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of apint codegen failure is the DAG combiner doing the wrong thing because it was comparing MVT's using < rather than comparing the number of bits. Removing the < method makes this mistake impossible to commit. Instead, add helper methods for comparing bits and use them. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@52098 91177308-0d34-0410-b5e6-96231b3b80d8
1136 lines
41 KiB
C++
1136 lines
41 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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using namespace llvm;
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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((intptr_t)&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 OptimizeLoadStoreInst(Instruction *I, Value *Addr,
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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 (DestBB->getSinglePredecessor()) {
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// If DestBB has single-entry PHI nodes, fold them.
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while (PHINode *PN = dyn_cast<PHINode>(DestBB->begin())) {
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PN->replaceAllUsesWith(PN->getIncomingValue(0));
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PN->eraseFromParent();
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}
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// Splice all the PHI nodes from BB over to DestBB.
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DestBB->getInstList().splice(DestBB->begin(), BB->getInstList(),
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BB->begin(), BI);
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// Anything that branched to BB now branches to DestBB.
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BB->replaceAllUsesWith(DestBB);
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// Nuke BB.
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BB->eraseFromParent();
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DOUT << "AFTER:\n" << *DestBB << "\n\n\n";
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return;
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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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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.
|
|
if (CI->use_empty())
|
|
CI->eraseFromParent();
|
|
|
|
return MadeChange;
|
|
}
|
|
|
|
/// EraseDeadInstructions - Erase any dead instructions
|
|
static void EraseDeadInstructions(Value *V) {
|
|
Instruction *I = dyn_cast<Instruction>(V);
|
|
if (!I || !I->use_empty()) return;
|
|
|
|
SmallPtrSet<Instruction*, 16> Insts;
|
|
Insts.insert(I);
|
|
|
|
while (!Insts.empty()) {
|
|
I = *Insts.begin();
|
|
Insts.erase(I);
|
|
if (isInstructionTriviallyDead(I)) {
|
|
for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
|
|
if (Instruction *U = dyn_cast<Instruction>(I->getOperand(i)))
|
|
Insts.insert(U);
|
|
I->eraseFromParent();
|
|
}
|
|
}
|
|
}
|
|
|
|
namespace {
|
|
|
|
/// ExtAddrMode - This is an extended version of TargetLowering::AddrMode which
|
|
/// holds actual Value*'s for register values.
|
|
struct ExtAddrMode : public TargetLowering::AddrMode {
|
|
Value *BaseReg;
|
|
Value *ScaledReg;
|
|
ExtAddrMode() : BaseReg(0), ScaledReg(0) {}
|
|
void dump() const;
|
|
};
|
|
|
|
static std::ostream &operator<<(std::ostream &OS, const ExtAddrMode &AM) {
|
|
bool NeedPlus = false;
|
|
OS << "[";
|
|
if (AM.BaseGV)
|
|
OS << (NeedPlus ? " + " : "")
|
|
<< "GV:%" << AM.BaseGV->getName(), NeedPlus = true;
|
|
|
|
if (AM.BaseOffs)
|
|
OS << (NeedPlus ? " + " : "") << AM.BaseOffs, NeedPlus = true;
|
|
|
|
if (AM.BaseReg)
|
|
OS << (NeedPlus ? " + " : "")
|
|
<< "Base:%" << AM.BaseReg->getName(), NeedPlus = true;
|
|
if (AM.Scale)
|
|
OS << (NeedPlus ? " + " : "")
|
|
<< AM.Scale << "*%" << AM.ScaledReg->getName(), NeedPlus = true;
|
|
|
|
return OS << "]";
|
|
}
|
|
|
|
void ExtAddrMode::dump() const {
|
|
cerr << *this << "\n";
|
|
}
|
|
|
|
}
|
|
|
|
static bool TryMatchingScaledValue(Value *ScaleReg, int64_t Scale,
|
|
const Type *AccessTy, ExtAddrMode &AddrMode,
|
|
SmallVector<Instruction*, 16> &AddrModeInsts,
|
|
const TargetLowering &TLI, unsigned Depth);
|
|
|
|
/// FindMaximalLegalAddressingMode - If we can, try to merge the computation of
|
|
/// Addr into the specified addressing mode. If Addr can't be added to AddrMode
|
|
/// this returns false. This assumes that Addr is either a pointer type or
|
|
/// intptr_t for the target.
