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-rw-r--r--contrib/llvm/lib/Transforms/Scalar/GVN.cpp447
1 files changed, 234 insertions, 213 deletions
diff --git a/contrib/llvm/lib/Transforms/Scalar/GVN.cpp b/contrib/llvm/lib/Transforms/Scalar/GVN.cpp
index 106eba099ca0..ac13eebf8275 100644
--- a/contrib/llvm/lib/Transforms/Scalar/GVN.cpp
+++ b/contrib/llvm/lib/Transforms/Scalar/GVN.cpp
@@ -20,10 +20,12 @@
#include "llvm/ADT/DepthFirstIterator.h"
#include "llvm/ADT/Hashing.h"
#include "llvm/ADT/MapVector.h"
+#include "llvm/ADT/PostOrderIterator.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/AliasAnalysis.h"
+#include "llvm/Analysis/AssumptionCache.h"
#include "llvm/Analysis/CFG.h"
#include "llvm/Analysis/ConstantFolding.h"
#include "llvm/Analysis/InstructionSimplify.h"
@@ -45,6 +47,7 @@
#include "llvm/Support/Debug.h"
#include "llvm/Target/TargetLibraryInfo.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
+#include "llvm/Transforms/Utils/Local.h"
#include "llvm/Transforms/Utils/SSAUpdater.h"
#include <vector>
using namespace llvm;
@@ -590,6 +593,7 @@ namespace {
DominatorTree *DT;
const DataLayout *DL;
const TargetLibraryInfo *TLI;
+ AssumptionCache *AC;
SetVector<BasicBlock *> DeadBlocks;
ValueTable VN;
@@ -679,6 +683,7 @@ namespace {
// This transformation requires dominator postdominator info
void getAnalysisUsage(AnalysisUsage &AU) const override {
+ AU.addRequired<AssumptionCacheTracker>();
AU.addRequired<DominatorTreeWrapperPass>();
AU.addRequired<TargetLibraryInfo>();
if (!NoLoads)
@@ -705,6 +710,7 @@ namespace {
void dump(DenseMap<uint32_t, Value*> &d);
bool iterateOnFunction(Function &F);
bool performPRE(Function &F);
+ bool performScalarPRE(Instruction *I);
Value *findLeader(const BasicBlock *BB, uint32_t num);
void cleanupGlobalSets();
void verifyRemoved(const Instruction *I) const;
@@ -727,6 +733,7 @@ FunctionPass *llvm::createGVNPass(bool NoLoads) {
}
INITIALIZE_PASS_BEGIN(GVN, "gvn", "Global Value Numbering", false, false)
+INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
INITIALIZE_PASS_DEPENDENCY(MemoryDependenceAnalysis)
INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfo)
@@ -1616,7 +1623,7 @@ bool GVN::PerformLoadPRE(LoadInst *LI, AvailValInBlkVect &ValuesPerBlock,
// If all preds have a single successor, then we know it is safe to insert
// the load on the pred (?!?), so we can insert code to materialize the
// pointer if it is not available.
- PHITransAddr Address(LI->getPointerOperand(), DL);
+ PHITransAddr Address(LI->getPointerOperand(), DL, AC);
Value *LoadPtr = nullptr;
LoadPtr = Address.PHITranslateWithInsertion(LoadBB, UnavailablePred,
*DT, NewInsts);
@@ -1669,9 +1676,11 @@ bool GVN::PerformLoadPRE(LoadInst *LI, AvailValInBlkVect &ValuesPerBlock,
LI->getAlignment(),
UnavailablePred->getTerminator());
- // Transfer the old load's TBAA tag to the new load.
- if (MDNode *Tag = LI->getMetadata(LLVMContext::MD_tbaa))
- NewLoad->setMetadata(LLVMContext::MD_tbaa, Tag);
+ // Transfer the old load's AA tags to the new load.
+ AAMDNodes Tags;
+ LI->getAAMetadata(Tags);
+ if (Tags)
+ NewLoad->setAAMetadata(Tags);
// Transfer DebugLoc.
