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[InstCombine] Extend foldICmpBinOp to add-like or. (#71396)
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InstCombine canonicalizes `add` to `or` when possible, but this makes
some optimizations applicable to `add` to be missed because they don't
realize that the `or` is equivalent to `add`.

In this patch we generalize `foldICmpBinOp` to handle such cases.
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@mgudim
mgudim authored Dec 20, 2023
1 parent cf4dd91 commit 8773c9b
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Showing 2 changed files with 126 additions and 53 deletions.
62 changes: 33 additions & 29 deletions llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -4624,27 +4624,35 @@ Instruction *InstCombinerImpl::foldICmpBinOp(ICmpInst &I,
}

bool NoOp0WrapProblem = false, NoOp1WrapProblem = false;
if (BO0 && isa<OverflowingBinaryOperator>(BO0))
NoOp0WrapProblem =
ICmpInst::isEquality(Pred) ||
(CmpInst::isUnsigned(Pred) && BO0->hasNoUnsignedWrap()) ||
(CmpInst::isSigned(Pred) && BO0->hasNoSignedWrap());
if (BO1 && isa<OverflowingBinaryOperator>(BO1))
NoOp1WrapProblem =
ICmpInst::isEquality(Pred) ||
(CmpInst::isUnsigned(Pred) && BO1->hasNoUnsignedWrap()) ||
(CmpInst::isSigned(Pred) && BO1->hasNoSignedWrap());

bool Op0HasNUW = false, Op1HasNUW = false;
bool Op0HasNSW = false, Op1HasNSW = false;
// Analyze the case when either Op0 or Op1 is an add instruction.
// Op0 = A + B (or A and B are null); Op1 = C + D (or C and D are null).
auto hasNoWrapProblem = [](const BinaryOperator &BO, CmpInst::Predicate Pred,
bool &HasNSW, bool &HasNUW) -> bool {
if (isa<OverflowingBinaryOperator>(BO)) {
HasNUW = BO.hasNoUnsignedWrap();
HasNSW = BO.hasNoSignedWrap();
return ICmpInst::isEquality(Pred) ||
(CmpInst::isUnsigned(Pred) && HasNUW) ||
(CmpInst::isSigned(Pred) && HasNSW);
} else if (BO.getOpcode() == Instruction::Or) {
HasNUW = true;
HasNSW = true;
return true;
} else {
return false;
}
};
Value *A = nullptr, *B = nullptr, *C = nullptr, *D = nullptr;
if (BO0 && BO0->getOpcode() == Instruction::Add) {
A = BO0->getOperand(0);
B = BO0->getOperand(1);

if (BO0) {
match(BO0, m_AddLike(m_Value(A), m_Value(B)));
NoOp0WrapProblem = hasNoWrapProblem(*BO0, Pred, Op0HasNSW, Op0HasNUW);
}
if (BO1 && BO1->getOpcode() == Instruction::Add) {
C = BO1->getOperand(0);
D = BO1->getOperand(1);
if (BO1) {
match(BO1, m_AddLike(m_Value(C), m_Value(D)));
NoOp1WrapProblem = hasNoWrapProblem(*BO1, Pred, Op1HasNSW, Op1HasNUW);
}

