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InstCombineSelect.cpp
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InstCombineSelect.cpp
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//===- InstCombineSelect.cpp ----------------------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the visitSelect function.
//
//===----------------------------------------------------------------------===//
#include "InstCombineInternal.h"
#include "llvm/Analysis/ConstantFolding.h"
#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/PatternMatch.h"
#include "llvm/Crellvm/ValidationUnit.h"
#include "llvm/Crellvm/Structure.h"
#include "llvm/Crellvm/Infrules.h"
#include "llvm/Crellvm/InstCombine/InfrulesSelect.h"
#include "llvm/Crellvm/Hintgen.h"
using namespace llvm;
using namespace PatternMatch;
#define DEBUG_TYPE "instcombine"
static SelectPatternFlavor
getInverseMinMaxSelectPattern(SelectPatternFlavor SPF) {
switch (SPF) {
default:
llvm_unreachable("unhandled!");
case SPF_SMIN:
return SPF_SMAX;
case SPF_UMIN:
return SPF_UMAX;
case SPF_SMAX:
return SPF_SMIN;
case SPF_UMAX:
return SPF_UMIN;
}
}
static CmpInst::Predicate getICmpPredicateForMinMax(SelectPatternFlavor SPF) {
switch (SPF) {
default:
llvm_unreachable("unhandled!");
case SPF_SMIN:
return ICmpInst::ICMP_SLT;
case SPF_UMIN:
return ICmpInst::ICMP_ULT;
case SPF_SMAX:
return ICmpInst::ICMP_SGT;
case SPF_UMAX:
return ICmpInst::ICMP_UGT;
}
}
static Value *generateMinMaxSelectPattern(InstCombiner::BuilderTy *Builder,
SelectPatternFlavor SPF, Value *A,
Value *B) {
CmpInst::Predicate Pred = getICmpPredicateForMinMax(SPF);
return Builder->CreateSelect(Builder->CreateICmp(Pred, A, B), A, B);
}
/// GetSelectFoldableOperands - We want to turn code that looks like this:
/// %C = or %A, %B
/// %D = select %cond, %C, %A
/// into:
/// %C = select %cond, %B, 0
/// %D = or %A, %C
///
/// Assuming that the specified instruction is an operand to the select, return
/// a bitmask indicating which operands of this instruction are foldable if they
/// equal the other incoming value of the select.
///
static unsigned GetSelectFoldableOperands(Instruction *I) {
switch (I->getOpcode()) {
case Instruction::Add:
case Instruction::Mul:
case Instruction::And:
case Instruction::Or:
case Instruction::Xor:
return 3; // Can fold through either operand.
case Instruction::Sub: // Can only fold on the amount subtracted.
case Instruction::Shl: // Can only fold on the shift amount.
case Instruction::LShr:
case Instruction::AShr:
return 1;
default:
return 0; // Cannot fold
}
}
/// GetSelectFoldableConstant - For the same transformation as the previous
/// function, return the identity constant that goes into the select.
static Constant *GetSelectFoldableConstant(Instruction *I) {
switch (I->getOpcode()) {
default: llvm_unreachable("This cannot happen!");
case Instruction::Add:
case Instruction::Sub:
case Instruction::Or:
case Instruction::Xor:
case Instruction::Shl:
case Instruction::LShr:
case Instruction::AShr:
return Constant::getNullValue(I->getType());
case Instruction::And:
return Constant::getAllOnesValue(I->getType());
case Instruction::Mul:
return ConstantInt::get(I->getType(), 1);
}
}
/// FoldSelectOpOp - Here we have (select c, TI, FI), and we know that TI and FI
/// have the same opcode and only one use each. Try to simplify this.
Instruction *InstCombiner::FoldSelectOpOp(SelectInst &SI, Instruction *TI,
Instruction *FI) {
if (TI->getNumOperands() == 1) {
// If this is a non-volatile load or a cast from the same type,
// merge.
if (TI->isCast()) {
Type *FIOpndTy = FI->getOperand(0)->getType();
if (TI->getOperand(0)->getType() != FIOpndTy)
return nullptr;
// The select condition may be a vector. We may only change the operand
// type if the vector width remains the same (and matches the condition).
Type *CondTy = SI.getCondition()->getType();
if (CondTy->isVectorTy() && (!FIOpndTy->isVectorTy() ||
CondTy->getVectorNumElements() != FIOpndTy->getVectorNumElements()))
return nullptr;
} else {
return nullptr; // unknown unary op.
}
// Fold this by inserting a select from the input values.
Value *NewSI = Builder->CreateSelect(SI.getCondition(), TI->getOperand(0),
FI->getOperand(0), SI.getName()+".v");
return CastInst::Create(Instruction::CastOps(TI->getOpcode()), NewSI,
TI->getType());
}
// Only handle binary operators here.
if (!isa<BinaryOperator>(TI))
return nullptr;
crellvm::ValidationUnit::Begin("select_bop_fold", SI);
// Figure out if the operations have any operands in common.
