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[InstCombine] Fold xored one-complemented operand comparisons #69882

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Merged
merged 2 commits into from
Nov 14, 2023
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[InstCombine] Fold xored one-complemented operand comparisons #69882

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f42483f
[InstCombine] Add test coverage for comparisons of operands including…
elhewaty Oct 24, 2023
b348c46
[InstCombine] Fold xored one-complemented operand comparisons.
elhewaty Nov 13, 2023
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18 changes: 17 additions & 1 deletion llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -7022,7 +7022,7 @@ Instruction *InstCombinerImpl::visitICmpInst(ICmpInst &I) {
return Res;

{
Value *X, *Y;
Value *X, *Y, *Z;
// Transform (X & ~Y) == 0 --> (X & Y) != 0
// and (X & ~Y) != 0 --> (X & Y) == 0
// if A is a power of 2.
Expand All @@ -7032,6 +7032,22 @@ Instruction *InstCombinerImpl::visitICmpInst(ICmpInst &I) {
return new ICmpInst(I.getInversePredicate(), Builder.CreateAnd(X, Y),
Op1);

// Transform (~X ^ Y) s< ~Z --> (X ^ Y) s> Z,
// (~X ^ Y) s> ~Z --> (X ^ Y) s< Z,
// (~X ^ Y) s<= ~Z --> (X ^ Y) s>= Z,
// (~X ^ Y) s>= ~Z --> (X ^ Y) s<= Z,
// (~X ^ Y) u< ~Z --> (X ^ Y) u< Z,
// (~X ^ Y) u> ~Z --> (X ^ Y) u< Z,
// (~X ^ Y) u<= ~Z --> (X ^ Y) u>= Z,
// (~X ^ Y) u>= ~Z --> (X ^ Y) u<= Z,
// (~X ^ Y) == ~Z --> (X ^ Y) == Z,
// and (~X ^ Y) != ~Z --> (X ^ Y) != Z,
if (match(&I, m_c_ICmp(Pred, m_c_Xor(m_Not(m_Value(X)), m_Value(Y)),
m_Not(m_Value(Z)))) &&
(I.getOperand(0)->hasOneUse() || I.getOperand(1)->hasOneUse()))
return new ICmpInst(I.getSwappedPredicate(Pred), Builder.CreateXor(X, Y),
Z);

// ~X < ~Y --> Y < X
// ~X < C --> X > ~C
if (match(Op0, m_Not(m_Value(X)))) {
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279 changes: 279 additions & 0 deletions llvm/test/Transforms/InstCombine/icmp-of-xor-x.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,285 @@

declare void @llvm.assume(i1)
declare void @barrier()
declare void @use.i8(i8)

; test for (~x ^ y) < ~z
define i1 @test_xor1(i8 %x, i8 %y, i8 %z) {
; CHECK-LABEL: @test_xor1(
; CHECK-NEXT: [[XOR:%.*]] = xor i8 [[X:%.*]], -1
; CHECK-NEXT: call void @use.i8(i8 [[XOR]])
; CHECK-NEXT: [[TMP1:%.*]] = xor i8 [[X]], [[Y:%.*]]
; CHECK-NEXT: [[R:%.*]] = icmp sgt i8 [[TMP1]], [[Z:%.*]]
; CHECK-NEXT: ret i1 [[R]]
;
%xor = xor i8 %x, -1
call void @use.i8(i8 %xor)
%xor2 = xor i8 %xor, %y
%nz = xor i8 %z, -1
%r = icmp slt i8 %xor2, %nz
ret i1 %r
}

; test for ~z <= (x ^ ~y)
define i1 @test_xor2(i8 %x, i8 %y, i8 %z) {
; CHECK-LABEL: @test_xor2(
; CHECK-NEXT: [[XOR:%.*]] = xor i8 [[Y:%.*]], -1
; CHECK-NEXT: call void @use.i8(i8 [[XOR]])
; CHECK-NEXT: [[TMP1:%.*]] = xor i8 [[Y]], [[X:%.*]]
; CHECK-NEXT: [[R:%.*]] = icmp sle i8 [[TMP1]], [[Z:%.*]]
; CHECK-NEXT: ret i1 [[R]]
;
%nz = xor i8 %z, -1
%xor = xor i8 %y, -1
call void @use.i8(i8 %xor)
%xor2 = xor i8 %xor, %x
%r = icmp sle i8 %nz, %xor2
ret i1 %r
}

