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predecessor is itself. This doesn't make sense, and this is a dead infinite loop anyway. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60210 91177308-0d34-0410-b5e6-96231b3b80d8
1428 lines
53 KiB
C++
1428 lines
53 KiB
C++
//===- CodeGenPrepare.cpp - Prepare a function for code generation --------===//
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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 pass munges the code in the input function to better prepare it for
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// SelectionDAG-based code generation. This works around limitations in it's
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// basic-block-at-a-time approach. It should eventually be removed.
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//
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "codegenprepare"
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#include "llvm/Transforms/Scalar.h"
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#include "llvm/Constants.h"
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#include "llvm/DerivedTypes.h"
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#include "llvm/Function.h"
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#include "llvm/InlineAsm.h"
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#include "llvm/Instructions.h"
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#include "llvm/Pass.h"
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#include "llvm/Target/TargetAsmInfo.h"
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#include "llvm/Target/TargetData.h"
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#include "llvm/Target/TargetLowering.h"
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#include "llvm/Target/TargetMachine.h"
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#include "llvm/Transforms/Utils/BasicBlockUtils.h"
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#include "llvm/Transforms/Utils/Local.h"
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#include "llvm/ADT/DenseMap.h"
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#include "llvm/ADT/SmallSet.h"
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#include "llvm/Support/CallSite.h"
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#include "llvm/Support/Compiler.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/GetElementPtrTypeIterator.h"
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#include "llvm/Support/PatternMatch.h"
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using namespace llvm;
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using namespace llvm::PatternMatch;
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namespace {
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class VISIBILITY_HIDDEN CodeGenPrepare : public FunctionPass {
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/// TLI - Keep a pointer of a TargetLowering to consult for determining
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/// transformation profitability.
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const TargetLowering *TLI;
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public:
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static char ID; // Pass identification, replacement for typeid
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explicit CodeGenPrepare(const TargetLowering *tli = 0)
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: FunctionPass(&ID), TLI(tli) {}
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bool runOnFunction(Function &F);
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private:
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bool EliminateMostlyEmptyBlocks(Function &F);
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bool CanMergeBlocks(const BasicBlock *BB, const BasicBlock *DestBB) const;
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void EliminateMostlyEmptyBlock(BasicBlock *BB);
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bool OptimizeBlock(BasicBlock &BB);
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bool OptimizeMemoryInst(Instruction *I, Value *Addr, const Type *AccessTy,
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DenseMap<Value*,Value*> &SunkAddrs);
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bool OptimizeInlineAsmInst(Instruction *I, CallSite CS,
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DenseMap<Value*,Value*> &SunkAddrs);
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bool OptimizeExtUses(Instruction *I);
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};
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}
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char CodeGenPrepare::ID = 0;
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static RegisterPass<CodeGenPrepare> X("codegenprepare",
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"Optimize for code generation");
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FunctionPass *llvm::createCodeGenPreparePass(const TargetLowering *TLI) {
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return new CodeGenPrepare(TLI);
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}
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bool CodeGenPrepare::runOnFunction(Function &F) {
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bool EverMadeChange = false;
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// First pass, eliminate blocks that contain only PHI nodes and an
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// unconditional branch.
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EverMadeChange |= EliminateMostlyEmptyBlocks(F);
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bool MadeChange = true;
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while (MadeChange) {
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MadeChange = false;
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for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
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MadeChange |= OptimizeBlock(*BB);
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EverMadeChange |= MadeChange;
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}
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return EverMadeChange;
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}
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/// EliminateMostlyEmptyBlocks - eliminate blocks that contain only PHI nodes
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/// and an unconditional branch. Passes before isel (e.g. LSR/loopsimplify)
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/// often split edges in ways that are non-optimal for isel. Start by
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/// eliminating these blocks so we can split them the way we want them.
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bool CodeGenPrepare::EliminateMostlyEmptyBlocks(Function &F) {
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bool MadeChange = false;
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// Note that this intentionally skips the entry block.
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for (Function::iterator I = ++F.begin(), E = F.end(); I != E; ) {
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BasicBlock *BB = I++;
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// If this block doesn't end with an uncond branch, ignore it.
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BranchInst *BI = dyn_cast<BranchInst>(BB->getTerminator());
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if (!BI || !BI->isUnconditional())
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continue;
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// If the instruction before the branch isn't a phi node, then other stuff
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// is happening here.
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BasicBlock::iterator BBI = BI;
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if (BBI != BB->begin()) {
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--BBI;
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if (!isa<PHINode>(BBI)) continue;
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}
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// Do not break infinite loops.
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BasicBlock *DestBB = BI->getSuccessor(0);
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if (DestBB == BB)
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continue;
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if (!CanMergeBlocks(BB, DestBB))
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continue;
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EliminateMostlyEmptyBlock(BB);
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MadeChange = true;
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}
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return MadeChange;
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}
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/// CanMergeBlocks - Return true if we can merge BB into DestBB if there is a
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/// single uncond branch between them, and BB contains no other non-phi
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/// instructions.
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bool CodeGenPrepare::CanMergeBlocks(const BasicBlock *BB,
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const BasicBlock *DestBB) const {
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// We only want to eliminate blocks whose phi nodes are used by phi nodes in
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// the successor. If there are more complex condition (e.g. preheaders),
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// don't mess around with them.
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BasicBlock::const_iterator BBI = BB->begin();
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while (const PHINode *PN = dyn_cast<PHINode>(BBI++)) {
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for (Value::use_const_iterator UI = PN->use_begin(), E = PN->use_end();
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UI != E; ++UI) {
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const Instruction *User = cast<Instruction>(*UI);
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if (User->getParent() != DestBB || !isa<PHINode>(User))
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return false;
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// If User is inside DestBB block and it is a PHINode then check
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// incoming value. If incoming value is not from BB then this is
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// a complex condition (e.g. preheaders) we want to avoid here.
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if (User->getParent() == DestBB) {
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if (const PHINode *UPN = dyn_cast<PHINode>(User))
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for (unsigned I = 0, E = UPN->getNumIncomingValues(); I != E; ++I) {
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Instruction *Insn = dyn_cast<Instruction>(UPN->getIncomingValue(I));
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if (Insn && Insn->getParent() == BB &&
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Insn->getParent() != UPN->getIncomingBlock(I))
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return false;
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}
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}
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}
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}
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// If BB and DestBB contain any common predecessors, then the phi nodes in BB
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// and DestBB may have conflicting incoming values for the block. If so, we
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// can't merge the block.
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const PHINode *DestBBPN = dyn_cast<PHINode>(DestBB->begin());
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if (!DestBBPN) return true; // no conflict.
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// Collect the preds of BB.
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SmallPtrSet<const BasicBlock*, 16> BBPreds;
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if (const PHINode *BBPN = dyn_cast<PHINode>(BB->begin())) {
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// It is faster to get preds from a PHI than with pred_iterator.
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for (unsigned i = 0, e = BBPN->getNumIncomingValues(); i != e; ++i)
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BBPreds.insert(BBPN->getIncomingBlock(i));
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} else {
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BBPreds.insert(pred_begin(BB), pred_end(BB));
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}
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// Walk the preds of DestBB.
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for (unsigned i = 0, e = DestBBPN->getNumIncomingValues(); i != e; ++i) {
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BasicBlock *Pred = DestBBPN->getIncomingBlock(i);
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if (BBPreds.count(Pred)) { // Common predecessor?
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BBI = DestBB->begin();
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while (const PHINode *PN = dyn_cast<PHINode>(BBI++)) {
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const Value *V1 = PN->getIncomingValueForBlock(Pred);
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const Value *V2 = PN->getIncomingValueForBlock(BB);
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// If V2 is a phi node in BB, look up what the mapped value will be.
