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[InstCombine] Fold binary operator into select, when one of the opera… #166241

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52 changes: 52 additions & 0 deletions llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,7 @@
#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/IR/ConstantRange.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Instruction.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/Intrinsics.h"
#include "llvm/IR/PatternMatch.h"
Expand Down Expand Up @@ -345,6 +346,45 @@ getMaskedTypeForICmpPair(Value *&A, Value *&B, Value *&C, Value *&D, Value *&E,
std::make_pair(LeftType, RightType));
}

static Instruction *foldBinOpIntoSelectWhenConditionIsOperand(Instruction &I) {
Type *Ty = I.getType();
Value *CommonInput;
ConstantInt *SelLeft, *SelRight;
bool MatchRes =
match(&I, m_c_BinOp(m_Select(m_Value(CommonInput), m_ConstantInt(SelLeft),
m_ConstantInt(SelRight)),
m_ZExtOrTruncOrSelf(m_Deferred(CommonInput))));
if (!MatchRes)
return nullptr;

switch (I.getOpcode()) {
case Instruction::Or:
return SelectInst::Create(
CommonInput, ConstantInt::get(Ty, SelLeft->getValue() | 1), SelRight);
case Instruction::And:
return SelectInst::Create(CommonInput,
ConstantInt::get(Ty, SelLeft->getValue() & 1),
ConstantInt::getNullValue(Ty));
case Instruction::Xor:
return SelectInst::Create(CommonInput,
ConstantInt::get(Ty, SelLeft->getValue() ^ 1),
ConstantInt::get(Ty, SelRight->getValue() ^ 0));
case Instruction::Add:
return SelectInst::Create(CommonInput,
ConstantInt::get(Ty, SelLeft->getValue() + 1),
SelRight);
case Instruction::Sub:
return SelectInst::Create(CommonInput,
ConstantInt::get(Ty, SelLeft->getValue() - 1),
SelRight);
case Instruction::Mul:
return SelectInst::Create(CommonInput,
ConstantInt::get(Ty, SelLeft->getValue()),
ConstantInt::getNullValue(Ty));
}
return nullptr;
}

/// Try to fold (icmp(A & B) ==/!= C) &/| (icmp(A & D) ==/!= E) into a single
/// (icmp(A & X) ==/!= Y), where the left-hand side is of type Mask_NotAllZeros
/// and the right hand side is of type BMask_Mixed. For example,
Expand Down Expand Up @@ -2470,6 +2510,10 @@ Instruction *InstCombinerImpl::visitAnd(BinaryOperator &I) {
return SelectInst::Create(Cmp, ConstantInt::getNullValue(Ty), Y);
}


if (Instruction *Res = foldBinOpIntoSelectWhenConditionIsOperand(I))
return Res;

// Canonicalize:
// (X +/- Y) & Y --> ~X & Y when Y is a power of 2.
if (match(&I, m_c_And(m_Value(Y), m_OneUse(m_CombineOr(
Expand Down Expand Up @@ -4099,6 +4143,10 @@ Instruction *InstCombinerImpl::visitOr(BinaryOperator &I) {
return BinaryOperator::CreateXor(Or, ConstantInt::get(Ty, *CV));
}

if (Instruction *Res = foldBinOpIntoSelectWhenConditionIsOperand(I))
return Res;


// If the operands have no common bits set:
// or (mul X, Y), X --> add (mul X, Y), X --> mul X, (Y + 1)
if (match(&I, m_c_DisjointOr(m_OneUse(m_Mul(m_Value(X), m_Value(Y))),
Expand Down Expand Up @@ -5196,6 +5244,10 @@ Instruction *InstCombinerImpl::visitXor(BinaryOperator &I) {
return BinaryOperator::CreateXor(XorBC, X);
}

if (Instruction *Res = foldBinOpIntoSelectWhenConditionIsOperand(I))
return Res;


// Fold (X & M) ^ (Y & ~M) -> (X & M) | (Y & ~M)
// This it a special case in haveNoCommonBitsSet, but the computeKnownBits
// calls in there are unnecessary as SimplifyDemandedInstructionBits should
Expand Down
143 changes: 143 additions & 0 deletions llvm/test/Transforms/InstCombine/binop-select.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -403,3 +403,146 @@ define i32 @ashr_sel_op1_use(i1 %b) {
%r = ashr i32 -2, %s
ret i32 %r
}

define i8 @commonArgWithOr0(i1 %arg0) {
; CHECK-LABEL: @commonArgWithOr0(
; CHECK-NEXT: [[V3:%.*]] = select i1 [[ARG0:%.*]], i8 17, i8 24
; CHECK-NEXT: ret i8 [[V3]]
;
%v0 = zext i1 %arg0 to i8
%v1 = select i1 %arg0, i8 0, i8 8
%v2 = or i8 %v1, %v0
%v3 = or i8 %v2, 16
ret i8 %v3
}

define i8 @commonArgWithOr1(i1 %arg0) {
; CHECK-LABEL: @commonArgWithOr1(
; CHECK-NEXT: [[V3:%.*]] = select i1 [[ARG0:%.*]], i8 17, i8 23
; CHECK-NEXT: ret i8 [[V3]]
;
%v0 = zext i1 %arg0 to i8
%v1 = select i1 %arg0, i8 1, i8 7
%v2 = or i8 %v1, %v0
%v3 = or i8 %v2, 16
ret i8 %v3
}