NewLoad->setDebugLoc(LI->getDebugLoc());
@@ -1700,8 +1709,7 @@ bool GVN::PerformLoadPRE(LoadInst *LI, AvailValInBlkVect &ValuesPerBlock,
bool GVN::processNonLocalLoad(LoadInst *LI) {
// Step 1: Find the non-local dependencies of the load.
LoadDepVect Deps;
- AliasAnalysis::Location Loc = VN.getAliasAnalysis()->getLocation(LI);
- MD->getNonLocalPointerDependency(Loc, true, LI->getParent(), Deps);
+ MD->getNonLocalPointerDependency(LI, Deps);
// If we had to process more than one hundred blocks to find the
// dependencies, this load isn't worth worrying about. Optimizing
@@ -1722,6 +1730,15 @@ bool GVN::processNonLocalLoad(LoadInst *LI) {
return false;
}
+ // If this load follows a GEP, see if we can PRE the indices before analyzing.
+ if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(LI->getOperand(0))) {
+ for (GetElementPtrInst::op_iterator OI = GEP->idx_begin(),
+ OE = GEP->idx_end();
+ OI != OE; ++OI)
+ if (Instruction *I = dyn_cast<Instruction>(OI->get()))
+ performScalarPRE(I);
+ }
+
// Step 2: Analyze the availability of the load
AvailValInBlkVect ValuesPerBlock;
UnavailBlkVect UnavailableBlocks;
@@ -1774,36 +1791,24 @@ static void patchReplacementInstruction(Instruction *I, Value *Repl) {
ReplOp->setHasNoUnsignedWrap(false);
}
if (Instruction *ReplInst = dyn_cast<Instruction>(Repl)) {
- SmallVector<std::pair<unsigned, MDNode*>, 4> Metadata;
- ReplInst->getAllMetadataOtherThanDebugLoc(Metadata);
- for (int i = 0, n = Metadata.size(); i < n; ++i) {
- unsigned Kind = Metadata[i].first;
- MDNode *IMD = I->getMetadata(Kind);
- MDNode *ReplMD = Metadata[i].second;
- switch(Kind) {
- default:
- ReplInst->setMetadata(Kind, nullptr); // Remove unknown metadata
- break;
- case LLVMContext::MD_dbg:
- llvm_unreachable("getAllMetadataOtherThanDebugLoc returned a MD_dbg");
- case LLVMContext::MD_tbaa:
- ReplInst->setMetadata(Kind, MDNode::getMostGenericTBAA(IMD, ReplMD));
- break;
- case LLVMContext::MD_range:
- ReplInst->setMetadata(Kind, MDNode::getMostGenericRange(IMD, ReplMD));
- break;
- case LLVMContext::MD_prof:
- llvm_unreachable("MD_prof in a non-terminator instruction");
- break;
- case LLVMContext::MD_fpmath:
- ReplInst->setMetadata(Kind, MDNode::getMostGenericFPMath(IMD, ReplMD));
- break;
- case LLVMContext::MD_invariant_load:
- // Only set the !invariant.load if it is present in both instructions.
- ReplInst->setMetadata(Kind, IMD);
- break;
- }
- }
+ // FIXME: If both the original and replacement value are part of the
+ // same control-flow region (meaning that the execution of one
+ // guarentees the executation of the other), then we can combine the
+ // noalias scopes here and do better than the general conservative
+ // answer used in combineMetadata().
+
+ // In general, GVN unifies expressions over different control-flow
+ // regions, and so we need a conservative combination of the noalias
+ // scopes.
+ unsigned KnownIDs[] = {
+ LLVMContext::MD_tbaa,
+ LLVMContext::MD_alias_scope,
+ LLVMContext::MD_noalias,
+ LLVMContext::MD_range,
+ LLVMContext::MD_fpmath,
+ LLVMContext::MD_invariant_load,
+ };
+ combineMetadata(ReplInst, I, KnownIDs);
}
}
@@ -2101,15 +2106,15 @@ bool GVN::propagateEquality(Value *LHS, Value *RHS,
std::swap(LHS, RHS);
assert((isa<Argument>(LHS) || isa<Instruction>(LHS)) && "Unexpected value!");
- // If there is no obvious reason to prefer the left-hand side over the right-
- // hand side, ensure the longest lived term is on the right-hand side, so the
- // shortest lived term will be replaced by the longest lived. This tends to
- // expose more simplifications.