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if (const PHINode *V2PN = dyn_cast<PHINode>(V2))
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if (V2PN->getParent() == BB)
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V2 = V2PN->getIncomingValueForBlock(Pred);
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// If there is a conflict, bail out.
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if (V1 != V2) return false;
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}
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}
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}
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return true;
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}
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/// EliminateMostlyEmptyBlock - Eliminate a basic block that have only phi's and
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/// an unconditional branch in it.
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void CodeGenPrepare::EliminateMostlyEmptyBlock(BasicBlock *BB) {
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BranchInst *BI = cast<BranchInst>(BB->getTerminator());
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BasicBlock *DestBB = BI->getSuccessor(0);
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DOUT << "MERGING MOSTLY EMPTY BLOCKS - BEFORE:\n" << *BB << *DestBB;
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// If the destination block has a single pred, then this is a trivial edge,
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// just collapse it.
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if (BasicBlock *SinglePred = DestBB->getSinglePredecessor()) {
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if (SinglePred != DestBB) {
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// Remember if SinglePred was the entry block of the function. If so, we
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// will need to move BB back to the entry position.
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bool isEntry = SinglePred == &SinglePred->getParent()->getEntryBlock();
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MergeBasicBlockIntoOnlyPred(DestBB);
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if (isEntry && BB != &BB->getParent()->getEntryBlock())
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BB->moveBefore(&BB->getParent()->getEntryBlock());
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DOUT << "AFTER:\n" << *DestBB << "\n\n\n";
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return;
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}
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}
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// Otherwise, we have multiple predecessors of BB. Update the PHIs in DestBB
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// to handle the new incoming edges it is about to have.
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PHINode *PN;
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for (BasicBlock::iterator BBI = DestBB->begin();
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(PN = dyn_cast<PHINode>(BBI)); ++BBI) {
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// Remove the incoming value for BB, and remember it.
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Value *InVal = PN->removeIncomingValue(BB, false);
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// Two options: either the InVal is a phi node defined in BB or it is some
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// value that dominates BB.
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PHINode *InValPhi = dyn_cast<PHINode>(InVal);
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if (InValPhi && InValPhi->getParent() == BB) {
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// Add all of the input values of the input PHI as inputs of this phi.
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for (unsigned i = 0, e = InValPhi->getNumIncomingValues(); i != e; ++i)
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PN->addIncoming(InValPhi->getIncomingValue(i),
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InValPhi->getIncomingBlock(i));
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} else {
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// Otherwise, add one instance of the dominating value for each edge that
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// we will be adding.
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if (PHINode *BBPN = dyn_cast<PHINode>(BB->begin())) {
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for (unsigned i = 0, e = BBPN->getNumIncomingValues(); i != e; ++i)
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PN->addIncoming(InVal, BBPN->getIncomingBlock(i));
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} else {
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for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI)
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PN->addIncoming(InVal, *PI);
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}
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}
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}
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// The PHIs are now updated, change everything that refers to BB to use
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// DestBB and remove BB.
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BB->replaceAllUsesWith(DestBB);
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BB->eraseFromParent();
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DOUT << "AFTER:\n" << *DestBB << "\n\n\n";
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}
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/// SplitEdgeNicely - Split the critical edge from TI to its specified
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/// successor if it will improve codegen. We only do this if the successor has
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/// phi nodes (otherwise critical edges are ok). If there is already another
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/// predecessor of the succ that is empty (and thus has no phi nodes), use it
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/// instead of introducing a new block.
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static void SplitEdgeNicely(TerminatorInst *TI, unsigned SuccNum, Pass *P) {
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BasicBlock *TIBB = TI->getParent();
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BasicBlock *Dest = TI->getSuccessor(SuccNum);
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assert(isa<PHINode>(Dest->begin()) &&
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"This should only be called if Dest has a PHI!");
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// As a hack, never split backedges of loops. Even though the copy for any
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// PHIs inserted on the backedge would be dead for exits from the loop, we
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// assume that the cost of *splitting* the backedge would be too high.
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if (Dest == TIBB)
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return;
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/// TIPHIValues - This array is lazily computed to determine the values of
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/// PHIs in Dest that TI would provide.
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SmallVector<Value*, 32> TIPHIValues;
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// Check to see if Dest has any blocks that can be used as a split edge for
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// this terminator.
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for (pred_iterator PI = pred_begin(Dest), E = pred_end(Dest); PI != E; ++PI) {
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BasicBlock *Pred = *PI;
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// To be usable, the pred has to end with an uncond branch to the dest.
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BranchInst *PredBr = dyn_cast<BranchInst>(Pred->getTerminator());
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if (!PredBr || !PredBr->isUnconditional() ||
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// Must be empty other than the branch.
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&Pred->front() != PredBr ||
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// Cannot be the entry block; its label does not get emitted.
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Pred == &(Dest->getParent()->getEntryBlock()))
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continue;
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// Finally, since we know that Dest has phi nodes in it, we have to make
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// sure that jumping to Pred will have the same affect as going to Dest in
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// terms of PHI values.
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PHINode *PN;
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unsigned PHINo = 0;
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bool FoundMatch = true;
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for (BasicBlock::iterator I = Dest->begin();
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(PN = dyn_cast<PHINode>(I)); ++I, ++PHINo) {
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if (PHINo == TIPHIValues.size())
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TIPHIValues.push_back(PN->getIncomingValueForBlock(TIBB));
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// If the PHI entry doesn't work, we can't use this pred.
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if (TIPHIValues[PHINo] != PN->getIncomingValueForBlock(Pred)) {
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FoundMatch = false;
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break;
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}
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}
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// If we found a workable predecessor, change TI to branch to Succ.
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if (FoundMatch) {
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Dest->removePredecessor(TIBB);
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TI->setSuccessor(SuccNum, Pred);
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return;
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}
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}
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SplitCriticalEdge(TI, SuccNum, P, true);
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}
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/// OptimizeNoopCopyExpression - If the specified cast instruction is a noop
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/// copy (e.g. it's casting from one pointer type to another, int->uint, or
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/// int->sbyte on PPC), sink it into user blocks to reduce the number of virtual
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/// registers that must be created and coalesced.
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///
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/// Return true if any changes are made.
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///
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static bool OptimizeNoopCopyExpression(CastInst *CI, const TargetLowering &TLI){
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// If this is a noop copy,
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MVT SrcVT = TLI.getValueType(CI->getOperand(0)->getType());
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MVT DstVT = TLI.getValueType(CI->getType());
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// This is an fp<->int conversion?
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if (SrcVT.isInteger() != DstVT.isInteger())
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return false;
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// If this is an extension, it will be a zero or sign extension, which
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// isn't a noop.
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if (SrcVT.bitsLT(DstVT)) return false;
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// If these values will be promoted, find out what they will be promoted
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// to. This helps us consider truncates on PPC as noop copies when they
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// are.
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if (TLI.getTypeAction(SrcVT) == TargetLowering::Promote)
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SrcVT = TLI.getTypeToTransformTo(SrcVT);
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if (TLI.getTypeAction(DstVT) == TargetLowering::Promote)
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DstVT = TLI.getTypeToTransformTo(DstVT);
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// If, after promotion, these are the same types, this is a noop copy.
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if (SrcVT != DstVT)
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return false;
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BasicBlock *DefBB = CI->getParent();
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/// InsertedCasts - Only insert a cast in each block once.
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DenseMap<BasicBlock*, CastInst*> InsertedCasts;
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bool MadeChange = false;
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for (Value::use_iterator UI = CI->use_begin(), E = CI->use_end();
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UI != E; ) {
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Use &TheUse = UI.getUse();
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Instruction *User = cast<Instruction>(*UI);
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// Figure out which BB this cast is used in. For PHI's this is the
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// appropriate predecessor block.