|
|
static bool FindMaximalLegalAddressingMode(Value *Addr, const Type *AccessTy,
|
|
ExtAddrMode &AddrMode,
|
|
SmallVector<Instruction*, 16> &AddrModeInsts,
|
|
const TargetLowering &TLI,
|
|
unsigned Depth) {
|
|
|
|
// If this is a global variable, fold it into the addressing mode if possible.
|
|
if (GlobalValue *GV = dyn_cast<GlobalValue>(Addr)) {
|
|
if (AddrMode.BaseGV == 0) {
|
|
AddrMode.BaseGV = GV;
|
|
if (TLI.isLegalAddressingMode(AddrMode, AccessTy))
|
|
return true;
|
|
AddrMode.BaseGV = 0;
|
|
}
|
|
} else if (ConstantInt *CI = dyn_cast<ConstantInt>(Addr)) {
|
|
AddrMode.BaseOffs += CI->getSExtValue();
|
|
if (TLI.isLegalAddressingMode(AddrMode, AccessTy))
|
|
return true;
|
|
AddrMode.BaseOffs -= CI->getSExtValue();
|
|
} else if (isa<ConstantPointerNull>(Addr)) {
|
|
return true;
|
|
}
|
|
|
|
// Look through constant exprs and instructions.
|
|
unsigned Opcode = ~0U;
|
|
User *AddrInst = 0;
|
|
if (Instruction *I = dyn_cast<Instruction>(Addr)) {
|
|
Opcode = I->getOpcode();
|
|
AddrInst = I;
|
|
} else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Addr)) {
|
|
Opcode = CE->getOpcode();
|
|
AddrInst = CE;
|
|
}
|
|
|
|
// Limit recursion to avoid exponential behavior.
|
|
if (Depth == 5) { AddrInst = 0; Opcode = ~0U; }
|
|
|
|
// If this is really an instruction, add it to our list of related
|
|
// instructions.
|
|
if (Instruction *I = dyn_cast_or_null<Instruction>(AddrInst))
|
|
AddrModeInsts.push_back(I);
|
|
|
|
switch (Opcode) {
|
|
case Instruction::PtrToInt:
|
|
// PtrToInt is always a noop, as we know that the int type is pointer sized.
|
|
if (FindMaximalLegalAddressingMode(AddrInst->getOperand(0), AccessTy,
|
|
AddrMode, AddrModeInsts, TLI, Depth))
|
|
return true;
|
|
break;
|
|
case Instruction::IntToPtr:
|
|
// This inttoptr is a no-op if the integer type is pointer sized.
|
|
if (TLI.getValueType(AddrInst->getOperand(0)->getType()) ==
|
|
TLI.getPointerTy()) {
|
|
if (FindMaximalLegalAddressingMode(AddrInst->getOperand(0), AccessTy,
|
|
AddrMode, AddrModeInsts, TLI, Depth))
|
|
return true;
|
|
}
|
|
break;
|
|
case Instruction::Add: {
|
|
// Check to see if we can merge in the RHS then the LHS. If so, we win.
|
|
ExtAddrMode BackupAddrMode = AddrMode;
|
|
unsigned OldSize = AddrModeInsts.size();
|
|
if (FindMaximalLegalAddressingMode(AddrInst->getOperand(1), AccessTy,
|
|
AddrMode, AddrModeInsts, TLI, Depth+1) &&
|
|
FindMaximalLegalAddressingMode(AddrInst->getOperand(0), AccessTy,
|
|
AddrMode, AddrModeInsts, TLI, Depth+1))
|
|
return true;
|
|
|
|
// Restore the old addr mode info.
