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[MemoryLocation][DSE] Allow other read effects in MemoryLocation::getForDest() #144343

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Merged
merged 3 commits into from
Jun 17, 2025
Merged

[MemoryLocation][DSE] Allow other read effects in MemoryLocation::getForDest() #144343

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ffbf398
Add test for call dse with additional read effects
nikic Jun 16, 2025
18a2cd3
[MemoryLocation][DSE] Allow other read effects in MemoryLocation::get…
nikic Jun 16, 2025
cf14cfa
Add additional negative test with write effect
nikic Jun 16, 2025
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4 changes: 3 additions & 1 deletion llvm/lib/Analysis/MemoryLocation.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -111,7 +111,9 @@ MemoryLocation MemoryLocation::getForDest(const AnyMemIntrinsic *MI) {

std::optional<MemoryLocation>
MemoryLocation::getForDest(const CallBase *CB, const TargetLibraryInfo &TLI) {
if (!CB->onlyAccessesArgMemory())
// Check that the only possible writes are to arguments.
MemoryEffects WriteME = CB->getMemoryEffects() & MemoryEffects::writeOnly();
if (!WriteME.onlyAccessesArgPointees())
return std::nullopt;

if (CB->hasOperandBundles())
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32 changes: 32 additions & 0 deletions llvm/test/Transforms/DeadStoreElimination/trivial-dse-calls.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -286,3 +286,35 @@ define void @test_dse_non_alloca() {
ret void
}

define void @test_other_read_effects() {
; CHECK-LABEL: @test_other_read_effects(
; CHECK-NEXT: ret void
;
%a = alloca i32, align 4
call void @f(ptr %a) memory(read, argmem: readwrite) nounwind willreturn
ret void
}

define i32 @test_other_read_effects_read_after() {
; CHECK-LABEL: @test_other_read_effects_read_after(
; CHECK-NEXT: [[A:%.*]] = alloca i32, align 4
; CHECK-NEXT: call void @f(ptr [[A]]) #[[ATTR5:[0-9]+]]
; CHECK-NEXT: [[V:%.*]] = load i32, ptr [[A]], align 4
; CHECK-NEXT: ret i32 [[V]]
;
%a = alloca i32, align 4
call void @f(ptr %a) memory(read, argmem: readwrite) nounwind willreturn
%v = load i32, ptr %a
ret i32 %v
}

define void @test_other_write_effects() {
; CHECK-LABEL: @test_other_write_effects(
; CHECK-NEXT: [[A:%.*]] = alloca i32, align 4
; CHECK-NEXT: call void @f(ptr [[A]]) #[[ATTR6:[0-9]+]]
; CHECK-NEXT: ret void
;
%a = alloca i32, align 4
call void @f(ptr %a) memory(write, argmem: readwrite) nounwind willreturn
ret void
}
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