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BasicBlock *UserBB = User->getParent();
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if (PHINode *PN = dyn_cast<PHINode>(User)) {
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unsigned OpVal = UI.getOperandNo()/2;
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UserBB = PN->getIncomingBlock(OpVal);
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}
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// Preincrement use iterator so we don't invalidate it.
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++UI;
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// If this user is in the same block as the cast, don't change the cast.
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if (UserBB == DefBB) continue;
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// If we have already inserted a cast into this block, use it.
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CastInst *&InsertedCast = InsertedCasts[UserBB];
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if (!InsertedCast) {
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BasicBlock::iterator InsertPt = UserBB->getFirstNonPHI();
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InsertedCast =
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CastInst::Create(CI->getOpcode(), CI->getOperand(0), CI->getType(), "",
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InsertPt);
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MadeChange = true;
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}
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// Replace a use of the cast with a use of the new cast.
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TheUse = InsertedCast;
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}
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// If we removed all uses, nuke the cast.
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if (CI->use_empty()) {
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CI->eraseFromParent();
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MadeChange = true;
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}
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return MadeChange;
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}
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/// OptimizeCmpExpression - sink the given CmpInst into user blocks to reduce
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/// the number of virtual registers that must be created and coalesced. This is
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/// a clear win except on targets with multiple condition code registers
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/// (PowerPC), where it might lose; some adjustment may be wanted there.
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///
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/// Return true if any changes are made.
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static bool OptimizeCmpExpression(CmpInst *CI) {
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BasicBlock *DefBB = CI->getParent();
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/// InsertedCmp - Only insert a cmp in each block once.
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DenseMap<BasicBlock*, CmpInst*> InsertedCmps;
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bool MadeChange = false;
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for (Value::use_iterator UI = CI->use_begin(), E = CI->use_end();
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UI != E; ) {
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Use &TheUse = UI.getUse();
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Instruction *User = cast<Instruction>(*UI);
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// Preincrement use iterator so we don't invalidate it.
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++UI;
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// Don't bother for PHI nodes.
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if (isa<PHINode>(User))
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continue;
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// Figure out which BB this cmp is used in.
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BasicBlock *UserBB = User->getParent();
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// If this user is in the same block as the cmp, don't change the cmp.
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if (UserBB == DefBB) continue;
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// If we have already inserted a cmp into this block, use it.
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CmpInst *&InsertedCmp = InsertedCmps[UserBB];
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if (!InsertedCmp) {
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BasicBlock::iterator InsertPt = UserBB->getFirstNonPHI();
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InsertedCmp =
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CmpInst::Create(CI->getOpcode(), CI->getPredicate(), CI->getOperand(0),
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CI->getOperand(1), "", InsertPt);
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MadeChange = true;
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}
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// Replace a use of the cmp with a use of the new cmp.
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TheUse = InsertedCmp;
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}
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// If we removed all uses, nuke the cmp.
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if (CI->use_empty())
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CI->eraseFromParent();
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return MadeChange;
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}
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//===----------------------------------------------------------------------===//
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// Addressing Mode Analysis and Optimization
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//===----------------------------------------------------------------------===//
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namespace {
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/// ExtAddrMode - This is an extended version of TargetLowering::AddrMode
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/// which holds actual Value*'s for register values.
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struct ExtAddrMode : public TargetLowering::AddrMode {
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Value *BaseReg;
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Value *ScaledReg;
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ExtAddrMode() : BaseReg(0), ScaledReg(0) {}
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void print(OStream &OS) const;
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void dump() const {
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print(cerr);
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cerr << '\n';
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}
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};
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} // end anonymous namespace
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static inline OStream &operator<<(OStream &OS, const ExtAddrMode &AM) {
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AM.print(OS);
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return OS;
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}
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void ExtAddrMode::print(OStream &OS) const {
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bool NeedPlus = false;
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OS << "[";
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if (BaseGV)
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OS << (NeedPlus ? " + " : "")
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<< "GV:%" << BaseGV->getName(), NeedPlus = true;
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if (BaseOffs)
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OS << (NeedPlus ? " + " : "") << BaseOffs, NeedPlus = true;
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if (BaseReg)
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OS << (NeedPlus ? " + " : "")
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<< "Base:%" << BaseReg->getName(), NeedPlus = true;
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if (Scale)
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OS << (NeedPlus ? " + " : "")
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<< Scale << "*%" << ScaledReg->getName(), NeedPlus = true;
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OS << ']';
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}
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namespace {
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/// AddressingModeMatcher - This class exposes a single public method, which is
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/// used to construct a "maximal munch" of the addressing mode for the target
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/// specified by TLI for an access to "V" with an access type of AccessTy. This
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/// returns the addressing mode that is actually matched by value, but also
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/// returns the list of instructions involved in that addressing computation in
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/// AddrModeInsts.
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class AddressingModeMatcher {
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SmallVectorImpl<Instruction*> &AddrModeInsts;
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const TargetLowering &TLI;
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/// AccessTy/MemoryInst - This is the type for the access (e.g. double) and
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/// the memory instruction that we're computing this address for.
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const Type *AccessTy;
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Instruction *MemoryInst;
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/// AddrMode - This is the addressing mode that we're building up. This is
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/// part of the return value of this addressing mode matching stuff.
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ExtAddrMode &AddrMode;
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/// IgnoreProfitability - This is set to true when we should not do
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/// profitability checks. When true, IsProfitableToFoldIntoAddressingMode
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/// always returns true.
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bool IgnoreProfitability;
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AddressingModeMatcher(SmallVectorImpl<Instruction*> &AMI,
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const TargetLowering &T, const Type *AT,
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Instruction *MI, ExtAddrMode &AM)
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: AddrModeInsts(AMI), TLI(T), AccessTy(AT), MemoryInst(MI), AddrMode(AM) {
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IgnoreProfitability = false;
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}
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public:
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/// Match - Find the maximal addressing mode that a load/store of V can fold,
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/// give an access type of AccessTy. This returns a list of involved
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/// instructions in AddrModeInsts.
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static ExtAddrMode Match(Value *V, const Type *AccessTy,
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Instruction *MemoryInst,
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SmallVectorImpl<Instruction*> &AddrModeInsts,
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const TargetLowering &TLI) {
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ExtAddrMode Result;
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bool Success =
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AddressingModeMatcher(AddrModeInsts, TLI, AccessTy,
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MemoryInst, Result).MatchAddr(V, 0);
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Success = Success; assert(Success && "Couldn't select *anything*?");
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return Result;
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}
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private:
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bool MatchScaledValue(Value *ScaleReg, int64_t Scale, unsigned Depth);
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bool MatchAddr(Value *V, unsigned Depth);
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bool MatchOperationAddr(User *Operation, unsigned Opcode, unsigned Depth);
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bool IsProfitableToFoldIntoAddressingMode(Instruction *I,
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ExtAddrMode &AMBefore,
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ExtAddrMode &AMAfter);
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bool ValueAlreadyLiveAtInst(Value *Val, Value *KnownLive1, Value *KnownLive2);
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};
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} // end anonymous namespace
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/// MatchScaledValue - Try adding ScaleReg*Scale to the current addressing mode.
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/// Return true and update AddrMode if this addr mode is legal for the target,
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/// false if not.
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bool AddressingModeMatcher::MatchScaledValue(Value *ScaleReg, int64_t Scale,
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unsigned Depth) {
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// If Scale is 1, then this is the same as adding ScaleReg to the addressing
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// mode. Just process that directly.
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if (Scale == 1)
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return MatchAddr(ScaleReg, Depth);
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// If the scale is 0, it takes nothing to add this.
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if (Scale == 0)
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return true;
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// If we already have a scale of this value, we can add to it, otherwise, we
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// need an available scale field.
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if (AddrMode.Scale != 0 && AddrMode.ScaledReg != ScaleReg)
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return false;
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ExtAddrMode TestAddrMode = AddrMode;
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// Add scale to turn X*4+X*3 -> X*7. This could also do things like
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// [A+B + A*7] -> [B+A*8].
