mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2024-12-14 11:32:34 +00:00
7eb589d3f9
The bug that broke i386 linux has been fixed in r115191. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@115204 91177308-0d34-0410-b5e6-96231b3b80d8
966 lines
35 KiB
C++
966 lines
35 KiB
C++
//===- CodeGenPrepare.cpp - Prepare a function for code generation --------===//
|
|
//
|
|
// The LLVM Compiler Infrastructure
|
|
//
|
|
// This file is distributed under the University of Illinois Open Source
|
|
// License. See LICENSE.TXT for details.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
//
|
|
// This pass munges the code in the input function to better prepare it for
|
|
// SelectionDAG-based code generation. This works around limitations in it's
|
|
// basic-block-at-a-time approach. It should eventually be removed.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#define DEBUG_TYPE "codegenprepare"
|
|
#include "llvm/Transforms/Scalar.h"
|
|
#include "llvm/Constants.h"
|
|
#include "llvm/DerivedTypes.h"
|
|
#include "llvm/Function.h"
|
|
#include "llvm/InlineAsm.h"
|
|
#include "llvm/Instructions.h"
|
|
#include "llvm/IntrinsicInst.h"
|
|
#include "llvm/Pass.h"
|
|
#include "llvm/Analysis/ProfileInfo.h"
|
|
#include "llvm/Target/TargetData.h"
|
|
#include "llvm/Target/TargetLowering.h"
|
|
#include "llvm/Transforms/Utils/AddrModeMatcher.h"
|
|
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
|
|
#include "llvm/Transforms/Utils/Local.h"
|
|
#include "llvm/Transforms/Utils/BuildLibCalls.h"
|
|
#include "llvm/ADT/DenseMap.h"
|
|
#include "llvm/ADT/SmallSet.h"
|
|
#include "llvm/ADT/Statistic.h"
|
|
#include "llvm/Assembly/Writer.h"
|
|
#include "llvm/Support/CallSite.h"
|
|
#include "llvm/Support/CommandLine.h"
|
|
#include "llvm/Support/Debug.h"
|
|
#include "llvm/Support/GetElementPtrTypeIterator.h"
|
|
#include "llvm/Support/PatternMatch.h"
|
|
#include "llvm/Support/raw_ostream.h"
|
|
#include "llvm/Support/IRBuilder.h"
|
|
using namespace llvm;
|
|
using namespace llvm::PatternMatch;
|
|
|
|
STATISTIC(NumElim, "Number of blocks eliminated");
|
|
|
|
static cl::opt<bool>
|
|
CriticalEdgeSplit("cgp-critical-edge-splitting",
|
|
cl::desc("Split critical edges during codegen prepare"),
|
|
cl::init(false), cl::Hidden);
|
|
|
|
namespace {
|
|
class CodeGenPrepare : public FunctionPass {
|
|
/// TLI - Keep a pointer of a TargetLowering to consult for determining
|
|
/// transformation profitability.
|
|
const TargetLowering *TLI;
|
|
ProfileInfo *PFI;
|
|
|
|
/// BackEdges - Keep a set of all the loop back edges.
|
|
///
|
|
SmallSet<std::pair<const BasicBlock*, const BasicBlock*>, 8> BackEdges;
|
|
public:
|
|
static char ID; // Pass identification, replacement for typeid
|
|
explicit CodeGenPrepare(const TargetLowering *tli = 0)
|
|
: FunctionPass(ID), TLI(tli) {}
|
|
bool runOnFunction(Function &F);
|
|
|
|
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
|
|
AU.addPreserved<ProfileInfo>();
|
|
}
|
|
|
|
virtual void releaseMemory() {
|
|
BackEdges.clear();
|
|
}
|
|
|
|
private:
|
|
bool EliminateMostlyEmptyBlocks(Function &F);
|
|
bool CanMergeBlocks(const BasicBlock *BB, const BasicBlock *DestBB) const;
|
|
void EliminateMostlyEmptyBlock(BasicBlock *BB);
|
|
bool OptimizeBlock(BasicBlock &BB);
|
|
bool OptimizeMemoryInst(Instruction *I, Value *Addr, const Type *AccessTy,
|
|
DenseMap<Value*,Value*> &SunkAddrs);
|
|
bool OptimizeInlineAsmInst(Instruction *I, CallSite CS,
|
|
DenseMap<Value*,Value*> &SunkAddrs);
|
|
bool OptimizeCallInst(CallInst *CI);
|
|
bool MoveExtToFormExtLoad(Instruction *I);
|
|
bool OptimizeExtUses(Instruction *I);
|
|
void findLoopBackEdges(const Function &F);
|
|
};
|
|
}
|
|
|
|
char CodeGenPrepare::ID = 0;
|
|
INITIALIZE_PASS(CodeGenPrepare, "codegenprepare",
|
|
"Optimize for code generation", false, false);
|
|
|
|
FunctionPass *llvm::createCodeGenPreparePass(const TargetLowering *TLI) {
|
|
return new CodeGenPrepare(TLI);
|
|
}
|
|
|
|
/// findLoopBackEdges - Do a DFS walk to find loop back edges.