Value *MatchOp, *OtherOpT, *OtherOpF;
bool MatchIsOpZero;
if (TI->getOperand(0) == FI->getOperand(0)) {
MatchOp = TI->getOperand(0);
OtherOpT = TI->getOperand(1);
OtherOpF = FI->getOperand(1);
MatchIsOpZero = true;
INTRUDE(CAPTURE(), {
data.create<crellvm::ArgForFoldSelectOpOp>()->the_case = crellvm::FoldSelectOpOpArg::XY_XZ;
});
} else if (TI->getOperand(1) == FI->getOperand(1)) {
MatchOp = TI->getOperand(1);
OtherOpT = TI->getOperand(0);
OtherOpF = FI->getOperand(0);
MatchIsOpZero = false;
INTRUDE(CAPTURE(), {
data.create<crellvm::ArgForFoldSelectOpOp>()->the_case = crellvm::FoldSelectOpOpArg::YX_ZX;
});
} else if (!TI->isCommutative()) {
crellvm::ValidationUnit::GetInstance()->setIsAborted();
crellvm::ValidationUnit::End();
return nullptr;
} else if (TI->getOperand(0) == FI->getOperand(1)) {
MatchOp = TI->getOperand(0);
OtherOpT = TI->getOperand(1);
OtherOpF = FI->getOperand(0);
MatchIsOpZero = true;
INTRUDE(CAPTURE(), {
data.create<crellvm::ArgForFoldSelectOpOp>()->the_case = crellvm::FoldSelectOpOpArg::XY_ZX;
});
} else if (TI->getOperand(1) == FI->getOperand(0)) {
MatchOp = TI->getOperand(1);
OtherOpT = TI->getOperand(0);
OtherOpF = FI->getOperand(1);
MatchIsOpZero = true;
INTRUDE(CAPTURE(), {
data.create<crellvm::ArgForFoldSelectOpOp>()->the_case = crellvm::FoldSelectOpOpArg::YX_XZ;
});
} else {
crellvm::ValidationUnit::GetInstance()->setIsAborted();
crellvm::ValidationUnit::End();
return nullptr;
}
// If we reach here, they do have operations in common.
Value *NewSI = Builder->CreateSelect(SI.getCondition(), OtherOpT,
OtherOpF, SI.getName()+".v");
INTRUDE(CAPTURE(&SI, &TI, &FI, &MatchOp, &NewSI, &OtherOpT, &OtherOpF), {
auto the_case = data.get<crellvm::ArgForFoldSelectOpOp>()->the_case;
// case == "XY/XZ" :
// <src> | <tgt>
// R = X bop Y | R = X bop Y
// S = X bop Z | S = X bop Z
// <nop> | T' = select C ? Y : Z
// T0 = select C ? R : S | T0 = X bop T'
// or,
// case == "YX/ZX" :
// <src> | <tgt>
// R = Y bop X | R = Y bop X
// S = Z bop X | S = Z bop X
// <nop> | T' = select C ? Y : Z
// T0 = select C ? R : S | T0 = T' bop X
// or,
// case == "XY/ZX" :
// <src> | <tgt>
// R = X bop Y | R = X bop Y
// S = Z bop X | S = Z bop X
// <nop> | T' = select C ? Y : Z
// T0 = select C ? R : S | T0 = X bop T'
// or,
// case == "YX/XZ" :
// <src> | <tgt>
// R = Y bop X | R = Y bop X
// S = X bop Z | S = X bop Z
// <nop> | T' = select C ? Y : Z
// T0 = select C ? R : S | T0 = X bop T'
BinaryOperator *R = dyn_cast<BinaryOperator>(TI), *S = dyn_cast<BinaryOperator>(FI);
SelectInst *T0 = &SI, *Tprime = dyn_cast<SelectInst>(NewSI);
//assert(R);
//assert(S);
//assert(Tprime);
switch(R->getOpcode()) {
case Instruction::UDiv: case Instruction::SDiv:
case Instruction::URem: case Instruction::SRem:
// This optimization is controversial because its correctness
// depends on the semantics of `select`. If C is poison,
// the program after transformation may contain UB.
// See PLDI17 [Taming Undefined Behavior in LLVM].
hints.setReturnCodeToAdmitted();
return;
}
Value *X = MatchOp, *Y = OtherOpT, *Z = OtherOpF, *C = SI.getCondition();
Instruction::BinaryOps bop = R->getOpcode();
crellvm::insertSrcNopAtTgtI(hints, Tprime);
PROPAGATE(MAYDIFF(crellvm::getVariable(*Tprime), Physical), crellvm::ConsGlobal::make());
crellvm::propagateInstruction(hints, R, T0, TGT);
crellvm::propagateInstruction(hints, S, T0, TGT);
crellvm::propagateInstruction(hints, Tprime, T0, TGT);
// auto: (XY_ZX case) If S = Z bop X, apply commutativity
//if (the_case == crellvm::FoldSelectOpOpArg::XY_ZX)
// crellvm::applyCommutativity(hints, T0, S, TGT);
// auto: (YX_XZ case) If R = Y bop X, apply commutativity
//else if (the_case == crellvm::FoldSelectOpOpArg::YX_XZ)
// crellvm::applyCommutativity(hints, T0, R, TGT);
if (the_case == crellvm::FoldSelectOpOpArg::YX_ZX) {
if(crellvm::isFloatOpcode(bop))
INFRULE(INSTPOS(TGT, T0), crellvm::ConsFbopDistributiveOverSelectinst2::make(
crellvm::getFbop(bop), REGISTER(*R), REGISTER(*S), REGISTER(*Tprime),
REGISTER(*T0), VAL(X), VAL(Y), VAL(Z),VAL(C), crellvm::getFloatType(R->getType()), VALTYPE(C->getType())));
else
INFRULE(INSTPOS(TGT, T0), crellvm::ConsBopDistributiveOverSelectinst2::make(
crellvm::getBop(bop), REGISTER(*R), REGISTER(*S), REGISTER(*Tprime),
REGISTER(*T0), VAL(X), VAL(Y), VAL(Z), VAL(C), BITSIZE(*R), VALTYPE(C->getType())));
} else {
if(crellvm::isFloatOpcode(bop))
INFRULE(INSTPOS(TGT, T0), crellvm::ConsFbopDistributiveOverSelectinst::make(
crellvm::getFbop(bop), REGISTER(*R), REGISTER(*S), REGISTER(*Tprime), REGISTER(*T0),
VAL(X), VAL(Y), VAL(Z), VAL(C), crellvm::getFloatType(R->getType()), VALTYPE(C->getType())));
else
INFRULE(INSTPOS(TGT, T0), crellvm::ConsBopDistributiveOverSelectinst::make(
crellvm::getBop(bop), REGISTER(*R), REGISTER(*S), REGISTER(*Tprime), REGISTER(*T0),
VAL(X), VAL(Y), VAL(Z), VAL(C), BITSIZE(*R), VALTYPE(C->getType())));
}
});
if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TI)) {
if (MatchIsOpZero)
return BinaryOperator::Create(BO->getOpcode(), MatchOp, NewSI);
else
return BinaryOperator::Create(BO->getOpcode(), NewSI, MatchOp);
}
llvm_unreachable("Shouldn't get here");
}
static bool isSelect01(Constant *C1, Constant *C2) {
ConstantInt *C1I = dyn_cast<ConstantInt>(C1);
if (!C1I)
return false;
ConstantInt *C2I = dyn_cast<ConstantInt>(C2);
if (!C2I)
return false;
if (!C1I->isZero() && !C2I->isZero()) // One side must be zero.