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TestAddrMode.Scale += Scale;
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TestAddrMode.ScaledReg = ScaleReg;
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// If the new address isn't legal, bail out.
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if (!TLI.isLegalAddressingMode(TestAddrMode, AccessTy))
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return false;
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// It was legal, so commit it.
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AddrMode = TestAddrMode;
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// Okay, we decided that we can add ScaleReg+Scale to AddrMode. Check now
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// to see if ScaleReg is actually X+C. If so, we can turn this into adding
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// X*Scale + C*Scale to addr mode.
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ConstantInt *CI; Value *AddLHS;
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if (match(ScaleReg, m_Add(m_Value(AddLHS), m_ConstantInt(CI)))) {
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TestAddrMode.ScaledReg = AddLHS;
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TestAddrMode.BaseOffs += CI->getSExtValue()*TestAddrMode.Scale;
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// If this addressing mode is legal, commit it and remember that we folded
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// this instruction.
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if (TLI.isLegalAddressingMode(TestAddrMode, AccessTy)) {
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AddrModeInsts.push_back(cast<Instruction>(ScaleReg));
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AddrMode = TestAddrMode;
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return true;
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}
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}
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// Otherwise, not (x+c)*scale, just return what we have.
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return true;
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}
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/// MightBeFoldableInst - This is a little filter, which returns true if an
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/// addressing computation involving I might be folded into a load/store
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/// accessing it. This doesn't need to be perfect, but needs to accept at least
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/// the set of instructions that MatchOperationAddr can.
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static bool MightBeFoldableInst(Instruction *I) {
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switch (I->getOpcode()) {
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case Instruction::BitCast:
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// Don't touch identity bitcasts.
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if (I->getType() == I->getOperand(0)->getType())
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return false;
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return isa<PointerType>(I->getType()) || isa<IntegerType>(I->getType());
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case Instruction::PtrToInt:
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// PtrToInt is always a noop, as we know that the int type is pointer sized.
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return true;
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case Instruction::IntToPtr:
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// We know the input is intptr_t, so this is foldable.
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return true;
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case Instruction::Add:
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return true;
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case Instruction::Mul:
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case Instruction::Shl:
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// Can only handle X*C and X << C.
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return isa<ConstantInt>(I->getOperand(1));
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case Instruction::GetElementPtr:
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return true;
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default:
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return false;
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}
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}
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/// MatchOperationAddr - Given an instruction or constant expr, see if we can
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/// fold the operation into the addressing mode. If so, update the addressing
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/// mode and return true, otherwise return false without modifying AddrMode.
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bool AddressingModeMatcher::MatchOperationAddr(User *AddrInst, unsigned Opcode,
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unsigned Depth) {
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// Avoid exponential behavior on extremely deep expression trees.
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if (Depth >= 5) return false;
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switch (Opcode) {
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case Instruction::PtrToInt:
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// PtrToInt is always a noop, as we know that the int type is pointer sized.
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return MatchAddr(AddrInst->getOperand(0), Depth);
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case Instruction::IntToPtr:
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// This inttoptr is a no-op if the integer type is pointer sized.
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if (TLI.getValueType(AddrInst->getOperand(0)->getType()) ==
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TLI.getPointerTy())
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return MatchAddr(AddrInst->getOperand(0), Depth);
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return false;
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case Instruction::BitCast:
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// BitCast is always a noop, and we can handle it as long as it is
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// int->int or pointer->pointer (we don't want int<->fp or something).
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if ((isa<PointerType>(AddrInst->getOperand(0)->getType()) ||
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isa<IntegerType>(AddrInst->getOperand(0)->getType())) &&
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// Don't touch identity bitcasts. These were probably put here by LSR,
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// and we don't want to mess around with them. Assume it knows what it
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// is doing.
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AddrInst->getOperand(0)->getType() != AddrInst->getType())
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return MatchAddr(AddrInst->getOperand(0), Depth);
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return false;
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case Instruction::Add: {
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// Check to see if we can merge in the RHS then the LHS. If so, we win.
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ExtAddrMode BackupAddrMode = AddrMode;
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unsigned OldSize = AddrModeInsts.size();
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if (MatchAddr(AddrInst->getOperand(1), Depth+1) &&
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MatchAddr(AddrInst->getOperand(0), Depth+1))
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return true;
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// Restore the old addr mode info.
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AddrMode = BackupAddrMode;
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AddrModeInsts.resize(OldSize);
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// Otherwise this was over-aggressive. Try merging in the LHS then the RHS.
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if (MatchAddr(AddrInst->getOperand(0), Depth+1) &&
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MatchAddr(AddrInst->getOperand(1), Depth+1))
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return true;
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// Otherwise we definitely can't merge the ADD in.
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AddrMode = BackupAddrMode;
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AddrModeInsts.resize(OldSize);
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break;
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}
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//case Instruction::Or:
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// TODO: We can handle "Or Val, Imm" iff this OR is equivalent to an ADD.
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//break;
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case Instruction::Mul:
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case Instruction::Shl: {
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// Can only handle X*C and X << C.
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ConstantInt *RHS = dyn_cast<ConstantInt>(AddrInst->getOperand(1));
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if (!RHS) return false;
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int64_t Scale = RHS->getSExtValue();
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if (Opcode == Instruction::Shl)
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Scale = 1 << Scale;
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return MatchScaledValue(AddrInst->getOperand(0), Scale, Depth);
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}
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case Instruction::GetElementPtr: {
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// Scan the GEP. We check it if it contains constant offsets and at most
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// one variable offset.
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int VariableOperand = -1;
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unsigned VariableScale = 0;
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int64_t ConstantOffset = 0;
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const TargetData *TD = TLI.getTargetData();
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gep_type_iterator GTI = gep_type_begin(AddrInst);
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for (unsigned i = 1, e = AddrInst->getNumOperands(); i != e; ++i, ++GTI) {
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if (const StructType *STy = dyn_cast<StructType>(*GTI)) {
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const StructLayout *SL = TD->getStructLayout(STy);
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unsigned Idx =
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cast<ConstantInt>(AddrInst->getOperand(i))->getZExtValue();
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ConstantOffset += SL->getElementOffset(Idx);
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} else {
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uint64_t TypeSize = TD->getABITypeSize(GTI.getIndexedType());
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if (ConstantInt *CI = dyn_cast<ConstantInt>(AddrInst->getOperand(i))) {
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ConstantOffset += CI->getSExtValue()*TypeSize;
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} else if (TypeSize) { // Scales of zero don't do anything.
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// We only allow one variable index at the moment.
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if (VariableOperand != -1)
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return false;
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// Remember the variable index.
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VariableOperand = i;
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VariableScale = TypeSize;
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}
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}
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}
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// A common case is for the GEP to only do a constant offset. In this case,
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// just add it to the disp field and check validity.
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if (VariableOperand == -1) {
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AddrMode.BaseOffs += ConstantOffset;
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if (ConstantOffset == 0 || TLI.isLegalAddressingMode(AddrMode, AccessTy)){
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// Check to see if we can fold the base pointer in too.
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if (MatchAddr(AddrInst->getOperand(0), Depth+1))
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return true;
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}
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AddrMode.BaseOffs -= ConstantOffset;
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return false;
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}
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// Save the valid addressing mode in case we can't match.
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ExtAddrMode BackupAddrMode = AddrMode;
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// Check that this has no base reg yet. If so, we won't have a place to
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// put the base of the GEP (assuming it is not a null ptr).
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bool SetBaseReg = true;
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if (isa<ConstantPointerNull>(AddrInst->getOperand(0)))
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SetBaseReg = false; // null pointer base doesn't need representation.
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else if (AddrMode.HasBaseReg)
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return false; // Base register already specified, can't match GEP.
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else {
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// Otherwise, we'll use the GEP base as the BaseReg.