|
|
///
|
|
void CodeGenPrepare::findLoopBackEdges(const Function &F) {
|
|
SmallVector<std::pair<const BasicBlock*,const BasicBlock*>, 32> Edges;
|
|
FindFunctionBackedges(F, Edges);
|
|
|
|
BackEdges.insert(Edges.begin(), Edges.end());
|
|
}
|
|
|
|
|
|
bool CodeGenPrepare::runOnFunction(Function &F) {
|
|
bool EverMadeChange = false;
|
|
|
|
PFI = getAnalysisIfAvailable<ProfileInfo>();
|
|
// First pass, eliminate blocks that contain only PHI nodes and an
|
|
// unconditional branch.
|
|
EverMadeChange |= EliminateMostlyEmptyBlocks(F);
|
|
|
|
// Now find loop back edges.
|
|
findLoopBackEdges(F);
|
|
|
|
bool MadeChange = true;
|
|
while (MadeChange) {
|
|
MadeChange = false;
|
|
for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
|
|
MadeChange |= OptimizeBlock(*BB);
|
|
EverMadeChange |= MadeChange;
|
|
}
|
|
return EverMadeChange;
|
|
}
|
|
|
|
/// EliminateMostlyEmptyBlocks - eliminate blocks that contain only PHI nodes,
|
|
/// debug info directives, and an unconditional branch. Passes before isel
|
|
/// (e.g. LSR/loopsimplify) often split edges in ways that are non-optimal for
|
|
/// isel. Start by eliminating these blocks so we can split them the way we
|
|
/// want them.
|
|
bool CodeGenPrepare::EliminateMostlyEmptyBlocks(Function &F) {
|
|
bool MadeChange = false;
|
|
// Note that this intentionally skips the entry block.
|
|
for (Function::iterator I = ++F.begin(), E = F.end(); I != E; ) {
|
|
BasicBlock *BB = I++;
|
|
|
|
// If this block doesn't end with an uncond branch, ignore it.
|
|
BranchInst *BI = dyn_cast<BranchInst>(BB->getTerminator());
|
|
if (!BI || !BI->isUnconditional())
|
|
continue;
|
|
|
|
// If the instruction before the branch (skipping debug info) isn't a phi
|
|
// node, then other stuff is happening here.
|
|
BasicBlock::iterator BBI = BI;
|
|
if (BBI != BB->begin()) {
|
|
--BBI;
|
|
while (isa<DbgInfoIntrinsic>(BBI)) {
|
|
if (BBI == BB->begin())
|
|
break;
|
|
--BBI;
|
|
}
|
|
if (!isa<DbgInfoIntrinsic>(BBI) && !isa<PHINode>(BBI))
|
|
continue;
|
|
}
|
|
|
|
// Do not break infinite loops.
|
|
BasicBlock *DestBB = BI->getSuccessor(0);
|
|
if (DestBB == BB)
|
|
continue;
|
|
|
|
if (!CanMergeBlocks(BB, DestBB))
|
|
continue;
|
|
|
|
EliminateMostlyEmptyBlock(BB);
|
|
MadeChange = true;
|
|
}
|
|
return MadeChange;
|
|
}
|
|
|
|
/// CanMergeBlocks - Return true if we can merge BB into DestBB if there is a
|
|
/// single uncond branch between them, and BB contains no other non-phi
|
|
/// instructions.
|
|
bool CodeGenPrepare::CanMergeBlocks(const BasicBlock *BB,
|
|
const BasicBlock *DestBB) const {
|
|
// We only want to eliminate blocks whose phi nodes are used by phi nodes in
|
|
// the successor. If there are more complex condition (e.g. preheaders),
|
|
// don't mess around with them.