+ // If there is no obvious reason to prefer the left-hand side over the
+ // right-hand side, ensure the longest lived term is on the right-hand side,
+ // so the shortest lived term will be replaced by the longest lived.
+ // This tends to expose more simplifications.
uint32_t LVN = VN.lookup_or_add(LHS);
if ((isa<Argument>(LHS) && isa<Argument>(RHS)) ||
(isa<Instruction>(LHS) && isa<Instruction>(RHS))) {
- // Move the 'oldest' value to the right-hand side, using the value number as
- // a proxy for age.
+ // Move the 'oldest' value to the right-hand side, using the value number
+ // as a proxy for age.
uint32_t RVN = VN.lookup_or_add(RHS);
if (LVN < RVN) {
std::swap(LHS, RHS);
@@ -2138,10 +2143,10 @@ bool GVN::propagateEquality(Value *LHS, Value *RHS,
NumGVNEqProp += NumReplacements;
}
- // Now try to deduce additional equalities from this one. For example, if the
- // known equality was "(A != B)" == "false" then it follows that A and B are
- // equal in the scope. Only boolean equalities with an explicit true or false
- // RHS are currently supported.
+ // Now try to deduce additional equalities from this one. For example, if
+ // the known equality was "(A != B)" == "false" then it follows that A and B
+ // are equal in the scope. Only boolean equalities with an explicit true or
+ // false RHS are currently supported.
if (!RHS->getType()->isIntegerTy(1))
// Not a boolean equality - bail out.
continue;
@@ -2166,7 +2171,7 @@ bool GVN::propagateEquality(Value *LHS, Value *RHS,
// If we are propagating an equality like "(A == B)" == "true" then also
// propagate the equality A == B. When propagating a comparison such as
// "(A >= B)" == "true", replace all instances of "A < B" with "false".
- if (ICmpInst *Cmp = dyn_cast<ICmpInst>(LHS)) {
+ if (CmpInst *Cmp = dyn_cast<CmpInst>(LHS)) {
Value *Op0 = Cmp->getOperand(0), *Op1 = Cmp->getOperand(1);
// If "A == B" is known true, or "A != B" is known false, then replace
@@ -2175,12 +2180,24 @@ bool GVN::propagateEquality(Value *LHS, Value *RHS,
(isKnownFalse && Cmp->getPredicate() == CmpInst::ICMP_NE))
Worklist.push_back(std::make_pair(Op0, Op1));
+ // Handle the floating point versions of equality comparisons too.
+ if ((isKnownTrue && Cmp->getPredicate() == CmpInst::FCMP_OEQ) ||
+ (isKnownFalse && Cmp->getPredicate() == CmpInst::FCMP_UNE)) {
+ // Floating point -0.0 and 0.0 compare equal, so we can't
+ // propagate a constant based on that comparison.
+ // FIXME: We should do this optimization if 'no signed zeros' is
+ // applicable via an instruction-level fast-math-flag or some other
+ // indicator that relaxed FP semantics are being used.
+ if (!isa<ConstantFP>(Op1) || !cast<ConstantFP>(Op1)->isZero())
+ Worklist.push_back(std::make_pair(Op0, Op1));
+ }
+
// If "A >= B" is known true, replace "A < B" with false everywhere.
CmpInst::Predicate NotPred = Cmp->getInversePredicate();
Constant *NotVal = ConstantInt::get(Cmp->getType(), isKnownFalse);
- // Since we don't have the instruction "A < B" immediately to hand, work out
- // the value number that it would have and use that to find an appropriate
- // instruction (if any).
+ // Since we don't have the instruction "A < B" immediately to hand, work
+ // out the value number that it would have and use that to find an
+ // appropriate instruction (if any).
uint32_t NextNum = VN.getNextUnusedValueNumber();
uint32_t Num = VN.lookup_or_add_cmp(Cmp->getOpcode(), NotPred, Op0, Op1);
// If the number we were assigned was brand new then there is no point in
@@ -2219,7 +2236,7 @@ bool GVN::processInstruction(Instruction *I) {
// to value numbering it. Value numbering often exposes redundancies, for
// example if it determines that %y is equal to %x then the instruction
// "%z = and i32 %x, %y" becomes "%z = and i32 %x, %x" which we now simplify.