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AddrMode.HasBaseReg = true;
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AddrMode.BaseReg = AddrInst->getOperand(0);
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}
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// See if the scale and offset amount is valid for this target.
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AddrMode.BaseOffs += ConstantOffset;
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if (!MatchScaledValue(AddrInst->getOperand(VariableOperand), VariableScale,
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Depth)) {
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AddrMode = BackupAddrMode;
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return false;
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}
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// If we have a null as the base of the GEP, folding in the constant offset
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// plus variable scale is all we can do.
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if (!SetBaseReg) return true;
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// If this match succeeded, we know that we can form an address with the
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// GepBase as the basereg. Match the base pointer of the GEP more
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// aggressively by zeroing out BaseReg and rematching. If the base is
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// (for example) another GEP, this allows merging in that other GEP into
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// the addressing mode we're forming.
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AddrMode.HasBaseReg = false;
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AddrMode.BaseReg = 0;
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bool Success = MatchAddr(AddrInst->getOperand(0), Depth+1);
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assert(Success && "MatchAddr should be able to fill in BaseReg!");
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Success=Success;
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return true;
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}
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}
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return false;
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}
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|
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/// MatchAddr - If we can, try to add the value of 'Addr' into the current
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/// addressing mode. If Addr can't be added to AddrMode this returns false and
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/// leaves AddrMode unmodified. This assumes that Addr is either a pointer type
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/// or intptr_t for the target.
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///
|
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bool AddressingModeMatcher::MatchAddr(Value *Addr, unsigned Depth) {
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if (ConstantInt *CI = dyn_cast<ConstantInt>(Addr)) {
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// Fold in immediates if legal for the target.
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AddrMode.BaseOffs += CI->getSExtValue();
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if (TLI.isLegalAddressingMode(AddrMode, AccessTy))
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return true;
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AddrMode.BaseOffs -= CI->getSExtValue();
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} else if (GlobalValue *GV = dyn_cast<GlobalValue>(Addr)) {
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// If this is a global variable, try to fold it into the addressing mode.
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if (AddrMode.BaseGV == 0) {
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AddrMode.BaseGV = GV;
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if (TLI.isLegalAddressingMode(AddrMode, AccessTy))
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return true;
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AddrMode.BaseGV = 0;
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}
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} else if (Instruction *I = dyn_cast<Instruction>(Addr)) {
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ExtAddrMode BackupAddrMode = AddrMode;
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unsigned OldSize = AddrModeInsts.size();
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|
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// Check to see if it is possible to fold this operation.
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if (MatchOperationAddr(I, I->getOpcode(), Depth)) {
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// Okay, it's possible to fold this. Check to see if it is actually
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// *profitable* to do so. We use a simple cost model to avoid increasing
|
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// register pressure too much.
|
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if (I->hasOneUse() ||
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IsProfitableToFoldIntoAddressingMode(I, BackupAddrMode, AddrMode)) {
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AddrModeInsts.push_back(I);
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return true;
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}
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|
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// It isn't profitable to do this, roll back.
|
|
//cerr << "NOT FOLDING: " << *I;
|
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AddrMode = BackupAddrMode;
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AddrModeInsts.resize(OldSize);
|
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}
|
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} else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Addr)) {
|
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if (MatchOperationAddr(CE, CE->getOpcode(), Depth))
|
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return true;
|
|
} else if (isa<ConstantPointerNull>(Addr)) {
|
|
// Null pointer gets folded without affecting the addressing mode.
|
|
return true;
|
|
}
|
|
|
|
// Worse case, the target should support [reg] addressing modes. :)
|
|
if (!AddrMode.HasBaseReg) {
|
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AddrMode.HasBaseReg = true;
|
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AddrMode.BaseReg = Addr;
|
|
// Still check for legality in case the target supports [imm] but not [i+r].
|
|
if (TLI.isLegalAddressingMode(AddrMode, AccessTy))
|
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return true;
|
|
AddrMode.HasBaseReg = false;
|
|
AddrMode.BaseReg = 0;
|
|
}
|
|
|
|
// If the base register is already taken, see if we can do [r+r].
|
|
if (AddrMode.Scale == 0) {
|
|
AddrMode.Scale = 1;
|
|
AddrMode.ScaledReg = Addr;
|
|
if (TLI.isLegalAddressingMode(AddrMode, AccessTy))
|
|
return true;
|
|
AddrMode.Scale = 0;
|
|
AddrMode.ScaledReg = 0;
|
|
}
|
|
// Couldn't match.
|
|
return false;
|
|
}
|
|
|
|
|
|
/// IsOperandAMemoryOperand - Check to see if all uses of OpVal by the specified
|
|
/// inline asm call are due to memory operands. If so, return true, otherwise
|
|
/// return false.
|
|
static bool IsOperandAMemoryOperand(CallInst *CI, InlineAsm *IA, Value *OpVal,
|
|
const TargetLowering &TLI) {
|
|
std::vector<InlineAsm::ConstraintInfo>
|
|
Constraints = IA->ParseConstraints();
|
|
|
|
unsigned ArgNo = 1; // ArgNo - The operand of the CallInst.
|
|
for (unsigned i = 0, e = Constraints.size(); i != e; ++i) {
|
|
TargetLowering::AsmOperandInfo OpInfo(Constraints[i]);
|
|
|
|
// Compute the value type for each operand.
|
|
switch (OpInfo.Type) {
|
|
case InlineAsm::isOutput:
|
|
if (OpInfo.isIndirect)
|
|
OpInfo.CallOperandVal = CI->getOperand(ArgNo++);
|
|
break;
|
|
case InlineAsm::isInput:
|
|
OpInfo.CallOperandVal = CI->getOperand(ArgNo++);
|
|
break;
|
|
case InlineAsm::isClobber:
|
|
// Nothing to do.
|
|
break;
|
|
}
|
|
|
|
// Compute the constraint code and ConstraintType to use.
|
|
TLI.ComputeConstraintToUse(OpInfo, SDValue(),
|
|
OpInfo.ConstraintType == TargetLowering::C_Memory);
|
|
|
|
// If this asm operand is our Value*, and if it isn't an indirect memory
|
|
// operand, we can't fold it!
|
|
if (OpInfo.CallOperandVal == OpVal &&
|
|
(OpInfo.ConstraintType != TargetLowering::C_Memory ||
|
|
!OpInfo.isIndirect))
|
|
return false;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
|
|
/// FindAllMemoryUses - Recursively walk all the uses of I until we find a
|
|
/// memory use. If we find an obviously non-foldable instruction, return true.
|
|
/// Add the ultimately found memory instructions to MemoryUses.
|
|
static bool FindAllMemoryUses(Instruction *I,
|
|
SmallVectorImpl<std::pair<Instruction*,unsigned> > &MemoryUses,
|
|
SmallPtrSet<Instruction*, 16> &ConsideredInsts,
|
|
const TargetLowering &TLI) {
|
|
// If we already considered this instruction, we're done.
|
|
if (!ConsideredInsts.insert(I))
|
|
return false;
|
|
|
|
// If this is an obviously unfoldable instruction, bail out.
|
|
if (!MightBeFoldableInst(I))
|
|
return true;
|
|
|
|
// Loop over all the uses, recursively processing them.
|
|
for (Value::use_iterator UI = I->use_begin(), E = I->use_end();
|
|
UI != E; ++UI) {
|
|
if (LoadInst *LI = dyn_cast<LoadInst>(*UI)) {
|
|
MemoryUses.push_back(std::make_pair(LI, UI.getOperandNo()));
|
|
continue;
|
|
}
|
|
|
|
if (StoreInst *SI = dyn_cast<StoreInst>(*UI)) {
|
|
if (UI.getOperandNo() == 0) return true; // Storing addr, not into addr.
