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[LV] Don't create WidePtrAdd recipes for scalar VFs (#169344)

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While attempting to remove the use of undef from more loop vectoriser
tests I discovered a bug where this assert was firing:

```
llvm::Constant* llvm::Constant::getSplatValue(bool) const: Assertion `this->getType()->isVectorTy() && "Only valid for vectors!"' failed.
...
 #8 0x0000aaaab9e2fba4 llvm::Constant::getSplatValue
 #9 0x0000aaaab9dfb844 llvm::ConstantFoldBinaryInstruction
```

This seems to be happening because we are incorrectly generating
WidePtrAdd recipes for scalar VFs. The PR fixes this by checking whether
a plan has a scalar VF only in legalizeAndOptimizeInductions.

This PR also removes the use of undef from the test `both` in
Transforms/LoopVectorize/iv_outside_user.ll, which is what started
triggering the assert.

Fixes #169334
This commit is contained in:
David Sherwood
2025-12-01 08:12:41 +00:00
committed by GitHub
parent 4d7abe5355
commit 17677ad7eb
2 changed files with 95 additions and 47 deletions
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3
llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
View File

@@ -769,7 +769,8 @@ static void legalizeAndOptimizeInductions(VPlan &Plan) {
// Replace wide pointer inductions which have only their scalars used by
// PtrAdd(IndStart, ScalarIVSteps (0, Step)).
if (auto *PtrIV = dyn_cast<VPWidenPointerInductionRecipe>(&Phi)) {
if (!PtrIV->onlyScalarsGenerated(Plan.hasScalableVF()))
if (!Plan.hasScalarVFOnly() &&
!PtrIV->onlyScalarsGenerated(Plan.hasScalableVF()))
continue;
VPValue *PtrAdd = scalarizeVPWidenPointerInduction(PtrIV, Plan, Builder);

139
llvm/test/Transforms/LoopVectorize/iv_outside_user.ll
View File

@@ -152,59 +152,106 @@ for.end:
ret ptr %ptr.phi
}
define ptr @both(i32 %k) {
; CHECK-LABEL: define ptr @both(
; CHECK-SAME: i32 [[K:%.*]]) {
; CHECK-NEXT: [[ENTRY:.*]]:
; CHECK-NEXT: [[BASE:%.*]] = getelementptr inbounds i32, ptr undef, i64 1
; CHECK-NEXT: [[TMP0:%.*]] = add i32 [[K]], -1
; CHECK-NEXT: [[TMP1:%.*]] = zext i32 [[TMP0]] to i64
; CHECK-NEXT: [[TMP2:%.*]] = add nuw nsw i64 [[TMP1]], 1
; CHECK-NEXT: [[MIN_ITERS_CHECK:%.*]] = icmp ult i64 [[TMP2]], 2
