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[InstCombine] Use existing (icmp pred (add x, y), C) folds with or disjoint #87937

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[InstCombine] Use existing (icmp pred (add x, y), C) folds with or disjoint #87937

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12db1e9
[InstCombine] Add tests for folding `(icmp eq/ne (add nuw x, y), 0)`;…
goldsteinn Apr 7, 2024
820b359
[InstCombine] Fold `(icmp eq/ne (add nuw x, y), 0)` -> `(icmp eq/ne (…
goldsteinn Apr 7, 2024
337903c
[InstCombine] Use existing `(icmp pred (add x, y), C)` folds with `or…
goldsteinn Apr 7, 2024
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55 changes: 32 additions & 23 deletions llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2986,10 +2986,10 @@ Instruction *InstCombinerImpl::foldICmpAddConstant(ICmpInst &Cmp,
Value *Op0, *Op1;
Instruction *Ext0, *Ext1;
const CmpInst::Predicate Pred = Cmp.getPredicate();
if (match(Add,
m_Add(m_CombineAnd(m_Instruction(Ext0), m_ZExtOrSExt(m_Value(Op0))),
m_CombineAnd(m_Instruction(Ext1),
m_ZExtOrSExt(m_Value(Op1))))) &&
if (match(Add, m_AddLike(m_CombineAnd(m_Instruction(Ext0),
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Duplicate of #75899.

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Alright, ill sit on this for a bit, if he gets back in the next month or so ill close. Ill pull out the add nuw patch.