|
|
MemoryUses.push_back(std::make_pair(SI, UI.getOperandNo()));
|
|
continue;
|
|
}
|
|
|
|
if (CallInst *CI = dyn_cast<CallInst>(*UI)) {
|
|
InlineAsm *IA = dyn_cast<InlineAsm>(CI->getCalledValue());
|
|
if (IA == 0) return true;
|
|
|
|
// If this is a memory operand, we're cool, otherwise bail out.
|
|
if (!IsOperandAMemoryOperand(CI, IA, I, TLI))
|
|
return true;
|
|
continue;
|
|
}
|
|
|
|
if (FindAllMemoryUses(cast<Instruction>(*UI), MemoryUses, ConsideredInsts,
|
|
TLI))
|
|
return true;
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
|
|
/// ValueAlreadyLiveAtInst - Retrn true if Val is already known to be live at
|
|
/// the use site that we're folding it into. If so, there is no cost to
|
|
/// include it in the addressing mode. KnownLive1 and KnownLive2 are two values
|
|
/// that we know are live at the instruction already.
|
|
bool AddressingModeMatcher::ValueAlreadyLiveAtInst(Value *Val,Value *KnownLive1,
|
|
Value *KnownLive2) {
|
|
// If Val is either of the known-live values, we know it is live!
|
|
if (Val == 0 || Val == KnownLive1 || Val == KnownLive2)
|
|
return true;
|
|
|
|
// All values other than instructions and arguments (e.g. constants) are live.
|
|
if (!isa<Instruction>(Val) && !isa<Argument>(Val)) return true;
|
|
|
|
// If Val is a constant sized alloca in the entry block, it is live, this is
|
|
// true because it is just a reference to the stack/frame pointer, which is
|
|
// live for the whole function.
|
|
if (AllocaInst *AI = dyn_cast<AllocaInst>(Val))
|
|
if (AI->isStaticAlloca())
|
|
return true;
|
|
|
|
// Check to see if this value is already used in the memory instruction's
|
|
// block. If so, it's already live into the block at the very least, so we
|
|
// can reasonably fold it.
|
|
BasicBlock *MemBB = MemoryInst->getParent();
|
|
for (Value::use_iterator UI = Val->use_begin(), E = Val->use_end();
|
|
UI != E; ++UI)
|
|
// We know that uses of arguments and instructions have to be instructions.
|
|
if (cast<Instruction>(*UI)->getParent() == MemBB)
|
|
return true;
|
|
|
|
return false;
|
|
}
|
|
|
|
|
|
|
|
/// IsProfitableToFoldIntoAddressingMode - It is possible for the addressing
|
|
/// mode of the machine to fold the specified instruction into a load or store
|
|
/// that ultimately uses it. However, the specified instruction has multiple
|
|
/// uses. Given this, it may actually increase register pressure to fold it
|
|
/// into the load. For example, consider this code:
|
|
///
|
|
/// X = ...
|
|
/// Y = X+1
|
|
/// use(Y) -> nonload/store
|
|
/// Z = Y+1
|
|
/// load Z
|
|
///
|
|
/// In this case, Y has multiple uses, and can be folded into the load of Z
|
|
/// (yielding load [X+2]). However, doing this will cause both "X" and "X+1" to
|
|
/// be live at the use(Y) line. If we don't fold Y into load Z, we use one
|
|
/// fewer register. Since Y can't be folded into "use(Y)" we don't increase the
|
|
/// number of computations either.
|
|
///
|
|
/// Note that this (like most of CodeGenPrepare) is just a rough heuristic. If
|
|
/// X was live across 'load Z' for other reasons, we actually *would* want to
|
|
/// fold the addressing mode in the Z case. This would make Y die earlier.
|
|
bool AddressingModeMatcher::
|
|
IsProfitableToFoldIntoAddressingMode(Instruction *I, ExtAddrMode &AMBefore,
|
|
ExtAddrMode &AMAfter) {
|
|
if (IgnoreProfitability) return true;
|
|
|
|
// AMBefore is the addressing mode before this instruction was folded into it,
|
|
// and AMAfter is the addressing mode after the instruction was folded. Get
|
|
// the set of registers referenced by AMAfter and subtract out those
|
|
// referenced by AMBefore: this is the set of values which folding in this
|
|
// address extends the lifetime of.
|
|
//
|
|
// Note that there are only two potential values being referenced here,
|
|
// BaseReg and ScaleReg (global addresses are always available, as are any
|
|
// folded immediates).
|
|
Value *BaseReg = AMAfter.BaseReg, *ScaledReg = AMAfter.ScaledReg;
|
|
|
|
// If the BaseReg or ScaledReg was referenced by the previous addrmode, their
|
|
// lifetime wasn't extended by adding this instruction.
|
|
if (ValueAlreadyLiveAtInst(BaseReg, AMBefore.BaseReg, AMBefore.ScaledReg))
|
|
BaseReg = 0;
|
|
if (ValueAlreadyLiveAtInst(ScaledReg, AMBefore.BaseReg, AMBefore.ScaledReg))
|
|
ScaledReg = 0;
|
|
|
|
// If folding this instruction (and it's subexprs) didn't extend any live
|
|
// ranges, we're ok with it.
|
|
if (BaseReg == 0 && ScaledReg == 0)
|
|
return true;
|
|
|
|
// If all uses of this instruction are ultimately load/store/inlineasm's,
|
|
// check to see if their addressing modes will include this instruction. If
|
|
// so, we can fold it into all uses, so it doesn't matter if it has multiple
|
|
// uses.
|
|
SmallVector<std::pair<Instruction*,unsigned>, 16> MemoryUses;
|
|
SmallPtrSet<Instruction*, 16> ConsideredInsts;
|
|
if (FindAllMemoryUses(I, MemoryUses, ConsideredInsts, TLI))
|
|
return false; // Has a non-memory, non-foldable use!
|
|
|
|
// Now that we know that all uses of this instruction are part of a chain of
|
|
// computation involving only operations that could theoretically be folded
|
|
// into a memory use, loop over each of these uses and see if they could
|
|
// *actually* fold the instruction.
|
|
SmallVector<Instruction*, 32> MatchedAddrModeInsts;
|
|
for (unsigned i = 0, e = MemoryUses.size(); i != e; ++i) {
|
|
Instruction *User = MemoryUses[i].first;
|
|
unsigned OpNo = MemoryUses[i].second;
|
|
|
|
// Get the access type of this use. If the use isn't a pointer, we don't
|
|
// know what it accesses.
|
|
Value *Address = User->getOperand(OpNo);
|
|
if (!isa<PointerType>(Address->getType()))
|
|
return false;
|
|
const Type *AddressAccessTy =
|
|
cast<PointerType>(Address->getType())->getElementType();
|
|
|
|
// Do a match against the root of this address, ignoring profitability. This
|
|
// will tell us if the addressing mode for the memory operation will
|
|
// *actually* cover the shared instruction.
|
|
ExtAddrMode Result;
|
|
AddressingModeMatcher Matcher(MatchedAddrModeInsts, TLI, AddressAccessTy,
|
|
MemoryInst, Result);
|
|
Matcher.IgnoreProfitability = true;
|
|
bool Success = Matcher.MatchAddr(Address, 0);
|
|
Success = Success; assert(Success && "Couldn't select *anything*?");
|
|
|
|
// If the match didn't cover I, then it won't be shared by it.
|
|
if (std::find(MatchedAddrModeInsts.begin(), MatchedAddrModeInsts.end(),
|
|
I) == MatchedAddrModeInsts.end())
|
|
return false;
|
|
|
|
MatchedAddrModeInsts.clear();
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
// Memory Optimization
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
/// IsNonLocalValue - Return true if the specified values are defined in a
|
|
/// different basic block than BB.
