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0196dc5733
the operands have pointer type, so that the resulting type matches the original SCEV type, and so that unnecessary ptrtoints are avoided in common cases. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@75680 91177308-0d34-0410-b5e6-96231b3b80d8
729 lines
29 KiB
C++
729 lines
29 KiB
C++
//===- ScalarEvolutionExpander.cpp - Scalar Evolution Analysis --*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file contains the implementation of the scalar evolution expander,
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// which is used to generate the code corresponding to a given scalar evolution
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// expression.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Analysis/ScalarEvolutionExpander.h"
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#include "llvm/Analysis/LoopInfo.h"
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#include "llvm/LLVMContext.h"
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#include "llvm/Target/TargetData.h"
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#include "llvm/ADT/STLExtras.h"
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using namespace llvm;
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/// InsertNoopCastOfTo - Insert a cast of V to the specified type,
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/// which must be possible with a noop cast, doing what we can to share
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/// the casts.
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Value *SCEVExpander::InsertNoopCastOfTo(Value *V, const Type *Ty) {
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Instruction::CastOps Op = CastInst::getCastOpcode(V, false, Ty, false);
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assert((Op == Instruction::BitCast ||
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Op == Instruction::PtrToInt ||
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Op == Instruction::IntToPtr) &&
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"InsertNoopCastOfTo cannot perform non-noop casts!");
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assert(SE.getTypeSizeInBits(V->getType()) == SE.getTypeSizeInBits(Ty) &&
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"InsertNoopCastOfTo cannot change sizes!");
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// Short-circuit unnecessary bitcasts.
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if (Op == Instruction::BitCast && V->getType() == Ty)
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return V;
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// Short-circuit unnecessary inttoptr<->ptrtoint casts.
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if ((Op == Instruction::PtrToInt || Op == Instruction::IntToPtr) &&
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SE.getTypeSizeInBits(Ty) == SE.getTypeSizeInBits(V->getType())) {
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if (CastInst *CI = dyn_cast<CastInst>(V))
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if ((CI->getOpcode() == Instruction::PtrToInt ||
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CI->getOpcode() == Instruction::IntToPtr) &&
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SE.getTypeSizeInBits(CI->getType()) ==
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SE.getTypeSizeInBits(CI->getOperand(0)->getType()))
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return CI->getOperand(0);
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if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
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if ((CE->getOpcode() == Instruction::PtrToInt ||
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CE->getOpcode() == Instruction::IntToPtr) &&
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SE.getTypeSizeInBits(CE->getType()) ==
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SE.getTypeSizeInBits(CE->getOperand(0)->getType()))
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return CE->getOperand(0);
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}
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// FIXME: keep track of the cast instruction.
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if (Constant *C = dyn_cast<Constant>(V))
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return getContext()->getConstantExprCast(Op, C, Ty);
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if (Argument *A = dyn_cast<Argument>(V)) {
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// Check to see if there is already a cast!
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for (Value::use_iterator UI = A->use_begin(), E = A->use_end();
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UI != E; ++UI)
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if ((*UI)->getType() == Ty)
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if (CastInst *CI = dyn_cast<CastInst>(cast<Instruction>(*UI)))
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if (CI->getOpcode() == Op) {
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// If the cast isn't the first instruction of the function, move it.
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if (BasicBlock::iterator(CI) !=
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A->getParent()->getEntryBlock().begin()) {
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// Recreate the cast at the beginning of the entry block.
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// The old cast is left in place in case it is being used
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// as an insert point.
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Instruction *NewCI =
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CastInst::Create(Op, V, Ty, "",
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A->getParent()->getEntryBlock().begin());
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NewCI->takeName(CI);
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CI->replaceAllUsesWith(NewCI);
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return NewCI;
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}
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return CI;
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}
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Instruction *I = CastInst::Create(Op, V, Ty, V->getName(),
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A->getParent()->getEntryBlock().begin());
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InsertedValues.insert(I);
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return I;
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}
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Instruction *I = cast<Instruction>(V);
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// Check to see if there is already a cast. If there is, use it.
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for (Value::use_iterator UI = I->use_begin(), E = I->use_end();
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UI != E; ++UI) {
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if ((*UI)->getType() == Ty)
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if (CastInst *CI = dyn_cast<CastInst>(cast<Instruction>(*UI)))
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if (CI->getOpcode() == Op) {
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BasicBlock::iterator It = I; ++It;
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if (isa<InvokeInst>(I))
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It = cast<InvokeInst>(I)->getNormalDest()->begin();
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while (isa<PHINode>(It)) ++It;
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if (It != BasicBlock::iterator(CI)) {
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// Recreate the cast at the beginning of the entry block.
