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[SLP] Invariant loads cannot have a memory dependency on stores. #167929

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Merged
merged 4 commits into from
Nov 18, 2025
Merged

[SLP] Invariant loads cannot have a memory dependency on stores. #167929

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513c986
[SLP] Invariant loads cannot have a memory dependency on stores.
mjbedy Nov 13, 2025
4d014b8
Update location; exclude invariant (and simple) loads from memory ins…
mjbedy Nov 14, 2025
d6fdd3d
Fix nit.
mjbedy Nov 14, 2025
2fa73c5
Merge branch 'main' into slp_invariant_pr
dstutt Nov 17, 2025
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11 changes: 11 additions & 0 deletions llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -21479,7 +21479,18 @@ void BoUpSLP::BlockScheduling::initScheduleData(Instruction *FromI,
"new ScheduleData already in scheduling region");
SD->init(SchedulingRegionID, I);

auto CanIgnoreLoad = [](const Instruction *I) {
const auto *LI = dyn_cast<LoadInst>(I);
// If there is a simple load marked as invariant, we can ignore it.
// But, in the (unlikely) case of non-simple invariant load,
// we should not ignore it.
return LI && LI->isSimple() &&
LI->getMetadata(LLVMContext::MD_invariant_load);
};

if (I->mayReadOrWriteMemory() &&
// Simple InvariantLoad does not depend on other memory accesses.
!CanIgnoreLoad(I) &&
(!isa<IntrinsicInst>(I) ||
(cast<IntrinsicInst>(I)->getIntrinsicID() != Intrinsic::sideeffect &&
cast<IntrinsicInst>(I)->getIntrinsicID() !=
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121 changes: 121 additions & 0 deletions llvm/test/Transforms/SLPVectorizer/AMDGPU/invariant-load-no-alias-store.ll
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@@ -0,0 +1,121 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 6
; RUN: opt -passes="function(slp-vectorizer)" -mtriple=amdgcn-amd-amdhsa -mcpu=gfx1200 %s -S | FileCheck %s

define void @test(ptr addrspace(1) %base, ptr addrspace(1) %otherA, ptr addrspace(1) %otherB) #0 {
; CHECK-LABEL: define void @test(
; CHECK-SAME: ptr addrspace(1) [[BASE:%.*]], ptr addrspace(1) [[OTHERA:%.*]], ptr addrspace(1) [[OTHERB:%.*]]) #[[ATTR0:[0-9]+]] {
; CHECK-NEXT: [[ENTRY:.*:]]
; CHECK-NEXT: [[P0:%.*]] = getelementptr half, ptr addrspace(1) [[BASE]], i32 0
; CHECK-NEXT: [[A0PTR:%.*]] = getelementptr half, ptr addrspace(1) [[OTHERA]], i32 0
; CHECK-NEXT: [[B0PTR:%.*]] = getelementptr half, ptr addrspace(1) [[OTHERB]], i32 0
; CHECK-NEXT: [[TMP0:%.*]] = load <2 x half>, ptr addrspace(1) [[A0PTR]], align 2, !invariant.load [[META0:![0-9]+]]
; CHECK-NEXT: [[TMP1:%.*]] = load <2 x half>, ptr addrspace(1) [[B0PTR]], align 2, !invariant.load [[META0]]
; CHECK-NEXT: [[TMP2:%.*]] = fadd reassoc <2 x half> [[TMP0]], [[TMP1]]
; CHECK-NEXT: store <2 x half> [[TMP2]], ptr addrspace(1) [[P0]], align 2
; CHECK-NEXT: ret void
;
entry:
%p0 = getelementptr half, ptr addrspace(1) %base, i32 0
%p1 = getelementptr half, ptr addrspace(1) %base, i32 1
; First pair of invariant loads from otherA.
%A0PTR = getelementptr half, ptr addrspace(1) %otherA, i32 0
%B0PTR = getelementptr half, ptr addrspace(1) %otherB, i32 0
%A0 = load half, ptr addrspace(1) %A0PTR, align 2, !invariant.load !0
%B0 = load half, ptr addrspace(1) %B0PTR, align 2, !invariant.load !0
%add0 = fadd reassoc half %A0, %B0
store half %add0, ptr addrspace(1) %p0, align 2
%A1PTR = getelementptr half, ptr addrspace(1) %otherA, i32 1
%B1PTR = getelementptr half, ptr addrspace(1) %otherB, i32 1
%A1 = load half, ptr addrspace(1) %A1PTR, align 2, !invariant.load !0
%B1 = load half, ptr addrspace(1) %B1PTR, align 2, !invariant.load !0
%add1 = fadd reassoc half %A1, %B1
store half %add1, ptr addrspace(1) %p1, align 2
ret void
}