// icmp (A+B), A -> icmp B, 0 for equalities or if there is no overflow.
Expand Down Expand Up @@ -4764,17 +4772,15 @@ Instruction *InstCombinerImpl::foldICmpBinOp(ICmpInst &I,
APInt AP2Abs = AP2->abs();
if (AP1Abs.uge(AP2Abs)) {
APInt Diff = *AP1 - *AP2;
bool HasNUW = BO0->hasNoUnsignedWrap() && Diff.ule(*AP1);
bool HasNSW = BO0->hasNoSignedWrap();
Constant *C3 = Constant::getIntegerValue(BO0->getType(), Diff);
Value *NewAdd = Builder.CreateAdd(A, C3, "", HasNUW, HasNSW);
Value *NewAdd = Builder.CreateAdd(
A, C3, "", Op0HasNUW && Diff.ule(*AP1), Op0HasNSW);
return new ICmpInst(Pred, NewAdd, C);
} else {
APInt Diff = *AP2 - *AP1;
bool HasNUW = BO1->hasNoUnsignedWrap() && Diff.ule(*AP2);
bool HasNSW = BO1->hasNoSignedWrap();
Constant *C3 = Constant::getIntegerValue(BO0->getType(), Diff);
Value *NewAdd = Builder.CreateAdd(C, C3, "", HasNUW, HasNSW);
Value *NewAdd = Builder.CreateAdd(
C, C3, "", Op1HasNUW && Diff.ule(*AP1), Op1HasNSW);
return new ICmpInst(Pred, A, NewAdd);
}
}
Expand Down Expand Up @@ -4868,16 +4874,14 @@ Instruction *InstCombinerImpl::foldICmpBinOp(ICmpInst &I,
isKnownNonZero(Z, Q.DL, /*Depth=*/0, Q.AC, Q.CxtI, Q.DT);
// if Z != 0 and nsw(X * Z) and nsw(Y * Z)
// X * Z eq/ne Y * Z -> X eq/ne Y
if (NonZero && BO0 && BO1 && BO0->hasNoSignedWrap() &&
BO1->hasNoSignedWrap())
if (NonZero && BO0 && BO1 && Op0HasNSW && Op1HasNSW)
return new ICmpInst(Pred, X, Y);
} else
NonZero = isKnownNonZero(Z, Q.DL, /*Depth=*/0, Q.AC, Q.CxtI, Q.DT);

// If Z != 0 and nuw(X * Z) and nuw(Y * Z)
// X * Z u{lt/le/gt/ge}/eq/ne Y * Z -> X u{lt/le/gt/ge}/eq/ne Y
if (NonZero && BO0 && BO1 && BO0->hasNoUnsignedWrap() &&
BO1->hasNoUnsignedWrap())
if (NonZero && BO0 && BO1 && Op0HasNUW && Op1HasNUW)
return new ICmpInst(Pred, X, Y);
}
}
Expand Down Expand Up @@ -4976,8 +4980,8 @@ Instruction *InstCombinerImpl::foldICmpBinOp(ICmpInst &I,
return new ICmpInst(Pred, BO0->getOperand(0), BO1->getOperand(0));