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// The old cast is left in place in case it is being used
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// as an insert point.
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Instruction *NewCI = CastInst::Create(Op, V, Ty, "", It);
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NewCI->takeName(CI);
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CI->replaceAllUsesWith(NewCI);
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return NewCI;
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}
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return CI;
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}
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}
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BasicBlock::iterator IP = I; ++IP;
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if (InvokeInst *II = dyn_cast<InvokeInst>(I))
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IP = II->getNormalDest()->begin();
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while (isa<PHINode>(IP)) ++IP;
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Instruction *CI = CastInst::Create(Op, V, Ty, V->getName(), IP);
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InsertedValues.insert(CI);
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return CI;
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}
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/// InsertBinop - Insert the specified binary operator, doing a small amount
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/// of work to avoid inserting an obviously redundant operation.
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Value *SCEVExpander::InsertBinop(Instruction::BinaryOps Opcode,
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Value *LHS, Value *RHS) {
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// Fold a binop with constant operands.
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if (Constant *CLHS = dyn_cast<Constant>(LHS))
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if (Constant *CRHS = dyn_cast<Constant>(RHS))
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return getContext()->getConstantExpr(Opcode, CLHS, CRHS);
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// Do a quick scan to see if we have this binop nearby. If so, reuse it.
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unsigned ScanLimit = 6;
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BasicBlock::iterator BlockBegin = Builder.GetInsertBlock()->begin();
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// Scanning starts from the last instruction before the insertion point.
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BasicBlock::iterator IP = Builder.GetInsertPoint();
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if (IP != BlockBegin) {
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--IP;
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for (; ScanLimit; --IP, --ScanLimit) {
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if (IP->getOpcode() == (unsigned)Opcode && IP->getOperand(0) == LHS &&
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IP->getOperand(1) == RHS)
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return IP;
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if (IP == BlockBegin) break;
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}
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}
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// If we haven't found this binop, insert it.
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Value *BO = Builder.CreateBinOp(Opcode, LHS, RHS, "tmp");
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InsertedValues.insert(BO);
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return BO;
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}
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/// FactorOutConstant - Test if S is divisible by Factor, using signed
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/// division. If so, update S with Factor divided out and return true.
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/// S need not be evenly divisble if a reasonable remainder can be
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/// computed.
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/// TODO: When ScalarEvolution gets a SCEVSDivExpr, this can be made
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/// unnecessary; in its place, just signed-divide Ops[i] by the scale and
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/// check to see if the divide was folded.
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static bool FactorOutConstant(const SCEV *&S,
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const SCEV *&Remainder,
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const APInt &Factor,
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ScalarEvolution &SE) {
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// Everything is divisible by one.
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if (Factor == 1)
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return true;
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// For a Constant, check for a multiple of the given factor.
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if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S)) {
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ConstantInt *CI =
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SE.getContext()->getConstantInt(C->getValue()->getValue().sdiv(Factor));
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// If the quotient is zero and the remainder is non-zero, reject
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// the value at this scale. It will be considered for subsequent
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// smaller scales.
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if (C->isZero() || !CI->isZero()) {
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const SCEV *Div = SE.getConstant(CI);
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S = Div;
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Remainder =
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SE.getAddExpr(Remainder,
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SE.getConstant(C->getValue()->getValue().srem(Factor)));
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return true;
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}
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}
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// In a Mul, check if there is a constant operand which is a multiple
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// of the given factor.
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if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(S))
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if (const SCEVConstant *C = dyn_cast<SCEVConstant>(M->getOperand(0)))
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if (!C->getValue()->getValue().srem(Factor)) {
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const SmallVectorImpl<const SCEV *> &MOperands = M->getOperands();
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SmallVector<const SCEV *, 4> NewMulOps(MOperands.begin(),
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MOperands.end());
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NewMulOps[0] =
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SE.getConstant(C->getValue()->getValue().sdiv(Factor));
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S = SE.getMulExpr(NewMulOps);
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return true;
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}
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// In an AddRec, check if both start and step are divisible.