m_ZExtOrSExt(m_Value(Op0))),
m_CombineAnd(m_Instruction(Ext1),
m_ZExtOrSExt(m_Value(Op1))))) &&
Op0->getType()->isIntOrIntVectorTy(1) &&
Op1->getType()->isIntOrIntVectorTy(1)) {
unsigned BW = C.getBitWidth();
Expand Down Expand Up @@ -3021,9 +3021,9 @@ Instruction *InstCombinerImpl::foldICmpAddConstant(ICmpInst &Cmp,
// If the add does not wrap, we can always adjust the compare by subtracting
// the constants. Equality comparisons are handled elsewhere. SGE/SLE/UGE/ULE
// are canonicalized to SGT/SLT/UGT/ULT.
if ((Add->hasNoSignedWrap() &&
if ((match(Add, m_NSWAddLike(m_Value(), m_Value())) &&
(Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SLT)) ||
(Add->hasNoUnsignedWrap() &&
(match(Add, m_NUWAddLike(m_Value(), m_Value())) &&
(Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_ULT))) {
bool Overflow;
APInt NewC =
Expand Down Expand Up @@ -3438,6 +3438,20 @@ Instruction *InstCombinerImpl::foldICmpBinOpEqualityWithConstant(
}
}
break;
case Instruction::Or: {
const APInt *BOC;
if (match(BOp1, m_APInt(BOC)) && BO->hasOneUse() && RHS->isAllOnesValue()) {
// Comparing if all bits outside of a constant mask are set?
// Replace (X | C) == -1 with (X & ~C) == ~C.
// This removes the -1 constant.
Constant *NotBOC = ConstantExpr::getNot(cast<Constant>(BOp1));
Value *And = Builder.CreateAnd(BOp0, NotBOC);
return new ICmpInst(Pred, And, NotBOC);
}
if (!cast<PossiblyDisjointInst>(BO)->isDisjoint())
break;
[[fallthrough]];
}
case Instruction::Add: {
// (A + C2) == C --> A == (C - C2)
// (A + C2) != C --> A != (C - C2)
Expand All @@ -3452,7 +3466,12 @@ Instruction *InstCombinerImpl::foldICmpBinOpEqualityWithConstant(
return new ICmpInst(Pred, BOp0, NegVal);
if (Value *NegVal = dyn_castNegVal(BOp0))
return new ICmpInst(Pred, NegVal, BOp1);
if (BO->hasOneUse()) {
if (BO->hasOneUse() && BO->getOpcode() != Instruction::Or) {
// (add nuw A, B) != 0 -> (or A, B) != 0
if (match(BO, m_NUWAdd(m_Value(), m_Value()))) {
Value *Or = Builder.CreateOr(BOp0, BOp1);
return new ICmpInst(Pred, Or, Constant::getNullValue(BO->getType()));
}
Value *Neg = Builder.CreateNeg(BOp1);
Neg->takeName(BO);
return new ICmpInst(Pred, BOp0, Neg);
Expand All @@ -3472,18 +3491,6 @@ Instruction *InstCombinerImpl::foldICmpBinOpEqualityWithConstant(
}
}
break;
case Instruction::Or: {
const APInt *BOC;
if (match(BOp1, m_APInt(BOC)) && BO->hasOneUse() && RHS->isAllOnesValue()) {
// Comparing if all bits outside of a constant mask are set?
// Replace (X | C) == -1 with (X & ~C) == ~C.
// This removes the -1 constant.
Constant *NotBOC = ConstantExpr::getNot(cast<Constant>(BOp1));
Value *And = Builder.CreateAnd(BOp0, NotBOC);
return new ICmpInst(Pred, And, NotBOC);
}
break;
}
case Instruction::UDiv:
case Instruction::SDiv:
if (BO->isExact()) {
Expand Down Expand Up @@ -3756,10 +3763,6 @@ Instruction *InstCombinerImpl::foldICmpBinOpWithConstant(ICmpInst &Cmp,
if (Instruction *I = foldICmpAndConstant(Cmp, BO, C))
return I;
break;
case Instruction::Or:
if (Instruction *I = foldICmpOrConstant(Cmp, BO, C))
return I;
break;
case Instruction::Mul:
if (Instruction *I = foldICmpMulConstant(Cmp, BO, C))
return I;
Expand Down Expand Up @@ -3789,6 +3792,12 @@ Instruction *InstCombinerImpl::foldICmpBinOpWithConstant(ICmpInst &Cmp,
if (Instruction *I = foldICmpSubConstant(Cmp, BO, C))
return I;
break;
case Instruction::Or:
if (Instruction *I = foldICmpOrConstant(Cmp, BO, C))
return I;
if (!cast<PossiblyDisjointInst>(BO)->isDisjoint())
break;
[[fallthrough]];
case Instruction::Add:
if (Instruction *I = foldICmpAddConstant(Cmp, BO, C))
return I;
Expand Down
63 changes: 39 additions & 24 deletions llvm/test/Transforms/InstCombine/icmp-add.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -9,10 +9,8 @@ declare void @use(i32)
define i1 @cvt_icmp_0_zext_plus_zext_eq_i16(i16 %arg, i16 %arg1) {
; CHECK-LABEL: @cvt_icmp_0_zext_plus_zext_eq_i16(
; CHECK-NEXT: bb:
; CHECK-NEXT: [[I:%.*]] = zext i16 [[ARG:%.*]] to i32
; CHECK-NEXT: [[I2:%.*]] = zext i16 [[ARG1:%.*]] to i32
; CHECK-NEXT: [[I3:%.*]] = sub nsw i32 0, [[I]]
; CHECK-NEXT: [[I4:%.*]] = icmp eq i32 [[I2]], [[I3]]
; CHECK-NEXT: [[TMP0:%.*]] = or i16 [[ARG1:%.*]], [[ARG:%.*]]
; CHECK-NEXT: [[I4:%.*]] = icmp eq i16 [[TMP0]], 0
; CHECK-NEXT: ret i1 [[I4]]
;
bb:
Expand All @@ -27,10 +25,8 @@ bb:
define i1 @cvt_icmp_0_zext_plus_zext_eq_i8(i8 %arg, i8 %arg1) {
; CHECK-LABEL: @cvt_icmp_0_zext_plus_zext_eq_i8(
; CHECK-NEXT: bb:
; CHECK-NEXT: [[I:%.*]] = zext i8 [[ARG:%.*]] to i32
; CHECK-NEXT: [[I2:%.*]] = zext i8 [[ARG1:%.*]] to i32
; CHECK-NEXT: [[I3:%.*]] = sub nsw i32 0, [[I]]
; CHECK-NEXT: [[I4:%.*]] = icmp eq i32 [[I2]], [[I3]]
; CHECK-NEXT: [[TMP0:%.*]] = or i8 [[ARG1:%.*]], [[ARG:%.*]]
; CHECK-NEXT: [[I4:%.*]] = icmp eq i8 [[TMP0]], 0
; CHECK-NEXT: ret i1 [[I4]]
;
bb:
Expand Down Expand Up @@ -1802,22 +1798,17 @@ define i1 @test4(i32 %a) {
ret i1 %c
}

define { i32, i1 } @test4multiuse(i32 %a) {
; CHECK-LABEL: @test4multiuse(
; CHECK-NEXT: [[B:%.*]] = add nsw i32 [[A:%.*]], -2147483644
; CHECK-NEXT: [[C:%.*]] = icmp slt i32 [[A]], 2147483640
; CHECK-NEXT: [[TMP:%.*]] = insertvalue { i32, i1 } undef, i32 [[B]], 0
; CHECK-NEXT: [[RES:%.*]] = insertvalue { i32, i1 } [[TMP]], i1 [[C]], 1
; CHECK-NEXT: ret { i32, i1 } [[RES]]
define {
i32, i1 } @test4multiuse(i32 %a) {
;

%b = add nsw i32 %a, -2147483644
%c = icmp slt i32 %b, -4
%b = add nsw i32 %a, -2147483644
%c = icmp slt i32 %b, -4