|
|
AddrMode = BackupAddrMode;
|
|
AddrModeInsts.resize(OldSize);
|
|
|
|
// Otherwise this was over-aggressive. Try merging in the LHS then the RHS.
|
|
if (FindMaximalLegalAddressingMode(AddrInst->getOperand(0), AccessTy,
|
|
AddrMode, AddrModeInsts, TLI, Depth+1) &&
|
|
FindMaximalLegalAddressingMode(AddrInst->getOperand(1), AccessTy,
|
|
AddrMode, AddrModeInsts, TLI, Depth+1))
|
|
return true;
|
|
|
|
// Otherwise we definitely can't merge the ADD in.
|
|
AddrMode = BackupAddrMode;
|
|
AddrModeInsts.resize(OldSize);
|
|
break;
|
|
}
|
|
case Instruction::Or: {
|
|
ConstantInt *RHS = dyn_cast<ConstantInt>(AddrInst->getOperand(1));
|
|
if (!RHS) break;
|
|
// TODO: We can handle "Or Val, Imm" iff this OR is equivalent to an ADD.
|
|
break;
|
|
}
|
|
case Instruction::Mul:
|
|
case Instruction::Shl: {
|
|
// Can only handle X*C and X << C, and can only handle this when the scale
|
|
// field is available.
|
|
ConstantInt *RHS = dyn_cast<ConstantInt>(AddrInst->getOperand(1));
|
|
if (!RHS) break;
|
|
int64_t Scale = RHS->getSExtValue();
|
|
if (Opcode == Instruction::Shl)
|
|
Scale = 1 << Scale;
|
|
|
|
if (TryMatchingScaledValue(AddrInst->getOperand(0), Scale, AccessTy,
|
|
AddrMode, AddrModeInsts, TLI, Depth))
|
|
return true;
|
|
break;
|
|
}
|
|
case Instruction::GetElementPtr: {
|
|
// Scan the GEP. We check it if it contains constant offsets and at most
|
|
// one variable offset.
|
|
int VariableOperand = -1;
|
|
unsigned VariableScale = 0;
|
|
|
|
int64_t ConstantOffset = 0;
|
|
const TargetData *TD = TLI.getTargetData();
|
|
gep_type_iterator GTI = gep_type_begin(AddrInst);
|
|
for (unsigned i = 1, e = AddrInst->getNumOperands(); i != e; ++i, ++GTI) {
|
|
if (const StructType *STy = dyn_cast<StructType>(*GTI)) {
|
|
const StructLayout *SL = TD->getStructLayout(STy);
|
|
unsigned Idx =
|
|
cast<ConstantInt>(AddrInst->getOperand(i))->getZExtValue();
|
|
ConstantOffset += SL->getElementOffset(Idx);
|
|
} else {
|
|
uint64_t TypeSize = TD->getABITypeSize(GTI.getIndexedType());
|
|
if (ConstantInt *CI = dyn_cast<ConstantInt>(AddrInst->getOperand(i))) {
|
|
ConstantOffset += CI->getSExtValue()*TypeSize;
|
|
} else if (TypeSize) { // Scales of zero don't do anything.
|
|
// We only allow one variable index at the moment.
|
|
if (VariableOperand != -1) {
|
|
VariableOperand = -2;
|
|
break;
|
|
}
|
|
|
|
// Remember the variable index.
|
|
VariableOperand = i;
|
|
VariableScale = TypeSize;
|
|
}
|
|
}
|
|
}
|
|
|
|
// If the GEP had multiple variable indices, punt.
|
|
if (VariableOperand == -2)
|
|
break;
|
|
|
|
// A common case is for the GEP to only do a constant offset. In this case,
|
|
// just add it to the disp field and check validity.