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if (const SCEVAddRecExpr *A = dyn_cast<SCEVAddRecExpr>(S)) {
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const SCEV *Step = A->getStepRecurrence(SE);
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const SCEV *StepRem = SE.getIntegerSCEV(0, Step->getType());
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if (!FactorOutConstant(Step, StepRem, Factor, SE))
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return false;
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if (!StepRem->isZero())
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return false;
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const SCEV *Start = A->getStart();
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if (!FactorOutConstant(Start, Remainder, Factor, SE))
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return false;
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S = SE.getAddRecExpr(Start, Step, A->getLoop());
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return true;
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}
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return false;
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}
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/// expandAddToGEP - Expand a SCEVAddExpr with a pointer type into a GEP
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/// instead of using ptrtoint+arithmetic+inttoptr. This helps
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/// BasicAliasAnalysis analyze the result. However, it suffers from the
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/// underlying bug described in PR2831. Addition in LLVM currently always
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/// has two's complement wrapping guaranteed. However, the semantics for
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/// getelementptr overflow are ambiguous. In the common case though, this
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/// expansion gets used when a GEP in the original code has been converted
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/// into integer arithmetic, in which case the resulting code will be no
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/// more undefined than it was originally.
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///
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/// Design note: It might seem desirable for this function to be more
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/// loop-aware. If some of the indices are loop-invariant while others
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/// aren't, it might seem desirable to emit multiple GEPs, keeping the
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/// loop-invariant portions of the overall computation outside the loop.
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/// However, there are a few reasons this is not done here. Hoisting simple
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/// arithmetic is a low-level optimization that often isn't very
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/// important until late in the optimization process. In fact, passes
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/// like InstructionCombining will combine GEPs, even if it means
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/// pushing loop-invariant computation down into loops, so even if the
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/// GEPs were split here, the work would quickly be undone. The
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/// LoopStrengthReduction pass, which is usually run quite late (and
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/// after the last InstructionCombining pass), takes care of hoisting
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/// loop-invariant portions of expressions, after considering what
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/// can be folded using target addressing modes.
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///
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Value *SCEVExpander::expandAddToGEP(const SCEV *const *op_begin,
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const SCEV *const *op_end,
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const PointerType *PTy,
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const Type *Ty,
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Value *V) {
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const Type *ElTy = PTy->getElementType();
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SmallVector<Value *, 4> GepIndices;
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SmallVector<const SCEV *, 8> Ops(op_begin, op_end);
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bool AnyNonZeroIndices = false;
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// Decend down the pointer's type and attempt to convert the other
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// operands into GEP indices, at each level. The first index in a GEP
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// indexes into the array implied by the pointer operand; the rest of
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// the indices index into the element or field type selected by the
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// preceding index.
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for (;;) {
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APInt ElSize = APInt(SE.getTypeSizeInBits(Ty),
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ElTy->isSized() ? SE.TD->getTypeAllocSize(ElTy) : 0);
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SmallVector<const SCEV *, 8> NewOps;
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SmallVector<const SCEV *, 8> ScaledOps;
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for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
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// Split AddRecs up into parts as either of the parts may be usable
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// without the other.
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if (const SCEVAddRecExpr *A = dyn_cast<SCEVAddRecExpr>(Ops[i]))
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if (!A->getStart()->isZero()) {
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const SCEV *Start = A->getStart();
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Ops.push_back(SE.getAddRecExpr(SE.getIntegerSCEV(0, A->getType()),
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A->getStepRecurrence(SE),
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A->getLoop()));
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Ops[i] = Start;
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++e;
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}
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// If the scale size is not 0, attempt to factor out a scale.
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if (ElSize != 0) {
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const SCEV *Op = Ops[i];
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const SCEV *Remainder = SE.getIntegerSCEV(0, Op->getType());
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if (FactorOutConstant(Op, Remainder, ElSize, SE)) {
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ScaledOps.push_back(Op); // Op now has ElSize factored out.
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NewOps.push_back(Remainder);
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continue;
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}
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}
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// If the operand was not divisible, add it to the list of operands
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// we'll scan next iteration.
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NewOps.push_back(Ops[i]);
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}
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Ops = NewOps;
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AnyNonZeroIndices |= !ScaledOps.empty();
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Value *Scaled = ScaledOps.empty() ?
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getContext()->getNullValue(Ty) :
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expandCodeFor(SE.getAddExpr(ScaledOps), Ty);
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GepIndices.push_back(Scaled);
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// Collect struct field index operands.