; CHECK-NEXT: br i1 [[MIN_ITERS_CHECK]], label %[[SCALAR_PH:.*]], label %[[VECTOR_PH:.*]]
; CHECK: [[VECTOR_PH]]:
; CHECK-NEXT: [[N_MOD_VF:%.*]] = urem i64 [[TMP2]], 2
; CHECK-NEXT: [[N_VEC:%.*]] = sub i64 [[TMP2]], [[N_MOD_VF]]
; CHECK-NEXT: [[IND_END:%.*]] = trunc i64 [[N_VEC]] to i32
; CHECK-NEXT: [[TMP3:%.*]] = mul i64 [[N_VEC]], 4
; CHECK-NEXT: [[IND_END1:%.*]] = getelementptr i8, ptr [[BASE]], i64 [[TMP3]]
; CHECK-NEXT: [[TMP4:%.*]] = mul i64 [[N_VEC]], 4
; CHECK-NEXT: [[IND_END2:%.*]] = getelementptr i8, ptr undef, i64 [[TMP4]]
; CHECK-NEXT: br label %[[VECTOR_BODY:.*]]
; CHECK: [[VECTOR_BODY]]:
; CHECK-NEXT: [[INDEX:%.*]] = phi i64 [ 0, %[[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], %[[VECTOR_BODY]] ]
; CHECK-NEXT: [[INDEX_NEXT]] = add nuw i64 [[INDEX]], 2
; CHECK-NEXT: [[TMP5:%.*]] = icmp eq i64 [[INDEX_NEXT]], [[N_VEC]]
; CHECK-NEXT: br i1 [[TMP5]], label %[[MIDDLE_BLOCK:.*]], label %[[VECTOR_BODY]], {{!llvm.loop ![0-9]+}}
; CHECK: [[MIDDLE_BLOCK]]:
; CHECK-NEXT: [[CMP_N:%.*]] = icmp eq i64 [[TMP2]], [[N_VEC]]
; CHECK-NEXT: [[IND_ESCAPE:%.*]] = getelementptr i8, ptr [[IND_END1]], i64 -4
; CHECK-NEXT: br i1 [[CMP_N]], label %[[FOR_END:.*]], label %[[SCALAR_PH]]
; CHECK: [[SCALAR_PH]]:
; CHECK-NEXT: [[BC_RESUME_VAL:%.*]] = phi i32 [ [[IND_END]], %[[MIDDLE_BLOCK]] ], [ 0, %[[ENTRY]] ]
; CHECK-NEXT: [[BC_RESUME_VAL1:%.*]] = phi ptr [ [[IND_END1]], %[[MIDDLE_BLOCK]] ], [ [[BASE]], %[[ENTRY]] ]
; CHECK-NEXT: [[BC_RESUME_VAL2:%.*]] = phi ptr [ [[IND_END2]], %[[MIDDLE_BLOCK]] ], [ undef, %[[ENTRY]] ]
; CHECK-NEXT: br label %[[FOR_BODY:.*]]
; CHECK: [[FOR_BODY]]:
; CHECK-NEXT: [[INC_PHI:%.*]] = phi i32 [ [[BC_RESUME_VAL]], %[[SCALAR_PH]] ], [ [[INC:%.*]], %[[FOR_BODY]] ]
; CHECK-NEXT: [[INC_LAG1:%.*]] = phi ptr [ [[BC_RESUME_VAL1]], %[[SCALAR_PH]] ], [ [[TMP:%.*]], %[[FOR_BODY]] ]
; CHECK-NEXT: [[INC_LAG2:%.*]] = phi ptr [ [[BC_RESUME_VAL2]], %[[SCALAR_PH]] ], [ [[INC_LAG1]], %[[FOR_BODY]] ]
; CHECK-NEXT: [[TMP]] = getelementptr inbounds i32, ptr [[INC_LAG1]], i64 1
; CHECK-NEXT: [[INC]] = add nsw i32 [[INC_PHI]], 1
; CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[INC]], [[K]]
; CHECK-NEXT: br i1 [[CMP]], label %[[FOR_END]], label %[[FOR_BODY]], {{!llvm.loop ![0-9]+}}
; CHECK: [[FOR_END]]:
; CHECK-NEXT: [[INC_LAG1_LCSSA:%.*]] = phi ptr [ [[INC_LAG1]], %[[FOR_BODY]] ], [ [[IND_ESCAPE]], %[[MIDDLE_BLOCK]] ]
; CHECK-NEXT: ret ptr [[INC_LAG1_LCSSA]]
define ptr @both(ptr %p, i32 %k) {
; VEC-LABEL: define ptr @both(
; VEC-SAME: ptr [[P:%.*]], i32 [[K:%.*]]) {
; VEC-NEXT: [[ENTRY:.*]]:
; VEC-NEXT: [[BASE:%.*]] = getelementptr inbounds i32, ptr [[P]], i64 1
; VEC-NEXT: [[TMP0:%.*]] = add i32 [[K]], -1
; VEC-NEXT: [[TMP1:%.*]] = zext i32 [[TMP0]] to i64
; VEC-NEXT: [[TMP2:%.*]] = add nuw nsw i64 [[TMP1]], 1
; VEC-NEXT: [[MIN_ITERS_CHECK:%.*]] = icmp ult i64 [[TMP2]], 2
; VEC-NEXT: br i1 [[MIN_ITERS_CHECK]], label %[[SCALAR_PH:.*]], label %[[VECTOR_PH:.*]]
; VEC: [[VECTOR_PH]]:
; VEC-NEXT: [[N_MOD_VF:%.*]] = urem i64 [[TMP2]], 2
; VEC-NEXT: [[N_VEC:%.*]] = sub i64 [[TMP2]], [[N_MOD_VF]]
; VEC-NEXT: [[TMP3:%.*]] = trunc i64 [[N_VEC]] to i32
; VEC-NEXT: [[TMP4:%.*]] = mul i64 [[N_VEC]], 4
; VEC-NEXT: [[TMP5:%.*]] = getelementptr i8, ptr [[BASE]], i64 [[TMP4]]
; VEC-NEXT: br label %[[VECTOR_BODY:.*]]
; VEC: [[VECTOR_BODY]]:
; VEC-NEXT: [[INDEX:%.*]] = phi i64 [ 0, %[[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], %[[VECTOR_BODY]] ]
; VEC-NEXT: [[POINTER_PHI:%.*]] = phi ptr [ [[BASE]], %[[VECTOR_PH]] ], [ [[PTR_IND:%.*]], %[[VECTOR_BODY]] ]
; VEC-NEXT: [[VECTOR_GEP:%.*]] = getelementptr i8, ptr [[POINTER_PHI]], <2 x i64> <i64 0, i64 4>
; VEC-NEXT: [[INDEX_NEXT]] = add nuw i64 [[INDEX]], 2
; VEC-NEXT: [[PTR_IND]] = getelementptr i8, ptr [[POINTER_PHI]], i64 8
; VEC-NEXT: [[TMP6:%.*]] = icmp eq i64 [[INDEX_NEXT]], [[N_VEC]]
; VEC-NEXT: br i1 [[TMP6]], label %[[MIDDLE_BLOCK:.*]], label %[[VECTOR_BODY]], {{!llvm.loop ![0-9]+}}
; VEC: [[MIDDLE_BLOCK]]:
; VEC-NEXT: [[VECTOR_RECUR_EXTRACT:%.*]] = extractelement <2 x ptr> [[VECTOR_GEP]], i32 1
; VEC-NEXT: [[CMP_N:%.*]] = icmp eq i64 [[TMP2]], [[N_VEC]]
; VEC-NEXT: [[IND_ESCAPE:%.*]] = getelementptr i8, ptr [[TMP5]], i64 -4
; VEC-NEXT: br i1 [[CMP_N]], label %[[FOR_END:.*]], label %[[SCALAR_PH]]
; VEC: [[SCALAR_PH]]:
; VEC-NEXT: [[BC_RESUME_VAL:%.*]] = phi i32 [ [[TMP3]], %[[MIDDLE_BLOCK]] ], [ 0, %[[ENTRY]] ]
; VEC-NEXT: [[BC_RESUME_VAL1:%.*]] = phi ptr [ [[TMP5]], %[[MIDDLE_BLOCK]] ], [ [[BASE]], %[[ENTRY]] ]