|
|
BasicBlock::const_iterator BBI = BB->begin();
|
|
while (const PHINode *PN = dyn_cast<PHINode>(BBI++)) {
|
|
for (Value::const_use_iterator UI = PN->use_begin(), E = PN->use_end();
|
|
UI != E; ++UI) {
|
|
const Instruction *User = cast<Instruction>(*UI);
|
|
if (User->getParent() != DestBB || !isa<PHINode>(User))
|
|
return false;
|
|
// If User is inside DestBB block and it is a PHINode then check
|
|
// incoming value. If incoming value is not from BB then this is
|
|
// a complex condition (e.g. preheaders) we want to avoid here.
|
|
if (User->getParent() == DestBB) {
|
|
if (const PHINode *UPN = dyn_cast<PHINode>(User))
|
|
for (unsigned I = 0, E = UPN->getNumIncomingValues(); I != E; ++I) {
|
|
Instruction *Insn = dyn_cast<Instruction>(UPN->getIncomingValue(I));
|
|
if (Insn && Insn->getParent() == BB &&
|
|
Insn->getParent() != UPN->getIncomingBlock(I))
|
|
return false;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
// If BB and DestBB contain any common predecessors, then the phi nodes in BB
|
|
// and DestBB may have conflicting incoming values for the block. If so, we
|
|
// can't merge the block.
|
|
const PHINode *DestBBPN = dyn_cast<PHINode>(DestBB->begin());
|
|
if (!DestBBPN) return true; // no conflict.
|
|
|
|
// Collect the preds of BB.
|
|
SmallPtrSet<const BasicBlock*, 16> BBPreds;
|
|
if (const PHINode *BBPN = dyn_cast<PHINode>(BB->begin())) {
|
|
// It is faster to get preds from a PHI than with pred_iterator.
|
|
for (unsigned i = 0, e = BBPN->getNumIncomingValues(); i != e; ++i)
|
|
BBPreds.insert(BBPN->getIncomingBlock(i));
|
|
} else {
|
|
BBPreds.insert(pred_begin(BB), pred_end(BB));
|
|
}
|
|
|
|
// Walk the preds of DestBB.
|
|
for (unsigned i = 0, e = DestBBPN->getNumIncomingValues(); i != e; ++i) {
|
|
BasicBlock *Pred = DestBBPN->getIncomingBlock(i);
|
|
if (BBPreds.count(Pred)) { // Common predecessor?
|
|
BBI = DestBB->begin();
|
|
while (const PHINode *PN = dyn_cast<PHINode>(BBI++)) {
|
|
const Value *V1 = PN->getIncomingValueForBlock(Pred);
|
|
const Value *V2 = PN->getIncomingValueForBlock(BB);
|
|
|
|
// If V2 is a phi node in BB, look up what the mapped value will be.
|
|
if (const PHINode *V2PN = dyn_cast<PHINode>(V2))
|
|
if (V2PN->getParent() == BB)
|
|
V2 = V2PN->getIncomingValueForBlock(Pred);
|
|
|
|
// If there is a conflict, bail out.
|
|
if (V1 != V2) return false;
|
|
}
|
|
}
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
|
|
/// EliminateMostlyEmptyBlock - Eliminate a basic block that have only phi's and
|
|
/// an unconditional branch in it.
|
|
void CodeGenPrepare::EliminateMostlyEmptyBlock(BasicBlock *BB) {
|
|
BranchInst *BI = cast<BranchInst>(BB->getTerminator());
|
|
BasicBlock *DestBB = BI->getSuccessor(0);
|
|
|
|
DEBUG(dbgs() << "MERGING MOSTLY EMPTY BLOCKS - BEFORE:\n" << *BB << *DestBB);
|
|
|
|
// If the destination block has a single pred, then this is a trivial edge,
|
|
// just collapse it.
|
|
if (BasicBlock *SinglePred = DestBB->getSinglePredecessor()) {
|
|
if (SinglePred != DestBB) {
|
|
// Remember if SinglePred was the entry block of the function. If so, we
|
|
// will need to move BB back to the entry position.
|
|
bool isEntry = SinglePred == &SinglePred->getParent()->getEntryBlock();
|
|
MergeBasicBlockIntoOnlyPred(DestBB, this);
|
|
|
|
if (isEntry && BB != &BB->getParent()->getEntryBlock())
|
|
BB->moveBefore(&BB->getParent()->getEntryBlock());
|
|
|
|
DEBUG(dbgs() << "AFTER:\n" << *DestBB << "\n\n\n");
|
|
return;
|
|
}
|
|
}
|
|
|
|
// Otherwise, we have multiple predecessors of BB. Update the PHIs in DestBB
|
|
// to handle the new incoming edges it is about to have.