return false;
return C1I->isOne() || C1I->isAllOnesValue() ||
C2I->isOne() || C2I->isAllOnesValue();
}
/// FoldSelectIntoOp - Try fold the select into one of the operands to
/// facilitate further optimization.
Instruction *InstCombiner::FoldSelectIntoOp(SelectInst &SI, Value *TrueVal,
Value *FalseVal) {
// See the comment above GetSelectFoldableOperands for a description of the
// transformation we are doing here.
if (Instruction *TVI = dyn_cast<Instruction>(TrueVal)) {
if (TVI->hasOneUse() && TVI->getNumOperands() == 2 &&
!isa<Constant>(FalseVal)) {
if (unsigned SFO = GetSelectFoldableOperands(TVI)) {
unsigned OpToFold = 0;
if ((SFO & 1) && FalseVal == TVI->getOperand(0)) {
OpToFold = 1;
} else if ((SFO & 2) && FalseVal == TVI->getOperand(1)) {
OpToFold = 2;
}
if (OpToFold) {
Constant *C = GetSelectFoldableConstant(TVI);
Value *OOp = TVI->getOperand(2-OpToFold);
// Avoid creating select between 2 constants unless it's selecting
// between 0, 1 and -1.
if (!isa<Constant>(OOp) || isSelect01(C, cast<Constant>(OOp))) {
Value *NewSel = Builder->CreateSelect(SI.getCondition(), OOp, C);
NewSel->takeName(TVI);
BinaryOperator *TVI_BO = cast<BinaryOperator>(TVI);
BinaryOperator *BO = BinaryOperator::Create(TVI_BO->getOpcode(),
FalseVal, NewSel);
if (isa<PossiblyExactOperator>(BO))
BO->setIsExact(TVI_BO->isExact());
if (isa<OverflowingBinaryOperator>(BO)) {
BO->setHasNoUnsignedWrap(TVI_BO->hasNoUnsignedWrap());
BO->setHasNoSignedWrap(TVI_BO->hasNoSignedWrap());
}
return BO;
}
}
}
}
}
if (Instruction *FVI = dyn_cast<Instruction>(FalseVal)) {
if (FVI->hasOneUse() && FVI->getNumOperands() == 2 &&
!isa<Constant>(TrueVal)) {
if (unsigned SFO = GetSelectFoldableOperands(FVI)) {
unsigned OpToFold = 0;
if ((SFO & 1) && TrueVal == FVI->getOperand(0)) {
OpToFold = 1;
} else if ((SFO & 2) && TrueVal == FVI->getOperand(1)) {
OpToFold = 2;
}
if (OpToFold) {
Constant *C = GetSelectFoldableConstant(FVI);
Value *OOp = FVI->getOperand(2-OpToFold);
// Avoid creating select between 2 constants unless it's selecting
// between 0, 1 and -1.
if (!isa<Constant>(OOp) || isSelect01(C, cast<Constant>(OOp))) {
Value *NewSel = Builder->CreateSelect(SI.getCondition(), C, OOp);
NewSel->takeName(FVI);
BinaryOperator *FVI_BO = cast<BinaryOperator>(FVI);
BinaryOperator *BO = BinaryOperator::Create(FVI_BO->getOpcode(),
TrueVal, NewSel);
if (isa<PossiblyExactOperator>(BO))
BO->setIsExact(FVI_BO->isExact());
if (isa<OverflowingBinaryOperator>(BO)) {
BO->setHasNoUnsignedWrap(FVI_BO->hasNoUnsignedWrap());
BO->setHasNoSignedWrap(FVI_BO->hasNoSignedWrap());
}
return BO;
}
}
}
}
}
return nullptr;
}
/// foldSelectICmpAndOr - We want to turn:
/// (select (icmp eq (and X, C1), 0), Y, (or Y, C2))
/// into:
/// (or (shl (and X, C1), C3), y)
/// iff:
/// C1 and C2 are both powers of 2
/// where:
/// C3 = Log(C2) - Log(C1)
///
/// This transform handles cases where:
/// 1. The icmp predicate is inverted
/// 2. The select operands are reversed
/// 3. The magnitude of C2 and C1 are flipped
static Value *foldSelectICmpAndOr(const SelectInst &SI, Value *TrueVal,
Value *FalseVal,
InstCombiner::BuilderTy *Builder) {
const ICmpInst *IC = dyn_cast<ICmpInst>(SI.getCondition());
if (!IC || !IC->isEquality() || !SI.getType()->isIntegerTy())
return nullptr;
Value *CmpLHS = IC->getOperand(0);
Value *CmpRHS = IC->getOperand(1);
if (!match(CmpRHS, m_Zero()))
return nullptr;
Value *X;
const APInt *C1;
if (!match(CmpLHS, m_And(m_Value(X), m_Power2(C1))))
return nullptr;
const APInt *C2;
bool OrOnTrueVal = false;
bool OrOnFalseVal = match(FalseVal, m_Or(m_Specific(TrueVal), m_Power2(C2)));
if (!OrOnFalseVal)
OrOnTrueVal = match(TrueVal, m_Or(m_Specific(FalseVal), m_Power2(C2)));
if (!OrOnFalseVal && !OrOnTrueVal)
return nullptr;
Value *V = CmpLHS;
Value *Y = OrOnFalseVal ? TrueVal : FalseVal;
unsigned C1Log = C1->logBase2();
unsigned C2Log = C2->logBase2();
if (C2Log > C1Log) {
V = Builder->CreateZExtOrTrunc(V, Y->getType());
V = Builder->CreateShl(V, C2Log - C1Log);
} else if (C1Log > C2Log) {
V = Builder->CreateLShr(V, C1Log - C2Log);
V = Builder->CreateZExtOrTrunc(V, Y->getType());
} else
V = Builder->CreateZExtOrTrunc(V, Y->getType());
ICmpInst::Predicate Pred = IC->getPredicate();
if ((Pred == ICmpInst::ICMP_NE && OrOnFalseVal) ||
(Pred == ICmpInst::ICMP_EQ && OrOnTrueVal))
V = Builder->CreateXor(V, *C2);
return Builder->CreateOr(V, Y);
}
/// Attempt to fold a cttz/ctlz followed by a icmp plus select into a single
/// call to cttz/ctlz with flag 'is_zero_undef' cleared.