- if (Value *V = SimplifyInstruction(I, DL, TLI, DT)) {
+ if (Value *V = SimplifyInstruction(I, DL, TLI, DT, AC)) {
I->replaceAllUsesWith(V);
if (MD && V->getType()->getScalarType()->isPointerTy())
MD->invalidateCachedPointerInfo(V);
@@ -2339,6 +2356,7 @@ bool GVN::runOnFunction(Function& F) {
DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
DL = DLP ? &DLP->getDataLayout() : nullptr;
+ AC = &getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F);
TLI = &getAnalysis<TargetLibraryInfo>();
VN.setAliasAnalysis(&getAnalysis<AliasAnalysis>());
VN.setMemDep(MD);
@@ -2435,175 +2453,182 @@ bool GVN::processBlock(BasicBlock *BB) {
return ChangedFunction;
}
-/// performPRE - Perform a purely local form of PRE that looks for diamond
-/// control flow patterns and attempts to perform simple PRE at the join point.
-bool GVN::performPRE(Function &F) {
- bool Changed = false;
+bool GVN::performScalarPRE(Instruction *CurInst) {
SmallVector<std::pair<Value*, BasicBlock*>, 8> predMap;
- for (BasicBlock *CurrentBlock : depth_first(&F.getEntryBlock())) {
- // Nothing to PRE in the entry block.
- if (CurrentBlock == &F.getEntryBlock()) continue;
- // Don't perform PRE on a landing pad.
- if (CurrentBlock->isLandingPad()) continue;
+ if (isa<AllocaInst>(CurInst) || isa<TerminatorInst>(CurInst) ||
+ isa<PHINode>(CurInst) || CurInst->getType()->isVoidTy() ||
+ CurInst->mayReadFromMemory() || CurInst->mayHaveSideEffects() ||
+ isa<DbgInfoIntrinsic>(CurInst))
+ return false;
- for (BasicBlock::iterator BI = CurrentBlock->begin(),
- BE = CurrentBlock->end(); BI != BE; ) {
- Instruction *CurInst = BI++;
+ // Don't do PRE on compares. The PHI would prevent CodeGenPrepare from
+ // sinking the compare again, and it would force the code generator to
+ // move the i1 from processor flags or predicate registers into a general
+ // purpose register.
+ if (isa<CmpInst>(CurInst))
+ return false;
- if (isa<AllocaInst>(CurInst) ||
- isa<TerminatorInst>(CurInst) || isa<PHINode>(CurInst) ||
- CurInst->getType()->isVoidTy() ||
- CurInst->mayReadFromMemory() || CurInst->mayHaveSideEffects() ||
- isa<DbgInfoIntrinsic>(CurInst))
- continue;
+ // We don't currently value number ANY inline asm calls.
+ if (CallInst *CallI = dyn_cast<CallInst>(CurInst))
+ if (CallI->isInlineAsm())
+ return false;
- // Don't do PRE on compares. The PHI would prevent CodeGenPrepare from
- // sinking the compare again, and it would force the code generator to
- // move the i1 from processor flags or predicate registers into a general
- // purpose register.
- if (isa<CmpInst>(CurInst))
- continue;
+ uint32_t ValNo = VN.lookup(CurInst);
+
+ // Look for the predecessors for PRE opportunities. We're
+ // only trying to solve the basic diamond case, where
+ // a value is computed in the successor and one predecessor,
+ // but not the other. We also explicitly disallow cases
+ // where the successor is its own predecessor, because they're
+ // more complicated to get right.
+ unsigned NumWith = 0;
+ unsigned NumWithout = 0;
+ BasicBlock *PREPred = nullptr;
+ BasicBlock *CurrentBlock = CurInst->getParent();
+ predMap.clear();
+
+ for (pred_iterator PI = pred_begin(CurrentBlock), PE = pred_end(CurrentBlock);
+ PI != PE; ++PI) {
+ BasicBlock *P = *PI;
+ // We're not interested in PRE where the block is its
+ // own predecessor, or in blocks with predecessors
+ // that are not reachable.