|
|
PHINode *PN;
|
|
for (BasicBlock::iterator BBI = DestBB->begin();
|
|
(PN = dyn_cast<PHINode>(BBI)); ++BBI) {
|
|
// Remove the incoming value for BB, and remember it.
|
|
Value *InVal = PN->removeIncomingValue(BB, false);
|
|
|
|
// Two options: either the InVal is a phi node defined in BB or it is some
|
|
// value that dominates BB.
|
|
PHINode *InValPhi = dyn_cast<PHINode>(InVal);
|
|
if (InValPhi && InValPhi->getParent() == BB) {
|
|
// Add all of the input values of the input PHI as inputs of this phi.
|
|
for (unsigned i = 0, e = InValPhi->getNumIncomingValues(); i != e; ++i)
|
|
PN->addIncoming(InValPhi->getIncomingValue(i),
|
|
InValPhi->getIncomingBlock(i));
|
|
} else {
|
|
// Otherwise, add one instance of the dominating value for each edge that
|
|
// we will be adding.
|
|
if (PHINode *BBPN = dyn_cast<PHINode>(BB->begin())) {
|
|
for (unsigned i = 0, e = BBPN->getNumIncomingValues(); i != e; ++i)
|
|
PN->addIncoming(InVal, BBPN->getIncomingBlock(i));
|
|
} else {
|
|
for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI)
|
|
PN->addIncoming(InVal, *PI);
|
|
}
|
|
}
|
|
}
|
|
|
|
// The PHIs are now updated, change everything that refers to BB to use
|
|
// DestBB and remove BB.
|
|
BB->replaceAllUsesWith(DestBB);
|
|
if (PFI) {
|
|
PFI->replaceAllUses(BB, DestBB);
|
|
PFI->removeEdge(ProfileInfo::getEdge(BB, DestBB));
|
|
}
|
|
BB->eraseFromParent();
|
|
++NumElim;
|
|
|
|
DEBUG(dbgs() << "AFTER:\n" << *DestBB << "\n\n\n");
|
|
}
|
|
|
|
/// FindReusablePredBB - Check all of the predecessors of the block DestPHI
|
|
/// lives in to see if there is a block that we can reuse as a critical edge
|
|
/// from TIBB.
|
|
static BasicBlock *FindReusablePredBB(PHINode *DestPHI, BasicBlock *TIBB) {
|
|
BasicBlock *Dest = DestPHI->getParent();
|
|
|
|
/// TIPHIValues - This array is lazily computed to determine the values of
|
|
/// PHIs in Dest that TI would provide.
|
|
SmallVector<Value*, 32> TIPHIValues;
|
|
|
|
/// TIBBEntryNo - This is a cache to speed up pred queries for TIBB.
|
|
unsigned TIBBEntryNo = 0;
|
|
|
|
// Check to see if Dest has any blocks that can be used as a split edge for
|
|
// this terminator.
|
|
for (unsigned pi = 0, e = DestPHI->getNumIncomingValues(); pi != e; ++pi) {
|
|
BasicBlock *Pred = DestPHI->getIncomingBlock(pi);
|
|
// To be usable, the pred has to end with an uncond branch to the dest.
|
|
BranchInst *PredBr = dyn_cast<BranchInst>(Pred->getTerminator());
|
|
if (!PredBr || !PredBr->isUnconditional())
|
|
continue;
|
|
// Must be empty other than the branch and debug info.
|
|
BasicBlock::iterator I = Pred->begin();
|
|
while (isa<DbgInfoIntrinsic>(I))
|
|
I++;
|
|
if (&*I != PredBr)
|
|
continue;
|
|
// Cannot be the entry block; its label does not get emitted.
|
|
if (Pred == &Dest->getParent()->getEntryBlock())
|
|
continue;
|
|
|
|
// Finally, since we know that Dest has phi nodes in it, we have to make
|
|
// sure that jumping to Pred will have the same effect as going to Dest in
|
|
// terms of PHI values.