case Instruction::Shl: {
bool NUW = BO0->hasNoUnsignedWrap() && BO1->hasNoUnsignedWrap();
bool NSW = BO0->hasNoSignedWrap() && BO1->hasNoSignedWrap();
bool NUW = Op0HasNUW && Op1HasNUW;
bool NSW = Op0HasNSW && Op1HasNSW;
if (!NUW && !NSW)
break;
if (!NSW && I.isSigned())
Expand Down
117 changes: 93 additions & 24 deletions llvm/test/Transforms/InstCombine/icmp.ll
View file
Original file line number Diff line number Diff line change
Expand Up @@ -3862,10 +3862,9 @@ define <8 x i1> @bitreverse_vec_ne(<8 x i16> %x, <8 x i16> %y) {
define i1 @knownbits1(i8 %a, i8 %b) {
; CHECK-LABEL: @knownbits1(
; CHECK-NEXT: [[A1:%.*]] = and i8 [[A:%.*]], 1
; CHECK-NEXT: [[A2:%.*]] = or disjoint i8 [[A1]], 4
; CHECK-NEXT: [[B1:%.*]] = and i8 [[B:%.*]], 2
; CHECK-NEXT: [[B2:%.*]] = or disjoint i8 [[B1]], 5
; CHECK-NEXT: [[C:%.*]] = icmp eq i8 [[A2]], [[B2]]
; CHECK-NEXT: [[TMP1:%.*]] = or disjoint i8 [[B1]], 1
; CHECK-NEXT: [[C:%.*]] = icmp eq i8 [[A1]], [[TMP1]]
; CHECK-NEXT: ret i1 [[C]]
;
%a1 = and i8 %a, 5
Expand All @@ -3879,10 +3878,9 @@ define i1 @knownbits1(i8 %a, i8 %b) {
define i1 @knownbits2(i8 %a, i8 %b) {
; CHECK-LABEL: @knownbits2(
; CHECK-NEXT: [[A1:%.*]] = and i8 [[A:%.*]], 1
; CHECK-NEXT: [[A2:%.*]] = or disjoint i8 [[A1]], 4
; CHECK-NEXT: [[B1:%.*]] = and i8 [[B:%.*]], 2
; CHECK-NEXT: [[B2:%.*]] = or disjoint i8 [[B1]], 5
; CHECK-NEXT: [[C:%.*]] = icmp ne i8 [[A2]], [[B2]]
; CHECK-NEXT: [[TMP1:%.*]] = or disjoint i8 [[B1]], 1
; CHECK-NEXT: [[C:%.*]] = icmp ne i8 [[A1]], [[TMP1]]
; CHECK-NEXT: ret i1 [[C]]
;
%a1 = and i8 %a, 5
Expand All @@ -3896,10 +3894,9 @@ define i1 @knownbits2(i8 %a, i8 %b) {
define i1 @knownbits3(i8 %a, i8 %b) {
; CHECK-LABEL: @knownbits3(
; CHECK-NEXT: [[A1:%.*]] = and i8 [[A:%.*]], 1
; CHECK-NEXT: [[A2:%.*]] = or disjoint i8 [[A1]], 4
; CHECK-NEXT: [[B1:%.*]] = and i8 [[B:%.*]], 2
; CHECK-NEXT: [[B2:%.*]] = or disjoint i8 [[B1]], 5
; CHECK-NEXT: [[C:%.*]] = icmp eq i8 [[B2]], [[A2]]
; CHECK-NEXT: [[TMP1:%.*]] = or disjoint i8 [[B1]], 1
; CHECK-NEXT: [[C:%.*]] = icmp eq i8 [[TMP1]], [[A1]]
; CHECK-NEXT: ret i1 [[C]]
;
%a1 = and i8 %a, 5
Expand All @@ -3913,10 +3910,9 @@ define i1 @knownbits3(i8 %a, i8 %b) {
define <2 x i1> @knownbits4(<2 x i8> %a, <2 x i8> %b) {
; CHECK-LABEL: @knownbits4(
; CHECK-NEXT: [[A1:%.*]] = and <2 x i8> [[A:%.*]], <i8 1, i8 1>
; CHECK-NEXT: [[A2:%.*]] = or disjoint <2 x i8> [[A1]], <i8 4, i8 4>
; CHECK-NEXT: [[B1:%.*]] = and <2 x i8> [[B:%.*]], <i8 2, i8 2>
; CHECK-NEXT: [[B2:%.*]] = or disjoint <2 x i8> [[B1]], <i8 5, i8 5>
; CHECK-NEXT: [[C:%.*]] = icmp ne <2 x i8> [[B2]], [[A2]]
; CHECK-NEXT: [[TMP1:%.*]] = or disjoint <2 x i8> [[B1]], <i8 1, i8 1>
