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[InstCombine] Simplify compare abs(X) and X. (#76385)
fix #72653 proof: https://alive2.llvm.org/ce/z/LZzZaj
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‎llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp

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Original file line numberDiff line numberDiff line change
@@ -6868,6 +6868,57 @@ Instruction *InstCombinerImpl::foldICmpCommutative(ICmpInst::Predicate Pred,
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return foldICmpAddOpConst(X, *C, Pred);
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}
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// abs(X) >= X --> true
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// abs(X) u<= X --> true
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// abs(X) < X --> false
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// abs(X) u> X --> false
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// abs(X) u>= X --> IsIntMinPosion ? `X > -1`: `X u<= INTMIN`
6876+
// abs(X) <= X --> IsIntMinPosion ? `X > -1`: `X u<= INTMIN`
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// abs(X) == X --> IsIntMinPosion ? `X > -1`: `X u<= INTMIN`
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// abs(X) u< X --> IsIntMinPosion ? `X < 0` : `X > INTMIN`
6879+
// abs(X) > X --> IsIntMinPosion ? `X < 0` : `X > INTMIN`
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// abs(X) != X --> IsIntMinPosion ? `X < 0` : `X > INTMIN`
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{
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Value *X;
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Constant *C;
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if (match(Op0, m_Intrinsic<Intrinsic::abs>(m_Value(X), m_Constant(C))) &&
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match(Op1, m_Specific(X))) {
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Value *NullValue = Constant::getNullValue(X->getType());
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Value *AllOnesValue = Constant::getAllOnesValue(X->getType());
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const APInt SMin =
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APInt::getSignedMinValue(X->getType()->getScalarSizeInBits());
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bool IsIntMinPosion = C->isAllOnesValue();
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switch (Pred) {
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case CmpInst::ICMP_ULE:
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case CmpInst::ICMP_SGE:
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return replaceInstUsesWith(CxtI, ConstantInt::getTrue(CxtI.getType()));
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case CmpInst::ICMP_UGT:
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case CmpInst::ICMP_SLT:
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return replaceInstUsesWith(CxtI, ConstantInt::getFalse(CxtI.getType()));
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case CmpInst::ICMP_UGE:
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case CmpInst::ICMP_SLE:
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case CmpInst::ICMP_EQ: {
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return replaceInstUsesWith(
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CxtI, IsIntMinPosion
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? Builder.CreateICmpSGT(X, AllOnesValue)
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: Builder.CreateICmpULT(
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X, ConstantInt::get(X->getType(), SMin + 1)));
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}
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case CmpInst::ICMP_ULT:
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case CmpInst::ICMP_SGT:
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case CmpInst::ICMP_NE: {
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return replaceInstUsesWith(
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CxtI, IsIntMinPosion
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? Builder.CreateICmpSLT(X, NullValue)
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: Builder.CreateICmpUGT(
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X, ConstantInt::get(X->getType(), SMin)));
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}
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default:
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llvm_unreachable("Invalid predicate!");
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}
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}
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}
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68716922
return nullptr;
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}
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‎llvm/test/Transforms/InstCombine/icmp-abs.ll

