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AMDGPU: Handle invariant loads when considering if a load can be scalar #168787

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Merged
merged 1 commit into from
Nov 20, 2025
Merged

AMDGPU: Handle invariant loads when considering if a load can be scalar #168787

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3 changes: 2 additions & 1 deletion llvm/lib/Target/AMDGPU/AMDGPUISelDAGToDAG.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -4437,7 +4437,8 @@ bool AMDGPUDAGToDAGISel::isUniformLoad(const SDNode *N) const {
Ld->getAlign() >=
Align(std::min(MMO->getSize().getValue().getKnownMinValue(),
uint64_t(4))) &&
((Ld->getAddressSpace() == AMDGPUAS::CONSTANT_ADDRESS ||
(MMO->isInvariant() ||
(Ld->getAddressSpace() == AMDGPUAS::CONSTANT_ADDRESS ||
Ld->getAddressSpace() == AMDGPUAS::CONSTANT_ADDRESS_32BIT) ||
(Subtarget->getScalarizeGlobalBehavior() &&
Ld->getAddressSpace() == AMDGPUAS::GLOBAL_ADDRESS &&
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15 changes: 14 additions & 1 deletion llvm/test/CodeGen/AMDGPU/invariant-load-no-alias-store.ll
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Expand Up @@ -10,7 +10,7 @@
; GCN-DAG: buffer_load_dwordx2 [[PTR:v\[[0-9]+:[0-9]+\]]],
; GCN-DAG: v_mov_b32_e32 [[K:v[0-9]+]], 0x1c8007b
; GCN: buffer_store_dword [[K]], [[PTR]]
define amdgpu_kernel void @test_merge_store_constant_i16_invariant_global_pointer_load(ptr addrspace(1) dereferenceable(4096) nonnull %in) #0 {
define void @test_merge_store_constant_i16_invariant_global_pointer_load(ptr addrspace(1) dereferenceable(4096) nonnull %in) #0 {
%ptr = load ptr addrspace(1), ptr addrspace(1) %in, !invariant.load !0
%ptr.1 = getelementptr i16, ptr addrspace(1) %ptr, i64 1
store i16 123, ptr addrspace(1) %ptr, align 4
Expand All @@ -30,6 +30,19 @@ define amdgpu_kernel void @test_merge_store_constant_i16_invariant_constant_poin
ret void
}

; Invariant global load should be equivalently handled to constant.
; GCN-LABEL: {{^}}test_merge_store_global_i16_invariant_uniform_global_pointer_load:
; GCN: s_load_dwordx2 s[[[SPTR_LO:[0-9]+]]:[[SPTR_HI:[0-9]+]]]
; GCN: v_mov_b32_e32 [[K:v[0-9]+]], 0x1c8007b
; GCN: buffer_store_dword [[K]], off, s[[[SPTR_LO]]:
define amdgpu_kernel void @test_merge_store_global_i16_invariant_uniform_global_pointer_load(ptr addrspace(1) dereferenceable(4096) nonnull %in) #0 {
%ptr = load ptr addrspace(1), ptr addrspace(1) %in, !invariant.load !0
%ptr.1 = getelementptr i16, ptr addrspace(1) %ptr, i64 1
store i16 123, ptr addrspace(1) %ptr, align 4
store i16 456, ptr addrspace(1) %ptr.1
ret void
}

!0 = !{}

attributes #0 = { nounwind }