; CHECK-NEXT: [[C:%.*]] = icmp ne <2 x i8> [[TMP1]], [[A1]]
; CHECK-NEXT: ret <2 x i1> [[C]]
;
%a1 = and <2 x i8> %a, <i8 5, i8 5>
Expand All @@ -3932,10 +3928,9 @@ define <2 x i1> @knownbits4(<2 x i8> %a, <2 x i8> %b) {
define i1 @knownbits5(i8 %a, i8 %b) {
; CHECK-LABEL: @knownbits5(
; CHECK-NEXT: [[A1:%.*]] = and i8 [[A:%.*]], -127
; CHECK-NEXT: [[A2:%.*]] = or disjoint i8 [[A1]], 4
; CHECK-NEXT: [[B1:%.*]] = and i8 [[B:%.*]], 2
; CHECK-NEXT: [[B2:%.*]] = or disjoint i8 [[B1]], 5
; CHECK-NEXT: [[C:%.*]] = icmp eq i8 [[A2]], [[B2]]
; CHECK-NEXT: [[TMP1:%.*]] = or disjoint i8 [[B1]], 1
; CHECK-NEXT: [[C:%.*]] = icmp eq i8 [[A1]], [[TMP1]]
; CHECK-NEXT: ret i1 [[C]]
;
%a1 = and i8 %a, 133
Expand All @@ -3949,10 +3944,9 @@ define i1 @knownbits5(i8 %a, i8 %b) {
define i1 @knownbits6(i8 %a, i8 %b) {
; CHECK-LABEL: @knownbits6(
; CHECK-NEXT: [[A1:%.*]] = and i8 [[A:%.*]], -127
; CHECK-NEXT: [[A2:%.*]] = or disjoint i8 [[A1]], 4
; CHECK-NEXT: [[B1:%.*]] = and i8 [[B:%.*]], 2
; CHECK-NEXT: [[B2:%.*]] = or disjoint i8 [[B1]], 5
; CHECK-NEXT: [[C:%.*]] = icmp ne i8 [[A2]], [[B2]]
; CHECK-NEXT: [[TMP1:%.*]] = or disjoint i8 [[B1]], 1
; CHECK-NEXT: [[C:%.*]] = icmp ne i8 [[A1]], [[TMP1]]
; CHECK-NEXT: ret i1 [[C]]
;
%a1 = and i8 %a, 133
Expand All @@ -3966,10 +3960,9 @@ define i1 @knownbits6(i8 %a, i8 %b) {
define <2 x i1> @knownbits7(<2 x i8> %a, <2 x i8> %b) {
; CHECK-LABEL: @knownbits7(
; CHECK-NEXT: [[A1:%.*]] = and <2 x i8> [[A:%.*]], <i8 -127, i8 -127>
; CHECK-NEXT: [[A2:%.*]] = or disjoint <2 x i8> [[A1]], <i8 4, i8 4>
; CHECK-NEXT: [[B1:%.*]] = and <2 x i8> [[B:%.*]], <i8 2, i8 2>
; CHECK-NEXT: [[B2:%.*]] = or disjoint <2 x i8> [[B1]], <i8 5, i8 5>
; CHECK-NEXT: [[C:%.*]] = icmp eq <2 x i8> [[B2]], [[A2]]
; CHECK-NEXT: [[TMP1:%.*]] = or disjoint <2 x i8> [[B1]], <i8 1, i8 1>
; CHECK-NEXT: [[C:%.*]] = icmp eq <2 x i8> [[TMP1]], [[A1]]
; CHECK-NEXT: ret <2 x i1> [[C]]
;
%a1 = and <2 x i8> %a, <i8 133, i8 133>
Expand All @@ -3983,10 +3976,9 @@ define <2 x i1> @knownbits7(<2 x i8> %a, <2 x i8> %b) {
define i1 @knownbits8(i8 %a, i8 %b) {
; CHECK-LABEL: @knownbits8(
; CHECK-NEXT: [[A1:%.*]] = and i8 [[A:%.*]], -127
; CHECK-NEXT: [[A2:%.*]] = or disjoint i8 [[A1]], 4
; CHECK-NEXT: [[B1:%.*]] = and i8 [[B:%.*]], 2
; CHECK-NEXT: [[B2:%.*]] = or disjoint i8 [[B1]], 5
; CHECK-NEXT: [[C:%.*]] = icmp ne i8 [[B2]], [[A2]]
; CHECK-NEXT: [[TMP1:%.*]] = or disjoint i8 [[B1]], 1
; CHECK-NEXT: [[C:%.*]] = icmp ne i8 [[TMP1]], [[A1]]
; CHECK-NEXT: ret i1 [[C]]
;
%a1 = and i8 %a, 133
Expand Down Expand Up @@ -4912,3 +4904,80 @@ define i1 @or_positive_sgt_zero_multi_use(i8 %a) {
%cmp = icmp sgt i8 %b, 0
ret i1 %cmp
}