Lines changed: 219 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,219 @@
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; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
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; RUN: opt < %s -passes=instcombine -S | FileCheck %s
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declare i4 @llvm.abs.i4(i4, i1)
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define i1 @icmp_sge_abs(i4 %arg) {
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; CHECK-LABEL: @icmp_sge_abs(
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; CHECK-NEXT: ret i1 true
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;
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%abs = call i4 @llvm.abs.i4(i4 %arg, i1 true)
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%cmp = icmp sge i4 %abs, %arg
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ret i1 %cmp
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}
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define i1 @icmp_sge_abs_false(i4 %arg) {
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; CHECK-LABEL: @icmp_sge_abs_false(
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; CHECK-NEXT: ret i1 true
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;
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%abs = call i4 @llvm.abs.i4(i4 %arg, i1 false)
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%cmp = icmp sge i4 %abs, %arg
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ret i1 %cmp
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}
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define i1 @icmp_eq_abs(i4 %arg) {
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; CHECK-LABEL: @icmp_eq_abs(
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; CHECK-NEXT: [[CMP:%.*]] = icmp sgt i4 [[ARG:%.*]], -1
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; CHECK-NEXT: ret i1 [[CMP]]
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;
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%abs = call i4 @llvm.abs.i4(i4 %arg, i1 true)
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%cmp = icmp eq i4 %abs, %arg
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ret i1 %cmp
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}
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define i1 @icmp_eq_abs_false(i4 %arg) {
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; CHECK-LABEL: @icmp_eq_abs_false(
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; CHECK-NEXT: [[CMP:%.*]] = icmp ult i4 [[ARG:%.*]], -7
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; CHECK-NEXT: ret i1 [[CMP]]
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;
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%abs = call i4 @llvm.abs.i4(i4 %arg, i1 false)
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%cmp = icmp eq i4 %abs, %arg
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ret i1 %cmp
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}
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44+
define i1 @icmp_ne_abs(i4 %arg) {
45+
; CHECK-LABEL: @icmp_ne_abs(
46+
; CHECK-NEXT: [[CMP:%.*]] = icmp slt i4 [[ARG:%.*]], 0
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; CHECK-NEXT: ret i1 [[CMP]]
48+
;
49+
%abs = call i4 @llvm.abs.i4(i4 %arg, i1 true)
50+
%cmp = icmp ne i4 %abs, %arg
51+
ret i1 %cmp
52+
}
53+
54+
define i1 @icmp_ne_abs_false(i4 %arg) {
55+
; CHECK-LABEL: @icmp_ne_abs_false(
56+
; CHECK-NEXT: [[CMP:%.*]] = icmp ugt i4 [[ARG:%.*]], -8
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; CHECK-NEXT: ret i1 [[CMP]]
58+
;
59+
%abs = call i4 @llvm.abs.i4(i4 %arg, i1 false)
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%cmp = icmp ne i4 %abs, %arg
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ret i1 %cmp
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}
63+
64+
define i1 @icmp_sle_abs(i4 %arg) {
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; CHECK-LABEL: @icmp_sle_abs(
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; CHECK-NEXT: [[CMP:%.*]] = icmp sgt i4 [[ARG:%.*]], -1
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; CHECK-NEXT: ret i1 [[CMP]]
68+
;
69+
%abs = call i4 @llvm.abs.i4(i4 %arg, i1 true)
70+
%cmp = icmp sle i4 %abs, %arg
71+
ret i1 %cmp
72+
}
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74+
define i1 @icmp_sle_abs_false(i4 %arg) {
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; CHECK-LABEL: @icmp_sle_abs_false(
76+
; CHECK-NEXT: [[CMP:%.*]] = icmp ult i4 [[ARG:%.*]], -7
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; CHECK-NEXT: ret i1 [[CMP]]
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;
79+
%abs = call i4 @llvm.abs.i4(i4 %arg, i1 false)
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%cmp = icmp sle i4 %abs, %arg
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ret i1 %cmp
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}