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if (!Ops.empty())
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while (const StructType *STy = dyn_cast<StructType>(ElTy)) {
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if (const SCEVConstant *C = dyn_cast<SCEVConstant>(Ops[0]))
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if (SE.getTypeSizeInBits(C->getType()) <= 64) {
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const StructLayout &SL = *SE.TD->getStructLayout(STy);
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uint64_t FullOffset = C->getValue()->getZExtValue();
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if (FullOffset < SL.getSizeInBytes()) {
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unsigned ElIdx = SL.getElementContainingOffset(FullOffset);
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GepIndices.push_back(
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getContext()->getConstantInt(Type::Int32Ty, ElIdx));
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ElTy = STy->getTypeAtIndex(ElIdx);
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Ops[0] =
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SE.getConstant(Ty, FullOffset - SL.getElementOffset(ElIdx));
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AnyNonZeroIndices = true;
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continue;
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}
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}
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break;
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}
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if (const ArrayType *ATy = dyn_cast<ArrayType>(ElTy)) {
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ElTy = ATy->getElementType();
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continue;
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}
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break;
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}
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// If none of the operands were convertable to proper GEP indices, cast
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// the base to i8* and do an ugly getelementptr with that. It's still
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// better than ptrtoint+arithmetic+inttoptr at least.
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if (!AnyNonZeroIndices) {
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V = InsertNoopCastOfTo(V,
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Type::Int8Ty->getPointerTo(PTy->getAddressSpace()));
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Value *Idx = expandCodeFor(SE.getAddExpr(Ops), Ty);
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// Fold a GEP with constant operands.
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if (Constant *CLHS = dyn_cast<Constant>(V))
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if (Constant *CRHS = dyn_cast<Constant>(Idx))
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return getContext()->getConstantExprGetElementPtr(CLHS, &CRHS, 1);
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// Do a quick scan to see if we have this GEP nearby. If so, reuse it.
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unsigned ScanLimit = 6;
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BasicBlock::iterator BlockBegin = Builder.GetInsertBlock()->begin();
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// Scanning starts from the last instruction before the insertion point.
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BasicBlock::iterator IP = Builder.GetInsertPoint();
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if (IP != BlockBegin) {
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--IP;
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for (; ScanLimit; --IP, --ScanLimit) {
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if (IP->getOpcode() == Instruction::GetElementPtr &&
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IP->getOperand(0) == V && IP->getOperand(1) == Idx)
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return IP;
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if (IP == BlockBegin) break;
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}
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}
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Value *GEP = Builder.CreateGEP(V, Idx, "scevgep");
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InsertedValues.insert(GEP);
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return GEP;
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}
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// Insert a pretty getelementptr.
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Value *GEP = Builder.CreateGEP(V,
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GepIndices.begin(),
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GepIndices.end(),
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"scevgep");
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Ops.push_back(SE.getUnknown(GEP));
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InsertedValues.insert(GEP);
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return expand(SE.getAddExpr(Ops));
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}
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Value *SCEVExpander::visitAddExpr(const SCEVAddExpr *S) {
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const Type *Ty = SE.getEffectiveSCEVType(S->getType());
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Value *V = expand(S->getOperand(S->getNumOperands()-1));
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// Turn things like ptrtoint+arithmetic+inttoptr into GEP. See the
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// comments on expandAddToGEP for details.
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if (SE.TD)
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if (const PointerType *PTy = dyn_cast<PointerType>(V->getType())) {
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const SmallVectorImpl<const SCEV *> &Ops = S->getOperands();
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return expandAddToGEP(&Ops[0], &Ops[Ops.size() - 1], PTy, Ty, V);
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}
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V = InsertNoopCastOfTo(V, Ty);
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// Emit a bunch of add instructions
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for (int i = S->getNumOperands()-2; i >= 0; --i) {
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Value *W = expandCodeFor(S->getOperand(i), Ty);
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V = InsertBinop(Instruction::Add, V, W);
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}
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return V;
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}
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Value *SCEVExpander::visitMulExpr(const SCEVMulExpr *S) {
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const Type *Ty = SE.getEffectiveSCEVType(S->getType());
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int FirstOp = 0; // Set if we should emit a subtract.
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if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(S->getOperand(0)))
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if (SC->getValue()->isAllOnesValue())
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FirstOp = 1;
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int i = S->getNumOperands()-2;
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Value *V = expandCodeFor(S->getOperand(i+1), Ty);
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// Emit a bunch of multiply instructions
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for (; i >= FirstOp; --i) {
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Value *W = expandCodeFor(S->getOperand(i), Ty);
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V = InsertBinop(Instruction::Mul, V, W);
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}
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// -1 * ... ---> 0 - ...
