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[VPlan] Fix crash with inloop fmuladd reductions with blend #131154

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Merged
merged 3 commits into from
Mar 14, 2025
Merged

[VPlan] Fix crash with inloop fmuladd reductions with blend #131154

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3d62e26
[VPlan] Fix crash with inloop fmuladd reductions with blend
lukel97 Mar 13, 2025
9c23bd9
Enclose if in braces
lukel97 Mar 13, 2025
7872782
Fix test formatting
lukel97 Mar 14, 2025
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27 changes: 13 additions & 14 deletions llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -9713,6 +9713,19 @@ void LoopVectorizationPlanner::adjustRecipesForReductions(
// condition directly.
VPSingleDefRecipe *PreviousLink = PhiR; // Aka Worklist[0].
for (VPSingleDefRecipe *CurrentLink : Worklist.getArrayRef().drop_front()) {
if (auto *Blend = dyn_cast<VPBlendRecipe>(CurrentLink)) {
assert(Blend->getNumIncomingValues() == 2 &&
"Blend must have 2 incoming values");
if (Blend->getIncomingValue(0) == PhiR) {
Blend->replaceAllUsesWith(Blend->getIncomingValue(1));
} else {
assert(Blend->getIncomingValue(1) == PhiR &&
"PhiR must be an operand of the blend");
Blend->replaceAllUsesWith(Blend->getIncomingValue(0));
}
continue;
}

Instruction *CurrentLinkI = CurrentLink->getUnderlyingInstr();

// Index of the first operand which holds a non-mask vector operand.
Expand Down Expand Up @@ -9741,20 +9754,6 @@ void LoopVectorizationPlanner::adjustRecipesForReductions(
LinkVPBB->insert(FMulRecipe, CurrentLink->getIterator());
VecOp = FMulRecipe;
} else {
auto *Blend = dyn_cast<VPBlendRecipe>(CurrentLink);
if (PhiR->isInLoop() && Blend) {
assert(Blend->getNumIncomingValues() == 2 &&
"Blend must have 2 incoming values");
if (Blend->getIncomingValue(0) == PhiR)
Blend->replaceAllUsesWith(Blend->getIncomingValue(1));
else {
assert(Blend->getIncomingValue(1) == PhiR &&
"PhiR must be an operand of the blend");
Blend->replaceAllUsesWith(Blend->getIncomingValue(0));
}
continue;
}

if (RecurrenceDescriptor::isMinMaxRecurrenceKind(Kind)) {
if (isa<VPWidenRecipe>(CurrentLink)) {
assert(isa<CmpInst>(CurrentLinkI) &&
Expand Down
95 changes: 89 additions & 6 deletions llvm/test/Transforms/LoopVectorize/reduction-inloop.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -1106,6 +1106,89 @@ for.end:
ret float %muladd
}