%tmp = insertvalue { i32, i1 } undef, i32 %b, 0
%res = insertvalue { i32, i1 } %tmp, i1 %c, 1
%tmp = insertvalue { i32, i1 } undef, i32 %b, 0
%res = insertvalue { i32, i1 } %tmp, i1 %c, 1

ret { i32, i1 } %res
ret { i32, i1 } %res
}

define <2 x i1> @test4vec(<2 x i32> %a) {
Expand Down Expand Up @@ -2857,7 +2848,7 @@ define i1 @icmp_add_add_C_comm2(i32 %X, i32 %b) {
; CHECK-NEXT: [[CMP:%.*]] = icmp ugt i32 [[A]], [[TMP1]]
; CHECK-NEXT: ret i1 [[CMP]]
;
%a = udiv i32 42, %X ; thwart complexity-based canonicalization
%a = udiv i32 42, %X ; thwart complexity-based canonicalization
%add1 = add i32 %a, %b
%add2 = add i32 %add1, -1
%cmp = icmp ugt i32 %a, %add2
Expand All @@ -2871,7 +2862,7 @@ define i1 @icmp_add_add_C_comm2_pred(i32 %X, i32 %b) {
; CHECK-NEXT: [[CMP:%.*]] = icmp ule i32 [[A]], [[TMP1]]
; CHECK-NEXT: ret i1 [[CMP]]
;
%a = udiv i32 42, %X ; thwart complexity-based canonicalization
%a = udiv i32 42, %X ; thwart complexity-based canonicalization
%add1 = add i32 %a, %b
%add2 = add i32 %add1, -1
%cmp = icmp ule i32 %a, %add2
Expand All @@ -2886,7 +2877,7 @@ define i1 @icmp_add_add_C_comm2_wrong_pred(i32 %X, i32 %b) {
; CHECK-NEXT: [[CMP:%.*]] = icmp ult i32 [[A]], [[ADD2]]
; CHECK-NEXT: ret i1 [[CMP]]
;
%a = udiv i32 42, %X ; thwart complexity-based canonicalization
%a = udiv i32 42, %X ; thwart complexity-based canonicalization
%add1 = add i32 %a, %b
%add2 = add i32 %add1, -1
%cmp = icmp ult i32 %a, %add2
Expand All @@ -2900,7 +2891,7 @@ define i1 @icmp_add_add_C_comm3(i32 %X, i32 %b) {
; CHECK-NEXT: [[CMP:%.*]] = icmp ugt i32 [[A]], [[TMP1]]
; CHECK-NEXT: ret i1 [[CMP]]
;
%a = udiv i32 42, %X ; thwart complexity-based canonicalization
%a = udiv i32 42, %X ; thwart complexity-based canonicalization
%add1 = add i32 %b, %a
%add2 = add i32 %add1, -1
%cmp = icmp ugt i32 %a, %add2
Expand Down Expand Up @@ -3003,4 +2994,28 @@ define i1 @icmp_dec_notnonzero(i8 %x) {
ret i1 %c
}

define i1 @icmp_addnuw_nonzero(i8 %x, i8 %y) {
; CHECK-LABEL: @icmp_addnuw_nonzero(
; CHECK-NEXT: [[TMP1:%.*]] = or i8 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: [[C:%.*]] = icmp eq i8 [[TMP1]], 0
; CHECK-NEXT: ret i1 [[C]]
;
%i = add nuw i8 %x, %y
%c = icmp eq i8 %i, 0
ret i1 %c
}

define i1 @icmp_addnuw_nonzero_fail_multiuse(i32 %x, i32 %y) {
; CHECK-LABEL: @icmp_addnuw_nonzero_fail_multiuse(
; CHECK-NEXT: [[I:%.*]] = add nuw i32 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: [[C:%.*]] = icmp eq i32 [[I]], 0
; CHECK-NEXT: call void @use(i32 [[I]])
; CHECK-NEXT: ret i1 [[C]]
;
%i = add nuw i32 %x, %y
%c = icmp eq i32 %i, 0
call void @use(i32 %i)
ret i1 %c
}

declare void @llvm.assume(i1)
3 changes: 1 addition & 2 deletions llvm/test/Transforms/InstCombine/known-bits.ll
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Expand Up @@ -483,8 +483,7 @@ if.else:
define i1 @test_icmp_or_distjoint(i8 %n, i1 %other) {
; CHECK-LABEL: @test_icmp_or_distjoint(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[N_OR:%.*]] = or disjoint i8 [[N:%.*]], 16
; CHECK-NEXT: [[CMP:%.*]] = icmp ugt i8 [[N_OR]], -111
; CHECK-NEXT: [[CMP:%.*]] = icmp ugt i8 [[N:%.*]], -127
; CHECK-NEXT: br i1 [[CMP]], label [[IF_THEN:%.*]], label [[IF_ELSE:%.*]]
; CHECK: if.then:
; CHECK-NEXT: ret i1 true
Expand Down