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84+
define i1 @icmp_slt_abs(i4 %arg) {
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; CHECK-LABEL: @icmp_slt_abs(
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; CHECK-NEXT: ret i1 false
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;
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%abs = call i4 @llvm.abs.i4(i4 %arg, i1 true)
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%cmp = icmp slt i4 %abs, %arg
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ret i1 %cmp
91+
}
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define i1 @icmp_slt_abs_false(i4 %arg) {
94+
; CHECK-LABEL: @icmp_slt_abs_false(
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; CHECK-NEXT: ret i1 false
96+
;
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%abs = call i4 @llvm.abs.i4(i4 %arg, i1 false)
98+
%cmp = icmp slt i4 %abs, %arg
99+
ret i1 %cmp
100+
}
101+
102+
define i1 @icmp_sgt_abs(i4 %arg) {
103+
; CHECK-LABEL: @icmp_sgt_abs(
104+
; CHECK-NEXT: [[CMP:%.*]] = icmp slt i4 [[ARG:%.*]], 0
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; CHECK-NEXT: ret i1 [[CMP]]
106+
;
107+
%abs = call i4 @llvm.abs.i4(i4 %arg, i1 true)
108+
%cmp = icmp sgt i4 %abs, %arg
109+
ret i1 %cmp
110+
}
111+
112+
define i1 @icmp_sgt_abs_false(i4 %arg) {
113+
; CHECK-LABEL: @icmp_sgt_abs_false(
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; CHECK-NEXT: [[CMP:%.*]] = icmp ugt i4 [[ARG:%.*]], -8
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; CHECK-NEXT: ret i1 [[CMP]]
116+
;
117+
%abs = call i4 @llvm.abs.i4(i4 %arg, i1 false)
118+
%cmp = icmp sgt i4 %abs, %arg
119+
ret i1 %cmp
120+
}
121+
122+
define i1 @icmp_ugt_abs(i4 %arg) {
123+
; CHECK-LABEL: @icmp_ugt_abs(
124+
; CHECK-NEXT: ret i1 false
125+
;
126+
%abs = call i4 @llvm.abs.i4(i4 %arg, i1 true)
127+
%cmp = icmp ugt i4 %abs, %arg
128+
ret i1 %cmp
129+
}
130+
131+
define i1 @icmp_ugt_abs_false(i4 %arg) {
132+
; CHECK-LABEL: @icmp_ugt_abs_false(
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; CHECK-NEXT: ret i1 false
134+
;
135+
%abs = call i4 @llvm.abs.i4(i4 %arg, i1 false)
136+
%cmp = icmp ugt i4 %abs, %arg
137+
ret i1 %cmp
138+
}
139+
140+
define i1 @icmp_uge_abs(i4 %arg) {
141+
; CHECK-LABEL: @icmp_uge_abs(
142+
; CHECK-NEXT: [[CMP:%.*]] = icmp sgt i4 [[ARG:%.*]], -1
143+
; CHECK-NEXT: ret i1 [[CMP]]
144+
;
145+
%abs = call i4 @llvm.abs.i4(i4 %arg, i1 true)
146+
%cmp = icmp uge i4 %abs, %arg
147+
ret i1 %cmp
148+
}
149+
150+
define i1 @icmp_uge_abs_false(i4 %arg) {
151+
; CHECK-LABEL: @icmp_uge_abs_false(
152+
; CHECK-NEXT: [[CMP:%.*]] = icmp ult i4 [[ARG:%.*]], -7
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; CHECK-NEXT: ret i1 [[CMP]]
154+
;
155+
%abs = call i4 @llvm.abs.i4(i4 %arg, i1 false)
156+
%cmp = icmp uge i4 %abs, %arg
157+
ret i1 %cmp
158+
}
159+
160+
define i1 @icmp_ule_abs(i4 %arg) {
161+
; CHECK-LABEL: @icmp_ule_abs(
162+
; CHECK-NEXT: ret i1 true
163+
;
164+
%abs = call i4 @llvm.abs.i4(i4 %arg, i1 true)
165+
%cmp = icmp ule i4 %abs, %arg
166+
ret i1 %cmp
167+
}
168+
169+
define i1 @icmp_ule_abs_false(i4 %arg) {
170+
; CHECK-LABEL: @icmp_ule_abs_false(
171+
; CHECK-NEXT: ret i1 true
172+
;
173+
%abs = call i4 @llvm.abs.i4(i4 %arg, i1 false)
174+
%cmp = icmp ule i4 %abs, %arg
175+
ret i1 %cmp
176+
}
177+
178+
define i1 @icmp_ult_abs(i4 %arg) {
179+
; CHECK-LABEL: @icmp_ult_abs(
180+
; CHECK-NEXT: [[CMP:%.*]] = icmp slt i4 [[ARG:%.*]], 0
181+
; CHECK-NEXT: ret i1 [[CMP]]
182+
;
183+
%abs = call i4 @llvm.abs.i4(i4 %arg, i1 true)
184+
%cmp = icmp ult i4 %abs, %arg
185+
ret i1 %cmp
186+
}
187+
188+
define i1 @icmp_ult_abs_false(i4 %arg) {
189+
; CHECK-LABEL: @icmp_ult_abs_false(
190+
; CHECK-NEXT: [[CMP:%.*]] = icmp ugt i4 [[ARG:%.*]], -8
191+
; CHECK-NEXT: ret i1 [[CMP]]
192+
;
193+
%abs = call i4 @llvm.abs.i4(i4 %arg, i1 false)
194+
%cmp = icmp ult i4 %abs, %arg
195+
ret i1 %cmp
196+
}
197+
198+
define i1 @icmp_sge_abs2(i4 %arg) {
199+
; CHECK-LABEL: @icmp_sge_abs2(
200+
; CHECK-NEXT: [[X:%.*]] = mul i4 [[ARG:%.*]], [[ARG]]
201+
; CHECK-NEXT: [[CMP:%.*]] = icmp sgt i4 [[X]], -1
202+
; CHECK-NEXT: ret i1 [[CMP]]
203+
;
204+
%x = mul i4 %arg, %arg ; thwart complexity-based canonicalization
205+
%abs = call i4 @llvm.abs.i4(i4 %x, i1 true)
206+
%cmp = icmp sge i4 %x, %abs
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ret i1 %cmp
208+
}
209+
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define i1 @icmp_sge_abs_mismatched_op(i4 %arg, i4 %arg2) {
211+
; CHECK-LABEL: @icmp_sge_abs_mismatched_op(
212+
; CHECK-NEXT: [[ABS:%.*]] = call i4 @llvm.abs.i4(i4 [[ARG:%.*]], i1 true)
213+
; CHECK-NEXT: [[CMP:%.*]] = icmp sge i4 [[ABS]], [[ARG2:%.*]]
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; CHECK-NEXT: ret i1 [[CMP]]
215+
;
216+
%abs = call i4 @llvm.abs.i4(i4 %arg, i1 true)
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%cmp = icmp sge i4 %abs, %arg2
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ret i1 %cmp
219+
}

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