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[VPlan] Fix alias logic in canHoistOrSinkWithNoAliasCheck (#179504)

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The correct way to check if two memory locations may alias is outlined
in ScopedNoAliasAAResult::alias: extract this into a helper, to fix the
current logic.
This commit is contained in:
Ramkumar Ramachandra 2026-02-24 16:14:44 +00:00 committed by GitHub
parent fff4a4642b
commit e147b3a05e
No known key found for this signature in database
GPG Key ID: B5690EEEBB952194
4 changed files with 19 additions and 43 deletions
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6
llvm/include/llvm/Analysis/ScopedNoAliasAA.h
View File

@ -37,9 +37,11 @@ public:
return false;
}
LLVM_ABI static AliasResult alias(const MemoryLocation &LocA,
const MemoryLocation &LocB);
LLVM_ABI AliasResult alias(const MemoryLocation &LocA,
const MemoryLocation &LocB, AAQueryInfo &AAQI,
const Instruction *CtxI);
const MemoryLocation &LocB, AAQueryInfo &,
const Instruction *);
LLVM_ABI ModRefInfo getModRefInfo(const CallBase *Call,
const MemoryLocation &Loc,
AAQueryInfo &AAQI);

10
llvm/lib/Analysis/ScopedNoAliasAA.cpp
View File

@ -52,9 +52,7 @@ static cl::opt<bool> EnableScopedNoAlias("enable-scoped-noalias",
cl::init(true), cl::Hidden);
AliasResult ScopedNoAliasAAResult::alias(const MemoryLocation &LocA,
const MemoryLocation &LocB,
AAQueryInfo &AAQI,
const Instruction *) {
const MemoryLocation &LocB) {
if (!EnableScopedNoAlias)
return AliasResult::MayAlias;
@ -72,6 +70,12 @@ AliasResult ScopedNoAliasAAResult::alias(const MemoryLocation &LocA,
return AliasResult::MayAlias;
}
AliasResult ScopedNoAliasAAResult::alias(const MemoryLocation &LocA,
const MemoryLocation &LocB,
AAQueryInfo &, const Instruction *) {
return alias(LocA, LocB);
}
ModRefInfo ScopedNoAliasAAResult::getModRefInfo(const CallBase *Call,
const MemoryLocation &Loc,
AAQueryInfo &AAQI) {

13
llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
View File

@ -201,8 +201,6 @@ canHoistOrSinkWithNoAliasCheck(const MemoryLocation &MemLoc,
if (!MemLoc.AATags.Scope)
return false;
const AAMDNodes &MemAA = MemLoc.AATags;
for (VPBlockBase *Block = FirstBB; Block;
Block = Block->getSingleSuccessor()) {
assert(Block->getNumSuccessors() <= 1 &&
@ -222,16 +220,7 @@ canHoistOrSinkWithNoAliasCheck(const MemoryLocation &MemLoc,
// location.
return false;
// For reads, check if they don't alias in the reverse direction and
// skip if so.
if (CheckReads && R.mayReadFromMemory() &&
!ScopedNoAliasAAResult::mayAliasInScopes(Loc->AATags.Scope,
MemAA.NoAlias))
continue;
// Check if the memory operations may alias in the forward direction.
if (ScopedNoAliasAAResult::mayAliasInScopes(MemAA.Scope,
Loc->AATags.NoAlias))
if (ScopedNoAliasAAResult::alias(*Loc, MemLoc) != AliasResult::NoAlias)
return false;
}

33
llvm/test/Transforms/LoopVectorize/hoist-predicated-loads-with-predicated-stores.ll
View File