; VEC-NEXT: [[SCALAR_RECUR_INIT:%.*]] = phi ptr [ [[VECTOR_RECUR_EXTRACT]], %[[MIDDLE_BLOCK]] ], [ [[BASE]], %[[ENTRY]] ]
; VEC-NEXT: br label %[[FOR_BODY:.*]]
; VEC: [[FOR_BODY]]:
; VEC-NEXT: [[INC_PHI:%.*]] = phi i32 [ [[BC_RESUME_VAL]], %[[SCALAR_PH]] ], [ [[INC:%.*]], %[[FOR_BODY]] ]
; VEC-NEXT: [[INC_LAG1:%.*]] = phi ptr [ [[BC_RESUME_VAL1]], %[[SCALAR_PH]] ], [ [[TMP:%.*]], %[[FOR_BODY]] ]
; VEC-NEXT: [[INC_LAG2:%.*]] = phi ptr [ [[SCALAR_RECUR_INIT]], %[[SCALAR_PH]] ], [ [[INC_LAG1]], %[[FOR_BODY]] ]
; VEC-NEXT: [[TMP]] = getelementptr inbounds i32, ptr [[INC_LAG1]], i64 1
; VEC-NEXT: [[INC]] = add nsw i32 [[INC_PHI]], 1
; VEC-NEXT: [[CMP:%.*]] = icmp eq i32 [[INC]], [[K]]
; VEC-NEXT: br i1 [[CMP]], label %[[FOR_END]], label %[[FOR_BODY]], {{!llvm.loop ![0-9]+}}
; VEC: [[FOR_END]]:
; VEC-NEXT: [[INC_LAG1_LCSSA:%.*]] = phi ptr [ [[INC_LAG1]], %[[FOR_BODY]] ], [ [[IND_ESCAPE]], %[[MIDDLE_BLOCK]] ]
; VEC-NEXT: ret ptr [[INC_LAG1_LCSSA]]
;
; INTERLEAVE-LABEL: define ptr @both(
; INTERLEAVE-SAME: ptr [[P:%.*]], i32 [[K:%.*]]) {
; INTERLEAVE-NEXT: [[ENTRY:.*]]:
; INTERLEAVE-NEXT: [[BASE:%.*]] = getelementptr inbounds i32, ptr [[P]], i64 1
; INTERLEAVE-NEXT: [[TMP0:%.*]] = add i32 [[K]], -1
; INTERLEAVE-NEXT: [[TMP1:%.*]] = zext i32 [[TMP0]] to i64
; INTERLEAVE-NEXT: [[TMP2:%.*]] = add nuw nsw i64 [[TMP1]], 1
; INTERLEAVE-NEXT: [[MIN_ITERS_CHECK:%.*]] = icmp ult i64 [[TMP2]], 2
; INTERLEAVE-NEXT: br i1 [[MIN_ITERS_CHECK]], label %[[SCALAR_PH:.*]], label %[[VECTOR_PH:.*]]
; INTERLEAVE: [[VECTOR_PH]]:
; INTERLEAVE-NEXT: [[N_MOD_VF:%.*]] = urem i64 [[TMP2]], 2
; INTERLEAVE-NEXT: [[N_VEC:%.*]] = sub i64 [[TMP2]], [[N_MOD_VF]]
; INTERLEAVE-NEXT: [[TMP3:%.*]] = trunc i64 [[N_VEC]] to i32
; INTERLEAVE-NEXT: [[TMP6:%.*]] = mul i64 [[N_VEC]], 4
; INTERLEAVE-NEXT: [[NEXT_GEP:%.*]] = getelementptr i8, ptr [[BASE]], i64 [[TMP6]]
; INTERLEAVE-NEXT: br label %[[VECTOR_BODY:.*]]
; INTERLEAVE: [[VECTOR_BODY]]:
; INTERLEAVE-NEXT: [[INDEX:%.*]] = phi i64 [ 0, %[[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], %[[VECTOR_BODY]] ]
; INTERLEAVE-NEXT: [[OFFSET_IDX:%.*]] = mul i64 [[INDEX]], 4
; INTERLEAVE-NEXT: [[TMP8:%.*]] = add i64 [[OFFSET_IDX]], 4
; INTERLEAVE-NEXT: [[NEXT_GEP1:%.*]] = getelementptr i8, ptr [[BASE]], i64 [[TMP8]]
; INTERLEAVE-NEXT: [[INDEX_NEXT]] = add nuw i64 [[INDEX]], 2