|
|
PHINode *PN;
|
|
unsigned PHINo = 0;
|
|
unsigned PredEntryNo = pi;
|
|
|
|
bool FoundMatch = true;
|
|
for (BasicBlock::iterator I = Dest->begin();
|
|
(PN = dyn_cast<PHINode>(I)); ++I, ++PHINo) {
|
|
if (PHINo == TIPHIValues.size()) {
|
|
if (PN->getIncomingBlock(TIBBEntryNo) != TIBB)
|
|
TIBBEntryNo = PN->getBasicBlockIndex(TIBB);
|
|
TIPHIValues.push_back(PN->getIncomingValue(TIBBEntryNo));
|
|
}
|
|
|
|
// If the PHI entry doesn't work, we can't use this pred.
|
|
if (PN->getIncomingBlock(PredEntryNo) != Pred)
|
|
PredEntryNo = PN->getBasicBlockIndex(Pred);
|
|
|
|
if (TIPHIValues[PHINo] != PN->getIncomingValue(PredEntryNo)) {
|
|
FoundMatch = false;
|
|
break;
|
|
}
|
|
}
|
|
|
|
// If we found a workable predecessor, change TI to branch to Succ.
|
|
if (FoundMatch)
|
|
return Pred;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
|
|
/// SplitEdgeNicely - Split the critical edge from TI to its specified
|
|
/// successor if it will improve codegen. We only do this if the successor has
|
|
/// phi nodes (otherwise critical edges are ok). If there is already another
|
|
/// predecessor of the succ that is empty (and thus has no phi nodes), use it
|
|
/// instead of introducing a new block.
|
|
static void SplitEdgeNicely(TerminatorInst *TI, unsigned SuccNum,
|
|
SmallSet<std::pair<const BasicBlock*,
|
|
const BasicBlock*>, 8> &BackEdges,
|
|
Pass *P) {
|
|
BasicBlock *TIBB = TI->getParent();
|
|
BasicBlock *Dest = TI->getSuccessor(SuccNum);
|
|
assert(isa<PHINode>(Dest->begin()) &&
|
|
"This should only be called if Dest has a PHI!");
|
|
PHINode *DestPHI = cast<PHINode>(Dest->begin());
|
|
|
|
// Do not split edges to EH landing pads.
|
|
if (InvokeInst *Invoke = dyn_cast<InvokeInst>(TI))
|
|
if (Invoke->getSuccessor(1) == Dest)
|
|
return;
|
|
|
|
// As a hack, never split backedges of loops. Even though the copy for any
|
|
// PHIs inserted on the backedge would be dead for exits from the loop, we
|
|
// assume that the cost of *splitting* the backedge would be too high.
|
|
if (BackEdges.count(std::make_pair(TIBB, Dest)))
|
|
return;
|
|
|
|
if (BasicBlock *ReuseBB = FindReusablePredBB(DestPHI, TIBB)) {
|
|
ProfileInfo *PFI = P->getAnalysisIfAvailable<ProfileInfo>();
|
|
if (PFI)
|
|
PFI->splitEdge(TIBB, Dest, ReuseBB);
|
|
Dest->removePredecessor(TIBB);
|
|
TI->setSuccessor(SuccNum, ReuseBB);
|
|
return;
|
|
}
|
|
|
|
SplitCriticalEdge(TI, SuccNum, P, true);
|
|
}
|
|
|
|
|
|
/// OptimizeNoopCopyExpression - If the specified cast instruction is a noop
|
|
/// copy (e.g. it's casting from one pointer type to another, i32->i8 on PPC),
|
|
/// sink it into user blocks to reduce the number of virtual
|
|
/// registers that must be created and coalesced.
|
|
///
|
|
/// Return true if any changes are made.
|
|
///
|
|
static bool OptimizeNoopCopyExpression(CastInst *CI, const TargetLowering &TLI){
|
|
// If this is a noop copy,
|
|
EVT SrcVT = TLI.getValueType(CI->getOperand(0)->getType());
|
|
EVT DstVT = TLI.getValueType(CI->getType());
|
|
|
|
// This is an fp<->int conversion?
|
|
if (SrcVT.isInteger() != DstVT.isInteger())
|
|
return false;
|
|
|
|
// If this is an extension, it will be a zero or sign extension, which
|
|
// isn't a noop.
|
|
if (SrcVT.bitsLT(DstVT)) return false;
|
|
|
|
// If these values will be promoted, find out what they will be promoted
|
|
// to. This helps us consider truncates on PPC as noop copies when they
|
|
// are.