|
|
if (VariableOperand == -1) {
|
|
AddrMode.BaseOffs += ConstantOffset;
|
|
if (ConstantOffset == 0 || TLI.isLegalAddressingMode(AddrMode, AccessTy)){
|
|
// Check to see if we can fold the base pointer in too.
|
|
if (FindMaximalLegalAddressingMode(AddrInst->getOperand(0), AccessTy,
|
|
AddrMode, AddrModeInsts, TLI,
|
|
Depth+1))
|
|
return true;
|
|
}
|
|
AddrMode.BaseOffs -= ConstantOffset;
|
|
} else {
|
|
// Check that this has no base reg yet. If so, we won't have a place to
|
|
// put the base of the GEP (assuming it is not a null ptr).
|
|
bool SetBaseReg = false;
|
|
if (AddrMode.HasBaseReg) {
|
|
if (!isa<ConstantPointerNull>(AddrInst->getOperand(0)))
|
|
break;
|
|
} else {
|
|
AddrMode.HasBaseReg = true;
|
|
AddrMode.BaseReg = AddrInst->getOperand(0);
|
|
SetBaseReg = true;
|
|
}
|
|
|
|
// See if the scale amount is valid for this target.
|
|
AddrMode.BaseOffs += ConstantOffset;
|
|
if (TryMatchingScaledValue(AddrInst->getOperand(VariableOperand),
|
|
VariableScale, AccessTy, AddrMode,
|
|
AddrModeInsts, TLI, Depth)) {
|
|
if (!SetBaseReg) return true;
|
|
|
|
// If this match succeeded, we know that we can form an address with the
|
|
// GepBase as the basereg. See if we can match *more*.
|
|
AddrMode.HasBaseReg = false;
|
|
AddrMode.BaseReg = 0;
|
|
if (FindMaximalLegalAddressingMode(AddrInst->getOperand(0), AccessTy,
|
|
AddrMode, AddrModeInsts, TLI,
|
|
Depth+1))
|
|
return true;
|
|
// Strange, shouldn't happen. Restore the base reg and succeed the easy
|
|
// way.
|
|
AddrMode.HasBaseReg = true;
|
|
AddrMode.BaseReg = AddrInst->getOperand(0);
|
|
return true;
|
|
}
|
|
|
|
AddrMode.BaseOffs -= ConstantOffset;
|
|
if (SetBaseReg) {
|
|
AddrMode.HasBaseReg = false;
|
|
AddrMode.BaseReg = 0;
|
|
}
|
|
}
|
|
break;
|
|
}
|
|
}
|
|
|
|
if (Instruction *I = dyn_cast_or_null<Instruction>(AddrInst)) {
|
|
assert(AddrModeInsts.back() == I && "Stack imbalance"); I = I;
|
|
AddrModeInsts.pop_back();
|
|
}
|
|
|
|
// Worse case, the target should support [reg] addressing modes. :)
|
|
if (!AddrMode.HasBaseReg) {
|
|
AddrMode.HasBaseReg = true;
|
|
// Still check for legality in case the target supports [imm] but not [i+r].
|
|
if (TLI.isLegalAddressingMode(AddrMode, AccessTy)) {
|
|
AddrMode.BaseReg = Addr;
|
|
return true;
|
|
}
|
|
AddrMode.HasBaseReg = false;
|
|
}
|
|
|
|
// If the base register is already taken, see if we can do [r+r].
|
|
if (AddrMode.Scale == 0) {
|
|
AddrMode.Scale = 1;
|
|
if (TLI.isLegalAddressingMode(AddrMode, AccessTy)) {
|
|
AddrMode.ScaledReg = Addr;
|
|
return true;
|
|
}
|
|
AddrMode.Scale = 0;
|
|
}
|
|
// Couldn't match.