+ if (P == CurrentBlock) {
+ NumWithout = 2;
+ break;
+ } else if (!DT->isReachableFromEntry(P)) {
+ NumWithout = 2;
+ break;
+ }
- // We don't currently value number ANY inline asm calls.
- if (CallInst *CallI = dyn_cast<CallInst>(CurInst))
- if (CallI->isInlineAsm())
- continue;
+ Value *predV = findLeader(P, ValNo);
+ if (!predV) {
+ predMap.push_back(std::make_pair(static_cast<Value *>(nullptr), P));
+ PREPred = P;
+ ++NumWithout;
+ } else if (predV == CurInst) {
+ /* CurInst dominates this predecessor. */
+ NumWithout = 2;
+ break;
+ } else {
+ predMap.push_back(std::make_pair(predV, P));
+ ++NumWith;
+ }
+ }
- uint32_t ValNo = VN.lookup(CurInst);
-
- // Look for the predecessors for PRE opportunities. We're
- // only trying to solve the basic diamond case, where
- // a value is computed in the successor and one predecessor,
- // but not the other. We also explicitly disallow cases
- // where the successor is its own predecessor, because they're
- // more complicated to get right.
- unsigned NumWith = 0;
- unsigned NumWithout = 0;
- BasicBlock *PREPred = nullptr;
- predMap.clear();
-
- for (pred_iterator PI = pred_begin(CurrentBlock),
- PE = pred_end(CurrentBlock); PI != PE; ++PI) {
- BasicBlock *P = *PI;
- // We're not interested in PRE where the block is its
- // own predecessor, or in blocks with predecessors
- // that are not reachable.
- if (P == CurrentBlock) {
- NumWithout = 2;
- break;
- } else if (!DT->isReachableFromEntry(P)) {
- NumWithout = 2;
- break;
- }
+ // Don't do PRE when it might increase code size, i.e. when
+ // we would need to insert instructions in more than one pred.
+ if (NumWithout != 1 || NumWith == 0)
+ return false;
- Value* predV = findLeader(P, ValNo);
- if (!predV) {
- predMap.push_back(std::make_pair(static_cast<Value *>(nullptr), P));
- PREPred = P;
- ++NumWithout;
- } else if (predV == CurInst) {
- /* CurInst dominates this predecessor. */
- NumWithout = 2;
- break;
- } else {
- predMap.push_back(std::make_pair(predV, P));
- ++NumWith;
- }
- }
+ // Don't do PRE across indirect branch.
+ if (isa<IndirectBrInst>(PREPred->getTerminator()))
+ return false;
- // Don't do PRE when it might increase code size, i.e. when
- // we would need to insert instructions in more than one pred.
- if (NumWithout != 1 || NumWith == 0)
- continue;
+ // We can't do PRE safely on a critical edge, so instead we schedule
+ // the edge to be split and perform the PRE the next time we iterate
+ // on the function.
+ unsigned SuccNum = GetSuccessorNumber(PREPred, CurrentBlock);
+ if (isCriticalEdge(PREPred->getTerminator(), SuccNum)) {
+ toSplit.push_back(std::make_pair(PREPred->getTerminator(), SuccNum));
+ return false;
+ }
- // Don't do PRE across indirect branch.
- if (isa<IndirectBrInst>(PREPred->getTerminator()))
- continue;
+ // Instantiate the expression in the predecessor that lacked it.
+ // Because we are going top-down through the block, all value numbers
+ // will be available in the predecessor by the time we need them. Any
+ // that weren't originally present will have been instantiated earlier
+ // in this loop.
+ Instruction *PREInstr = CurInst->clone();
+ bool success = true;
+ for (unsigned i = 0, e = CurInst->getNumOperands(); i != e; ++i) {
+ Value *Op = PREInstr->getOperand(i);
+ if (isa<Argument>(Op) || isa<Constant>(Op) || isa<GlobalValue>(Op))
+ continue;
- // We can't do PRE safely on a critical edge, so instead we schedule
- // the edge to be split and perform the PRE the next time we iterate
- // on the function.