; test for ~z > (~x ^ y)
define i1 @test_xor3(i8 %x, i8 %y, i8 %z) {
; CHECK-LABEL: @test_xor3(
; CHECK-NEXT: [[XOR:%.*]] = xor i8 [[X:%.*]], -1
; CHECK-NEXT: call void @use.i8(i8 [[XOR]])
; CHECK-NEXT: [[TMP1:%.*]] = xor i8 [[X]], [[Y:%.*]]
; CHECK-NEXT: [[R:%.*]] = icmp sgt i8 [[TMP1]], [[Z:%.*]]
; CHECK-NEXT: ret i1 [[R]]
;
%nz = xor i8 %z, -1
%xor = xor i8 %x, -1
call void @use.i8(i8 %xor)
%xor2 = xor i8 %xor, %y
%r = icmp sgt i8 %nz, %xor2
ret i1 %r
}

; tests for equality
define i1 @test_xor_ne(i8 %x, i8 %y, i8 %z) {
; CHECK-LABEL: @test_xor_ne(
; CHECK-NEXT: [[TMP1:%.*]] = xor i8 [[Y:%.*]], [[X:%.*]]
; CHECK-NEXT: [[R:%.*]] = icmp ne i8 [[TMP1]], [[Z:%.*]]
; CHECK-NEXT: ret i1 [[R]]
;
%nz = xor i8 %z, -1
%xor = xor i8 %y, -1
%xor2 = xor i8 %xor, %x
%r = icmp ne i8 %nz, %xor2
ret i1 %r
}

define i1 @test_xor_eq(i8 %x, i8 %y, i8 %z) {
; CHECK-LABEL: @test_xor_eq(
; CHECK-NEXT: [[TMP1:%.*]] = xor i8 [[Y:%.*]], [[X:%.*]]
; CHECK-NEXT: [[R:%.*]] = icmp eq i8 [[TMP1]], [[Z:%.*]]
; CHECK-NEXT: ret i1 [[R]]
;
%nz = xor i8 %z, -1
%xor = xor i8 %y, -1
%xor2 = xor i8 %xor, %x
%r = icmp eq i8 %nz, %xor2
ret i1 %r
}

; other tests
define i1 @test_xor4(i8 %x, i8 %y, i8 %z) {
; CHECK-LABEL: @test_xor4(
; CHECK-NEXT: [[XOR:%.*]] = xor i8 [[X:%.*]], -1
; CHECK-NEXT: call void @use.i8(i8 [[XOR]])
; CHECK-NEXT: [[TMP1:%.*]] = xor i8 [[X]], [[Y:%.*]]
; CHECK-NEXT: [[R:%.*]] = icmp sle i8 [[TMP1]], [[Z:%.*]]
; CHECK-NEXT: ret i1 [[R]]
;
%nz = xor i8 %z, -1
%xor = xor i8 %x, -1
call void @use.i8(i8 %xor)
%xor2 = xor i8 %xor, %y
%r = icmp sge i8 %xor2, %nz
ret i1 %r
}

define i1 @test_xor5(i8 %x, i8 %y, i8 %z) {
; CHECK-LABEL: @test_xor5(
; CHECK-NEXT: [[XOR:%.*]] = xor i8 [[X:%.*]], -1
; CHECK-NEXT: call void @use.i8(i8 [[XOR]])
; CHECK-NEXT: [[TMP1:%.*]] = xor i8 [[X]], [[Y:%.*]]
; CHECK-NEXT: [[R:%.*]] = icmp ugt i8 [[TMP1]], [[Z:%.*]]
; CHECK-NEXT: ret i1 [[R]]
;
%nz = xor i8 %z, -1
%xor = xor i8 %x, -1
call void @use.i8(i8 %xor)
%xor2 = xor i8 %xor, %y
%r = icmp ult i8 %xor2, %nz
ret i1 %r
}

