXT: store i32 0, ptr [[TMP17]], align 4 +; CHECK-NEXT: [[TMP18:%.*]] = getelementptr inbounds nuw [[FOO_VARARG]], ptr [[VARARG_BUFFER]], i32 0, i32 3 +; CHECK-NEXT: call void @llvm.memcpy.p0.p0.i64(ptr [[TMP18]], ptr [[T]], i64 2, i1 false) +; CHECK-NEXT: call spir_func void @varargs_simple(i32 0, ptr [[VARARG_BUFFER]]) +; CHECK-NEXT: call void @llvm.lifetime.end.p0(ptr [[VARARG_BUFFER]]) +; CHECK-NEXT: [[R:%.*]] = alloca [[STRUCT_S:%.*]], align 8 +; CHECK-NEXT: call void @llvm.memcpy.p0.p1.i64(ptr align 8 [[R]], ptr addrspace(1) align 8 @__const.bar.s, i64 16, i1 false) +; CHECK-NEXT: call void @llvm.lifetime.start.p0(ptr [[VARARG_BUFFER4]]) +; CHECK-NEXT: [[TMP19:%.*]] = getelementptr inbounds nuw [[FOO_VARARG_3]], ptr [[VARARG_BUFFER4]], i32 0, i32 0 +; CHECK-NEXT: store i32 1, ptr [[TMP19]], align 4 +; CHECK-NEXT: [[TMP20:%.*]] = getelementptr inbounds nuw [[FOO_VARARG_3]], ptr [[VARARG_BUFFER4]], i32 0, i32 2 +; CHECK-NEXT: store i64 1, ptr [[TMP20]], align 8 +; CHECK-NEXT: [[TMP21:%.*]] = getelementptr inbounds nuw [[FOO_VARARG_3]], ptr [[VARARG_BUFFER4]], i32 0, i32 3 +; CHECK-NEXT: store double 1.000000e+00, ptr [[TMP21]], align 8 +; CHECK-NEXT: call spir_func void @varargs_complex(ptr byval([[STRUCT_S]]) align 8 [[R]], ptr byval([[STRUCT_S]]) align 8 [[S]], ptr [[VARARG_BUFFER4]]) +; CHECK-NEXT: call void @llvm.lifetime.end.p0(ptr [[VARARG_BUFFER4]]) +; CHECK-NEXT: ret void +; +entry: + %c = alloca i8, align 1 + %s = alloca i16, align 2 + %i = alloca i32, align 4 + %l = alloca i64, align 8 + %f = alloca float, align 4 + %d = alloca double, align 8 + %a = alloca %struct.anon, align 4 + %v = alloca <4 x i32>, align 16 + %t = alloca %struct.anon.0, align 1 + store i8 1, ptr %c, align 1 + store i16 1, ptr %s, align 2 + store i32 1, ptr %i, align 4 + store i64 1, ptr %l, align 8 + store float 1.000000e+00, ptr %f, align 4 + store double 1.000000e+00, ptr %d, align 8 + %0 = load i8, ptr %c, align 1 + %conv = sext i8 %0 to i32 + %1 = load i16, ptr %s, align 2 + %conv1 = sext i16 %1 to i32 + %2 = load i32, ptr %i, align 4 + %3 = load i64, ptr %l, align 8 + %4 = load float, ptr %f, align 4 + %conv2 = fpext float %4 to double + %5 = load double, ptr %d, align 8 + call spir_func void (i32, ...) @varargs_simple(i32 0, i32 %conv, i32 %conv1, i32 %2, i64 %3, double %conv2, double %5) + call void @llvm.memcpy.p0.p1.i64(ptr align 4 %a, ptr addrspace(1) align 4 @__const.foo.a, i64 12, i1 false) + call spir_func void (i32, ...) @varargs_simple(i32 0, ptr byval(%struct.anon) align 4 %a) + store <4 x i32> splat (i32 1), ptr %v, align 16 + %6 = load <4 x i32>, ptr %v, align 16 + call spir_func void (i32, ...) @varargs_simple(i32 0, <4 x i32> %6) + call spir_func void (i32, ...) @varargs_simple(i32 0, ptr byval(%struct.anon.0) align 1 %t, ptr byval(%struct.anon.0) align 1 %t, i32 0, ptr byval(%struct.anon.0) align 1 %t) + %r = alloca %struct.S, align 8 + call void @llvm.memcpy.p0.p1.i64(ptr align 8 %r, ptr addrspace(1) align 8 @__const.bar.s, i64 16, i1 false) + call spir_func void (ptr, ptr, ...) @varargs_complex(ptr byval(%struct.S) align 8 %r, ptr byval(%struct.S) align 8 %s, i32 1, i64 1, double 1.000000e+00) + ret void +} + +declare spir_func void @varargs_simple(i32 noundef, ...) + +declare spir_func void @varargs_complex(ptr byval(%struct.S) align 8, ptr byval(%struct.S) align 8, ...) _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
