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- If an aggregate argument is indirectly accessed within kernels, direct
passing results in unpromotable `alloca`, which degrade performance
significantly. In additon, with the enhanced backend and the improved AA,
kernel argument coercion is no longer required.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D89980
Files:
clang/lib/CodeGen/TargetInfo.cpp
clang/test/CodeGenCUDA/amdgpu-kernel-arg-pointer-type.cu
Index: clang/test/CodeGenCUDA/amdgpu-kernel-arg-pointer-type.cu
===================================================================
--- clang/test/CodeGenCUDA/amdgpu-kernel-arg-pointer-type.cu
+++ /dev/null
@@ -1,113 +0,0 @@
-// REQUIRES: x86-registered-target
-// REQUIRES: amdgpu-registered-target
-
-// RUN: %clang_cc1 -triple amdgcn-amd-amdhsa -fcuda-is-device -emit-llvm -x hip %s -o - | FileCheck --check-prefixes=COMMON,CHECK %s
-// RUN: %clang_cc1 -triple amdgcn-amd-amdhsa -fcuda-is-device -emit-llvm -x hip %s -disable-O0-optnone -o - | opt -S -O2 | FileCheck %s --check-prefixes=COMMON,OPT
-// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-llvm -x hip %s -o - | FileCheck -check-prefix=HOST %s
-
-#include "Inputs/cuda.h"
-
-// Coerced struct from `struct S` without all generic pointers lowered into
-// global ones.
-// COMMON: %struct.S.coerce = type { i32 addrspace(1)*, float addrspace(1)* }
-// COMMON: %struct.T.coerce = type { [2 x float addrspace(1)*] }
-
-// On the host-side compilation, generic pointer won't be coerced.
-// HOST-NOT: %struct.S.coerce
-// HOST-NOT: %struct.T.coerce
-
-// HOST: define void @_Z22__device_stub__kernel1Pi(i32* %x)
-// COMMON-LABEL: define amdgpu_kernel void @_Z7kernel1Pi(i32 addrspace(1)*{{.*}} %x.coerce)
-// CHECK: = addrspacecast [[TYPE:.*]] addrspace(1)* %{{.*}} to [[TYPE]]*
-// CHECK-NOT: = addrspacecast [[TYPE:.*]] addrspace(1)* %{{.*}} to [[TYPE]]*
-// OPT: [[VAL:%.*]] = load i32, i32 addrspace(1)* %x.coerce, align 4
-// OPT: [[INC:%.*]] = add nsw i32 [[VAL]], 1
-// OPT: store i32 [[INC]], i32 addrspace(1)* %x.coerce, align 4
-// OPT: ret void
-__global__ void kernel1(int *x) {
- x[0]++;
-}
-
-// HOST: define void @_Z22__device_stub__kernel2Ri(i32* nonnull align 4 dereferenceable(4) %x)
-// COMMON-LABEL: define amdgpu_kernel void @_Z7kernel2Ri(i32 addrspace(1)*{{.*}} nonnull align 4 dereferenceable(4) %x.coerce)
-// CHECK: = addrspacecast [[TYPE:.*]] addrspace(1)* %{{.*}} to [[TYPE]]*
-// CHECK-NOT: = addrspacecast [[TYPE:.*]] addrspace(1)* %{{.*}} to [[TYPE]]*
-// OPT: [[VAL:%.*]] = load i32, i32 addrspace(1)* %x.coerce, align 4
-// OPT: [[INC:%.*]] = add nsw i32 [[VAL]], 1
-// OPT: store i32 [[INC]], i32 addrspace(1)* %x.coerce, align 4
-// OPT: ret void
-__global__ void kernel2(int &x) {
- x++;
-}
-
-// HOST: define void @_Z22__device_stub__kernel3PU3AS2iPU3AS1i(i32 addrspace(2)* %x, i32 addrspace(1)* %y)
-// CHECK-LABEL: define amdgpu_kernel void @_Z7kernel3PU3AS2iPU3AS1i(i32 addrspace(2)*{{.*}} %x, i32 addrspace(1)*{{.*}} %y)
-// CHECK-NOT: = addrspacecast [[TYPE:.*]] addrspace(1)* %{{.*}} to [[TYPE]]*
-__global__ void kernel3(__attribute__((address_space(2))) int *x,
- __attribute__((address_space(1))) int *y) {
- y[0] = x[0];
-}
-
-// COMMON-LABEL: define void @_Z4funcPi(i32*{{.*}} %x)
-// CHECK-NOT: = addrspacecast [[TYPE:.*]] addrspace(1)* %{{.*}} to [[TYPE]]*
-__device__ void func(int *x) {
- x[0]++;
-}
-
-struct S {
- int *x;
- float *y;
-};
-// `by-val` struct will be coerced into a similar struct with all generic
-// pointers lowerd into global ones.