define float @reduction_fmuladd_blend(ptr %a, ptr %b, i64 %n, i1 %c) {
; CHECK-LABEL: @reduction_fmuladd_blend(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[MIN_ITERS_CHECK:%.*]] = icmp ult i64 [[N:%.*]], 4
; CHECK-NEXT: br i1 [[MIN_ITERS_CHECK]], label [[SCALAR_PH:%.*]], label [[VECTOR_PH:%.*]]
; CHECK: vector.ph:
; CHECK-NEXT: [[N_VEC:%.*]] = and i64 [[N]], -4
; CHECK-NEXT: [[BROADCAST_SPLATINSERT:%.*]] = insertelement <4 x i1> poison, i1 [[C:%.*]], i64 0
; CHECK-NEXT: [[TMP0:%.*]] = xor <4 x i1> [[BROADCAST_SPLATINSERT]], <i1 true, i1 poison, i1 poison, i1 poison>
; CHECK-NEXT: [[TMP1:%.*]] = shufflevector <4 x i1> [[TMP0]], <4 x i1> poison, <4 x i32> zeroinitializer
; CHECK-NEXT: br label [[VECTOR_BODY:%.*]]
; CHECK: vector.body:
; CHECK-NEXT: [[INDEX:%.*]] = phi i64 [ 0, [[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], [[VECTOR_BODY]] ]
; CHECK-NEXT: [[VEC_PHI:%.*]] = phi float [ 0.000000e+00, [[VECTOR_PH]] ], [ [[TMP7:%.*]], [[VECTOR_BODY]] ]
; CHECK-NEXT: [[TMP2:%.*]] = getelementptr inbounds float, ptr [[A:%.*]], i64 [[INDEX]]
; CHECK-NEXT: [[WIDE_LOAD:%.*]] = load <4 x float>, ptr [[TMP2]], align 4
; CHECK-NEXT: [[TMP3:%.*]] = getelementptr inbounds float, ptr [[B:%.*]], i64 [[INDEX]]
; CHECK-NEXT: [[WIDE_LOAD1:%.*]] = load <4 x float>, ptr [[TMP3]], align 4
; CHECK-NEXT: [[TMP4:%.*]] = fmul <4 x float> [[WIDE_LOAD]], [[WIDE_LOAD1]]
; CHECK-NEXT: [[TMP5:%.*]] = select <4 x i1> [[TMP1]], <4 x float> [[TMP4]], <4 x float> splat (float -0.000000e+00)
; CHECK-NEXT: [[TMP6:%.*]] = call float @llvm.vector.reduce.fadd.v4f32(float -0.000000e+00, <4 x float> [[TMP5]])
; CHECK-NEXT: [[TMP7]] = fadd float [[TMP6]], [[VEC_PHI]]
; CHECK-NEXT: [[INDEX_NEXT]] = add nuw i64 [[INDEX]], 4
; CHECK-NEXT: [[TMP8:%.*]] = icmp eq i64 [[INDEX_NEXT]], [[N_VEC]]
; CHECK-NEXT: br i1 [[TMP8]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop [[LOOP38:![0-9]+]]
; CHECK: middle.block:
; CHECK-NEXT: [[CMP_N:%.*]] = icmp eq i64 [[N]], [[N_VEC]]
; CHECK-NEXT: br i1 [[CMP_N]], label [[FOR_END:%.*]], label [[SCALAR_PH]]
; CHECK: scalar.ph:
; CHECK-NEXT: [[BC_RESUME_VAL:%.*]] = phi i64 [ [[N_VEC]], [[MIDDLE_BLOCK]] ], [ 0, [[ENTRY:%.*]] ]
; CHECK-NEXT: [[BC_MERGE_RDX:%.*]] = phi float [ [[TMP7]], [[MIDDLE_BLOCK]] ], [ 0.000000e+00, [[ENTRY]] ]
; CHECK-NEXT: br label [[FOR_BODY:%.*]]
; CHECK: loop.header:
; CHECK-NEXT: [[IV:%.*]] = phi i64 [ [[BC_RESUME_VAL]], [[SCALAR_PH]] ], [ [[IV_NEXT:%.*]], [[LATCH:%.*]] ]
; CHECK-NEXT: [[SUM:%.*]] = phi float [ [[BC_MERGE_RDX]], [[SCALAR_PH]] ], [ [[SUM_NEXT:%.*]], [[LATCH]] ]
; CHECK-NEXT: br i1 [[C]], label [[FOO:%.*]], label [[BAR:%.*]]
; CHECK: if:
; CHECK-NEXT: br label [[LATCH]]
; CHECK: else:
; CHECK-NEXT: [[ARRAYIDX2:%.*]] = getelementptr inbounds float, ptr [[B]], i64 [[IV]]
; CHECK-NEXT: [[TMP9:%.*]] = load float, ptr [[ARRAYIDX2]], align 4
; CHECK-NEXT: [[ARRAYIDX:%.*]] = getelementptr inbounds float, ptr [[A]], i64 [[IV]]
; CHECK-NEXT: [[TMP10:%.*]] = load float, ptr [[ARRAYIDX]], align 4
; CHECK-NEXT: [[MULADD:%.*]] = tail call float @llvm.fmuladd.f32(float [[TMP10]], float [[TMP9]], float [[SUM]])
; CHECK-NEXT: br label [[LATCH]]
; CHECK: latch:
; CHECK-NEXT: [[SUM_NEXT]] = phi float [ [[SUM]], [[FOO]] ], [ [[MULADD]], [[BAR]] ]
; CHECK-NEXT: [[IV_NEXT]] = add nuw nsw i64 [[IV]], 1
; CHECK-NEXT: [[EXITCOND_NOT:%.*]] = icmp eq i64 [[IV_NEXT]], [[N]]
; CHECK-NEXT: br i1 [[EXITCOND_NOT]], label [[FOR_END]], label [[FOR_BODY]], !llvm.loop [[LOOP39:![0-9]+]]
; CHECK: exit:
; CHECK-NEXT: [[SUM_NEXT_LCSSA:%.*]] = phi float [ [[SUM_NEXT]], [[LATCH]] ], [ [[TMP7]], [[MIDDLE_BLOCK]] ]
; CHECK-NEXT: ret float [[SUM_NEXT_LCSSA]]
;
entry:
br label %loop.header