- unsigned SuccNum = GetSuccessorNumber(PREPred, CurrentBlock);
- if (isCriticalEdge(PREPred->getTerminator(), SuccNum)) {
- toSplit.push_back(std::make_pair(PREPred->getTerminator(), SuccNum));
- continue;
- }
+ if (Value *V = findLeader(PREPred, VN.lookup(Op))) {
+ PREInstr->setOperand(i, V);
+ } else {
+ success = false;
+ break;
+ }
+ }
- // Instantiate the expression in the predecessor that lacked it.
- // Because we are going top-down through the block, all value numbers
- // will be available in the predecessor by the time we need them. Any
- // that weren't originally present will have been instantiated earlier
- // in this loop.
- Instruction *PREInstr = CurInst->clone();
- bool success = true;
- for (unsigned i = 0, e = CurInst->getNumOperands(); i != e; ++i) {
- Value *Op = PREInstr->getOperand(i);
- if (isa<Argument>(Op) || isa<Constant>(Op) || isa<GlobalValue>(Op))
- continue;
+ // Fail out if we encounter an operand that is not available in
+ // the PRE predecessor. This is typically because of loads which
+ // are not value numbered precisely.
+ if (!success) {
+ DEBUG(verifyRemoved(PREInstr));
+ delete PREInstr;
+ return false;
+ }
- if (Value *V = findLeader(PREPred, VN.lookup(Op))) {
- PREInstr->setOperand(i, V);
- } else {
- success = false;
- break;
- }
- }
+ PREInstr->insertBefore(PREPred->getTerminator());
+ PREInstr->setName(CurInst->getName() + ".pre");
+ PREInstr->setDebugLoc(CurInst->getDebugLoc());
+ VN.add(PREInstr, ValNo);
+ ++NumGVNPRE;
- // Fail out if we encounter an operand that is not available in
- // the PRE predecessor. This is typically because of loads which
- // are not value numbered precisely.
- if (!success) {
- DEBUG(verifyRemoved(PREInstr));
- delete PREInstr;
- continue;
- }
+ // Update the availability map to include the new instruction.
+ addToLeaderTable(ValNo, PREInstr, PREPred);
- PREInstr->insertBefore(PREPred->getTerminator());
- PREInstr->setName(CurInst->getName() + ".pre");
- PREInstr->setDebugLoc(CurInst->getDebugLoc());
- VN.add(PREInstr, ValNo);
- ++NumGVNPRE;
-
- // Update the availability map to include the new instruction.
- addToLeaderTable(ValNo, PREInstr, PREPred);
-
- // Create a PHI to make the value available in this block.
- PHINode* Phi = PHINode::Create(CurInst->getType(), predMap.size(),
- CurInst->getName() + ".pre-phi",
- CurrentBlock->begin());
- for (unsigned i = 0, e = predMap.size(); i != e; ++i) {
- if (Value *V = predMap[i].first)
- Phi->addIncoming(V, predMap[i].second);
- else
- Phi->addIncoming(PREInstr, PREPred);
- }
+ // Create a PHI to make the value available in this block.
+ PHINode *Phi =
+ PHINode::Create(CurInst->getType(), predMap.size(),
+ CurInst->getName() + ".pre-phi", CurrentBlock->begin());
+ for (unsigned i = 0, e = predMap.size(); i != e; ++i) {
+ if (Value *V = predMap[i].first)
+ Phi->addIncoming(V, predMap[i].second);
+ else
+ Phi->addIncoming(PREInstr, PREPred);
+ }
- VN.add(Phi, ValNo);
- addToLeaderTable(ValNo, Phi, CurrentBlock);
- Phi->setDebugLoc(CurInst->getDebugLoc());
- CurInst->replaceAllUsesWith(Phi);
- if (Phi->getType()->getScalarType()->isPointerTy()) {
- // Because we have added a PHI-use of the pointer value, it has now
- // "escaped" from alias analysis' perspective. We need to inform
- // AA of this.
- for (unsigned ii = 0, ee = Phi->getNumIncomingValues(); ii != ee;
- ++ii) {
- unsigned jj = PHINode::getOperandNumForIncomingValue(ii);
- VN.getAliasAnalysis()->addEscapingUse(Phi->getOperandUse(jj));
- }
+ VN.add(Phi, ValNo);
+ addToLeaderTable(ValNo, Phi, CurrentBlock);
+ Phi->setDebugLoc(CurInst->getDebugLoc());
+ CurInst->replaceAllUsesWith(Phi);
+ if (Phi->getType()->getScalarType()->isPointerTy()) {
+ // Because we have added a PHI-use of the pointer value, it has now
+ // "escaped" from alias analysis' perspective. We need to inform
+ // AA of this.
