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[VPlan] Restore all-operands-inv WidenGEP logic (#174416)

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Restore the all-operands-invariant handling in WidenGEP::execute prior
to 37f7b31 (Reland [VPlan] Handle WidenGEP in narrowToSingleScalars), as
crashes have been reported.

Fixes #173761.
This commit is contained in:
Ramkumar Ramachandra 2026-01-06 13:05:37 +00:00 committed by GitHub
parent 8f18994009
commit bdc7681d63
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GPG Key ID: B5690EEEBB952194
2 changed files with 73 additions and 4 deletions
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26
llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp
View File

@ -2486,10 +2486,28 @@ void VPWidenGEPRecipe::execute(VPTransformState &State) {
// is vector-typed. Thus, to keep the representation compact, we only use
// vector-typed operands for loop-varying values.
assert(
any_of(operands(),
[](VPValue *Op) { return !Op->isDefinedOutsideLoopRegions(); }) &&
"Expected at least one loop-variant operand");
bool AllOperandsAreInvariant = all_of(operands(), [](VPValue *Op) {
return Op->isDefinedOutsideLoopRegions();
});
if (AllOperandsAreInvariant) {
// If we are vectorizing, but the GEP has only loop-invariant operands,
// the GEP we build (by only using vector-typed operands for
// loop-varying values) would be a scalar pointer. Thus, to ensure we
// produce a vector of pointers, we need to either arbitrarily pick an
// operand to broadcast, or broadcast a clone of the original GEP.
// Here, we broadcast a clone of the original.
SmallVector<Value *> Ops;
for (unsigned I = 0, E = getNumOperands(); I != E; I++)
Ops.push_back(State.get(getOperand(I), VPLane(0)));
auto *NewGEP =
State.Builder.CreateGEP(getSourceElementType(), Ops[0], drop_begin(Ops),
"", getGEPNoWrapFlags());
Value *Splat = State.Builder.CreateVectorSplat(State.VF, NewGEP);
State.set(this, Splat);
return;
}
// If the GEP has at least one loop-varying operand, we are sure to
// produce a vector of pointers unless VF is scalar.

51
llvm/test/Transforms/LoopVectorize/widen-gep-all-indices-invariant.ll
View File

@ -126,3 +126,54 @@ loop:
exit:
ret void
}
define void @pr173761(i8 %c, ptr %p, ptr noalias %q, ptr noalias %r) {
; CHECK-LABEL: define void @pr173761
; CHECK-SAME: (i8 [[C:%.*]], ptr [[P:%.*]], ptr noalias [[Q:%.*]], ptr noalias [[R:%.*]]) {
; CHECK-NEXT: entry:
; CHECK-NEXT: br label [[VECTOR_PH:%.*]]
; CHECK: vector.ph:
; CHECK-NEXT: [[BROADCAST_SPLATINSERT:%.*]] = insertelement <4 x i8> poison, i8 [[C]], i64 0
; CHECK-NEXT: [[BROADCAST_SPLAT:%.*]] = shufflevector <4 x i8> [[BROADCAST_SPLATINSERT]], <4 x i8> poison, <4 x i32> zeroinitializer
; CHECK-NEXT: [[BROADCAST_SPLATINSERT1:%.*]] = insertelement <4 x ptr> poison, ptr [[P]], i64 0
; CHECK-NEXT: [[BROADCAST_SPLAT2:%.*]] = shufflevector <4 x ptr> [[BROADCAST_SPLATINSERT1]], <4 x ptr> poison, <4 x i32> zeroinitializer
; CHECK-NEXT: [[TMP0:%.*]] = getelementptr inbounds nuw i8, ptr [[P]], i64 16
; CHECK-NEXT: [[BROADCAST_SPLATINSERT3:%.*]] = insertelement <4 x ptr> poison, ptr [[TMP0]], i64 0
; CHECK-NEXT: [[BROADCAST_SPLAT4:%.*]] = shufflevector <4 x ptr> [[BROADCAST_SPLATINSERT3]], <4 x ptr> poison, <4 x i32> zeroinitializer
; CHECK-NEXT: [[TMP1:%.*]] = trunc <4 x i8> [[BROADCAST_SPLAT]] to <4 x i1>
; CHECK-NEXT: [[TMP2:%.*]] = select <4 x i1> [[TMP1]], <4 x ptr> [[BROADCAST_SPLAT4]], <4 x ptr> [[BROADCAST_SPLAT2]]
; CHECK-NEXT: br label [[VECTOR_BODY:%.*]]
; CHECK: vector.body:
; CHECK-NEXT: [[INDEX:%.*]] = phi i32 [ 0, [[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], [[VECTOR_BODY]] ]
; CHECK-NEXT: [[TMP3:%.*]] = load i8, ptr [[P]], align 1
; CHECK-NEXT: store i8 [[TMP3]], ptr [[R]], align 1
; CHECK-NEXT: [[TMP4:%.*]] = extractelement <4 x ptr> [[TMP2]], i32 3
; CHECK-NEXT: [[TMP5:%.*]] = load i8, ptr [[TMP4]], align 1
; CHECK-NEXT: store i8 [[TMP5]], ptr [[Q]], align 1
; CHECK-NEXT: [[INDEX_NEXT]] = add nuw i32 [[INDEX]], 4
; CHECK-NEXT: [[TMP6:%.*]] = icmp eq i32 [[INDEX_NEXT]], 1024
; CHECK-NEXT: br i1 [[TMP6]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop [[LOOP5:![0-9]+]]
; CHECK: middle.block:
; CHECK-NEXT: br label [[EXIT:%.*]]
; CHECK: exit:
; CHECK-NEXT: ret void
;
entry:
br label %loop
loop:
%iv = phi i16 [ 0, %entry ], [ %iv.next, %loop ]
%ld.p = load i8, ptr %p
store i8 %ld.p, ptr %r
%gep.inv = getelementptr inbounds nuw i8, ptr %p, i64 16
%c.trunc = trunc i8 %c to i1
%sel.inv = select i1 %c.trunc, ptr %gep.inv, ptr %p
%ld.sel.inv = load i8, ptr %sel.inv
store i8 %ld.sel.inv, ptr %q
%iv.next = add i16 %iv, 1
%ec = icmp ne i16 %iv.next, 1024
br i1 %ec, label %loop, label %exit
exit:
ret void
}