loop.header:
%iv = phi i64 [ 0, %entry ], [ %iv.next, %latch ]
%sum = phi float [ 0.000000e+00, %entry ], [ %sum.next, %latch ]
%arrayidx = getelementptr inbounds float, ptr %a, i64 %iv
%0 = load float, ptr %arrayidx, align 4
%arrayidx2 = getelementptr inbounds float, ptr %b, i64 %iv
%1 = load float, ptr %arrayidx2, align 4
br i1 %c, label %if, label %else

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Suggested change

if:
br label %latch

else:
%muladd = tail call float @llvm.fmuladd.f32(float %0, float %1, float %sum)
br label %latch

latch:
%sum.next = phi float [ %sum, %if ], [ %muladd, %else ]
%iv.next = add nuw nsw i64 %iv, 1
%exitcond.not = icmp eq i64 %iv.next, %n
br i1 %exitcond.not, label %exit, label %loop.header

exit:
ret float %sum.next
}

; This case was previously failing verification due to the mask for the
; reduction being created after the reduction.
define i32 @predicated_not_dominates_reduction(ptr nocapture noundef readonly %h, i32 noundef %i) {
Expand All @@ -1130,7 +1213,7 @@ define i32 @predicated_not_dominates_reduction(ptr nocapture noundef readonly %h
; CHECK-NEXT: [[TMP7]] = add i32 [[TMP6]], [[VEC_PHI]]
; CHECK-NEXT: [[INDEX_NEXT]] = add nuw i32 [[INDEX]], 4
; CHECK-NEXT: [[TMP8:%.*]] = icmp eq i32 [[INDEX_NEXT]], [[N_VEC]]
; CHECK-NEXT: br i1 [[TMP8]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop [[LOOP38:![0-9]+]]
; CHECK-NEXT: br i1 [[TMP8]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop [[LOOP40:![0-9]+]]
; CHECK: middle.block:
; CHECK-NEXT: [[CMP_N:%.*]] = icmp eq i32 [[I]], [[N_VEC]]
; CHECK-NEXT: br i1 [[CMP_N]], label [[FOR_END7:%.*]], label [[SCALAR_PH]]
Expand All @@ -1157,7 +1240,7 @@ define i32 @predicated_not_dominates_reduction(ptr nocapture noundef readonly %h
; CHECK-NEXT: [[G_1]] = phi i32 [ [[ADD]], [[IF_THEN]] ], [ [[G_016]], [[FOR_BODY2]] ]
; CHECK-NEXT: [[INC6]] = add nuw nsw i32 [[A_117]], 1
; CHECK-NEXT: [[EXITCOND_NOT:%.*]] = icmp eq i32 [[INC6]], [[I]]
; CHECK-NEXT: br i1 [[EXITCOND_NOT]], label [[FOR_END7]], label [[FOR_BODY2]], !llvm.loop [[LOOP39:![0-9]+]]
; CHECK-NEXT: br i1 [[EXITCOND_NOT]], label [[FOR_END7]], label [[FOR_BODY2]], !llvm.loop [[LOOP41:![0-9]+]]
; CHECK: for.end7:
; CHECK-NEXT: [[G_1_LCSSA:%.*]] = phi i32 [ [[G_1]], [[FOR_INC5]] ], [ [[TMP7]], [[MIDDLE_BLOCK]] ]
; CHECK-NEXT: ret i32 [[G_1_LCSSA]]
