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[InstCombine] Fold (add (add A, 1), (sext (icmp ne A, 0))) to call umax(A, 1) #122491

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Jan 12, 2025
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[InstCombine] Fold (add (add A, 1), (sext (icmp ne A, 0))) to call umax(A, 1) #122491

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61f0c5e
[InstCombine] Pre-commit tests
Ruhung Jan 10, 2025
e4a4e38
[InstCombine] Fold (add (add A, 1), (sext (icmp ne A, 0))) to call um…
Ruhung Jan 10, 2025
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9 changes: 9 additions & 0 deletions llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1775,6 +1775,15 @@ Instruction *InstCombinerImpl::visitAdd(BinaryOperator &I) {
}
}

// (add (add A, 1), (sext (icmp ne A, 0))) => call umax(A, 1)
if (match(LHS, m_Add(m_Value(A), m_One())) &&
match(RHS, m_OneUse(m_SExt(m_OneUse(m_SpecificICmp(
ICmpInst::ICMP_NE, m_Specific(A), m_ZeroInt())))))) {
Value *OneConst = ConstantInt::get(A->getType(), 1);
Value *UMax = Builder.CreateBinaryIntrinsic(Intrinsic::umax, A, OneConst);
return replaceInstUsesWith(I, UMax);
}

if (Instruction *Ashr = foldAddToAshr(I))
return Ashr;

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139 changes: 139 additions & 0 deletions llvm/test/Transforms/InstCombine/add-sext-icmp.ll
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@@ -0,0 +1,139 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
; RUN: opt -S -passes=instcombine < %s | FileCheck %s

; The pattern:
; add(add A, 1), (sext(icmp ne A, 0))
; is transformed into:
; umax(A, 1)

define i32 @add_sext_icmp(i32 %A) {
; CHECK-LABEL: define i32 @add_sext_icmp(
; CHECK-SAME: i32 [[A:%.*]]) {
; CHECK-NEXT: [[ADD2:%.*]] = call i32 @llvm.umax.i32(i32 [[A]], i32 1)
; CHECK-NEXT: ret i32 [[ADD2]]
;
%add1 = add i32 %A, 1
%icmp = icmp ne i32 %A, 0
%sext = sext i1 %icmp to i32
%add2 = add i32 %add1, %sext
ret i32 %add2
}

define i32 @add_sext_icmp_commutative(i32 %A) {
; CHECK-LABEL: define i32 @add_sext_icmp_commutative(
; CHECK-SAME: i32 [[A:%.*]]) {
; CHECK-NEXT: [[ADD2:%.*]] = call i32 @llvm.umax.i32(i32 [[A]], i32 1)
; CHECK-NEXT: ret i32 [[ADD2]]
;
%add1 = add i32 %A, 1
%icmp = icmp ne i32 %A, 0
%sext = sext i1 %icmp to i32
%add2 = add i32 %sext, %add1
ret i32 %add2
}

; Negative test

define i32 @add_sext_icmp_negative_constant(i32 %A) {
; CHECK-LABEL: define i32 @add_sext_icmp_negative_constant(
; CHECK-SAME: i32 [[A:%.*]]) {
; CHECK-NEXT: [[ADD1:%.*]] = add i32 [[A]], 2
; CHECK-NEXT: [[ICMP:%.*]] = icmp ne i32 [[A]], 0
; CHECK-NEXT: [[SEXT:%.*]] = sext i1 [[ICMP]] to i32
; CHECK-NEXT: [[ADD2:%.*]] = add i32 [[ADD1]], [[SEXT]]
; CHECK-NEXT: ret i32 [[ADD2]]
;
%add1 = add i32 %A, 2
%icmp = icmp ne i32 %A, 0
%sext = sext i1 %icmp to i32
%add2 = add i32 %add1, %sext
ret i32 %add2
}

define i32 @add_sext_icmp_negative_pred(i32 %A) {
; CHECK-LABEL: define i32 @add_sext_icmp_negative_pred(
; CHECK-SAME: i32 [[A:%.*]]) {
; CHECK-NEXT: [[ADD1:%.*]] = add i32 [[A]], 1
; CHECK-NEXT: [[ICMP:%.*]] = icmp eq i32 [[A]], 0
; CHECK-NEXT: [[SEXT:%.*]] = sext i1 [[ICMP]] to i32
; CHECK-NEXT: [[ADD2:%.*]] = add i32 [[ADD1]], [[SEXT]]
; CHECK-NEXT: ret i32 [[ADD2]]
;
%add1 = add i32 %A, 1
%icmp = icmp eq i32 %A, 0
%sext = sext i1 %icmp to i32
%add2 = add i32 %add1, %sext
ret i32 %add2
}

