forked from OSchip/llvm-project
move the [Can]EvaluateInDifferentType functions out to InstCombineCasts.cpp
llvm-svn: 92469
This commit is contained in:
Chris Lattner
parent
2b295a0eba
commit
92be2adba6
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@ -17,7 +17,215 @@
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using namespace llvm;
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using namespace PatternMatch;
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// FIXME: InstCombiner::EvaluateInDifferentType!
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/// CanEvaluateInDifferentType - Return true if we can take the specified value
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/// and return it as type Ty without inserting any new casts and without
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/// changing the computed value. This is used by code that tries to decide
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/// whether promoting or shrinking integer operations to wider or smaller types
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/// will allow us to eliminate a truncate or extend.
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///
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/// This is a truncation operation if Ty is smaller than V->getType(), or an
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/// extension operation if Ty is larger.
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///
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/// If CastOpc is a truncation, then Ty will be a type smaller than V. We
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/// should return true if trunc(V) can be computed by computing V in the smaller
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/// type. If V is an instruction, then trunc(inst(x,y)) can be computed as
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/// inst(trunc(x),trunc(y)), which only makes sense if x and y can be
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/// efficiently truncated.
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///
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/// If CastOpc is a sext or zext, we are asking if the low bits of the value can
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/// bit computed in a larger type, which is then and'd or sext_in_reg'd to get
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/// the final result.
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bool InstCombiner::CanEvaluateInDifferentType(Value *V, const Type *Ty,
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unsigned CastOpc,
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int &NumCastsRemoved){
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// We can always evaluate constants in another type.
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if (isa<Constant>(V))
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return true;
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Instruction *I = dyn_cast<Instruction>(V);
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if (!I) return false;
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const Type *OrigTy = V->getType();
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// If this is an extension or truncate, we can often eliminate it.
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if (isa<TruncInst>(I) || isa<ZExtInst>(I) || isa<SExtInst>(I)) {
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// If this is a cast from the destination type, we can trivially eliminate
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// it, and this will remove a cast overall.
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if (I->getOperand(0)->getType() == Ty) {
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// If the first operand is itself a cast, and is eliminable, do not count
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// this as an eliminable cast. We would prefer to eliminate those two
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// casts first.
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if (!isa<CastInst>(I->getOperand(0)) && I->hasOneUse())
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++NumCastsRemoved;
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return true;
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}
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}
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// We can't extend or shrink something that has multiple uses: doing so would
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// require duplicating the instruction in general, which isn't profitable.
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if (!I->hasOneUse()) return false;
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unsigned Opc = I->getOpcode();
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switch (Opc) {
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case Instruction::Add:
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case Instruction::Sub:
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case Instruction::Mul:
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case Instruction::And:
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case Instruction::Or:
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case Instruction::Xor:
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// These operators can all arbitrarily be extended or truncated.
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return CanEvaluateInDifferentType(I->getOperand(0), Ty, CastOpc,
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NumCastsRemoved) &&
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CanEvaluateInDifferentType(I->getOperand(1), Ty, CastOpc,
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NumCastsRemoved);
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case Instruction::UDiv:
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case Instruction::URem: {
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// UDiv and URem can be truncated if all the truncated bits are zero.
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uint32_t OrigBitWidth = OrigTy->getScalarSizeInBits();
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uint32_t BitWidth = Ty->getScalarSizeInBits();
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if (BitWidth < OrigBitWidth) {
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APInt Mask = APInt::getHighBitsSet(OrigBitWidth, OrigBitWidth-BitWidth);
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if (MaskedValueIsZero(I->getOperand(0), Mask) &&
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MaskedValueIsZero(I->getOperand(1), Mask)) {
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return CanEvaluateInDifferentType(I->getOperand(0), Ty, CastOpc,
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NumCastsRemoved) &&
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CanEvaluateInDifferentType(I->getOperand(1), Ty, CastOpc,
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NumCastsRemoved);
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}
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}
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break;
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}
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case Instruction::Shl:
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// If we are truncating the result of this SHL, and if it's a shift of a
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// constant amount, we can always perform a SHL in a smaller type.
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if (ConstantInt *CI = dyn_cast<ConstantInt>(I->getOperand(1))) {
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uint32_t BitWidth = Ty->getScalarSizeInBits();
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if (BitWidth < OrigTy->getScalarSizeInBits() &&
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CI->getLimitedValue(BitWidth) < BitWidth)
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return CanEvaluateInDifferentType(I->getOperand(0), Ty, CastOpc,
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NumCastsRemoved);
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}
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break;
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case Instruction::LShr:
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// If this is a truncate of a logical shr, we can truncate it to a smaller
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// lshr iff we know that the bits we would otherwise be shifting in are
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// already zeros.