-// HOST: define void @_Z22__device_stub__kernel41S(i32* %s.coerce0, float* %s.coerce1)
-// COMMON-LABEL: define amdgpu_kernel void @_Z7kernel41S(%struct.S.coerce %s.coerce)
-// OPT: [[P0:%.*]] = extractvalue %struct.S.coerce %s.coerce, 0
-// OPT: [[P1:%.*]] = extractvalue %struct.S.coerce %s.coerce, 1
-// OPT: [[V0:%.*]] = load i32, i32 addrspace(1)* [[P0]], align 4
-// OPT: [[INC:%.*]] = add nsw i32 [[V0]], 1
-// OPT: store i32 [[INC]], i32 addrspace(1)* [[P0]], align 4
-// OPT: [[V1:%.*]] = load float, float addrspace(1)* [[P1]], align 4
-// OPT: [[ADD:%.*]] = fadd contract float [[V1]], 1.000000e+00
-// OPT: store float [[ADD]], float addrspace(1)* [[P1]], align 4
-// OPT: ret void
-__global__ void kernel4(struct S s) {
- s.x[0]++;
- s.y[0] += 1.f;
-}
-
-// If a pointer to struct is passed, only the pointer itself is coerced into the global one.
-// HOST: define void @_Z22__device_stub__kernel5P1S(%struct.S* %s)
-// COMMON-LABEL: define amdgpu_kernel void @_Z7kernel5P1S(%struct.S addrspace(1)*{{.*}} %s.coerce)
-__global__ void kernel5(struct S *s) {
- s->x[0]++;
- s->y[0] += 1.f;
-}
-
-struct T {
- float *x[2];
-};
-// `by-val` array is also coerced.
-// HOST: define void @_Z22__device_stub__kernel61T(float* %t.coerce0, float* %t.coerce1)
-// COMMON-LABEL: define amdgpu_kernel void @_Z7kernel61T(%struct.T.coerce %t.coerce)
-// OPT: [[ARR:%.*]] = extractvalue %struct.T.coerce %t.coerce, 0
-// OPT: [[P0:%.*]] = extractvalue [2 x float addrspace(1)*] [[ARR]], 0
-// OPT: [[P1:%.*]] = extractvalue [2 x float addrspace(1)*] [[ARR]], 1
-// OPT: [[V0:%.*]] = load float, float addrspace(1)* [[P0]], align 4
-// OPT: [[ADD0:%.*]] = fadd contract float [[V0]], 1.000000e+00
-// OPT: store float [[ADD0]], float addrspace(1)* [[P0]], align 4
-// OPT: [[V1:%.*]] = load float, float addrspace(1)* [[P1]], align 4
-// OPT: [[ADD1:%.*]] = fadd contract float [[V1]], 2.000000e+00
-// OPT: store float [[ADD1]], float addrspace(1)* [[P1]], align 4
-// OPT: ret void
-__global__ void kernel6(struct T t) {
- t.x[0][0] += 1.f;
- t.x[1][0] += 2.f;
-}
-
-// Check that coerced pointers retain the noalias attribute when qualified with __restrict.