@ -341,55 +341,36 @@ define void @test_memory_op_between_loads_alias(ptr %dst, ptr %src, ptr %cond, p
; CHECK: [[VECTOR_PH]]:
; CHECK-NEXT: br label %[[VECTOR_BODY:.*]]
; CHECK: [[VECTOR_BODY]]:
; CHECK-NEXT: [[INDEX:%.*]] = phi i32 [ 0, %[[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], %[[PRED_LOAD_CONTINUE15:.*]] ]
; CHECK-NEXT: [[INDEX:%.*]] = phi i32 [ 0, %[[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], %[[PRED_LOAD_CONTINUE11:.*]] ]
; CHECK-NEXT: [[TMP4:%.*]] = add i32 [[INDEX]], 0
; CHECK-NEXT: [[TMP5:%.*]] = add i32 [[INDEX]], 1
; CHECK-NEXT: [[TMP6:%.*]] = getelementptr inbounds i32, ptr [[COND]], i32 [[TMP4]]
; CHECK-NEXT: [[WIDE_LOAD:%.*]] = load <2 x i32>, ptr [[TMP6]], align 4, !alias.scope [[META35:![0-9]+]]
; CHECK-NEXT: [[TMP7:%.*]] = icmp ule <2 x i32> [[WIDE_LOAD]], splat (i32 11)
; CHECK-NEXT: [[TMP8:%.*]] = xor <2 x i1> [[TMP7]], splat (i1 true)
; CHECK-NEXT: [[TMP8:%.*]] = icmp ugt <2 x i32> [[WIDE_LOAD]], splat (i32 11)
; CHECK-NEXT: [[TMP9:%.*]] = extractelement <2 x i1> [[TMP8]], i32 0
; CHECK-NEXT: br i1 [[TMP9]], label %[[PRED_LOAD_IF:.*]], label %[[PRED_LOAD_CONTINUE:.*]]
; CHECK: [[PRED_LOAD_IF]]:
; CHECK-NEXT: [[TMP10:%.*]] = getelementptr inbounds i32, ptr [[SRC]], i32 [[TMP4]]
; CHECK-NEXT: store i32 0, ptr [[TMP10]], align 4, !alias.scope [[META38:![0-9]+]], !noalias [[META40:![0-9]+]]
; CHECK-NEXT: [[TMP11:%.*]] = load i32, ptr [[TMP10]], align 4, !alias.scope [[META38]], !noalias [[META40]]
; CHECK-NEXT: [[TMP12:%.*]] = insertelement <2 x i32> poison, i32 [[TMP11]], i32 0
; CHECK-NEXT: br label %[[PRED_LOAD_CONTINUE]]
; CHECK: [[PRED_LOAD_CONTINUE]]:
; CHECK-NEXT: [[TMP13:%.*]] = phi <2 x i32> [ poison, %[[VECTOR_BODY]] ], [ [[TMP12]], %[[PRED_LOAD_IF]] ]
; CHECK-NEXT: [[TMP14:%.*]] = extractelement <2 x i1> [[TMP8]], i32 1
; CHECK-NEXT: br i1 [[TMP14]], label %[[PRED_LOAD_IF10:.*]], label %[[PRED_LOAD_CONTINUE11:.*]]
; CHECK-NEXT: br i1 [[TMP14]], label %[[PRED_LOAD_IF10:.*]], label %[[PRED_LOAD_CONTINUE11]]
; CHECK: [[PRED_LOAD_IF10]]:
; CHECK-NEXT: [[TMP15:%.*]] = getelementptr inbounds i32, ptr [[SRC]], i32 [[TMP5]]
; CHECK-NEXT: store i32 0, ptr [[TMP15]], align 4, !alias.scope [[META38]], !noalias [[META40]]
; CHECK-NEXT: [[TMP16:%.*]] = load i32, ptr [[TMP15]], align 4, !alias.scope [[META38]], !noalias [[META40]]
; CHECK-NEXT: [[TMP17:%.*]] = insertelement <2 x i32> [[TMP13]], i32 [[TMP16]], i32 1
; CHECK-NEXT: br label %[[PRED_LOAD_CONTINUE11]]
