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[InstCombine] Regard zext nneg as sext when folding add(zext neg(add)) #88887

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Merged
merged 2 commits into from
Apr 19, 2024
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[InstCombine] Regard zext nneg as sext when folding add(zext neg(add)) #88887

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f38e5a5
[InstCombine] Add pre-commit tests.
ZelinMa557 Apr 19, 2024
0d8c7df
[InstCombine] Regard zext nneg as sext when folding add(zext neg(add))
ZelinMa557 Apr 19, 2024
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6 changes: 3 additions & 3 deletions llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -828,9 +828,10 @@ static Instruction *foldNoWrapAdd(BinaryOperator &Add,

// More general combining of constants in the wide type.
// (sext (X +nsw NarrowC)) + C --> (sext X) + (sext(NarrowC) + C)
// or (zext nneg (X +nsw NarrowC)) + C --> (sext X) + (sext(NarrowC) + C)
Constant *NarrowC;
if (match(Op0,
m_OneUse(m_SExt(m_NSWAddLike(m_Value(X), m_Constant(NarrowC)))))) {
if (match(Op0, m_OneUse(m_SExtLike(
m_NSWAddLike(m_Value(X), m_Constant(NarrowC)))))) {
Value *WideC = Builder.CreateSExt(NarrowC, Ty);
Value *NewC = Builder.CreateAdd(WideC, Op1C);
Value *WideX = Builder.CreateSExt(X, Ty);
Expand All @@ -844,7 +845,6 @@ static Instruction *foldNoWrapAdd(BinaryOperator &Add,
Value *WideX = Builder.CreateZExt(X, Ty);
return BinaryOperator::CreateAdd(WideX, NewC);
}

return nullptr;
}

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37 changes: 37 additions & 0 deletions llvm/test/Transforms/InstCombine/add.ll
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Expand Up @@ -4091,6 +4091,43 @@ define i32 @fold_zext_addition_fail2(i8 %x) {
ret i32 %r
}

define i32 @fold_zext_nneg_add_const(i8 %x) {
; CHECK-LABEL: @fold_zext_nneg_add_const(
; CHECK-NEXT: [[TMP1:%.*]] = sext i8 [[X:%.*]] to i32
; CHECK-NEXT: [[R:%.*]] = add nsw i32 [[TMP1]], 98
; CHECK-NEXT: ret i32 [[R]]
;
%xx = add nsw i8 %x, 123
%ze = zext nneg i8 %xx to i32
%r = add nsw i32 %ze, -25
ret i32 %r
}

define i32 @fold_zext_nneg_add_const_fail1(i8 %x) {
; CHECK-LABEL: @fold_zext_nneg_add_const_fail1(
; CHECK-NEXT: [[XX:%.*]] = add nsw i8 [[X:%.*]], 123
; CHECK-NEXT: [[ZE:%.*]] = zext i8 [[XX]] to i32
; CHECK-NEXT: [[R:%.*]] = add nsw i32 [[ZE]], -25
; CHECK-NEXT: ret i32 [[R]]
;
%xx = add nsw i8 %x, 123
%ze = zext i8 %xx to i32
%r = add nsw i32 %ze, -25
ret i32 %r
}

define i32 @fold_zext_nneg_add_const_fail2(i8 %x) {
; CHECK-LABEL: @fold_zext_nneg_add_const_fail2(
; CHECK-NEXT: [[XX:%.*]] = add i8 [[X:%.*]], 123
; CHECK-NEXT: [[ZE:%.*]] = zext nneg i8 [[XX]] to i32
; CHECK-NEXT: [[R:%.*]] = add nsw i32 [[ZE]], -25
; CHECK-NEXT: ret i32 [[R]]
;
%xx = add i8 %x, 123
%ze = zext nneg i8 %xx to i32
%r = add nsw i32 %ze, -25
ret i32 %r
}

declare void @llvm.assume(i1)
declare void @fake_func(i32)
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