|
|
return false;
|
|
}
|
|
|
|
/// TryMatchingScaledValue - Try adding ScaleReg*Scale to the specified
|
|
/// addressing mode. Return true if this addr mode is legal for the target,
|
|
/// false if not.
|
|
static bool TryMatchingScaledValue(Value *ScaleReg, int64_t Scale,
|
|
const Type *AccessTy, ExtAddrMode &AddrMode,
|
|
SmallVector<Instruction*, 16> &AddrModeInsts,
|
|
const TargetLowering &TLI, unsigned Depth) {
|
|
// If we already have a scale of this value, we can add to it, otherwise, we
|
|
// need an available scale field.
|
|
if (AddrMode.Scale != 0 && AddrMode.ScaledReg != ScaleReg)
|
|
return false;
|
|
|
|
ExtAddrMode InputAddrMode = AddrMode;
|
|
|
|
// Add scale to turn X*4+X*3 -> X*7. This could also do things like
|
|
// [A+B + A*7] -> [B+A*8].
|
|
AddrMode.Scale += Scale;
|
|
AddrMode.ScaledReg = ScaleReg;
|
|
|
|
if (TLI.isLegalAddressingMode(AddrMode, AccessTy)) {
|
|
// Okay, we decided that we can add ScaleReg+Scale to AddrMode. Check now
|
|
// to see if ScaleReg is actually X+C. If so, we can turn this into adding
|
|
// X*Scale + C*Scale to addr mode.
|
|
BinaryOperator *BinOp = dyn_cast<BinaryOperator>(ScaleReg);
|
|
if (BinOp && BinOp->getOpcode() == Instruction::Add &&
|
|
isa<ConstantInt>(BinOp->getOperand(1)) && InputAddrMode.ScaledReg ==0) {
|
|
|
|
InputAddrMode.Scale = Scale;
|
|
InputAddrMode.ScaledReg = BinOp->getOperand(0);
|
|
InputAddrMode.BaseOffs +=
|
|
cast<ConstantInt>(BinOp->getOperand(1))->getSExtValue()*Scale;
|
|
if (TLI.isLegalAddressingMode(InputAddrMode, AccessTy)) {
|
|
AddrModeInsts.push_back(BinOp);
|
|
AddrMode = InputAddrMode;
|
|
return true;
|
|
}
|
|
}
|
|
|
|
// Otherwise, not (x+c)*scale, just return what we have.
|
|
return true;
|
|
}
|
|
|
|
// Otherwise, back this attempt out.
|
|
AddrMode.Scale -= Scale;
|
|
if (AddrMode.Scale == 0) AddrMode.ScaledReg = 0;
|
|
|
|
return false;
|
|
}
|
|
|
|
|
|
/// 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;
|
|
}
|
|
|
|
/// OptimizeLoadStoreInst - 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.
|
|
bool CodeGenPrepare::OptimizeLoadStoreInst(Instruction *LdStInst, 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;
|
|
bool Success = FindMaximalLegalAddressingMode(Addr, AccessTy, AddrMode,
|
|
AddrModeInsts, *TLI, 0);
|
|
Success = Success; assert(Success && "Couldn't select *anything*?");
|
|
|
|
// 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], LdStInst->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 = LdStInst;
|
|
|
|
// 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);
|
|
}
|
|
|
|
LdStInst->replaceUsesOfWith(Addr, SunkAddr);
|
|
|
|
if (Addr->use_empty())
|
|
EraseDeadInstructions(Addr);
|
|
return true;
|
|
}
|
|
|
|
/// OptimizeInlineAsmInst - If there are any memory operands, use
|
|
/// OptimizeLoadStoreInt to sink their address computing into the block when
|
|
/// possible / profitable.
|
|
bool CodeGenPrepare::OptimizeInlineAsmInst(Instruction *I, CallSite CS,
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DenseMap<Value*,Value*> &SunkAddrs) {
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bool MadeChange = false;
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InlineAsm *IA = cast<InlineAsm>(CS.getCalledValue());
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// Do a prepass over the constraints, canonicalizing them, and building up the
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// ConstraintOperands list.