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if (FirstOp == 1)
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V = InsertBinop(Instruction::Sub, getContext()->getNullValue(Ty), V);
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return V;
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}
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Value *SCEVExpander::visitUDivExpr(const SCEVUDivExpr *S) {
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const Type *Ty = SE.getEffectiveSCEVType(S->getType());
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Value *LHS = expandCodeFor(S->getLHS(), Ty);
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if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(S->getRHS())) {
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const APInt &RHS = SC->getValue()->getValue();
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if (RHS.isPowerOf2())
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return InsertBinop(Instruction::LShr, LHS,
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getContext()->getConstantInt(Ty, RHS.logBase2()));
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}
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Value *RHS = expandCodeFor(S->getRHS(), Ty);
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return InsertBinop(Instruction::UDiv, LHS, RHS);
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}
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/// Move parts of Base into Rest to leave Base with the minimal
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/// expression that provides a pointer operand suitable for a
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/// GEP expansion.
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static void ExposePointerBase(const SCEV *&Base, const SCEV *&Rest,
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ScalarEvolution &SE) {
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while (const SCEVAddRecExpr *A = dyn_cast<SCEVAddRecExpr>(Base)) {
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Base = A->getStart();
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Rest = SE.getAddExpr(Rest,
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SE.getAddRecExpr(SE.getIntegerSCEV(0, A->getType()),
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A->getStepRecurrence(SE),
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A->getLoop()));
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}
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if (const SCEVAddExpr *A = dyn_cast<SCEVAddExpr>(Base)) {
|
|
Base = A->getOperand(A->getNumOperands()-1);
|
|
SmallVector<const SCEV *, 8> NewAddOps(A->op_begin(), A->op_end());
|
|
NewAddOps.back() = Rest;
|
|
Rest = SE.getAddExpr(NewAddOps);
|
|
ExposePointerBase(Base, Rest, SE);
|
|
}
|
|
}
|
|
|
|
Value *SCEVExpander::visitAddRecExpr(const SCEVAddRecExpr *S) {
|
|
const Type *Ty = SE.getEffectiveSCEVType(S->getType());
|
|
const Loop *L = S->getLoop();
|
|
|
|
// First check for an existing canonical IV in a suitable type.
|
|
PHINode *CanonicalIV = 0;
|
|
if (PHINode *PN = L->getCanonicalInductionVariable())
|
|
if (SE.isSCEVable(PN->getType()) &&
|
|
isa<IntegerType>(SE.getEffectiveSCEVType(PN->getType())) &&
|
|
SE.getTypeSizeInBits(PN->getType()) >= SE.getTypeSizeInBits(Ty))
|
|
CanonicalIV = PN;
|
|
|
|
// Rewrite an AddRec in terms of the canonical induction variable, if
|
|
// its type is more narrow.
|
|
if (CanonicalIV &&
|
|
SE.getTypeSizeInBits(CanonicalIV->getType()) >
|
|
SE.getTypeSizeInBits(Ty)) {
|
|
const SCEV *Start = SE.getAnyExtendExpr(S->getStart(),
|
|
CanonicalIV->getType());
|
|
const SCEV *Step = SE.getAnyExtendExpr(S->getStepRecurrence(SE),
|
|
CanonicalIV->getType());
|
|
Value *V = expand(SE.getAddRecExpr(Start, Step, S->getLoop()));
|
|
BasicBlock *SaveInsertBB = Builder.GetInsertBlock();
|
|
BasicBlock::iterator SaveInsertPt = Builder.GetInsertPoint();
|
|
BasicBlock::iterator NewInsertPt =
|
|
next(BasicBlock::iterator(cast<Instruction>(V)));
|
|
while (isa<PHINode>(NewInsertPt)) ++NewInsertPt;
|
|
V = expandCodeFor(SE.getTruncateExpr(SE.getUnknown(V), Ty), 0,
|
|
NewInsertPt);
|
|
Builder.SetInsertPoint(SaveInsertBB, SaveInsertPt);
|
|
return V;
|
|
}
|
|
|
|
// {X,+,F} --> X + {0,+,F}
|
|
if (!S->getStart()->isZero()) {
|
|
const SmallVectorImpl<const SCEV *> &SOperands = S->getOperands();
|
|
SmallVector<const SCEV *, 4> NewOps(SOperands.begin(), SOperands.end());
|
|
NewOps[0] = SE.getIntegerSCEV(0, Ty);
|
|
const SCEV *Rest = SE.getAddRecExpr(NewOps, L);
|
|
|
|
// Turn things like ptrtoint+arithmetic+inttoptr into GEP. See the
|
|
// comments on expandAddToGEP for details.