///
/// For example, we can fold the following code sequence:
/// \code
/// %0 = tail call i32 @llvm.cttz.i32(i32 %x, i1 true)
/// %1 = icmp ne i32 %x, 0
/// %2 = select i1 %1, i32 %0, i32 32
/// \code
///
/// into:
/// %0 = tail call i32 @llvm.cttz.i32(i32 %x, i1 false)
static Value *foldSelectCttzCtlz(ICmpInst *ICI, Value *TrueVal, Value *FalseVal,
InstCombiner::BuilderTy *Builder) {
ICmpInst::Predicate Pred = ICI->getPredicate();
Value *CmpLHS = ICI->getOperand(0);
Value *CmpRHS = ICI->getOperand(1);
// Check if the condition value compares a value for equality against zero.
if (!ICI->isEquality() || !match(CmpRHS, m_Zero()))
return nullptr;
Value *Count = FalseVal;
Value *ValueOnZero = TrueVal;
if (Pred == ICmpInst::ICMP_NE)
std::swap(Count, ValueOnZero);
// Skip zero extend/truncate.
Value *V = nullptr;
if (match(Count, m_ZExt(m_Value(V))) ||
match(Count, m_Trunc(m_Value(V))))
Count = V;
// Check if the value propagated on zero is a constant number equal to the
// sizeof in bits of 'Count'.
unsigned SizeOfInBits = Count->getType()->getScalarSizeInBits();
if (!match(ValueOnZero, m_SpecificInt(SizeOfInBits)))
return nullptr;
// Check that 'Count' is a call to intrinsic cttz/ctlz. Also check that the
// input to the cttz/ctlz is used as LHS for the compare instruction.
if (match(Count, m_Intrinsic<Intrinsic::cttz>(m_Specific(CmpLHS))) ||
match(Count, m_Intrinsic<Intrinsic::ctlz>(m_Specific(CmpLHS)))) {
IntrinsicInst *II = cast<IntrinsicInst>(Count);
IRBuilder<> Builder(II);
// Explicitly clear the 'undef_on_zero' flag.
IntrinsicInst *NewI = cast<IntrinsicInst>(II->clone());
Type *Ty = NewI->getArgOperand(1)->getType();
NewI->setArgOperand(1, Constant::getNullValue(Ty));
Builder.Insert(NewI);
return Builder.CreateZExtOrTrunc(NewI, ValueOnZero->getType());
}
return nullptr;
}
/// visitSelectInstWithICmp - Visit a SelectInst that has an
/// ICmpInst as its first operand.
///
Instruction *InstCombiner::visitSelectInstWithICmp(SelectInst &SI,
ICmpInst *ICI) {
bool Changed = false;
ICmpInst::Predicate Pred = ICI->getPredicate();
Value *CmpLHS = ICI->getOperand(0);
Value *CmpRHS = ICI->getOperand(1);
Value *TrueVal = SI.getTrueValue();
Value *FalseVal = SI.getFalseValue();
// Check cases where the comparison is with a constant that
// can be adjusted to fit the min/max idiom. We may move or edit ICI
// here, so make sure the select is the only user.
if (ICI->hasOneUse())
if (ConstantInt *CI = dyn_cast<ConstantInt>(CmpRHS)) {
switch (Pred) {
default: break;
case ICmpInst::ICMP_ULT:
case ICmpInst::ICMP_SLT:
case ICmpInst::ICMP_UGT:
case ICmpInst::ICMP_SGT: {
// These transformations only work for selects over integers.
IntegerType *SelectTy = dyn_cast<IntegerType>(SI.getType());
if (!SelectTy)
break;
Constant *AdjustedRHS;
if (Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_SGT)
AdjustedRHS = ConstantInt::get(CI->getContext(), CI->getValue() + 1);
else // (Pred == ICmpInst::ICMP_ULT || Pred == ICmpInst::ICMP_SLT)
AdjustedRHS = ConstantInt::get(CI->getContext(), CI->getValue() - 1);
crellvm::ValidationUnit::Begin("select_icmp_unknown_const", SI);
INTRUDE(CAPTURE(), {
auto ptr = data.create<crellvm::ArgForSelectIcmpConst>();
ptr->activated = false;
});
// X > C ? X : C+1 --> X < C+1 ? C+1 : X
// X < C ? X : C-1 --> X > C-1 ? C-1 : X
if ((CmpLHS == TrueVal && AdjustedRHS == FalseVal) ||
(CmpLHS == FalseVal && AdjustedRHS == TrueVal)) {
; // Nothing to do here. Values match without any sign/zero extension.