|
|
if (TLI.getTypeAction(SrcVT) == TargetLowering::Promote)
|
|
SrcVT = TLI.getTypeToTransformTo(CI->getContext(), SrcVT);
|
|
if (TLI.getTypeAction(DstVT) == TargetLowering::Promote)
|
|
DstVT = TLI.getTypeToTransformTo(CI->getContext(), DstVT);
|
|
|
|
// If, after promotion, these are the same types, this is a noop copy.
|
|
if (SrcVT != DstVT)
|
|
return false;
|
|
|
|
BasicBlock *DefBB = CI->getParent();
|
|
|
|
/// InsertedCasts - Only insert a cast in each block once.
|
|
DenseMap<BasicBlock*, CastInst*> InsertedCasts;
|
|
|
|
bool MadeChange = false;
|
|
for (Value::use_iterator UI = CI->use_begin(), E = CI->use_end();
|
|
UI != E; ) {
|
|
Use &TheUse = UI.getUse();
|
|
Instruction *User = cast<Instruction>(*UI);
|
|
|
|
// Figure out which BB this cast is used in. For PHI's this is the
|
|
// appropriate predecessor block.
|
|
BasicBlock *UserBB = User->getParent();
|
|
if (PHINode *PN = dyn_cast<PHINode>(User)) {
|
|
UserBB = PN->getIncomingBlock(UI);
|
|
}
|
|
|
|
// Preincrement use iterator so we don't invalidate it.
|
|
++UI;
|
|
|
|
// If this user is in the same block as the cast, don't change the cast.
|
|
if (UserBB == DefBB) continue;
|
|
|
|
// If we have already inserted a cast into this block, use it.
|
|
CastInst *&InsertedCast = InsertedCasts[UserBB];
|
|
|
|
if (!InsertedCast) {
|
|
BasicBlock::iterator InsertPt = UserBB->getFirstNonPHI();
|
|
|
|
InsertedCast =
|
|
CastInst::Create(CI->getOpcode(), CI->getOperand(0), CI->getType(), "",
|
|
InsertPt);
|
|
MadeChange = true;
|
|
}
|
|
|
|
// Replace a use of the cast with a use of the new cast.
|
|
TheUse = InsertedCast;
|
|
}
|
|
|
|
// If we removed all uses, nuke the cast.
|
|
if (CI->use_empty()) {
|
|
CI->eraseFromParent();
|
|
MadeChange = true;
|
|
}
|
|
|
|
return MadeChange;
|
|
}
|
|
|
|
/// OptimizeCmpExpression - sink the given CmpInst into user blocks to reduce
|
|
/// the number of virtual registers that must be created and coalesced. This is
|
|
/// a clear win except on targets with multiple condition code registers
|
|
/// (PowerPC), where it might lose; some adjustment may be wanted there.
|
|
///
|
|
/// Return true if any changes are made.
|
|
static bool OptimizeCmpExpression(CmpInst *CI) {
|
|
BasicBlock *DefBB = CI->getParent();
|
|
|
|
/// InsertedCmp - Only insert a cmp in each block once.
|
|
DenseMap<BasicBlock*, CmpInst*> InsertedCmps;
|
|
|
|
bool MadeChange = false;
|
|
for (Value::use_iterator UI = CI->use_begin(), E = CI->use_end();
|
|
UI != E; ) {
|
|
Use &TheUse = UI.getUse();
|
|
Instruction *User = cast<Instruction>(*UI);
|
|
|
|
// Preincrement use iterator so we don't invalidate it.
|
|
++UI;
|
|
|
|
// Don't bother for PHI nodes.
|
|
if (isa<PHINode>(User))
|
|
continue;
|
|
|
|
// Figure out which BB this cmp is used in.
|
|
BasicBlock *UserBB = User->getParent();
|
|
|
|
// If this user is in the same block as the cmp, don't change the cmp.
|
|
if (UserBB == DefBB) continue;
|
|
|
|
// If we have already inserted a cmp into this block, use it.
|
|
CmpInst *&InsertedCmp = InsertedCmps[UserBB];
|
|
|
|
if (!InsertedCmp) {
|
|
BasicBlock::iterator InsertPt = UserBB->getFirstNonPHI();
|
|
|
|
InsertedCmp =
|
|
CmpInst::Create(CI->getOpcode(),
|
|
CI->getPredicate(), CI->getOperand(0),
|
|
CI->getOperand(1), "", InsertPt);
|
|
MadeChange = true;
|
|
}
|
|
|
|
// Replace a use of the cmp with a use of the new cmp.