define void @aliastest(ptr addrspace(1) %base, ptr addrspace(1) %otherA, ptr addrspace(1) %otherB) #0 {
; CHECK-LABEL: define void @aliastest(
; CHECK-SAME: ptr addrspace(1) [[BASE:%.*]], ptr addrspace(1) [[OTHERA:%.*]], ptr addrspace(1) [[OTHERB:%.*]]) #[[ATTR0]] {
; CHECK-NEXT: [[ENTRY:.*:]]
; CHECK-NEXT: [[P0:%.*]] = getelementptr half, ptr addrspace(1) [[BASE]], i32 0
; CHECK-NEXT: [[P1:%.*]] = getelementptr half, ptr addrspace(1) [[BASE]], i32 1
; CHECK-NEXT: [[A0PTR:%.*]] = getelementptr half, ptr addrspace(1) [[OTHERA]], i32 0
; CHECK-NEXT: [[B0PTR:%.*]] = getelementptr half, ptr addrspace(1) [[OTHERB]], i32 0
; CHECK-NEXT: [[A0:%.*]] = load half, ptr addrspace(1) [[A0PTR]], align 2
; CHECK-NEXT: [[B0:%.*]] = load half, ptr addrspace(1) [[B0PTR]], align 2
; CHECK-NEXT: [[ADD0:%.*]] = fadd reassoc half [[A0]], [[B0]]
; CHECK-NEXT: store half [[ADD0]], ptr addrspace(1) [[P0]], align 2
; CHECK-NEXT: [[A1PTR:%.*]] = getelementptr half, ptr addrspace(1) [[OTHERA]], i32 1
; CHECK-NEXT: [[B1PTR:%.*]] = getelementptr half, ptr addrspace(1) [[OTHERB]], i32 1
; CHECK-NEXT: [[A1:%.*]] = load half, ptr addrspace(1) [[A1PTR]], align 2
; CHECK-NEXT: [[B1:%.*]] = load half, ptr addrspace(1) [[B1PTR]], align 2
; CHECK-NEXT: [[ADD1:%.*]] = fadd reassoc half [[A1]], [[B1]]
; CHECK-NEXT: store half [[ADD1]], ptr addrspace(1) [[P1]], align 2
; CHECK-NEXT: ret void
;
entry:
%p0 = getelementptr half, ptr addrspace(1) %base, i32 0
%p1 = getelementptr half, ptr addrspace(1) %base, i32 1
; First pair of invariant loads from otherA.
%A0PTR = getelementptr half, ptr addrspace(1) %otherA, i32 0
%B0PTR = getelementptr half, ptr addrspace(1) %otherB, i32 0
%A0 = load half, ptr addrspace(1) %A0PTR, align 2
%B0 = load half, ptr addrspace(1) %B0PTR, align 2
%add0 = fadd reassoc half %A0, %B0
store half %add0, ptr addrspace(1) %p0, align 2
%A1PTR = getelementptr half, ptr addrspace(1) %otherA, i32 1
%B1PTR = getelementptr half, ptr addrspace(1) %otherB, i32 1
%A1 = load half, ptr addrspace(1) %A1PTR, align 2
%B1 = load half, ptr addrspace(1) %B1PTR, align 2
%add1 = fadd reassoc half %A1, %B1
store half %add1, ptr addrspace(1) %p1, align 2
ret void
}