INTRUDE(CAPTURE(),
{ data.get<crellvm::ArgForSelectIcmpConst>()->activated = true; });
}
// Types do not match. Instead of calculating this with mixed types
// promote all to the larger type. This enables scalar evolution to
// analyze this expression.
else if (CmpRHS->getType()->getScalarSizeInBits() <
SelectTy->getBitWidth()) {
Constant *sextRHS = ConstantExpr::getSExt(AdjustedRHS, SelectTy);
// X = sext x; x >s c ? X : C+1 --> X = sext x; X <s C+1 ? C+1 : X
// X = sext x; x <s c ? X : C-1 --> X = sext x; X >s C-1 ? C-1 : X
// X = sext x; x >u c ? X : C+1 --> X = sext x; X <u C+1 ? C+1 : X
// X = sext x; x <u c ? X : C-1 --> X = sext x; X >u C-1 ? C-1 : X
if (match(TrueVal, m_SExt(m_Specific(CmpLHS))) &&
sextRHS == FalseVal) {
CmpLHS = TrueVal;
AdjustedRHS = sextRHS;
} else if (match(FalseVal, m_SExt(m_Specific(CmpLHS))) &&
sextRHS == TrueVal) {
CmpLHS = FalseVal;
AdjustedRHS = sextRHS;
} else if (ICI->isUnsigned()) {
Constant *zextRHS = ConstantExpr::getZExt(AdjustedRHS, SelectTy);
// X = zext x; x >u c ? X : C+1 --> X = zext x; X <u C+1 ? C+1 : X
// X = zext x; x <u c ? X : C-1 --> X = zext x; X >u C-1 ? C-1 : X
// zext + signed compare cannot be changed:
// 0xff <s 0x00, but 0x00ff >s 0x0000
if (match(TrueVal, m_ZExt(m_Specific(CmpLHS))) &&
zextRHS == FalseVal) {
CmpLHS = TrueVal;
AdjustedRHS = zextRHS;
} else if (match(FalseVal, m_ZExt(m_Specific(CmpLHS))) &&
zextRHS == TrueVal) {
CmpLHS = FalseVal;
AdjustedRHS = zextRHS;
} else {
crellvm::ValidationUnit::Abort();
break;
}
} else {
crellvm::ValidationUnit::Abort();
break;
}
} else {
crellvm::ValidationUnit::Abort();
break;
}
INTRUDE(CAPTURE(&ICI, &SI, &CI, &AdjustedRHS, &Pred), {
auto ptr = data.get<crellvm::ArgForSelectIcmpConst>();
if (ptr->activated) {
// <src> | <tgt>
// Y = icmp sgt/ugt X, C | Y = icmp slt/ult X, (C+1)
// Z = select Y, X, (C+1) | Z = select Y, (C+1), X
// <src> | <tgt>
// Y = icmp slt/ult X, C | Y = icmp sgt/ugt X, (C-1)
// Z = select Y, X, (C-1) | Z = select Y, (C-1), X
ptr->Z = &SI;
ptr->Y = ICI;
ptr->X = ptr->Y->getOperand(0);
ptr->C = CI;
ptr->Cprime = dyn_cast<ConstantInt>(AdjustedRHS);
ptr->Y_org_pos = INSTPOS(SRC, ICI);
ptr->isGtToLt = Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_SGT;
ptr->isUnsigned = Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_ULT;
ptr->selectCommutative = SI.getOperand(1) != ICI->getOperand(0);
crellvm::insertTgtNopAtSrcI(hints, ptr->Y);
crellvm::propagateMaydiffGlobal(hints, crellvm::getVariable(*ptr->Y), crellvm::Physical);
crellvm::propagateInstruction(hints, ptr->Y, ptr->Z, SRC);
} else {
crellvm::ValidationUnit::GetInstance()->setIsAborted();
}
});
Pred = ICmpInst::getSwappedPredicate(Pred);
CmpRHS = AdjustedRHS;
std::swap(FalseVal, TrueVal);
ICI->setPredicate(Pred);
ICI->setOperand(0, CmpLHS);
ICI->setOperand(1, CmpRHS);
SI.setOperand(1, TrueVal);
SI.setOperand(2, FalseVal);
// Move ICI instruction right before the select instruction. Otherwise
// the sext/zext value may be defined after the ICI instruction uses it.