|
|
TheUse = InsertedCmp;
|
|
}
|
|
|
|
// If we removed all uses, nuke the cmp.
|
|
if (CI->use_empty())
|
|
CI->eraseFromParent();
|
|
|
|
return MadeChange;
|
|
}
|
|
|
|
namespace {
|
|
class CodeGenPrepareFortifiedLibCalls : public SimplifyFortifiedLibCalls {
|
|
protected:
|
|
void replaceCall(Value *With) {
|
|
CI->replaceAllUsesWith(With);
|
|
CI->eraseFromParent();
|
|
}
|
|
bool isFoldable(unsigned SizeCIOp, unsigned, bool) const {
|
|
if (ConstantInt *SizeCI =
|
|
dyn_cast<ConstantInt>(CI->getArgOperand(SizeCIOp)))
|
|
return SizeCI->isAllOnesValue();
|
|
return false;
|
|
}
|
|
};
|
|
} // end anonymous namespace
|
|
|
|
bool CodeGenPrepare::OptimizeCallInst(CallInst *CI) {
|
|
// Lower all uses of llvm.objectsize.*
|
|
IntrinsicInst *II = dyn_cast<IntrinsicInst>(CI);
|
|
if (II && II->getIntrinsicID() == Intrinsic::objectsize) {
|
|
bool Min = (cast<ConstantInt>(II->getArgOperand(1))->getZExtValue() == 1);
|
|
const Type *ReturnTy = CI->getType();
|
|
Constant *RetVal = ConstantInt::get(ReturnTy, Min ? 0 : -1ULL);
|
|
CI->replaceAllUsesWith(RetVal);
|
|
CI->eraseFromParent();
|
|
return true;
|
|
}
|
|
|
|
// From here on out we're working with named functions.
|
|
if (CI->getCalledFunction() == 0) return false;
|
|
|
|
// We'll need TargetData from here on out.
|
|
const TargetData *TD = TLI ? TLI->getTargetData() : 0;
|
|
if (!TD) return false;
|
|
|
|
// Lower all default uses of _chk calls. This is very similar
|
|
// to what InstCombineCalls does, but here we are only lowering calls
|
|
// that have the default "don't know" as the objectsize. Anything else
|
|
// should be left alone.
|
|
CodeGenPrepareFortifiedLibCalls Simplifier;
|
|
return Simplifier.fold(CI, TD);
|
|
}
|
|
//===----------------------------------------------------------------------===//
|
|
// 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 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(dbgs() << "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(dbgs() << "CGP: Reusing nonlocal addrmode: " << AddrMode << " for "
|
|
<< *MemoryInst);
|
|
if (SunkAddr->getType() != Addr->getType())
|
|
SunkAddr = new BitCastInst(SunkAddr, Addr->getType(), "tmp", InsertPt);
|
|
} else {
|
|
DEBUG(dbgs() << "CGP: SINKING nonlocal addrmode: " << AddrMode << " for "
|
|
<< *MemoryInst);
|
|
const Type *IntPtrTy =
|
|
TLI->getTargetData()->getIntPtrType(AccessTy->getContext());
|
|
|
|
Value *Result = 0;
|
|
|
|
// Start with the base register. Do this first so that subsequent address
|
|
// matching finds it last, which will prevent it from trying to match it
|
|
// as the scaled value in case it happens to be a mul. That would be
|
|
// problematic if we've sunk a different mul for the scale, because then
|
|
// we'd end up sinking both muls.
|
|
if (AddrMode.BaseReg) {
|
|
Value *V = AddrMode.BaseReg;
|
|
if (V->getType()->isPointerTy())
|
|
V = new PtrToIntInst(V, IntPtrTy, "sunkaddr", InsertPt);
|
|
if (V->getType() != IntPtrTy)
|
|
V = CastInst::CreateIntegerCast(V, IntPtrTy, /*isSigned=*/true,
|
|
"sunkaddr", InsertPt);
|
|
Result = V;
|
|
}
|
|
|
|
// Add the scale value.
|
|
if (AddrMode.Scale) {
|
|
Value *V = AddrMode.ScaledReg;
|
|
if (V->getType() == IntPtrTy) {
|
|
// done.
|
|
} else if (V->getType()->isPointerTy()) {
|
|
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);
|
|
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);
|
|
// This address is now available for reassignment, so erase the table entry;
|
|
// we don't want to match some completely different instruction.
