bc78c09952
Introduces a string attribute, amdgpu-requires-module-lds, to allow eliding the module.lds block from kernels. Will allocate the block as before if the attribute is missing or has its default value of true. Patch uses the new attribute to detect the simplest possible instance of this, where a kernel makes no calls and thus cannot call any functions that use LDS. Tests updated to match, coverage was already good. Interesting cases is in lower-module-lds-offsets where annotating the kernel allows the backend to pick a different (in this case better) variable ordering than previously. A later patch will avoid moving kernel variables into module.lds when the kernel can have this attribute, allowing optimal ordering and locally unused variable elimination. Reviewed By: arsenm Differential Revision: https://reviews.llvm.org/D122091
64 lines
2.9 KiB
LLVM
64 lines
2.9 KiB
LLVM
; RUN: opt -S -mtriple=amdgcn-- -amdgpu-lower-module-lds < %s | FileCheck %s
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; RUN: opt -S -mtriple=amdgcn-- -passes=amdgpu-lower-module-lds < %s | FileCheck %s
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; Padding to meet alignment, so references to @var1 replaced with gep ptr, 0, 2
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; No i64 as addrspace(3) types with initializers are ignored. Likewise no addrspace(4).
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; CHECK: %llvm.amdgcn.module.lds.t = type { float, [4 x i8], i32 }
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; Variables removed by pass
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; CHECK-NOT: @var0
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; CHECK-NOT: @var1
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@var0 = addrspace(3) global float undef, align 8
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@var1 = addrspace(3) global i32 undef, align 8
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@ptr = addrspace(1) global i32 addrspace(3)* @var1, align 4
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; A variable that is unchanged by pass
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; CHECK: @with_init = addrspace(3) global i64 0
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@with_init = addrspace(3) global i64 0
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; Instance of new type, aligned to max of element alignment
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; CHECK: @llvm.amdgcn.module.lds = internal addrspace(3) global %llvm.amdgcn.module.lds.t undef, align 8
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; Use in func rewritten to access struct at address zero
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; CHECK-LABEL: @func()
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; CHECK: %dec = atomicrmw fsub float addrspace(3)* getelementptr inbounds (%llvm.amdgcn.module.lds.t, %llvm.amdgcn.module.lds.t addrspace(3)* @llvm.amdgcn.module.lds, i32 0, i32 0), float 1.0
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; CHECK: %val0 = load i32, i32 addrspace(3)* getelementptr inbounds (%llvm.amdgcn.module.lds.t, %llvm.amdgcn.module.lds.t addrspace(3)* @llvm.amdgcn.module.lds, i32 0, i32 2), align 8
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; CHECK: %val1 = add i32 %val0, 4
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; CHECK: store i32 %val1, i32 addrspace(3)* getelementptr inbounds (%llvm.amdgcn.module.lds.t, %llvm.amdgcn.module.lds.t addrspace(3)* @llvm.amdgcn.module.lds, i32 0, i32 2), align 8
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; CHECK: %unused0 = atomicrmw add i64 addrspace(3)* @with_init, i64 1 monotonic
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define void @func() {
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%dec = atomicrmw fsub float addrspace(3)* @var0, float 1.0 monotonic
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%val0 = load i32, i32 addrspace(3)* @var1, align 4
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%val1 = add i32 %val0, 4
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store i32 %val1, i32 addrspace(3)* @var1, align 4
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%unused0 = atomicrmw add i64 addrspace(3)* @with_init, i64 1 monotonic
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ret void
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}
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; This kernel calls a function that uses LDS so needs the block
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; CHECK-LABEL: @kern_call()
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; CHECK: call void @llvm.donothing() [ "ExplicitUse"(%llvm.amdgcn.module.lds.t addrspace(3)* @llvm.amdgcn.module.lds) ]
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; CHECK: call void @func()
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; CHECK: %dec = atomicrmw fsub float addrspace(3)* getelementptr inbounds (%llvm.amdgcn.module.lds.t, %llvm.amdgcn.module.lds.t addrspace(3)* @llvm.amdgcn.module.lds, i32 0, i32 0), float 2.000000e+00 monotonic, align 8
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define amdgpu_kernel void @kern_call() {
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call void @func()
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%dec = atomicrmw fsub float addrspace(3)* @var0, float 2.0 monotonic
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ret void
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}
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; This kernel does alloc the LDS block as it makes no calls
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; CHECK-LABEL: @kern_empty()
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; CHECK-NOT: call void @llvm.donothing()
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define spir_kernel void @kern_empty() #0{
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ret void
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}
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; Make sure we don't crash trying to insert code into a kernel
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; declaration.
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declare amdgpu_kernel void @kernel_declaration()
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attributes #0 = { "amdgpu-elide-module-lds" }
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; CHECK: attributes #0 = { "amdgpu-elide-module-lds" }
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