ICI->moveBefore(&SI);
INTRUDE(CAPTURE(), {
auto ptr = data.get<crellvm::ArgForSelectIcmpConst>();
if (ptr->activated) {
//unsigned int bitsize = ptr->C->getType()->getIntegerBitWidth();
auto Z = ptr->Z;
auto C = ptr->C;
auto Cprime = ptr->Cprime;
auto Y = ptr->Y;
auto X = ptr->X;
bool select_commutative = ptr->selectCommutative;
auto vY = crellvm::getVariable(*Y);
crellvm::insertSrcNopAtTgtI(hints, ptr->Y);
PROPAGATE(LESSDEF(RHS(vY, Physical, TGT), VAR(vY), TGT), BOUNDS(INSTPOS(TGT, Y), INSTPOS(TGT, Z)));
std::function<std::shared_ptr<crellvm::TyInfrule>(
std::shared_ptr<crellvm::TyRegister>,
std::shared_ptr<crellvm::TyValue>,
std::shared_ptr<crellvm::TyValue>,
std::shared_ptr<crellvm::TyConstInt>,
std::shared_ptr<crellvm::TyConstInt>, bool,
std::shared_ptr<crellvm::TySize>)> makeInfruleFunc = nullptr;
std::string optname = "";
if (ptr->isGtToLt) {
if (ptr->isUnsigned) makeInfruleFunc = crellvm::ConsSelectIcmpUgtConst::make;
else makeInfruleFunc = crellvm::ConsSelectIcmpSgtConst::make;
optname = "select_icmp_gt_const";
} else {
if (ptr->isUnsigned) makeInfruleFunc = crellvm::ConsSelectIcmpUltConst::make;
else makeInfruleFunc = crellvm::ConsSelectIcmpSltConst::make;
optname = "select_icmp_lt_const";
}
crellvm::ValidationUnit::GetInstance()->setOptimizationName(optname);
INFRULE(INSTPOS(SRC, Z), makeInfruleFunc(REGISTER(*Z), VAL(Y), VAL(X),
CONSTINT(C), CONSTINT(Cprime), select_commutative, BITSIZE(*C)));
} else
crellvm::ValidationUnit::GetInstance()->setIsAborted();
});
crellvm::ValidationUnit::End();
Changed = true;
break;
}
}
}
// Transform (X >s -1) ? C1 : C2 --> ((X >>s 31) & (C2 - C1)) + C1
// and (X <s 0) ? C2 : C1 --> ((X >>s 31) & (C2 - C1)) + C1
// FIXME: Type and constness constraints could be lifted, but we have to
// watch code size carefully. We should consider xor instead of
// sub/add when we decide to do that.
if (IntegerType *Ty = dyn_cast<IntegerType>(CmpLHS->getType())) {
if (TrueVal->getType() == Ty) {
if (ConstantInt *Cmp = dyn_cast<ConstantInt>(CmpRHS)) {
ConstantInt *C1 = nullptr, *C2 = nullptr;
if (Pred == ICmpInst::ICMP_SGT && Cmp->isAllOnesValue()) {
C1 = dyn_cast<ConstantInt>(TrueVal);
C2 = dyn_cast<ConstantInt>(FalseVal);
} else if (Pred == ICmpInst::ICMP_SLT && Cmp->isNullValue()) {
C1 = dyn_cast<ConstantInt>(FalseVal);
C2 = dyn_cast<ConstantInt>(TrueVal);
}
if (C1 && C2) {
// This shift results in either -1 or 0.
Value *AShr = Builder->CreateAShr(CmpLHS, Ty->getBitWidth()-1);
// Check if we can express the operation with a single or.
if (C2->isAllOnesValue())
return ReplaceInstUsesWith(SI, Builder->CreateOr(AShr, C1));
Value *And = Builder->CreateAnd(AShr, C2->getValue()-C1->getValue());
return ReplaceInstUsesWith(SI, Builder->CreateAdd(And, C1));
}
}
}
}
// NOTE: if we wanted to, this is where to detect integer MIN/MAX
if (CmpRHS != CmpLHS && isa<Constant>(CmpRHS)) {
if (CmpLHS == TrueVal && Pred == ICmpInst::ICMP_EQ) {
// Transform (X == C) ? X : Y -> (X == C) ? C : Y
crellvm::ValidationUnit::Begin("select_icmp_eq", SI);
INTRUDE(CAPTURE(&SI, &ICI, &CmpRHS, &CmpLHS, &FalseVal), {
// <src> | <tgt>
// Y = icmp eq, X, C | Y = icmp eq, X, C
// Z = select Y, X, V | Z = select Y, C, V
if (CmpRHS->getType()->isVectorTy()) {
crellvm::ValidationUnit::Abort();
return;
}
//SelectInst *Z = &SI;
//ICmpInst *Y = ICI;
//Value *X = CmpLHS;
//Value *V = FalseVal;
Constant *C = dyn_cast<Constant>(CmpRHS);
//crellvm::propagateInstruction(hints, Y, Z, SRC);
//INFRULE(INSTPOS(SRC, Z), crellvm::ConsSelectIcmpEq::make(
// VAL(Z), VAL(Y), VAL(X), VAL(V),
// CONSTANT(C), VALTYPE(C->getType())));
crellvm::propagateInstruction(hints, ICI, &SI, SRC);
INFRULE(INSTPOS(SRC, &SI), crellvm::ConsSelectIcmpEq::make(
VAL(&SI), VAL(ICI), VAL(CmpLHS), VAL(FalseVal), CONSTANT(C), VALTYPE(C->getType())));
});
SI.setOperand(1, CmpRHS);
crellvm::ValidationUnit::End();
Changed = true;
} else if (CmpLHS == FalseVal && Pred == ICmpInst::ICMP_NE) {
// Transform (X != C) ? Y : X -> (X != C) ? Y : C
crellvm::ValidationUnit::Begin("select_icmp_ne", SI);
INTRUDE(CAPTURE(&SI, &ICI, &CmpRHS, &CmpLHS, &TrueVal), {
// <src> | <tgt>
// Y = icmp ne, X, C | Y = icmp ne, X, C
// Z = select Y, V, X | Z = select Y, V, C
if (CmpRHS->getType()->isVectorTy()) {
crellvm::ValidationUnit::Abort();