|
|
static bool IsNonLocalValue(Value *V, BasicBlock *BB) {
|
|
if (Instruction *I = dyn_cast<Instruction>(V))
|
|
return I->getParent() != BB;
|
|
return false;
|
|
}
|
|
|
|
/// OptimizeMemoryInst - Load and Store Instructions have often have
|
|
/// addressing modes that can do significant amounts of computation. As such,
|
|
/// instruction selection will try to get the load or store to do as much
|
|
/// computation as possible for the program. The problem is that isel can only
|
|
/// see within a single block. As such, we sink as much legal addressing mode
|
|
/// stuff into the block as possible.
|
|
///
|
|
/// This method is used to optimize both load/store and inline asms with memory
|
|
/// operands.
|
|
bool CodeGenPrepare::OptimizeMemoryInst(Instruction *MemoryInst, Value *Addr,
|
|
const Type *AccessTy,
|
|
DenseMap<Value*,Value*> &SunkAddrs) {
|
|
// Figure out what addressing mode will be built up for this operation.
|
|
SmallVector<Instruction*, 16> AddrModeInsts;
|
|
ExtAddrMode AddrMode = AddressingModeMatcher::Match(Addr, AccessTy,MemoryInst,
|
|
AddrModeInsts, *TLI);
|
|
|
|
// Check to see if any of the instructions supersumed by this addr mode are
|
|
// non-local to I's BB.
|
|
bool AnyNonLocal = false;
|
|
for (unsigned i = 0, e = AddrModeInsts.size(); i != e; ++i) {
|
|
if (IsNonLocalValue(AddrModeInsts[i], MemoryInst->getParent())) {
|
|
AnyNonLocal = true;
|
|
break;
|
|
}
|
|
}
|
|
|
|
// If all the instructions matched are already in this BB, don't do anything.
|
|
if (!AnyNonLocal) {
|
|
DEBUG(cerr << "CGP: Found local addrmode: " << AddrMode << "\n");
|
|
return false;
|
|
}
|
|
|
|
// Insert this computation right after this user. Since our caller is
|
|
// scanning from the top of the BB to the bottom, reuse of the expr are
|
|
// guaranteed to happen later.
|
|
BasicBlock::iterator InsertPt = MemoryInst;
|
|
|
|
// Now that we determined the addressing expression we want to use and know
|
|
// that we have to sink it into this block. Check to see if we have already
|
|
// done this for some other load/store instr in this block. If so, reuse the
|
|
// computation.
|
|
Value *&SunkAddr = SunkAddrs[Addr];
|
|
if (SunkAddr) {
|
|
DEBUG(cerr << "CGP: Reusing nonlocal addrmode: " << AddrMode << "\n");
|
|
if (SunkAddr->getType() != Addr->getType())
|
|
SunkAddr = new BitCastInst(SunkAddr, Addr->getType(), "tmp", InsertPt);
|
|
} else {
|
|
DEBUG(cerr << "CGP: SINKING nonlocal addrmode: " << AddrMode << "\n");
|
|
const Type *IntPtrTy = TLI->getTargetData()->getIntPtrType();
|
|
|
|
Value *Result = 0;
|
|
// Start with the scale value.
|
|
if (AddrMode.Scale) {
|
|
Value *V = AddrMode.ScaledReg;
|
|
if (V->getType() == IntPtrTy) {
|
|
// done.
|
|
} else if (isa<PointerType>(V->getType())) {
|
|
V = new PtrToIntInst(V, IntPtrTy, "sunkaddr", InsertPt);
|
|
} else if (cast<IntegerType>(IntPtrTy)->getBitWidth() <
|
|
cast<IntegerType>(V->getType())->getBitWidth()) {
|
|
V = new TruncInst(V, IntPtrTy, "sunkaddr", InsertPt);
|
|
} else {
|
|
V = new SExtInst(V, IntPtrTy, "sunkaddr", InsertPt);
|
|
}
|
|
if (AddrMode.Scale != 1)
|
|
V = BinaryOperator::CreateMul(V, ConstantInt::get(IntPtrTy,
|
|
AddrMode.Scale),
|
|
"sunkaddr", InsertPt);
|
|
Result = V;
|
|
}
|
|
|
|
// Add in the base register.
|
|
if (AddrMode.BaseReg) {
|
|
Value *V = AddrMode.BaseReg;
|
|
if (V->getType() != IntPtrTy)
|
|
V = new PtrToIntInst(V, IntPtrTy, "sunkaddr", InsertPt);
|
|
if (Result)
|
|
Result = BinaryOperator::CreateAdd(Result, V, "sunkaddr", InsertPt);
|
|
else
|
|
Result = V;
|
|
}
|
|
|
|
// Add in the BaseGV if present.
|
|
if (AddrMode.BaseGV) {
|
|
Value *V = new PtrToIntInst(AddrMode.BaseGV, IntPtrTy, "sunkaddr",
|
|
InsertPt);
|
|
if (Result)
|
|
Result = BinaryOperator::CreateAdd(Result, V, "sunkaddr", InsertPt);
|
|
else
|
|
Result = V;
|
|
}
|
|
|
|
// Add in the Base Offset if present.
|
|
if (AddrMode.BaseOffs) {
|
|
Value *V = ConstantInt::get(IntPtrTy, AddrMode.BaseOffs);
|
|
if (Result)
|
|
Result = BinaryOperator::CreateAdd(Result, V, "sunkaddr", InsertPt);
|
|
else
|
|
Result = V;
|
|
}
|
|
|
|
if (Result == 0)
|
|
SunkAddr = Constant::getNullValue(Addr->getType());
|
|
else
|
|
SunkAddr = new IntToPtrInst(Result, Addr->getType(), "sunkaddr",InsertPt);
|
|
}
|
|
|
|
MemoryInst->replaceUsesOfWith(Addr, SunkAddr);
|
|
|
|
if (Addr->use_empty())
|
|
RecursivelyDeleteTriviallyDeadInstructions(Addr);
|
|
return true;
|
|
}
|
|
|
|
/// OptimizeInlineAsmInst - If there are any memory operands, use
|
|
/// OptimizeMemoryInst to sink their address computing into the block when
|
|
/// possible / profitable.
|
|
bool CodeGenPrepare::OptimizeInlineAsmInst(Instruction *I, CallSite CS,
|
|
DenseMap<Value*,Value*> &SunkAddrs) {
|
|
bool MadeChange = false;
|
|
InlineAsm *IA = cast<InlineAsm>(CS.getCalledValue());
|
|
|
|
// Do a prepass over the constraints, canonicalizing them, and building up the
|
|
// ConstraintOperands list.
|
|
std::vector<InlineAsm::ConstraintInfo>
|
|
ConstraintInfos = IA->ParseConstraints();
|
|
|
|
/// ConstraintOperands - Information about all of the constraints.
|
|
std::vector<TargetLowering::AsmOperandInfo> ConstraintOperands;
|
|
unsigned ArgNo = 0; // ArgNo - The argument of the CallInst.
|
|
for (unsigned i = 0, e = ConstraintInfos.size(); i != e; ++i) {
|
|
ConstraintOperands.
|
|
push_back(TargetLowering::AsmOperandInfo(ConstraintInfos[i]));
|
|
TargetLowering::AsmOperandInfo &OpInfo = ConstraintOperands.back();
|
|
|
|
// Compute the value type for each operand.
|
|
switch (OpInfo.Type) {
|
|
case InlineAsm::isOutput:
|
|
if (OpInfo.isIndirect)
|
|
OpInfo.CallOperandVal = CS.getArgument(ArgNo++);
|
|
break;
|
|
case InlineAsm::isInput:
|
|
OpInfo.CallOperandVal = CS.getArgument(ArgNo++);
|
|
break;
|
|
case InlineAsm::isClobber:
|
|
// Nothing to do.
|
|
break;
|
|
}
|
|
|
|
// Compute the constraint code and ConstraintType to use.