; multi-use test

define i32 @add_sext_icmp_multi_use_add2(i32 %A) {
; CHECK-LABEL: define i32 @add_sext_icmp_multi_use_add2(
; CHECK-SAME: i32 [[A:%.*]]) {
; CHECK-NEXT: [[ADD2:%.*]] = call i32 @llvm.umax.i32(i32 [[A]], i32 1)
; CHECK-NEXT: call void @use(i32 [[ADD2]])
; CHECK-NEXT: ret i32 [[ADD2]]
;
%add1 = add i32 %A, 1
%icmp = icmp ne i32 %A, 0
%sext = sext i1 %icmp to i32
%add2 = add i32 %add1, %sext
call void @use(i32 %add2)
ret i32 %add2
}

define i32 @add_sext_icmp_multi_use_sext(i32 %A) {
; CHECK-LABEL: define i32 @add_sext_icmp_multi_use_sext(
; CHECK-SAME: i32 [[A:%.*]]) {
; CHECK-NEXT: [[ADD1:%.*]] = add i32 [[A]], 1
; CHECK-NEXT: [[ICMP:%.*]] = icmp ne i32 [[A]], 0
; CHECK-NEXT: [[SEXT:%.*]] = sext i1 [[ICMP]] to i32
; CHECK-NEXT: call void @use(i32 [[SEXT]])
; CHECK-NEXT: [[ADD2:%.*]] = add i32 [[ADD1]], [[SEXT]]
; CHECK-NEXT: ret i32 [[ADD2]]
;
%add1 = add i32 %A, 1
%icmp = icmp ne i32 %A, 0
%sext = sext i1 %icmp to i32
call void @use(i32 %sext)
%add2 = add i32 %add1, %sext
ret i32 %add2
}

define i32 @add_sext_icmp_multi_use_icmp(i32 %A) {
; CHECK-LABEL: define i32 @add_sext_icmp_multi_use_icmp(
; CHECK-SAME: i32 [[A:%.*]]) {
; CHECK-NEXT: [[ADD1:%.*]] = add i32 [[A]], 1
; CHECK-NEXT: [[ICMP:%.*]] = icmp ne i32 [[A]], 0
; CHECK-NEXT: call void @use(i1 [[ICMP]])
; CHECK-NEXT: [[SEXT:%.*]] = sext i1 [[ICMP]] to i32
; CHECK-NEXT: [[ADD2:%.*]] = add i32 [[ADD1]], [[SEXT]]
; CHECK-NEXT: ret i32 [[ADD2]]
;
%add1 = add i32 %A, 1
%icmp = icmp ne i32 %A, 0
call void @use(i1 %icmp)
%sext = sext i1 %icmp to i32
%add2 = add i32 %add1, %sext
ret i32 %add2
}

define i32 @add_sext_icmp_multi_use_add1(i32 %A) {
; CHECK-LABEL: define i32 @add_sext_icmp_multi_use_add1(
; CHECK-SAME: i32 [[A:%.*]]) {
; CHECK-NEXT: [[ADD1:%.*]] = add i32 [[A]], 1
; CHECK-NEXT: call void @use(i32 [[ADD1]])
; CHECK-NEXT: [[ADD2:%.*]] = call i32 @llvm.umax.i32(i32 [[A]], i32 1)
; CHECK-NEXT: ret i32 [[ADD2]]
;
%add1 = add i32 %A, 1
call void @use(i32 %add1)
%icmp = icmp ne i32 %A, 0
%sext = sext i1 %icmp to i32
%add2 = add i32 %add1, %sext
ret i32 %add2
}

declare void @use(i32)

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