|
|
if (SE.TD) {
|
|
const SCEV *Base = S->getStart();
|
|
const SCEV *RestArray[1] = { Rest };
|
|
// Dig into the expression to find the pointer base for a GEP.
|
|
ExposePointerBase(Base, RestArray[0], SE);
|
|
// If we found a pointer, expand the AddRec with a GEP.
|
|
if (const PointerType *PTy = dyn_cast<PointerType>(Base->getType())) {
|
|
// Make sure the Base isn't something exotic, such as a multiplied
|
|
// or divided pointer value. In those cases, the result type isn't
|
|
// actually a pointer type.
|
|
if (!isa<SCEVMulExpr>(Base) && !isa<SCEVUDivExpr>(Base)) {
|
|
Value *StartV = expand(Base);
|
|
assert(StartV->getType() == PTy && "Pointer type mismatch for GEP!");
|
|
return expandAddToGEP(RestArray, RestArray+1, PTy, Ty, StartV);
|
|
}
|
|
}
|
|
}
|
|
|
|
// Just do a normal add. Pre-expand the operands to suppress folding.
|
|
return expand(SE.getAddExpr(SE.getUnknown(expand(S->getStart())),
|
|
SE.getUnknown(expand(Rest))));
|
|
}
|
|
|
|
// {0,+,1} --> Insert a canonical induction variable into the loop!
|
|
if (S->isAffine() &&
|
|
S->getOperand(1) == SE.getIntegerSCEV(1, Ty)) {
|
|
// If there's a canonical IV, just use it.
|
|
if (CanonicalIV) {
|
|
assert(Ty == SE.getEffectiveSCEVType(CanonicalIV->getType()) &&
|
|
"IVs with types different from the canonical IV should "
|
|
"already have been handled!");
|
|
return CanonicalIV;
|
|
}
|
|
|
|
// Create and insert the PHI node for the induction variable in the
|
|
// specified loop.
|
|
BasicBlock *Header = L->getHeader();
|
|
BasicBlock *Preheader = L->getLoopPreheader();
|
|
PHINode *PN = PHINode::Create(Ty, "indvar", Header->begin());
|
|
InsertedValues.insert(PN);
|
|
PN->addIncoming(getContext()->getNullValue(Ty), Preheader);
|
|
|
|
pred_iterator HPI = pred_begin(Header);
|
|
assert(HPI != pred_end(Header) && "Loop with zero preds???");
|
|
if (!L->contains(*HPI)) ++HPI;
|
|
assert(HPI != pred_end(Header) && L->contains(*HPI) &&
|
|
"No backedge in loop?");
|
|
|
|
// Insert a unit add instruction right before the terminator corresponding
|
|
// to the back-edge.
|
|
Constant *One = getContext()->getConstantInt(Ty, 1);
|
|
Instruction *Add = BinaryOperator::CreateAdd(PN, One, "indvar.next",
|
|
(*HPI)->getTerminator());
|
|
InsertedValues.insert(Add);
|
|
|
|
pred_iterator PI = pred_begin(Header);
|
|
if (*PI == Preheader)
|
|
++PI;
|
|
PN->addIncoming(Add, *PI);
|
|
return PN;
|
|
}
|
|
|
|
// {0,+,F} --> {0,+,1} * F
|
|
// Get the canonical induction variable I for this loop.
|
|
Value *I = CanonicalIV ?
|
|
CanonicalIV :
|
|
getOrInsertCanonicalInductionVariable(L, Ty);
|
|
|
|
// If this is a simple linear addrec, emit it now as a special case.
|
|
if (S->isAffine()) // {0,+,F} --> i*F
|
|
return
|
|
expand(SE.getTruncateOrNoop(
|
|
SE.getMulExpr(SE.getUnknown(I),
|
|
SE.getNoopOrAnyExtend(S->getOperand(1),
|
|
I->getType())),
|
|
Ty));
|
|
|
|
// If this is a chain of recurrences, turn it into a closed form, using the
|
|
// folders, then expandCodeFor the closed form. This allows the folders to
|
|
// simplify the expression without having to build a bunch of special code
|
|
// into this folder.