|
|
TLI->ComputeConstraintToUse(OpInfo, SDValue(),
|
|
OpInfo.ConstraintType == TargetLowering::C_Memory);
|
|
|
|
if (OpInfo.ConstraintType == TargetLowering::C_Memory &&
|
|
OpInfo.isIndirect) {
|
|
Value *OpVal = OpInfo.CallOperandVal;
|
|
MadeChange |= OptimizeMemoryInst(I, OpVal, OpVal->getType(), SunkAddrs);
|
|
}
|
|
}
|
|
|
|
return MadeChange;
|
|
}
|
|
|
|
bool CodeGenPrepare::OptimizeExtUses(Instruction *I) {
|
|
BasicBlock *DefBB = I->getParent();
|
|
|
|
// If both result of the {s|z}xt and its source are live out, rewrite all
|
|
// other uses of the source with result of extension.
|
|
Value *Src = I->getOperand(0);
|
|
if (Src->hasOneUse())
|
|
return false;
|
|
|
|
// Only do this xform if truncating is free.
|
|
if (TLI && !TLI->isTruncateFree(I->getType(), Src->getType()))
|
|
return false;
|
|
|
|
// Only safe to perform the optimization if the source is also defined in
|
|
// this block.
|
|
if (!isa<Instruction>(Src) || DefBB != cast<Instruction>(Src)->getParent())
|
|
return false;
|
|
|
|
bool DefIsLiveOut = false;
|
|
for (Value::use_iterator UI = I->use_begin(), E = I->use_end();
|
|
UI != E; ++UI) {
|
|
Instruction *User = cast<Instruction>(*UI);
|
|
|
|
// Figure out which BB this ext is used in.
|
|
BasicBlock *UserBB = User->getParent();
|
|
if (UserBB == DefBB) continue;
|
|
DefIsLiveOut = true;
|
|
break;
|
|
}
|
|
if (!DefIsLiveOut)
|
|
return false;
|
|
|
|
// Make sure non of the uses are PHI nodes.
|
|
for (Value::use_iterator UI = Src->use_begin(), E = Src->use_end();
|
|
UI != E; ++UI) {
|
|
Instruction *User = cast<Instruction>(*UI);
|
|
BasicBlock *UserBB = User->getParent();
|
|
if (UserBB == DefBB) continue;
|
|
// Be conservative. We don't want this xform to end up introducing
|
|
// reloads just before load / store instructions.
|
|
if (isa<PHINode>(User) || isa<LoadInst>(User) || isa<StoreInst>(User))
|
|
return false;
|
|
}
|
|
|
|
// InsertedTruncs - Only insert one trunc in each block once.
|
|
DenseMap<BasicBlock*, Instruction*> InsertedTruncs;
|
|
|
|
bool MadeChange = false;
|
|
for (Value::use_iterator UI = Src->use_begin(), E = Src->use_end();
|
|
UI != E; ++UI) {
|
|
Use &TheUse = UI.getUse();
|
|
Instruction *User = cast<Instruction>(*UI);
|
|
|
|
// Figure out which BB this ext is used in.
|
|
BasicBlock *UserBB = User->getParent();
|
|
if (UserBB == DefBB) continue;
|
|
|
|
// Both src and def are live in this block. Rewrite the use.
|
|
Instruction *&InsertedTrunc = InsertedTruncs[UserBB];
|
|
|
|
if (!InsertedTrunc) {
|
|
BasicBlock::iterator InsertPt = UserBB->getFirstNonPHI();
|
|
|
|
InsertedTrunc = new TruncInst(I, Src->getType(), "", InsertPt);
|
|
}
|
|
|
|
// Replace a use of the {s|z}ext source with a use of the result.
|
|
TheUse = InsertedTrunc;
|
|
|
|
MadeChange = true;
|
|
}
|
|
|
|
return MadeChange;
|
|
}
|
|
|
|
// In this pass we look for GEP and cast instructions that are used
|
|
// across basic blocks and rewrite them to improve basic-block-at-a-time
|
|
// selection.
|
|
bool CodeGenPrepare::OptimizeBlock(BasicBlock &BB) {
|
|
bool MadeChange = false;
|
|
|
|
// Split all critical edges where the dest block has a PHI and where the phi
|
|
// has shared immediate operands.
|
|
TerminatorInst *BBTI = BB.getTerminator();
|
|
if (BBTI->getNumSuccessors() > 1) {
|
|
for (unsigned i = 0, e = BBTI->getNumSuccessors(); i != e; ++i)
|
|
if (isa<PHINode>(BBTI->getSuccessor(i)->begin()) &&
|
|
isCriticalEdge(BBTI, i, true))
|
|
SplitEdgeNicely(BBTI, i, this);
|
|
}
|
|
|
|
|
|
// Keep track of non-local addresses that have been sunk into this block.
|
|
// This allows us to avoid inserting duplicate code for blocks with multiple
|
|
// load/stores of the same address.
|
|
DenseMap<Value*, Value*> SunkAddrs;
|
|
|
|
for (BasicBlock::iterator BBI = BB.begin(), E = BB.end(); BBI != E; ) {
|
|
Instruction *I = BBI++;
|
|
|
|
if (CastInst *CI = dyn_cast<CastInst>(I)) {
|
|
// If the source of the cast is a constant, then this should have
|
|
// already been constant folded. The only reason NOT to constant fold
|
|
// it is if something (e.g. LSR) was careful to place the constant
|
|
// evaluation in a block other than then one that uses it (e.g. to hoist
|
|
// the address of globals out of a loop). If this is the case, we don't
|
|
// want to forward-subst the cast.
|
|
if (isa<Constant>(CI->getOperand(0)))
|
|
continue;
|
|
|
|
bool Change = false;
|
|
if (TLI) {
|
|
Change = OptimizeNoopCopyExpression(CI, *TLI);
|
|
MadeChange |= Change;
|
|
}
|
|
|
|
if (!Change && (isa<ZExtInst>(I) || isa<SExtInst>(I)))
|
|
MadeChange |= OptimizeExtUses(I);
|
|
} else if (CmpInst *CI = dyn_cast<CmpInst>(I)) {
|
|
MadeChange |= OptimizeCmpExpression(CI);
|
|
} else if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
|
|
if (TLI)
|
|
MadeChange |= OptimizeMemoryInst(I, I->getOperand(0), LI->getType(),
|
|
SunkAddrs);
|
|
} else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
|
|
if (TLI)
|
|
MadeChange |= OptimizeMemoryInst(I, SI->getOperand(1),
|
|
SI->getOperand(0)->getType(),
|
|
SunkAddrs);
|
|
} else if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(I)) {
|
|
if (GEPI->hasAllZeroIndices()) {
|
|
/// The GEP operand must be a pointer, so must its result -> BitCast
|
|
Instruction *NC = new BitCastInst(GEPI->getOperand(0), GEPI->getType(),
|
|
GEPI->getName(), GEPI);
|
|
GEPI->replaceAllUsesWith(NC);
|
|
GEPI->eraseFromParent();
|
|
MadeChange = true;
|
|
BBI = NC;
|
|
}
|
|
} else if (CallInst *CI = dyn_cast<CallInst>(I)) {
|
|
// If we found an inline asm expession, and if the target knows how to
|
|
// lower it to normal LLVM code, do so now.
|
|
if (TLI && isa<InlineAsm>(CI->getCalledValue()))
|
|
if (const TargetAsmInfo *TAI =
|
|
TLI->getTargetMachine().getTargetAsmInfo()) {
|
|
if (TAI->ExpandInlineAsm(CI))
|
|
BBI = BB.begin();
|
|
else
|
|
// Sink address computing for memory operands into the block.
|
|
MadeChange |= OptimizeInlineAsmInst(I, &(*CI), SunkAddrs);
|
|
}
|
|
}
|
|
}
|
|
|
|
return MadeChange;
|
|
}
|