-// HOST: define void @_Z22__device_stub__kernel7Pi(i32* noalias %x)
-// COMMON-LABEL: define amdgpu_kernel void @_Z7kernel7Pi(i32 addrspace(1)* noalias{{.*}} %x.coerce)
-__global__ void kernel7(int *__restrict x) {
- x[0]++;
-}
Index: clang/lib/CodeGen/TargetInfo.cpp
===================================================================
--- clang/lib/CodeGen/TargetInfo.cpp
+++ clang/lib/CodeGen/TargetInfo.cpp
@@ -8707,42 +8707,6 @@
bool isHomogeneousAggregateSmallEnough(const Type *Base,
uint64_t Members) const override;
- // Coerce HIP pointer arguments from generic pointers to global ones.
- llvm::Type *coerceKernelArgumentType(llvm::Type *Ty, unsigned FromAS,
- unsigned ToAS) const {
- // Structure types.
- if (auto STy = dyn_cast<llvm::StructType>(Ty)) {
- SmallVector<llvm::Type *, 8> EltTys;
- bool Changed = false;
- for (auto T : STy->elements()) {
- auto NT = coerceKernelArgumentType(T, FromAS, ToAS);
- EltTys.push_back(NT);
- Changed |= (NT != T);
- }
- // Skip if there is no change in element types.
- if (!Changed)
- return STy;
- if (STy->hasName())
- return llvm::StructType::create(
- EltTys, (STy->getName() + ".coerce").str(), STy->isPacked());
- return llvm::StructType::get(getVMContext(), EltTys, STy->isPacked());
- }
- // Array types.
- if (auto ATy = dyn_cast<llvm::ArrayType>(Ty)) {
- auto T = ATy->getElementType();
- auto NT = coerceKernelArgumentType(T, FromAS, ToAS);
- // Skip if there is no change in that element type.
- if (NT == T)
- return ATy;
- return llvm::ArrayType::get(NT, ATy->getNumElements());
- }
- // Single value types.
- if (Ty->isPointerTy() && Ty->getPointerAddressSpace() == FromAS)
- return llvm::PointerType::get(
- cast<llvm::PointerType>(Ty)->getElementType(), ToAS);
- return Ty;
- }
-
public:
explicit AMDGPUABIInfo(CodeGen::CodeGenTypes &CGT) :
DefaultABIInfo(CGT) {}
@@ -8873,22 +8837,9 @@
if (const Type *SeltTy = isSingleElementStruct(Ty, getContext()))
Ty = QualType(SeltTy, 0);
- llvm::Type *OrigLTy = CGT.ConvertType(Ty);
- llvm::Type *LTy = OrigLTy;
- if (getContext().getLangOpts().HIP) {
- LTy = coerceKernelArgumentType(
- OrigLTy, /*FromAS=*/getContext().getTargetAddressSpace(LangAS::Default),
- /*ToAS=*/getContext().getTargetAddressSpace(LangAS::cuda_device));
- }
-
// FIXME: Should also use this for OpenCL, but it requires addressing the
// problem of kernels being called.
- //
- // FIXME: This doesn't apply the optimization of coercing pointers in structs
- // to global address space when using byref. This would require implementing a
- // new kind of coercion of the in-memory type when for indirect arguments.
- if (!getContext().getLangOpts().OpenCL && LTy == OrigLTy &&
- isAggregateTypeForABI(Ty)) {
+ if (!getContext().getLangOpts().OpenCL && isAggregateTypeForABI(Ty)) {
return ABIArgInfo::getIndirectAliased(
getContext().getTypeAlignInChars(Ty),
getContext().getTargetAddressSpace(LangAS::opencl_constant),
@@ -8898,6 +8849,7 @@
// If we set CanBeFlattened to true, CodeGen will expand the struct to its
// individual elements, which confuses the Clover OpenCL backend; therefore we
// have to set it to false here. Other args of getDirect() are just defaults.
+ llvm::Type *LTy = CGT.ConvertType(Ty);
return ABIArgInfo::getDirect(LTy, 0, nullptr, false);
}
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