|
|
const SCEV *IH = SE.getUnknown(I); // Get I as a "symbolic" SCEV.
|
|
|
|
// Promote S up to the canonical IV type, if the cast is foldable.
|
|
const SCEV *NewS = S;
|
|
const SCEV *Ext = SE.getNoopOrAnyExtend(S, I->getType());
|
|
if (isa<SCEVAddRecExpr>(Ext))
|
|
NewS = Ext;
|
|
|
|
const SCEV *V = cast<SCEVAddRecExpr>(NewS)->evaluateAtIteration(IH, SE);
|
|
//cerr << "Evaluated: " << *this << "\n to: " << *V << "\n";
|
|
|
|
// Truncate the result down to the original type, if needed.
|
|
const SCEV *T = SE.getTruncateOrNoop(V, Ty);
|
|
return expand(T);
|
|
}
|
|
|
|
Value *SCEVExpander::visitTruncateExpr(const SCEVTruncateExpr *S) {
|
|
const Type *Ty = SE.getEffectiveSCEVType(S->getType());
|
|
Value *V = expandCodeFor(S->getOperand(),
|
|
SE.getEffectiveSCEVType(S->getOperand()->getType()));
|
|
Value *I = Builder.CreateTrunc(V, Ty, "tmp");
|
|
InsertedValues.insert(I);
|
|
return I;
|
|
}
|
|
|
|
Value *SCEVExpander::visitZeroExtendExpr(const SCEVZeroExtendExpr *S) {
|
|
const Type *Ty = SE.getEffectiveSCEVType(S->getType());
|
|
Value *V = expandCodeFor(S->getOperand(),
|
|
SE.getEffectiveSCEVType(S->getOperand()->getType()));
|
|
Value *I = Builder.CreateZExt(V, Ty, "tmp");
|
|
InsertedValues.insert(I);
|
|
return I;
|
|
}
|
|
|
|
Value *SCEVExpander::visitSignExtendExpr(const SCEVSignExtendExpr *S) {
|
|
const Type *Ty = SE.getEffectiveSCEVType(S->getType());
|
|
Value *V = expandCodeFor(S->getOperand(),
|
|
SE.getEffectiveSCEVType(S->getOperand()->getType()));
|
|
Value *I = Builder.CreateSExt(V, Ty, "tmp");
|
|
InsertedValues.insert(I);
|
|
return I;
|
|
}
|
|
|
|
Value *SCEVExpander::visitSMaxExpr(const SCEVSMaxExpr *S) {
|
|
Value *LHS = expand(S->getOperand(S->getNumOperands()-1));
|
|
const Type *Ty = LHS->getType();
|
|
for (int i = S->getNumOperands()-2; i >= 0; --i) {
|
|
// In the case of mixed integer and pointer types, do the
|
|
// rest of the comparisons as integer.
|
|
if (S->getOperand(i)->getType() != Ty) {
|
|
Ty = SE.getEffectiveSCEVType(Ty);
|
|
LHS = InsertNoopCastOfTo(LHS, Ty);
|
|
}
|
|
Value *RHS = expandCodeFor(S->getOperand(i), Ty);
|
|
Value *ICmp = Builder.CreateICmpSGT(LHS, RHS, "tmp");
|
|
InsertedValues.insert(ICmp);
|
|
Value *Sel = Builder.CreateSelect(ICmp, LHS, RHS, "smax");
|
|
InsertedValues.insert(Sel);
|
|
LHS = Sel;
|
|
}
|
|
// In the case of mixed integer and pointer types, cast the
|
|
// final result back to the pointer type.
|
|
if (LHS->getType() != S->getType())
|
|
LHS = InsertNoopCastOfTo(LHS, S->getType());
|
|
return LHS;
|
|
}
|
|
|
|
Value *SCEVExpander::visitUMaxExpr(const SCEVUMaxExpr *S) {
|
|
Value *LHS = expand(S->getOperand(S->getNumOperands()-1));
|
|
const Type *Ty = LHS->getType();
|
|
for (int i = S->getNumOperands()-2; i >= 0; --i) {
|
|
// In the case of mixed integer and pointer types, do the
|
|
// rest of the comparisons as integer.