define i1 @disjoint_or_sgt_1(i8 %a, i8 %b) {
; CHECK-LABEL: @disjoint_or_sgt_1(
; CHECK-NEXT: [[B1:%.*]] = add nsw i8 [[B:%.*]], 2
; CHECK-NEXT: [[ICMP_:%.*]] = icmp sle i8 [[B1]], [[A:%.*]]
; CHECK-NEXT: ret i1 [[ICMP_]]
;
%a1 = or disjoint i8 %a, 1
%b1 = add nsw i8 %b, 2
%icmp_ = icmp sgt i8 %a1, %b1
ret i1 %icmp_
}

define i1 @disjoint_or_sgt_2(i8 %a, i8 %b) {
; CHECK-LABEL: @disjoint_or_sgt_2(
; CHECK-NEXT: [[A1:%.*]] = or disjoint i8 [[A:%.*]], 2
; CHECK-NEXT: [[B1:%.*]] = add i8 [[B:%.*]], 1
; CHECK-NEXT: [[ICMP_:%.*]] = icmp sgt i8 [[A1]], [[B1]]
; CHECK-NEXT: ret i1 [[ICMP_]]
;
%a1 = or disjoint i8 %a, 2
%b1 = add i8 %b, 1
%icmp_ = icmp sgt i8 %a1, %b1
ret i1 %icmp_
}

define i1 @disjoint_or_sgt_3(i8 %a, i8 %b) {
; CHECK-LABEL: @disjoint_or_sgt_3(
; CHECK-NEXT: [[A1:%.*]] = or disjoint i8 [[A:%.*]], 2
; CHECK-NEXT: [[B1:%.*]] = add nuw i8 [[B:%.*]], 1
; CHECK-NEXT: [[ICMP_:%.*]] = icmp sgt i8 [[A1]], [[B1]]
; CHECK-NEXT: ret i1 [[ICMP_]]
;
%a1 = or disjoint i8 %a, 2
%b1 = add nuw i8 %b, 1
%icmp_ = icmp sgt i8 %a1, %b1
ret i1 %icmp_
}

define i1 @disjoint_or_ugt_1(i8 %a, i8 %b) {
; CHECK-LABEL: @disjoint_or_ugt_1(
; CHECK-NEXT: [[B1:%.*]] = add nsw i8 [[B:%.*]], 2
; CHECK-NEXT: [[ICMP_:%.*]] = icmp ule i8 [[B1]], [[A:%.*]]
; CHECK-NEXT: ret i1 [[ICMP_]]
;
%a1 = or disjoint i8 %a, 1
%b1 = add nsw i8 %b, 2
%icmp_ = icmp ugt i8 %a1, %b1
ret i1 %icmp_
}

define i1 @disjoint_or_ugt_2(i8 %a, i8 %b) {
; CHECK-LABEL: @disjoint_or_ugt_2(
; CHECK-NEXT: [[A1:%.*]] = or disjoint i8 [[A:%.*]], 2
; CHECK-NEXT: [[B1:%.*]] = add i8 [[B:%.*]], 1
; CHECK-NEXT: [[ICMP_:%.*]] = icmp ugt i8 [[A1]], [[B1]]
; CHECK-NEXT: ret i1 [[ICMP_]]
;
%a1 = or disjoint i8 %a, 2
%b1 = add i8 %b, 1
%icmp_ = icmp ugt i8 %a1, %b1
ret i1 %icmp_
}

define i1 @disjoint_or_ugt_3(i8 %a, i8 %b) {
; CHECK-LABEL: @disjoint_or_ugt_3(
; CHECK-NEXT: [[A1:%.*]] = or disjoint i8 [[A:%.*]], 2
; CHECK-NEXT: [[B1:%.*]] = add nuw i8 [[B:%.*]], 1
; CHECK-NEXT: [[ICMP_:%.*]] = icmp ugt i8 [[A1]], [[B1]]
; CHECK-NEXT: ret i1 [[ICMP_]]
;
%a1 = or disjoint i8 %a, 2
%b1 = add nuw i8 %b, 1
%icmp_ = icmp ugt i8 %a1, %b1
ret i1 %icmp_
}

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