Expand Down Expand Up @@ -1219,7 +1302,7 @@ define i32 @predicated_not_dominates_reduction_twoadd(ptr nocapture noundef read
; CHECK-NEXT: [[TMP11]] = add i32 [[TMP10]], [[TMP8]]
; CHECK-NEXT: [[INDEX_NEXT]] = add nuw i32 [[INDEX]], 4
; CHECK-NEXT: [[TMP12:%.*]] = icmp eq i32 [[INDEX_NEXT]], [[N_VEC]]
; CHECK-NEXT: br i1 [[TMP12]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop [[LOOP40:![0-9]+]]
; CHECK-NEXT: br i1 [[TMP12]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop [[LOOP42:![0-9]+]]
; CHECK: middle.block:
; CHECK-NEXT: [[CMP_N:%.*]] = icmp eq i32 [[I]], [[N_VEC]]
; CHECK-NEXT: br i1 [[CMP_N]], label [[FOR_END7:%.*]], label [[SCALAR_PH]]
Expand Down Expand Up @@ -1247,7 +1330,7 @@ define i32 @predicated_not_dominates_reduction_twoadd(ptr nocapture noundef read
; CHECK-NEXT: [[G_1]] = phi i32 [ [[ADD]], [[IF_THEN]] ], [ [[G_016]], [[FOR_BODY2]] ]
; CHECK-NEXT: [[INC6]] = add nuw nsw i32 [[A_117]], 1
; CHECK-NEXT: [[EXITCOND_NOT:%.*]] = icmp eq i32 [[INC6]], [[I]]
; CHECK-NEXT: br i1 [[EXITCOND_NOT]], label [[FOR_END7]], label [[FOR_BODY2]], !llvm.loop [[LOOP41:![0-9]+]]
; CHECK-NEXT: br i1 [[EXITCOND_NOT]], label [[FOR_END7]], label [[FOR_BODY2]], !llvm.loop [[LOOP43:![0-9]+]]
; CHECK: for.end7:
; CHECK-NEXT: [[G_1_LCSSA:%.*]] = phi i32 [ [[G_1]], [[FOR_INC5]] ], [ [[TMP11]], [[MIDDLE_BLOCK]] ]
; CHECK-NEXT: ret i32 [[G_1_LCSSA]]
Expand Down Expand Up @@ -1362,7 +1445,7 @@ define i32 @predicated_or_dominates_reduction(ptr %b) {
; CHECK-NEXT: [[TMP48]] = add i32 [[VEC_PHI]], [[TMP47]]
; CHECK-NEXT: [[INDEX_NEXT]] = add nuw i32 [[INDEX]], 4
; CHECK-NEXT: [[TMP49:%.*]] = icmp eq i32 [[INDEX_NEXT]], 1000
; CHECK-NEXT: br i1 [[TMP49]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop [[LOOP42:![0-9]+]]
; CHECK-NEXT: br i1 [[TMP49]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop [[LOOP44:![0-9]+]]
; CHECK: middle.block:
; CHECK-NEXT: br i1 true, label [[FOR_COND_CLEANUP:%.*]], label [[SCALAR_PH]]
; CHECK: scalar.ph:
Expand All @@ -1377,7 +1460,7 @@ define i32 @predicated_or_dominates_reduction(ptr %b) {
; CHECK: if.then:
; CHECK-NEXT: br label [[FOR_INC]]
; CHECK: for.inc:
; CHECK-NEXT: br i1 poison, label [[FOR_COND_CLEANUP]], label [[FOR_BODY]], !llvm.loop [[LOOP43:![0-9]+]]
; CHECK-NEXT: br i1 poison, label [[FOR_COND_CLEANUP]], label [[FOR_BODY]], !llvm.loop [[LOOP45:![0-9]+]]
;
entry:
br label %for.body
Expand Down
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