; CHECK: [[PRED_LOAD_CONTINUE11]]:
; CHECK-NEXT: [[TMP18:%.*]] = phi <2 x i32> [ [[TMP13]], %[[PRED_LOAD_CONTINUE]] ], [ [[TMP17]], %[[PRED_LOAD_IF10]] ]
; CHECK-NEXT: [[TMP19:%.*]] = add <2 x i32> [[TMP18]], splat (i32 10)
; CHECK-NEXT: [[TMP26:%.*]] = extractelement <2 x i1> [[TMP7]], i32 0
; CHECK-NEXT: br i1 [[TMP26]], label %[[PRED_LOAD_IF12:.*]], label %[[PRED_LOAD_CONTINUE13:.*]]
; CHECK: [[PRED_LOAD_IF12]]:
; CHECK-NEXT: [[TMP27:%.*]] = getelementptr inbounds i32, ptr [[SRC]], i32 [[TMP4]]
; CHECK-NEXT: [[TMP20:%.*]] = load i32, ptr [[TMP27]], align 4, !alias.scope [[META38]], !noalias [[META40]]
; CHECK-NEXT: [[TMP23:%.*]] = insertelement <2 x i32> poison, i32 [[TMP20]], i32 0
; CHECK-NEXT: br label %[[PRED_LOAD_CONTINUE13]]
; CHECK: [[PRED_LOAD_CONTINUE13]]:
; CHECK-NEXT: [[TMP22:%.*]] = phi <2 x i32> [ poison, %[[PRED_LOAD_CONTINUE11]] ], [ [[TMP23]], %[[PRED_LOAD_IF12]] ]
; CHECK-NEXT: [[TMP30:%.*]] = extractelement <2 x i1> [[TMP7]], i32 1
; CHECK-NEXT: br i1 [[TMP30]], label %[[PRED_LOAD_IF14:.*]], label %[[PRED_LOAD_CONTINUE15]]
; CHECK: [[PRED_LOAD_IF14]]:
; CHECK-NEXT: [[TMP31:%.*]] = getelementptr inbounds i32, ptr [[SRC]], i32 [[TMP5]]
; CHECK-NEXT: [[TMP11:%.*]] = load i32, ptr [[TMP27]], align 4, !alias.scope [[META38]], !noalias [[META40]]
; CHECK-NEXT: [[TMP25:%.*]] = load i32, ptr [[TMP31]], align 4, !alias.scope [[META38]], !noalias [[META40]]
; CHECK-NEXT: [[TMP22:%.*]] = insertelement <2 x i32> poison, i32 [[TMP11]], i32 0
; CHECK-NEXT: [[TMP32:%.*]] = insertelement <2 x i32> [[TMP22]], i32 [[TMP25]], i32 1
; CHECK-NEXT: br label %[[PRED_LOAD_CONTINUE15]]
; CHECK: [[PRED_LOAD_CONTINUE15]]:
; CHECK-NEXT: [[TMP33:%.*]] = phi <2 x i32> [ [[TMP22]], %[[PRED_LOAD_CONTINUE13]] ], [ [[TMP32]], %[[PRED_LOAD_IF14]] ]
; CHECK-NEXT: [[TMP16:%.*]] = add <2 x i32> [[TMP32]], splat (i32 10)
; CHECK-NEXT: [[TMP36:%.*]] = getelementptr inbounds i32, ptr [[DST]], i32 [[TMP4]]
; CHECK-NEXT: [[TMP37:%.*]] = getelementptr inbounds i32, ptr [[DST]], i32 [[TMP5]]
; CHECK-NEXT: [[TMP28:%.*]] = select <2 x i1> [[TMP7]], <2 x i32> [[TMP33]], <2 x i32> [[TMP19]]
; CHECK-NEXT: [[TMP28:%.*]] = select <2 x i1> [[TMP8]], <2 x i32> [[TMP16]], <2 x i32> [[TMP32]]
; CHECK-NEXT: [[TMP29:%.*]] = extractelement <2 x i32> [[TMP28]], i32 0
; CHECK-NEXT: store i32 [[TMP29]], ptr [[TMP36]], align 4, !alias.scope [[META42:![0-9]+]], !noalias [[META35]]
; CHECK-NEXT: [[TMP35:%.*]] = extractelement <2 x i32> [[TMP28]], i32 1