|
|
if (S->getOperand(i)->getType() != Ty) {
|
|
Ty = SE.getEffectiveSCEVType(Ty);
|
|
LHS = InsertNoopCastOfTo(LHS, Ty);
|
|
}
|
|
Value *RHS = expandCodeFor(S->getOperand(i), Ty);
|
|
Value *ICmp = Builder.CreateICmpUGT(LHS, RHS, "tmp");
|
|
InsertedValues.insert(ICmp);
|
|
Value *Sel = Builder.CreateSelect(ICmp, LHS, RHS, "umax");
|
|
InsertedValues.insert(Sel);
|
|
LHS = Sel;
|
|
}
|
|
// In the case of mixed integer and pointer types, cast the
|
|
// final result back to the pointer type.
|
|
if (LHS->getType() != S->getType())
|
|
LHS = InsertNoopCastOfTo(LHS, S->getType());
|
|
return LHS;
|
|
}
|
|
|
|
Value *SCEVExpander::expandCodeFor(const SCEV *SH, const Type *Ty) {
|
|
// Expand the code for this SCEV.
|
|
Value *V = expand(SH);
|
|
if (Ty) {
|
|
assert(SE.getTypeSizeInBits(Ty) == SE.getTypeSizeInBits(SH->getType()) &&
|
|
"non-trivial casts should be done with the SCEVs directly!");
|
|
V = InsertNoopCastOfTo(V, Ty);
|
|
}
|
|
return V;
|
|
}
|
|
|
|
Value *SCEVExpander::expand(const SCEV *S) {
|
|
// Compute an insertion point for this SCEV object. Hoist the instructions
|
|
// as far out in the loop nest as possible.
|
|
Instruction *InsertPt = Builder.GetInsertPoint();
|
|
for (Loop *L = SE.LI->getLoopFor(Builder.GetInsertBlock()); ;
|
|
L = L->getParentLoop())
|
|
if (S->isLoopInvariant(L)) {
|
|
if (!L) break;
|
|
if (BasicBlock *Preheader = L->getLoopPreheader())
|
|
InsertPt = Preheader->getTerminator();
|
|
} else {
|
|
// If the SCEV is computable at this level, insert it into the header
|
|
// after the PHIs (and after any other instructions that we've inserted
|
|
// there) so that it is guaranteed to dominate any user inside the loop.
|
|
if (L && S->hasComputableLoopEvolution(L))
|
|
InsertPt = L->getHeader()->getFirstNonPHI();
|
|
while (isInsertedInstruction(InsertPt))
|
|
InsertPt = next(BasicBlock::iterator(InsertPt));
|
|
break;
|
|
}
|
|
|
|
// Check to see if we already expanded this here.
|
|
std::map<std::pair<const SCEV *, Instruction *>,
|
|
AssertingVH<Value> >::iterator I =
|
|
InsertedExpressions.find(std::make_pair(S, InsertPt));
|
|
if (I != InsertedExpressions.end())
|
|
return I->second;
|
|
|
|
BasicBlock *SaveInsertBB = Builder.GetInsertBlock();
|
|
BasicBlock::iterator SaveInsertPt = Builder.GetInsertPoint();
|
|
Builder.SetInsertPoint(InsertPt->getParent(), InsertPt);
|
|
|
|
// Expand the expression into instructions.
|
|
Value *V = visit(S);
|
|
|
|
// Remember the expanded value for this SCEV at this location.
|
|
InsertedExpressions[std::make_pair(S, InsertPt)] = V;
|
|
|
|
Builder.SetInsertPoint(SaveInsertBB, SaveInsertPt);
|
|
return V;
|
|
}
|
|
|
|
/// getOrInsertCanonicalInductionVariable - This method returns the
|
|
/// canonical induction variable of the specified type for the specified
|
|
/// loop (inserting one if there is none). A canonical induction variable
|
|
/// starts at zero and steps by one on each iteration.
|
|
Value *
|
|
SCEVExpander::getOrInsertCanonicalInductionVariable(const Loop *L,
|
|
const Type *Ty) {
|
|
assert(Ty->isInteger() && "Can only insert integer induction variables!");
|
|
const SCEV *H = SE.getAddRecExpr(SE.getIntegerSCEV(0, Ty),
|
|
SE.getIntegerSCEV(1, Ty), L);
|
|
BasicBlock *SaveInsertBB = Builder.GetInsertBlock();
|
|
BasicBlock::iterator SaveInsertPt = Builder.GetInsertPoint();
|
|
Value *V = expandCodeFor(H, 0, L->getHeader()->begin());
|
|
if (SaveInsertBB)
|
|
Builder.SetInsertPoint(SaveInsertBB, SaveInsertPt);
|
|
return V;
|
|
}
|