define void @voltest(ptr addrspace(1) %base, ptr addrspace(1) %otherA, ptr addrspace(1) %otherB) #0 {
; CHECK-LABEL: define void @voltest(
; CHECK-SAME: ptr addrspace(1) [[BASE:%.*]], ptr addrspace(1) [[OTHERA:%.*]], ptr addrspace(1) [[OTHERB:%.*]]) #[[ATTR0]] {
; CHECK-NEXT: [[ENTRY:.*:]]
; CHECK-NEXT: [[P0:%.*]] = getelementptr half, ptr addrspace(1) [[BASE]], i32 0
; CHECK-NEXT: [[P1:%.*]] = getelementptr half, ptr addrspace(1) [[BASE]], i32 1
; CHECK-NEXT: [[A0PTR:%.*]] = getelementptr half, ptr addrspace(1) [[OTHERA]], i32 0
; CHECK-NEXT: [[B0PTR:%.*]] = getelementptr half, ptr addrspace(1) [[OTHERB]], i32 0
; CHECK-NEXT: [[A0:%.*]] = load volatile half, ptr addrspace(1) [[A0PTR]], align 2, !invariant.load [[META0]]
; CHECK-NEXT: [[B0:%.*]] = load volatile half, ptr addrspace(1) [[B0PTR]], align 2, !invariant.load [[META0]]
; CHECK-NEXT: [[ADD0:%.*]] = fadd reassoc half [[A0]], [[B0]]
; CHECK-NEXT: store half [[ADD0]], ptr addrspace(1) [[P0]], align 2
; CHECK-NEXT: [[A1PTR:%.*]] = getelementptr half, ptr addrspace(1) [[OTHERA]], i32 1
; CHECK-NEXT: [[B1PTR:%.*]] = getelementptr half, ptr addrspace(1) [[OTHERB]], i32 1
; CHECK-NEXT: [[A1:%.*]] = load volatile half, ptr addrspace(1) [[A1PTR]], align 2, !invariant.load [[META0]]
; CHECK-NEXT: [[B1:%.*]] = load volatile half, ptr addrspace(1) [[B1PTR]], align 2, !invariant.load [[META0]]
; CHECK-NEXT: [[ADD1:%.*]] = fadd reassoc half [[A1]], [[B1]]
; CHECK-NEXT: store half [[ADD1]], ptr addrspace(1) [[P1]], align 2
; CHECK-NEXT: ret void
;
entry:
%p0 = getelementptr half, ptr addrspace(1) %base, i32 0
%p1 = getelementptr half, ptr addrspace(1) %base, i32 1
; First pair of invariant loads from otherA.
%A0PTR = getelementptr half, ptr addrspace(1) %otherA, i32 0
%B0PTR = getelementptr half, ptr addrspace(1) %otherB, i32 0
%A0 = load volatile half, ptr addrspace(1) %A0PTR, align 2, !invariant.load !0
%B0 = load volatile half, ptr addrspace(1) %B0PTR, align 2, !invariant.load !0
%add0 = fadd reassoc half %A0, %B0
store half %add0, ptr addrspace(1) %p0, align 2
%A1PTR = getelementptr half, ptr addrspace(1) %otherA, i32 1
%B1PTR = getelementptr half, ptr addrspace(1) %otherB, i32 1
%A1 = load volatile half, ptr addrspace(1) %A1PTR, align 2, !invariant.load !0
%B1 = load volatile half, ptr addrspace(1) %B1PTR, align 2, !invariant.load !0
%add1 = fadd reassoc half %A1, %B1
store half %add1, ptr addrspace(1) %p1, align 2
ret void
}


attributes #0 = { nounwind }

!0 = !{}
;.
; CHECK: [[META0]] = !{}
;.
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