+ for (unsigned ii = 0, ee = Phi->getNumIncomingValues(); ii != ee; ++ii) {
+ unsigned jj = PHINode::getOperandNumForIncomingValue(ii);
+ VN.getAliasAnalysis()->addEscapingUse(Phi->getOperandUse(jj));
+ }
- if (MD)
- MD->invalidateCachedPointerInfo(Phi);
- }
- VN.erase(CurInst);
- removeFromLeaderTable(ValNo, CurInst, CurrentBlock);
+ if (MD)
+ MD->invalidateCachedPointerInfo(Phi);
+ }
+ VN.erase(CurInst);
+ removeFromLeaderTable(ValNo, CurInst, CurrentBlock);
+
+ DEBUG(dbgs() << "GVN PRE removed: " << *CurInst << '\n');
+ if (MD)
+ MD->removeInstruction(CurInst);
+ DEBUG(verifyRemoved(CurInst));
+ CurInst->eraseFromParent();
+ return true;
+}
+
+/// performPRE - Perform a purely local form of PRE that looks for diamond
+/// control flow patterns and attempts to perform simple PRE at the join point.
+bool GVN::performPRE(Function &F) {
+ bool Changed = false;
+ for (BasicBlock *CurrentBlock : depth_first(&F.getEntryBlock())) {
+ // Nothing to PRE in the entry block.
+ if (CurrentBlock == &F.getEntryBlock())
+ continue;
+
+ // Don't perform PRE on a landing pad.
+ if (CurrentBlock->isLandingPad())
+ continue;
- DEBUG(dbgs() << "GVN PRE removed: " << *CurInst << '\n');
- if (MD) MD->removeInstruction(CurInst);
- DEBUG(verifyRemoved(CurInst));
- CurInst->eraseFromParent();
- Changed = true;
+ for (BasicBlock::iterator BI = CurrentBlock->begin(),
+ BE = CurrentBlock->end();
+ BI != BE;) {
+ Instruction *CurInst = BI++;
+ Changed = performScalarPRE(CurInst);
}
}
@@ -2641,25 +2666,21 @@ bool GVN::iterateOnFunction(Function &F) {
// Top-down walk of the dominator tree
bool Changed = false;
-#if 0
- // Needed for value numbering with phi construction to work.
- ReversePostOrderTraversal<Function*> RPOT(&F);
- for (ReversePostOrderTraversal<Function*>::rpo_iterator RI = RPOT.begin(),
- RE = RPOT.end(); RI != RE; ++RI)
- Changed |= processBlock(*RI);
-#else
// Save the blocks this function have before transformation begins. GVN may
// split critical edge, and hence may invalidate the RPO/DT iterator.
//
std::vector<BasicBlock *> BBVect;
BBVect.reserve(256);
- for (DomTreeNode *x : depth_first(DT->getRootNode()))
- BBVect.push_back(x->getBlock());
+ // Needed for value numbering with phi construction to work.
+ ReversePostOrderTraversal<Function *> RPOT(&F);
+ for (ReversePostOrderTraversal<Function *>::rpo_iterator RI = RPOT.begin(),
+ RE = RPOT.end();
+ RI != RE; ++RI)
+ BBVect.push_back(*RI);
for (std::vector<BasicBlock *>::iterator I = BBVect.begin(), E = BBVect.end();
I != E; I++)
Changed |= processBlock(*I);
-#endif
return Changed;
}
@@ -2802,7 +2823,7 @@ bool GVN::processFoldableCondBr(BranchInst *BI) {
return true;
}
-// performPRE() will trigger assert if it come across an instruciton without
+// performPRE() will trigger assert if it comes across an instruction without
// associated val-num. As it normally has far more live instructions than dead
// instructions, it makes more sense just to "fabricate" a val-number for the
// dead code than checking if instruction involved is dead or not.
generated by cgit v1.2.3 (git 2.25.1) at 2024-04-25 11:26:30 +0000