return;
}
Constant *C = dyn_cast<Constant>(CmpRHS);
crellvm::propagateInstruction(hints, ICI, &SI, SRC);
INFRULE(INSTPOS(SRC, &SI), crellvm::ConsSelectIcmpNe::make(
VAL(&SI), VAL(ICI), VAL(CmpLHS), VAL(TrueVal), CONSTANT(C), VALTYPE(C->getType())));
});
SI.setOperand(2, CmpRHS);
crellvm::ValidationUnit::End();
Changed = true;
}
}
{
unsigned BitWidth = DL.getTypeSizeInBits(TrueVal->getType());
APInt MinSignedValue = APInt::getSignBit(BitWidth);
Value *X;
const APInt *Y, *C;
bool TrueWhenUnset;
bool IsBitTest = false;
if (ICmpInst::isEquality(Pred) &&
match(CmpLHS, m_And(m_Value(X), m_Power2(Y))) &&
match(CmpRHS, m_Zero())) {
IsBitTest = true;
TrueWhenUnset = Pred == ICmpInst::ICMP_EQ;
} else if (Pred == ICmpInst::ICMP_SLT && match(CmpRHS, m_Zero())) {
X = CmpLHS;
Y = &MinSignedValue;
IsBitTest = true;
TrueWhenUnset = false;
} else if (Pred == ICmpInst::ICMP_SGT && match(CmpRHS, m_AllOnes())) {
X = CmpLHS;
Y = &MinSignedValue;
IsBitTest = true;
TrueWhenUnset = true;
}
if (IsBitTest) {
crellvm::ValidationUnit::Begin("select_icmp_unknown_xor", SI);
Value *V = nullptr;
// (X & Y) == 0 ? X : X ^ Y --> X & ~Y
if (TrueWhenUnset && TrueVal == X &&
match(FalseVal, m_Xor(m_Specific(X), m_APInt(C))) && *Y == *C)
V = Builder->CreateAnd(X, ~(*Y));
// (X & Y) != 0 ? X ^ Y : X --> X & ~Y
else if (!TrueWhenUnset && FalseVal == X &&
match(TrueVal, m_Xor(m_Specific(X), m_APInt(C))) && *Y == *C)
V = Builder->CreateAnd(X, ~(*Y));
// (X & Y) == 0 ? X ^ Y : X --> X | Y
else if (TrueWhenUnset && FalseVal == X &&
match(TrueVal, m_Xor(m_Specific(X), m_APInt(C))) && *Y == *C)
V = Builder->CreateOr(X, *Y);
// (X & Y) != 0 ? X : X ^ Y --> X | Y
else if (!TrueWhenUnset && TrueVal == X &&
match(FalseVal, m_Xor(m_Specific(X), m_APInt(C))) && *Y == *C)
V = Builder->CreateOr(X, *Y);
if (V) {
INTRUDE(CAPTURE(&SI, &ICI, &V, &Pred, &TrueVal, &FalseVal), {
using namespace crellvm;
name_instructions(*SI.getParent()->getParent());
SelectInst *Z = &SI;
BinaryOperator *Zp = dyn_cast<BinaryOperator>(V);
ICmpInst *V = ICI;
auto bsz = BITSIZE(Z->getType()->getIntegerBitWidth());
insertSrcNopAtTgtI(hints, Zp);
propagateMaydiffGlobal(hints, getVariable(*Zp), Physical);
propagateMaydiffGlobal(hints, getVariable(*Zp), Previous);
propagateInstruction(hints, V, Z, TGT);
propagateInstruction(hints, Zp, Z, TGT);
if (Pred == ICmpInst::ICMP_EQ || Pred == ICmpInst::ICMP_NE) {
BinaryOperator *W = dyn_cast<BinaryOperator>(V->getOperand(0));
Value *X = W->getOperand(0);
auto C = dyn_cast<ConstantInt>(W->getOperand(1));
auto Cp = dyn_cast<ConstantInt>(ConstantInt::get(C->getType(), ~(C->getValue())));
BinaryOperator *U = dyn_cast<BinaryOperator>(TrueVal == X ? FalseVal : TrueVal);
propagateInstruction(hints, U, Z, TGT);
propagateInstruction(hints, W, Z, TGT);
if (Pred == ICmpInst::ICMP_EQ) {
if (Z->getOperand(1) == X) {
ValidationUnit::GetInstance()->setOptimizationName("select_icmp_eq_xor1");
// <src> | <tgt>
// W = X & C | W = X & C
// V = icmp eq, W, 0 | V = icmp eq, W, 0
// U = X ^ C | U = X ^ C
// <nop> | Z' = X & ~C
// Z = select V, X, U | Z = select V, X, U
// | (replace Z with Z')
INFRULE(INSTPOS(TGT, Z), ConsSelectIcmpEqXor1::make(
VAL(Z), VAL(Zp), VAL(V), VAL(X), VAL(U), VAL(W), CONSTINT(C), CONSTINT(Cp), bsz));
} else if (Z->getOperand(1) == U) {
ValidationUnit::GetInstance()->setOptimizationName("select_icmp_eq_xor2");
// <src> | <tgt>
// W = X & C | W = X & C
// V = icmp eq, W, 0 | V = icmp eq, W, 0
// U = X ^ C | U = X ^ C
// <nop> | Z' = X | C
// Z = select V, U, X | Z = select V, U, X
// | (replace Z with Z')
INFRULE(INSTPOS(TGT, Z), ConsSelectIcmpEqXor2::make(
VAL(Z), VAL(Zp), VAL(V), VAL(X), VAL(U), VAL(W), CONSTINT(C), bsz));
}// else {
// assert(false && "Second operand of Z must be either X or U");
//}
} else {
if (Z->getOperand(1) == U) {
ValidationUnit::GetInstance()->setOptimizationName("select_icmp_ne_xor1");
// <src> | <tgt>
// W = X & C | W = X & C
// V = icmp ne, W, 0 | V = icmp ne, W, 0
// U = X ^ C | U = X ^ C
// <nop> | Z' = X & ~C
// Z = select V, U, X | Z = select V, U, X
// | (replace Z with Z')
INFRULE(INSTPOS(TGT, Z), ConsSelectIcmpNeXor1::make(
VAL(Z), VAL(Zp), VAL(V), VAL(X), VAL(U), VAL(W), CONSTINT(C), CONSTINT(Cp), bsz));
} else if (Z->getOperand(1) == X) {
