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[InstCombine] Add the missing insertion point before IRBuilder instruction creation #165315

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Merged
merged 1 commit into from
Oct 28, 2025
Merged

[InstCombine] Add the missing insertion point before IRBuilder instruction creation #165315

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2 changes: 2 additions & 0 deletions llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -105,6 +105,8 @@ static Value *simplifyShiftSelectingPackedElement(Instruction *I,
if (~KnownShrBits.Zero != ShlAmt)
return nullptr;

IRBuilderBase::InsertPointGuard Guard(IC.Builder);
IC.Builder.SetInsertPoint(I);
Value *ShrAmtZ =
IC.Builder.CreateICmpEQ(ShrAmt, Constant::getNullValue(ShrAmt->getType()),
ShrAmt->getName() + ".z");
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22 changes: 22 additions & 0 deletions llvm/test/Transforms/InstCombine/fold-selective-shift.ll
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Expand Up @@ -21,6 +21,28 @@ define i16 @selective_shift_16(i32 %mask, i16 %upper, i16 %lower) {
ret i16 %trunc
}

; Will assert if InsertPoint is not set before creating an instruction
; with IRBuilder
define i16 @selective_shift_16_insertpt(i32 %mask, i16 %upper, i16 %lower) {
; CHECK-LABEL: define i16 @selective_shift_16_insertpt(
; CHECK-SAME: i32 [[MASK:%.*]], i16 [[UPPER:%.*]], i16 [[LOWER:%.*]]) {
; CHECK-NEXT: [[MASK_BIT:%.*]] = and i32 [[MASK]], 16
; CHECK-NEXT: [[MASK_BIT_Z:%.*]] = icmp eq i32 [[MASK_BIT]], 0
; CHECK-NEXT: [[SEL_V:%.*]] = select i1 [[MASK_BIT_Z]], i16 [[LOWER]], i16 [[UPPER]]
; CHECK-NEXT: [[ADD_ONE:%.*]] = add i16 [[SEL_V]], 1
; CHECK-NEXT: ret i16 [[ADD_ONE]]
;
%mask.bit = and i32 %mask, 16
%upper.zext = zext i16 %upper to i32
%upper.shl = shl nuw i32 %upper.zext, 16
%lower.zext = zext i16 %lower to i32
%pack = or disjoint i32 %upper.shl, %lower.zext
%sel = lshr i32 %pack, %mask.bit
%add.one = add i32 %sel, 1
%trunc = trunc i32 %add.one to i16
ret i16 %trunc
}

define i16 @selective_shift_16.commute(i32 %mask, i16 %upper, i16 %lower) {
; CHECK-LABEL: define i16 @selective_shift_16.commute(
; CHECK-SAME: i32 [[MASK:%.*]], i16 [[UPPER:%.*]], i16 [[LOWER:%.*]]) {
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