define i1 @test_xor6(i8 %x, i8 %y, i8 %z) {
; CHECK-LABEL: @test_xor6(
; CHECK-NEXT: [[XOR:%.*]] = xor i8 [[X:%.*]], -1
; CHECK-NEXT: call void @use.i8(i8 [[XOR]])
; CHECK-NEXT: [[TMP1:%.*]] = xor i8 [[X]], [[Y:%.*]]
; CHECK-NEXT: [[R:%.*]] = icmp uge i8 [[TMP1]], [[Z:%.*]]
; CHECK-NEXT: ret i1 [[R]]
;
%nz = xor i8 %z, -1
%xor = xor i8 %x, -1
call void @use.i8(i8 %xor)
%xor2 = xor i8 %xor, %y
%r = icmp ule i8 %xor2, %nz
ret i1 %r
}

define i1 @test_xor7(i8 %x, i8 %y, i8 %z) {
; CHECK-LABEL: @test_xor7(
; CHECK-NEXT: [[XOR:%.*]] = xor i8 [[X:%.*]], -1
; CHECK-NEXT: call void @use.i8(i8 [[XOR]])
; CHECK-NEXT: [[TMP1:%.*]] = xor i8 [[X]], [[Y:%.*]]
; CHECK-NEXT: [[R:%.*]] = icmp ult i8 [[TMP1]], [[Z:%.*]]
; CHECK-NEXT: ret i1 [[R]]
;
%nz = xor i8 %z, -1
%xor = xor i8 %x, -1
call void @use.i8(i8 %xor)
%xor2 = xor i8 %xor, %y
%r = icmp ugt i8 %xor2, %nz
ret i1 %r
}

define i1 @test_xor8(i8 %x, i8 %y, i8 %z) {
; CHECK-LABEL: @test_xor8(
; CHECK-NEXT: [[XOR:%.*]] = xor i8 [[X:%.*]], -1
; CHECK-NEXT: call void @use.i8(i8 [[XOR]])
; CHECK-NEXT: [[TMP1:%.*]] = xor i8 [[X]], [[Y:%.*]]
; CHECK-NEXT: [[R:%.*]] = icmp ule i8 [[TMP1]], [[Z:%.*]]
; CHECK-NEXT: ret i1 [[R]]
;
%nz = xor i8 %z, -1
%xor = xor i8 %x, -1
call void @use.i8(i8 %xor)
%xor2 = xor i8 %xor, %y
%r = icmp uge i8 %xor2, %nz
ret i1 %r
}

; test (~a ^ b) < ~a
define i1 @test_slt_xor(i32 %x, i32 %y) {
; CHECK-LABEL: @test_slt_xor(
; CHECK-NEXT: [[TMP1:%.*]] = xor i32 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: [[R:%.*]] = icmp sgt i32 [[TMP1]], [[X]]
; CHECK-NEXT: ret i1 [[R]]
;
%xor1 = xor i32 %x, -1
%xor2 = xor i32 %xor1, %y
%r = icmp slt i32 %xor2, %xor1
ret i1 %r
}

; test (a ^ ~b) <= ~b
define i1 @test_sle_xor(i32 %x, i32 %y) {
; CHECK-LABEL: @test_sle_xor(
; CHECK-NEXT: [[TMP1:%.*]] = xor i32 [[Y:%.*]], [[X:%.*]]
; CHECK-NEXT: [[R:%.*]] = icmp sge i32 [[TMP1]], [[Y]]
; CHECK-NEXT: ret i1 [[R]]
;
%xor1 = xor i32 %y, -1
%xor2 = xor i32 %xor1, %x
%r = icmp sle i32 %xor2, %xor1
ret i1 %r
}