ValidationUnit::GetInstance()->setOptimizationName("select_icmp_ne_xor2");
// <src> | <tgt>
// W = X & C | W = X & C
// V = icmp ne, W, 0 | V = icmp ne, W, 0
// U = X ^ C | U = X ^ C
// <nop> | Z' = X | C
// Z = select V, X, U | Z = select V, X, U
// | (replace Z with Z')
INFRULE(INSTPOS(TGT, Z), ConsSelectIcmpNeXor2::make(
VAL(Z), VAL(Zp), VAL(V), VAL(X), VAL(U), VAL(W), CONSTINT(C), bsz));
}// else {
// assert(false && "Second operand of Z must be either X or U");
//}
}
} else {
Value *X = Zp->getOperand(0);
BinaryOperator *U = dyn_cast<BinaryOperator>(TrueVal == X ? FalseVal : TrueVal);
auto C = dyn_cast<ConstantInt>(U->getOperand(1));
auto Cp = dyn_cast<ConstantInt>(Zp->getOperand(1));
propagateInstruction(hints, U, Z, TGT);
if (Pred == ICmpInst::ICMP_SLT) {
if (Z->getOperand(1) == U) {
ValidationUnit::GetInstance()->setOptimizationName("select_icmp_slt_xor1");
// <src> | <tgt>
// U = X ^ C | U = X ^ C
// V = icmp slt X, 0 | V = icmp slt X, 0
// <nop> | Z' = X & ~C
// Z = select V, U, X | Z = select V, U, X
// | (replace Z with Z')
INFRULE(INSTPOS(TGT, Z), ConsSelectIcmpSltXor1::make(
VAL(Z), VAL(Zp), VAL(V), VAL(X), VAL(U), CONSTINT(C), CONSTINT(Cp), bsz));
} else if (Z->getOperand(1) == X) {
ValidationUnit::GetInstance()->setOptimizationName("select_icmp_slt_xor2");
// <src> | <tgt>
// U = X ^ C | U = X ^ C
// V = icmp slt X, 0 | V = icmp slt X, 0
// <nop> | Z' = X | C
// Z = select V, X, U | Z = select V, X, U
// | (replace Z with Z')
INFRULE(INSTPOS(TGT, Z), ConsSelectIcmpSltXor2::make(
VAL(Z), VAL(Zp), VAL(V), VAL(X), VAL(U), CONSTINT(C), bsz));
}// else {
// assert(false && "Second operand of Z must be either X or U");
//}
} else if (Pred == ICmpInst::ICMP_SGT) {
if (Z->getOperand(1) == X) {
ValidationUnit::GetInstance()->setOptimizationName("select_icmp_sgt_xor1");
// <src> | <tgt>
// U = X ^ C | U = X ^ C
// V = icmp sgt X, 0 | V = icmp sgt X, 0
// <nop> | Z' = X & ~C
// Z = select V, X, U | Z = select V, X, U
// | (replace Z with Z')
INFRULE(INSTPOS(TGT, Z), ConsSelectIcmpSgtXor1::make(
VAL(Z), VAL(Zp), VAL(V), VAL(X), VAL(U), CONSTINT(C), CONSTINT(Cp), bsz));
} else if (Z->getOperand(1) == U) {
ValidationUnit::GetInstance()->setOptimizationName("select_icmp_sgt_xor2");
// <src> | <tgt>
// U = X ^ C | U = X ^ C
// V = icmp sgt X, 0 | V = icmp sgt X, 0
// <nop> | Z' = X | C
// Z = select V, U, X | Z = select V, U, X
// | (replace Z with Z')
INFRULE(INSTPOS(TGT, Z), ConsSelectIcmpSgtXor2::make(
VAL(Z), VAL(Zp), VAL(V), VAL(X), VAL(U), CONSTINT(C), bsz));
}// else {
// assert(false && "Second operand of Z must be either X or U");
//}
}// else {
// assert(false && "Unknown predicate");
//}
}
generateHintForReplaceAllUsesWithAtTgt(Z, Zp);
});
return ReplaceInstUsesWith(SI, V);
}
crellvm::ValidationUnit::Abort();
}
}
if (Value *V = foldSelectICmpAndOr(SI, TrueVal, FalseVal, Builder))
return ReplaceInstUsesWith(SI, V);
if (Value *V = foldSelectCttzCtlz(ICI, TrueVal, FalseVal, Builder))
return ReplaceInstUsesWith(SI, V);
return Changed ? &SI : nullptr;
}
/// CanSelectOperandBeMappingIntoPredBlock - SI is a select whose condition is a
/// PHI node (but the two may be in different blocks). See if the true/false
/// values (V) are live in all of the predecessor blocks of the PHI. For
/// example, cases like this cannot be mapped:
///
/// X = phi [ C1, BB1], [C2, BB2]
/// Y = add
/// Z = select X, Y, 0
///
/// because Y is not live in BB1/BB2.
///
static bool CanSelectOperandBeMappingIntoPredBlock(const Value *V,
const SelectInst &SI) {
// If the value is a non-instruction value like a constant or argument, it
// can always be mapped.
const Instruction *I = dyn_cast<Instruction>(V);
if (!I) return true;
// If V is a PHI node defined in the same block as the condition PHI, we can
// map the arguments.
const PHINode *CondPHI = cast<PHINode>(SI.getCondition());
if (const PHINode *VP = dyn_cast<PHINode>(I))
if (VP->getParent() == CondPHI->getParent())
return true;
// Otherwise, if the PHI and select are defined in the same block and if V is
// defined in a different block, then we can transform it.
if (SI.getParent() == CondPHI->getParent() &&
I->getParent() != CondPHI->getParent())
return true;
// Otherwise we have a 'hard' case and we can't tell without doing more