define i8 @commonArgWithOr2(i1 %arg0) {
; CHECK-LABEL: @commonArgWithOr2(
; CHECK-NEXT: [[V3:%.*]] = select i1 [[ARG0:%.*]], i8 21, i8 58
; CHECK-NEXT: ret i8 [[V3]]
;
%v0 = zext i1 %arg0 to i8
%v1 = select i1 %arg0, i8 21, i8 42
%v2 = or i8 %v1, %v0
%v3 = or i8 %v2, 16
ret i8 %v3
}

define i8 @commonArgWithAnd0(i1 %arg0) {
; CHECK-LABEL: @commonArgWithAnd0(
; CHECK-NEXT: ret i8 16
;
%v0 = zext i1 %arg0 to i8
%v1 = select i1 %arg0, i8 0, i8 8
%v2 = and i8 %v1, %v0
%v3 = or i8 %v2, 16
ret i8 %v3
}

define i8 @commonArgWithAnd1(i1 %arg0) {
; CHECK-LABEL: @commonArgWithAnd1(
; CHECK-NEXT: ret i8 16
;
%v0 = zext i1 %arg0 to i8
%v1 = select i1 %arg0, i8 8, i8 1
%v2 = and i8 %v1, %v0
%v3 = or i8 %v2, 16
ret i8 %v3
}

define i8 @commonArgWithAnd2(i1 %arg0) {
; CHECK-LABEL: @commonArgWithAnd2(
; CHECK-NEXT: [[V2:%.*]] = zext i1 [[ARG0:%.*]] to i8
; CHECK-NEXT: [[V3:%.*]] = or disjoint i8 [[V2]], 16
; CHECK-NEXT: ret i8 [[V3]]
;
%v0 = zext i1 %arg0 to i8
%v1 = select i1 %arg0, i8 1, i8 7
%v2 = and i8 %v1, %v0
%v3 = or i8 %v2, 16
ret i8 %v3
}

define i8 @commonArgWithAnd3(i1 %arg0) {
; CHECK-LABEL: @commonArgWithAnd3(
; CHECK-NEXT: [[V2:%.*]] = zext i1 [[ARG0:%.*]] to i8
; CHECK-NEXT: [[V3:%.*]] = or disjoint i8 [[V2]], 16
; CHECK-NEXT: ret i8 [[V3]]
;
%v0 = zext i1 %arg0 to i8
%v1 = select i1 %arg0, i8 21, i8 42
%v2 = and i8 %v1, %v0
%v3 = or i8 %v2, 16
ret i8 %v3
}

define i8 @commonArgWithXor0(i1 %arg0) {
; CHECK-LABEL: @commonArgWithXor0(
; CHECK-NEXT: [[V3:%.*]] = select i1 [[ARG0:%.*]], i8 17, i8 24
; CHECK-NEXT: ret i8 [[V3]]
;
%v0 = zext i1 %arg0 to i8
%v1 = select i1 %arg0, i8 0, i8 8
%v2 = xor i8 %v1, %v0
%v3 = or i8 %v2, 16
ret i8 %v3
}

define i8 @commonArgWithXor1(i1 %arg0) {
; CHECK-LABEL: @commonArgWithXor1(
; CHECK-NEXT: [[V2:%.*]] = select i1 [[ARG0:%.*]], i8 8, i8 1
; CHECK-NEXT: ret i8 [[V2]]
;
%v0 = zext i1 %arg0 to i8
%v1 = select i1 %arg0, i8 9, i8 1
%v2 = xor i8 %v1, %v0
ret i8 %v2
}

define i8 @commonArgWithXor2(i1 %arg0) {
; CHECK-LABEL: @commonArgWithXor2(
; CHECK-NEXT: [[V3:%.*]] = select i1 [[ARG0:%.*]], i8 16, i8 23
; CHECK-NEXT: ret i8 [[V3]]
;
%v0 = zext i1 %arg0 to i8
%v1 = select i1 %arg0, i8 1, i8 7
%v2 = xor i8 %v1, %v0
%v3 = or i8 %v2, 16
ret i8 %v3
}

define i8 @commonArgWithXor3(i1 %arg0) {
; CHECK-LABEL: @commonArgWithXor3(
; CHECK-NEXT: [[V3:%.*]] = select i1 [[ARG0:%.*]], i8 20, i8 61
; CHECK-NEXT: ret i8 [[V3]]
;
%v0 = zext i1 %arg0 to i8
%v1 = select i1 %arg0, i8 21, i8 45
%v2 = xor i8 %v1, %v0
%v3 = or i8 %v2, 16
ret i8 %v3
}

define i8 @commonArgWithAdd0(i1 %arg0) {
; CHECK-LABEL: @commonArgWithXor3(
; CHECK-NEXT: [[V3:%.*]] = select i1 [[ARG0:%.*]], i8 20, i8 61
; CHECK-NEXT: ret i8 [[V3]]
;
%v0 = zext i1 %arg0 to i8
%v1 = select i1 %arg0, i8 21, i8 45
%v2 = add i8 %v1, %v0
%v3 = or i8 %v2, 16
ret i8 %v3
}
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