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if (ConstantInt *CI = dyn_cast<ConstantInt>(I->getOperand(1))) {
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uint32_t OrigBitWidth = OrigTy->getScalarSizeInBits();
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uint32_t BitWidth = Ty->getScalarSizeInBits();
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if (BitWidth < OrigBitWidth &&
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MaskedValueIsZero(I->getOperand(0),
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APInt::getHighBitsSet(OrigBitWidth, OrigBitWidth-BitWidth)) &&
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CI->getLimitedValue(BitWidth) < BitWidth) {
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return CanEvaluateInDifferentType(I->getOperand(0), Ty, CastOpc,
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NumCastsRemoved);
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}
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}
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break;
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case Instruction::ZExt:
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case Instruction::SExt:
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case Instruction::Trunc:
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// If this is the same kind of case as our original (e.g. zext+zext), we
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// can safely replace it. Note that replacing it does not reduce the number
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// of casts in the input.
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if (Opc == CastOpc)
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return true;
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// sext (zext ty1), ty2 -> zext ty2
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if (CastOpc == Instruction::SExt && Opc == Instruction::ZExt)
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return true;
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break;
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case Instruction::Select: {
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SelectInst *SI = cast<SelectInst>(I);
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return CanEvaluateInDifferentType(SI->getTrueValue(), Ty, CastOpc,
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NumCastsRemoved) &&
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CanEvaluateInDifferentType(SI->getFalseValue(), Ty, CastOpc,
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NumCastsRemoved);
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}
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case Instruction::PHI: {
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// We can change a phi if we can change all operands.
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PHINode *PN = cast<PHINode>(I);
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for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
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if (!CanEvaluateInDifferentType(PN->getIncomingValue(i), Ty, CastOpc,
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NumCastsRemoved))
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return false;
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return true;
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}
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default:
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// TODO: Can handle more cases here.
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break;
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}
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return false;
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}
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/// EvaluateInDifferentType - Given an expression that
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/// CanEvaluateInDifferentType returns true for, actually insert the code to
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/// evaluate the expression.
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Value *InstCombiner::EvaluateInDifferentType(Value *V, const Type *Ty,
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bool isSigned) {
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if (Constant *C = dyn_cast<Constant>(V))
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return ConstantExpr::getIntegerCast(C, Ty, isSigned /*Sext or ZExt*/);
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// Otherwise, it must be an instruction.
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Instruction *I = cast<Instruction>(V);
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Instruction *Res = 0;
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unsigned Opc = I->getOpcode();
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switch (Opc) {
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case Instruction::Add:
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case Instruction::Sub:
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case Instruction::Mul:
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case Instruction::And:
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case Instruction::Or:
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case Instruction::Xor:
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case Instruction::AShr:
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case Instruction::LShr:
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case Instruction::Shl:
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case Instruction::UDiv:
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case Instruction::URem: {
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Value *LHS = EvaluateInDifferentType(I->getOperand(0), Ty, isSigned);
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Value *RHS = EvaluateInDifferentType(I->getOperand(1), Ty, isSigned);
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Res = BinaryOperator::Create((Instruction::BinaryOps)Opc, LHS, RHS);
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break;
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}
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case Instruction::Trunc:
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case Instruction::ZExt:
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case Instruction::SExt:
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// If the source type of the cast is the type we're trying for then we can
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// just return the source. There's no need to insert it because it is not
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// new.
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if (I->getOperand(0)->getType() == Ty)
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return I->getOperand(0);
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// Otherwise, must be the same type of cast, so just reinsert a new one.
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Res = CastInst::Create(cast<CastInst>(I)->getOpcode(), I->getOperand(0),Ty);
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break;
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case Instruction::Select: {
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Value *True = EvaluateInDifferentType(I->getOperand(1), Ty, isSigned);
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Value *False = EvaluateInDifferentType(I->getOperand(2), Ty, isSigned);
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Res = SelectInst::Create(I->getOperand(0), True, False);
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break;
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}
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case Instruction::PHI: {
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PHINode *OPN = cast<PHINode>(I);
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PHINode *NPN = PHINode::Create(Ty);
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for (unsigned i = 0, e = OPN->getNumIncomingValues(); i != e; ++i) {
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Value *V =EvaluateInDifferentType(OPN->getIncomingValue(i), Ty, isSigned);
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NPN->addIncoming(V, OPN->getIncomingBlock(i));
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}
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Res = NPN;
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break;
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}
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default:
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// TODO: Can handle more cases here.