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std::vector<InlineAsm::ConstraintInfo>
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ConstraintInfos = IA->ParseConstraints();
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/// ConstraintOperands - Information about all of the constraints.
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std::vector<TargetLowering::AsmOperandInfo> ConstraintOperands;
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unsigned ArgNo = 0; // ArgNo - The argument of the CallInst.
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for (unsigned i = 0, e = ConstraintInfos.size(); i != e; ++i) {
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ConstraintOperands.
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push_back(TargetLowering::AsmOperandInfo(ConstraintInfos[i]));
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TargetLowering::AsmOperandInfo &OpInfo = ConstraintOperands.back();
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// Compute the value type for each operand.
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switch (OpInfo.Type) {
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case InlineAsm::isOutput:
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if (OpInfo.isIndirect)
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OpInfo.CallOperandVal = CS.getArgument(ArgNo++);
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break;
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case InlineAsm::isInput:
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OpInfo.CallOperandVal = CS.getArgument(ArgNo++);
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break;
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case InlineAsm::isClobber:
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// Nothing to do.
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break;
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}
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// Compute the constraint code and ConstraintType to use.
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TLI->ComputeConstraintToUse(OpInfo, SDOperand());
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if (OpInfo.ConstraintType == TargetLowering::C_Memory &&
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OpInfo.isIndirect) {
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Value *OpVal = OpInfo.CallOperandVal;
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MadeChange |= OptimizeLoadStoreInst(I, OpVal, OpVal->getType(),
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SunkAddrs);
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}
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}
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return MadeChange;
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}
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bool CodeGenPrepare::OptimizeExtUses(Instruction *I) {
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BasicBlock *DefBB = I->getParent();
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// If both result of the {s|z}xt and its source are live out, rewrite all
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// other uses of the source with result of extension.
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Value *Src = I->getOperand(0);
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if (Src->hasOneUse())
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return false;
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// Only do this xform if truncating is free.
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if (TLI && !TLI->isTruncateFree(I->getType(), Src->getType()))
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return false;
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// Only safe to perform the optimization if the source is also defined in
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// this block.
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if (!isa<Instruction>(Src) || DefBB != cast<Instruction>(Src)->getParent())
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return false;
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|
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bool DefIsLiveOut = false;
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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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Instruction *User = cast<Instruction>(*UI);
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// Figure out which BB this ext is used in.
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BasicBlock *UserBB = User->getParent();
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if (UserBB == DefBB) continue;
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DefIsLiveOut = true;
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break;
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}
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if (!DefIsLiveOut)
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return false;
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|
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// Make sure non of the uses are PHI nodes.
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for (Value::use_iterator UI = Src->use_begin(), E = Src->use_end();
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UI != E; ++UI) {
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Instruction *User = cast<Instruction>(*UI);
|
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BasicBlock *UserBB = User->getParent();
|
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if (UserBB == DefBB) continue;
|
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// Be conservative. We don't want this xform to end up introducing
|
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// reloads just before load / store instructions.
|
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if (isa<PHINode>(User) || isa<LoadInst>(User) || isa<StoreInst>(User))
|
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return false;
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}
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// InsertedTruncs - Only insert one trunc in each block once.
|
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DenseMap<BasicBlock*, Instruction*> InsertedTruncs;
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|
|
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bool MadeChange = false;
|
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for (Value::use_iterator UI = Src->use_begin(), E = Src->use_end();
|
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UI != E; ++UI) {
|
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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 |= OptimizeLoadStoreInst(I, I->getOperand(0), LI->getType(),
|
|
SunkAddrs);
|
|
} else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
|
|
if (TLI)
|
|
MadeChange |= OptimizeLoadStoreInst(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;
|
|
}
|
|
|