|
|
SunkAddrs[Addr] = 0;
|
|
}
|
|
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;
|
|
|
|
std::vector<TargetLowering::AsmOperandInfo> TargetConstraints = TLI->ParseConstraints(CS);
|
|
unsigned ArgNo = 0;
|
|
for (unsigned i = 0, e = TargetConstraints.size(); i != e; ++i) {
|
|
TargetLowering::AsmOperandInfo &OpInfo = TargetConstraints[i];
|
|
|
|
// Compute the constraint code and ConstraintType to use.
|
|
TLI->ComputeConstraintToUse(OpInfo, SDValue());
|
|
|
|
if (OpInfo.ConstraintType == TargetLowering::C_Memory &&
|
|
OpInfo.isIndirect) {
|
|
Value *OpVal = const_cast<Value *>(CS.getArgument(ArgNo++));
|
|
MadeChange |= OptimizeMemoryInst(I, OpVal, OpVal->getType(), SunkAddrs);
|
|
} else if (OpInfo.Type == InlineAsm::isInput)
|
|
ArgNo++;
|
|
}
|
|
|
|
return MadeChange;
|
|
}
|
|
|
|
/// MoveExtToFormExtLoad - Move a zext or sext fed by a load into the same
|
|
/// basic block as the load, unless conditions are unfavorable. This allows
|
|
/// SelectionDAG to fold the extend into the load.
|
|
///
|
|
bool CodeGenPrepare::MoveExtToFormExtLoad(Instruction *I) {
|
|
// Look for a load being extended.
|
|
LoadInst *LI = dyn_cast<LoadInst>(I->getOperand(0));
|
|
if (!LI) return false;
|
|
|
|
// If they're already in the same block, there's nothing to do.
|
|
if (LI->getParent() == I->getParent())
|
|
return false;
|
|
|
|
// If the load has other users and the truncate is not free, this probably
|
|
// isn't worthwhile.
|
|
if (!LI->hasOneUse() &&
|
|
TLI && (TLI->isTypeLegal(TLI->getValueType(LI->getType())) ||
|
|
!TLI->isTypeLegal(TLI->getValueType(I->getType()))) &&
|
|
!TLI->isTruncateFree(I->getType(), LI->getType()))
|
|
return false;
|
|
|
|
// Check whether the target supports casts folded into loads.
|
|
unsigned LType;
|
|
if (isa<ZExtInst>(I))
|
|
LType = ISD::ZEXTLOAD;
|
|
else {
|
|
assert(isa<SExtInst>(I) && "Unexpected ext type!");
|
|
LType = ISD::SEXTLOAD;
|
|
}
|
|
if (TLI && !TLI->isLoadExtLegal(LType, TLI->getValueType(LI->getType())))
|
|
return false;
|
|
|
|
// Move the extend into the same block as the load, so that SelectionDAG
|
|
// can fold it.
|
|
I->removeFromParent();
|
|
I->insertAfter(LI);
|
|
return true;
|
|
}
|
|
|
|
bool CodeGenPrepare::OptimizeExtUses(Instruction *I) {
|
|
BasicBlock *DefBB = I->getParent();
|
|
|
|
// If the result of a {s|z}ext and its source are both 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.
|
|
if (CriticalEdgeSplit) {
|
|
TerminatorInst *BBTI = BB.getTerminator();
|
|
if (BBTI->getNumSuccessors() > 1 && !isa<IndirectBrInst>(BBTI)) {
|
|
for (unsigned i = 0, e = BBTI->getNumSuccessors(); i != e; ++i) {
|
|
BasicBlock *SuccBB = BBTI->getSuccessor(i);
|
|
if (isa<PHINode>(SuccBB->begin()) && isCriticalEdge(BBTI, i, true))
|
|
SplitEdgeNicely(BBTI, i, BackEdges, 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 |= MoveExtToFormExtLoad(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 (TLI->ExpandInlineAsm(CI)) {
|
|
BBI = BB.begin();
|
|
// Avoid processing instructions out of order, which could cause
|
|
// reuse before a value is defined.
|
|
SunkAddrs.clear();
|
|
} else
|
|
// Sink address computing for memory operands into the block.
|
|
MadeChange |= OptimizeInlineAsmInst(I, &(*CI), SunkAddrs);
|
|
} else {
|
|
// Other CallInst optimizations that don't need to muck with the
|
|
// enclosing iterator here.
|
|
MadeChange |= OptimizeCallInst(CI);
|
|
}
|
|
}
|
|
}
|
|
|
|
return MadeChange;
|
|
}
|