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llvm_unreachable("Unreachable!");
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break;
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}
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Res->takeName(I);
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return InsertNewInstBefore(Res, *I);
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}
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/// This function is a wrapper around CastInst::isEliminableCastPair. It
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@ -4499,217 +4499,6 @@ Instruction *InstCombiner::PromoteCastOfAllocation(BitCastInst &CI,
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return ReplaceInstUsesWith(CI, New);
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}
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/// CanEvaluateInDifferentType - Return true if we can take the specified value
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/// and return it as type Ty without inserting any new casts and without
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/// changing the computed value. This is used by code that tries to decide
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/// whether promoting or shrinking integer operations to wider or smaller types
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/// will allow us to eliminate a truncate or extend.
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///
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/// This is a truncation operation if Ty is smaller than V->getType(), or an
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/// extension operation if Ty is larger.
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///
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/// If CastOpc is a truncation, then Ty will be a type smaller than V. We
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/// should return true if trunc(V) can be computed by computing V in the smaller
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/// type. If V is an instruction, then trunc(inst(x,y)) can be computed as
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/// inst(trunc(x),trunc(y)), which only makes sense if x and y can be
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/// efficiently truncated.
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///
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/// If CastOpc is a sext or zext, we are asking if the low bits of the value can
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/// bit computed in a larger type, which is then and'd or sext_in_reg'd to get
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/// the final result.
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bool InstCombiner::CanEvaluateInDifferentType(Value *V, const Type *Ty,
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unsigned CastOpc,
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int &NumCastsRemoved){
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// We can always evaluate constants in another type.
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if (isa<Constant>(V))
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return true;
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Instruction *I = dyn_cast<Instruction>(V);
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if (!I) return false;
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const Type *OrigTy = V->getType();
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// If this is an extension or truncate, we can often eliminate it.
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if (isa<TruncInst>(I) || isa<ZExtInst>(I) || isa<SExtInst>(I)) {
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// If this is a cast from the destination type, we can trivially eliminate
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// it, and this will remove a cast overall.
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if (I->getOperand(0)->getType() == Ty) {
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// If the first operand is itself a cast, and is eliminable, do not count
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// this as an eliminable cast. We would prefer to eliminate those two
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// casts first.
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if (!isa<CastInst>(I->getOperand(0)) && I->hasOneUse())
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++NumCastsRemoved;
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return true;
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}
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}
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// We can't extend or shrink something that has multiple uses: doing so would
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// require duplicating the instruction in general, which isn't profitable.
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if (!I->hasOneUse()) return false;
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unsigned Opc = I->getOpcode();
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switch (Opc) {
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case Instruction::Add:
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case Instruction::Sub:
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case Instruction::Mul:
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case Instruction::And:
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case Instruction::Or:
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case Instruction::Xor:
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// These operators can all arbitrarily be extended or truncated.
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return CanEvaluateInDifferentType(I->getOperand(0), Ty, CastOpc,
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NumCastsRemoved) &&
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CanEvaluateInDifferentType(I->getOperand(1), Ty, CastOpc,
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NumCastsRemoved);
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case Instruction::UDiv:
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case Instruction::URem: {
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// UDiv and URem can be truncated if all the truncated bits are zero.
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uint32_t OrigBitWidth = OrigTy->getScalarSizeInBits();
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uint32_t BitWidth = Ty->getScalarSizeInBits();
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if (BitWidth < OrigBitWidth) {
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APInt Mask = APInt::getHighBitsSet(OrigBitWidth, OrigBitWidth-BitWidth);
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if (MaskedValueIsZero(I->getOperand(0), Mask) &&
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MaskedValueIsZero(I->getOperand(1), Mask)) {
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return CanEvaluateInDifferentType(I->getOperand(0), Ty, CastOpc,
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NumCastsRemoved) &&
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CanEvaluateInDifferentType(I->getOperand(1), Ty, CastOpc,
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NumCastsRemoved);
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}
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}
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break;
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}
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case Instruction::Shl:
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// If we are truncating the result of this SHL, and if it's a shift of a
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// constant amount, we can always perform a SHL in a smaller type.
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if (ConstantInt *CI = dyn_cast<ConstantInt>(I->getOperand(1))) {
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uint32_t BitWidth = Ty->getScalarSizeInBits();
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if (BitWidth < OrigTy->getScalarSizeInBits() &&
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CI->getLimitedValue(BitWidth) < BitWidth)
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return CanEvaluateInDifferentType(I->getOperand(0), Ty, CastOpc,
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NumCastsRemoved);
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}
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break;
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case Instruction::LShr:
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// If this is a truncate of a logical shr, we can truncate it to a smaller
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// lshr iff we know that the bits we would otherwise be shifting in are
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// already zeros.