; test ~a > (~a ^ b)
define i1 @test_sgt_xor(i32 %x, i32 %y) {
; CHECK-LABEL: @test_sgt_xor(
; CHECK-NEXT: [[TMP1:%.*]] = xor i32 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: [[CMP:%.*]] = icmp slt i32 [[TMP1]], [[X]]
; CHECK-NEXT: ret i1 [[CMP]]
;
%xor1 = xor i32 %x, -1
%xor2 = xor i32 %xor1, %y
%cmp = icmp sgt i32 %xor2, %xor1
ret i1 %cmp
}

define i1 @test_sge_xor(i32 %x, i32 %y) {
; CHECK-LABEL: @test_sge_xor(
; CHECK-NEXT: [[TMP1:%.*]] = xor i32 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: [[CMP:%.*]] = icmp sle i32 [[TMP1]], [[X]]
; CHECK-NEXT: ret i1 [[CMP]]
;
%xor1 = xor i32 %x, -1
%xor2 = xor i32 %xor1, %y
%cmp = icmp sge i32 %xor2, %xor1
ret i1 %cmp
}

define i1 @test_ult_xor(i32 %x, i32 %y) {
; CHECK-LABEL: @test_ult_xor(
; CHECK-NEXT: [[TMP1:%.*]] = xor i32 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: [[CMP:%.*]] = icmp ugt i32 [[TMP1]], [[X]]
; CHECK-NEXT: ret i1 [[CMP]]
;
%xor1 = xor i32 %x, -1
%xor2 = xor i32 %xor1, %y
%cmp = icmp ult i32 %xor2, %xor1
ret i1 %cmp
}

define i1 @test_ule_xor(i32 %x, i32 %y) {
; CHECK-LABEL: @test_ule_xor(
; CHECK-NEXT: [[TMP1:%.*]] = xor i32 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: [[CMP:%.*]] = icmp uge i32 [[TMP1]], [[X]]
; CHECK-NEXT: ret i1 [[CMP]]
;
%xor1 = xor i32 %x, -1
%xor2 = xor i32 %xor1, %y
%cmp = icmp ule i32 %xor2, %xor1
ret i1 %cmp
}

define i1 @test_ugt_xor(i32 %x, i32 %y) {
; CHECK-LABEL: @test_ugt_xor(
; CHECK-NEXT: [[TMP1:%.*]] = xor i32 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: [[CMP:%.*]] = icmp ult i32 [[TMP1]], [[X]]
; CHECK-NEXT: ret i1 [[CMP]]
;
%xor1 = xor i32 %x, -1
%xor2 = xor i32 %xor1, %y
%cmp = icmp ugt i32 %xor2, %xor1
ret i1 %cmp
}

define i1 @test_uge_xor(i32 %x, i32 %y) {
; CHECK-LABEL: @test_uge_xor(
; CHECK-NEXT: [[TMP1:%.*]] = xor i32 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: [[CMP:%.*]] = icmp ule i32 [[TMP1]], [[X]]
; CHECK-NEXT: ret i1 [[CMP]]
;
%xor1 = xor i32 %x, -1
%xor2 = xor i32 %xor1, %y
%cmp = icmp uge i32 %xor2, %xor1
ret i1 %cmp
}

; Negative tests
define i1 @test_xor1_nofold_multi_use(i8 %x, i8 %y, i8 %z) {
; CHECK-LABEL: @test_xor1_nofold_multi_use(
; CHECK-NEXT: [[TMP1:%.*]] = xor i8 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: [[XOR2:%.*]] = xor i8 [[TMP1]], -1
; CHECK-NEXT: call void @use.i8(i8 [[XOR2]])
; CHECK-NEXT: [[NZ:%.*]] = xor i8 [[Z:%.*]], -1
; CHECK-NEXT: call void @use.i8(i8 [[NZ]])
; CHECK-NEXT: [[R:%.*]] = icmp sgt i8 [[TMP1]], [[Z]]
; CHECK-NEXT: ret i1 [[R]]
;
%xor = xor i8 %x, -1
%xor2 = xor i8 %xor, %y
call void @use.i8(i8 %xor2)
%nz = xor i8 %z, -1
call void @use.i8(i8 %nz)
%r = icmp slt i8 %xor2, %nz
ret i1 %r
}

define i1 @xor_uge(i8 %x, i8 %y) {
; CHECK-LABEL: @xor_uge(
Expand Down