; INTERLEAVE-NEXT: [[TMP7:%.*]] = icmp eq i64 [[INDEX_NEXT]], [[N_VEC]]
; INTERLEAVE-NEXT: br i1 [[TMP7]], label %[[MIDDLE_BLOCK:.*]], label %[[VECTOR_BODY]], {{!llvm.loop ![0-9]+}}
; INTERLEAVE: [[MIDDLE_BLOCK]]:
; INTERLEAVE-NEXT: [[CMP_N:%.*]] = icmp eq i64 [[TMP2]], [[N_VEC]]
; INTERLEAVE-NEXT: [[IND_ESCAPE:%.*]] = getelementptr i8, ptr [[NEXT_GEP]], i64 -4
; INTERLEAVE-NEXT: br i1 [[CMP_N]], label %[[FOR_END:.*]], label %[[SCALAR_PH]]
; INTERLEAVE: [[SCALAR_PH]]:
; INTERLEAVE-NEXT: [[BC_RESUME_VAL:%.*]] = phi i32 [ [[TMP3]], %[[MIDDLE_BLOCK]] ], [ 0, %[[ENTRY]] ]
; INTERLEAVE-NEXT: [[BC_RESUME_VAL1:%.*]] = phi ptr [ [[NEXT_GEP]], %[[MIDDLE_BLOCK]] ], [ [[BASE]], %[[ENTRY]] ]
; INTERLEAVE-NEXT: [[SCALAR_RECUR_INIT:%.*]] = phi ptr [ [[NEXT_GEP1]], %[[MIDDLE_BLOCK]] ], [ [[BASE]], %[[ENTRY]] ]
; INTERLEAVE-NEXT: br label %[[FOR_BODY:.*]]
; INTERLEAVE: [[FOR_BODY]]:
; INTERLEAVE-NEXT: [[INC_PHI:%.*]] = phi i32 [ [[BC_RESUME_VAL]], %[[SCALAR_PH]] ], [ [[INC:%.*]], %[[FOR_BODY]] ]
; INTERLEAVE-NEXT: [[INC_LAG1:%.*]] = phi ptr [ [[BC_RESUME_VAL1]], %[[SCALAR_PH]] ], [ [[TMP:%.*]], %[[FOR_BODY]] ]
; INTERLEAVE-NEXT: [[INC_LAG2:%.*]] = phi ptr [ [[SCALAR_RECUR_INIT]], %[[SCALAR_PH]] ], [ [[INC_LAG1]], %[[FOR_BODY]] ]
; INTERLEAVE-NEXT: [[TMP]] = getelementptr inbounds i32, ptr [[INC_LAG1]], i64 1
; INTERLEAVE-NEXT: [[INC]] = add nsw i32 [[INC_PHI]], 1
; INTERLEAVE-NEXT: [[CMP:%.*]] = icmp eq i32 [[INC]], [[K]]
; INTERLEAVE-NEXT: br i1 [[CMP]], label %[[FOR_END]], label %[[FOR_BODY]], {{!llvm.loop ![0-9]+}}
; INTERLEAVE: [[FOR_END]]:
; INTERLEAVE-NEXT: [[INC_LAG1_LCSSA:%.*]] = phi ptr [ [[INC_LAG1]], %[[FOR_BODY]] ], [ [[IND_ESCAPE]], %[[MIDDLE_BLOCK]] ]
; INTERLEAVE-NEXT: ret ptr [[INC_LAG1_LCSSA]]
;
entry:
%base = getelementptr inbounds i32, ptr undef, i64 1
%base = getelementptr inbounds i32, ptr %p, i64 1
br label %for.body
for.body:
%inc.phi = phi i32 [ 0, %entry ], [ %inc, %for.body ]
%inc.lag1 = phi ptr [ %base, %entry ], [ %tmp, %for.body]
%inc.lag2 = phi ptr [ undef, %entry ], [ %inc.lag1, %for.body]
%inc.lag2 = phi ptr [ %base, %entry ], [ %inc.lag1, %for.body]
%tmp = getelementptr inbounds i32, ptr %inc.lag1, i64 1
%inc = add nsw i32 %inc.phi, 1
%cmp = icmp eq i32 %inc, %k