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if (ConstantInt *CI = dyn_cast<ConstantInt>(I->getOperand(1))) {
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uint32_t OrigBitWidth = OrigTy->getScalarSizeInBits();
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uint32_t BitWidth = Ty->getScalarSizeInBits();
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if (BitWidth < OrigBitWidth &&
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MaskedValueIsZero(I->getOperand(0),
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APInt::getHighBitsSet(OrigBitWidth, OrigBitWidth-BitWidth)) &&
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CI->getLimitedValue(BitWidth) < BitWidth) {
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return CanEvaluateInDifferentType(I->getOperand(0), Ty, CastOpc,
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NumCastsRemoved);
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}
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}
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break;
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case Instruction::ZExt:
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case Instruction::SExt:
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case Instruction::Trunc:
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// If this is the same kind of case as our original (e.g. zext+zext), we
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// can safely replace it. Note that replacing it does not reduce the number
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// of casts in the input.
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if (Opc == CastOpc)
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return true;
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// sext (zext ty1), ty2 -> zext ty2
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if (CastOpc == Instruction::SExt && Opc == Instruction::ZExt)
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return true;
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break;
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case Instruction::Select: {
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SelectInst *SI = cast<SelectInst>(I);
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return CanEvaluateInDifferentType(SI->getTrueValue(), Ty, CastOpc,
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NumCastsRemoved) &&
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CanEvaluateInDifferentType(SI->getFalseValue(), Ty, CastOpc,
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NumCastsRemoved);
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}
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case Instruction::PHI: {
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// We can change a phi if we can change all operands.
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PHINode *PN = cast<PHINode>(I);
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for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
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if (!CanEvaluateInDifferentType(PN->getIncomingValue(i), Ty, CastOpc,
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NumCastsRemoved))
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return false;
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return true;
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}
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default:
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// TODO: Can handle more cases here.
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break;
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}
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return false;
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}
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/// EvaluateInDifferentType - Given an expression that
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/// CanEvaluateInDifferentType returns true for, actually insert the code to
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/// evaluate the expression.
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Value *InstCombiner::EvaluateInDifferentType(Value *V, const Type *Ty,
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bool isSigned) {
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if (Constant *C = dyn_cast<Constant>(V))
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return ConstantExpr::getIntegerCast(C, Ty, isSigned /*Sext or ZExt*/);
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// Otherwise, it must be an instruction.
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Instruction *I = cast<Instruction>(V);
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Instruction *Res = 0;
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unsigned Opc = I->getOpcode();
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switch (Opc) {
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case Instruction::Add:
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case Instruction::Sub:
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case Instruction::Mul:
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case Instruction::And:
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case Instruction::Or:
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case Instruction::Xor:
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case Instruction::AShr:
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case Instruction::LShr:
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case Instruction::Shl:
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case Instruction::UDiv:
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case Instruction::URem: {
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Value *LHS = EvaluateInDifferentType(I->getOperand(0), Ty, isSigned);
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Value *RHS = EvaluateInDifferentType(I->getOperand(1), Ty, isSigned);
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Res = BinaryOperator::Create((Instruction::BinaryOps)Opc, LHS, RHS);
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break;
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}
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case Instruction::Trunc:
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case Instruction::ZExt:
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case Instruction::SExt:
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// If the source type of the cast is the type we're trying for then we can
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// just return the source. There's no need to insert it because it is not
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// new.
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if (I->getOperand(0)->getType() == Ty)
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return I->getOperand(0);
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// Otherwise, must be the same type of cast, so just reinsert a new one.
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Res = CastInst::Create(cast<CastInst>(I)->getOpcode(), I->getOperand(0),Ty);
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break;
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case Instruction::Select: {
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Value *True = EvaluateInDifferentType(I->getOperand(1), Ty, isSigned);
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Value *False = EvaluateInDifferentType(I->getOperand(2), Ty, isSigned);
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Res = SelectInst::Create(I->getOperand(0), True, False);
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break;
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}
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case Instruction::PHI: {
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PHINode *OPN = cast<PHINode>(I);
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PHINode *NPN = PHINode::Create(Ty);
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for (unsigned i = 0, e = OPN->getNumIncomingValues(); i != e; ++i) {
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Value *V =EvaluateInDifferentType(OPN->getIncomingValue(i), Ty, isSigned);
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NPN->addIncoming(V, OPN->getIncomingBlock(i));
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}
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Res = NPN;
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break;
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}
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default:
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// TODO: Can handle more cases here.
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llvm_unreachable("Unreachable!");
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break;
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}
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||||
Res->takeName(I);
|
||||
return InsertNewInstBefore(Res, *I);
|
||||
}
|
||||
|
||||
|
||||
|
||||
/// FindElementAtOffset - Given a type and a constant offset, determine whether
|
||||
/// or not there is a sequence of GEP indices into the type that will land us at
|
||||
|
|
|
|||
Loading…
Reference in New Issue