#include "llvm/DerivedTypes.h"
#include "llvm/Instructions.h"
#include "llvm/Function.h"
+#include "llvm/Support/CFG.h"
#include "ValueMapper.h"
#include "llvm/Transforms/Utils/Local.h"
using namespace llvm;
// Loop over all instructions, and copy them over, DCE'ing as we go. This
// loop doesn't include the terminator.
- for (BasicBlock::const_iterator II = BB->begin(), IE = BB->end();
+ for (BasicBlock::const_iterator II = BB->begin(), IE = --BB->end();
II != IE; ++II) {
// If this instruction constant folds, don't bother cloning the instruction,
// instead, just add the constant to the value map.
}
}
+ // Finally, clone over the terminator.
+ const TerminatorInst *OldTI = BB->getTerminator();
+ bool TerminatorDone = false;
+ if (const BranchInst *BI = dyn_cast<BranchInst>(OldTI)) {
+ if (BI->isConditional()) {
+ // If the condition was a known constant in the callee...
+ ConstantBool *Cond = dyn_cast<ConstantBool>(BI->getCondition());
+ if (Cond == 0) // Or is a known constant in the caller...
+ Cond = dyn_cast_or_null<ConstantBool>(ValueMap[BI->getCondition()]);
+ if (Cond) { // Constant fold to uncond branch!
+ BasicBlock *Dest = BI->getSuccessor(!Cond->getValue());
+ ValueMap[OldTI] = new BranchInst(Dest, NewBB);
+ CloneBlock(Dest);
+ TerminatorDone = true;
+ }
+ }
+ } else if (const SwitchInst *SI = dyn_cast<SwitchInst>(OldTI)) {
+ // If switching on a value known constant in the caller.
+ ConstantInt *Cond = dyn_cast<ConstantInt>(SI->getCondition());
+ if (Cond == 0) // Or known constant after constant prop in the callee...
+ Cond = dyn_cast_or_null<ConstantInt>(ValueMap[SI->getCondition()]);
+ if (Cond) { // Constant fold to uncond branch!
+ BasicBlock *Dest = SI->getSuccessor(SI->findCaseValue(Cond));
+ ValueMap[OldTI] = new BranchInst(Dest, NewBB);
+ CloneBlock(Dest);
+ TerminatorDone = true;
+ }
+ }
+
+ if (!TerminatorDone) {
+ Instruction *NewInst = OldTI->clone();
+ if (OldTI->hasName())
+ NewInst->setName(OldTI->getName()+NameSuffix);
+ NewBB->getInstList().push_back(NewInst);
+ ValueMap[OldTI] = NewInst; // Add instruction map to value.
+
+ // Recursively clone any reachable successor blocks.
+ const TerminatorInst *TI = BB->getTerminator();
+ for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i)
+ CloneBlock(TI->getSuccessor(i));
+ }
+
if (CodeInfo) {
CodeInfo->ContainsCalls |= hasCalls;
- CodeInfo->ContainsUnwinds |= isa<UnwindInst>(BB->getTerminator());
+ CodeInfo->ContainsUnwinds |= isa<UnwindInst>(OldTI);
CodeInfo->ContainsDynamicAllocas |= hasDynamicAllocas;
CodeInfo->ContainsDynamicAllocas |= hasStaticAllocas &&
BB != &BB->getParent()->front();
if (ReturnInst *RI = dyn_cast<ReturnInst>(NewBB->getTerminator()))
Returns.push_back(RI);
-
- // Recursively clone any reachable successor blocks.
- const TerminatorInst *TI = BB->getTerminator();
- for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i)
- CloneBlock(TI->getSuccessor(i));
}
/// ConstantFoldMappedInstruction - Constant fold the specified instruction,
return ConstantFoldInstOperands(I->getOpcode(), I->getType(), Ops);
}
+#include <iostream>
/// CloneAndPruneFunctionInto - This works exactly like CloneFunctionInto,
/// except that it does some simple constant prop and DCE on the fly. The
// reachable, we have cloned it and the old block is now in the value map:
// insert it into the new function in the right order. If not, ignore it.
//
+ // Defer PHI resolution until rest of function is resolved.
+ std::vector<const PHINode*> PHIToResolve;
for (Function::const_iterator BI = OldFunc->begin(), BE = OldFunc->end();
BI != BE; ++BI) {
BasicBlock *NewBB = cast_or_null<BasicBlock>(ValueMap[BI]);
if (NewBB == 0) continue; // Dead block.
-
+
// Add the new block to the new function.
NewFunc->getBasicBlockList().push_back(NewBB);
// Handle PHI nodes specially, as we have to remove references to dead
// blocks.
if (PHINode *PN = dyn_cast<PHINode>(I)) {
- unsigned NumPreds = PN->getNumIncomingValues();
- for (; (PN = dyn_cast<PHINode>(I)); ++I) {
- for (unsigned pred = 0, e = NumPreds; pred != e; ++pred) {
- if (BasicBlock *MappedBlock =
- cast_or_null<BasicBlock>(ValueMap[PN->getIncomingBlock(pred)])) {
- Value *InVal = MapValue(PN->getIncomingValue(pred), ValueMap);
- assert(InVal && "Unknown input value?");
- PN->setIncomingValue(pred, InVal);
- PN->setIncomingBlock(pred, MappedBlock);
- } else {
- PN->removeIncomingValue(pred, false);
- --pred, --e; // Revisit the next entry.
- }
- }
- }
+ // Skip over all PHI nodes, remembering them for later.
+ BasicBlock::const_iterator OldI = BI->begin();
+ for (; (PN = dyn_cast<PHINode>(I)); ++I, ++OldI)
+ PHIToResolve.push_back(cast<PHINode>(OldI));
}
// Otherwise, remap the rest of the instructions normally.
for (; I != NewBB->end(); ++I)
RemapInstruction(I, ValueMap);
}
+
+ // Defer PHI resolution until rest of function is resolved, PHI resolution
+ // requires the CFG to be up-to-date.
+ for (unsigned phino = 0, e = PHIToResolve.size(); phino != e; ) {
+ const PHINode *OPN = PHIToResolve[phino];
+
+ unsigned NumPreds = OPN->getNumIncomingValues();
+
+ unsigned BBPHIStart = phino;
+ const BasicBlock *OldBB = OPN->getParent();
+ BasicBlock *NewBB = cast<BasicBlock>(ValueMap[OldBB]);
+
+ // Map operands for blocks that are live and remove operands for blocks
+ // that are dead.
+ for (; phino != PHIToResolve.size() &&
+ PHIToResolve[phino]->getParent() == OldBB; ++phino) {
+ OPN = PHIToResolve[phino];
+ PHINode *PN = cast<PHINode>(ValueMap[OPN]);
+ for (unsigned pred = 0, e = NumPreds; pred != e; ++pred) {
+ if (BasicBlock *MappedBlock =
+ cast_or_null<BasicBlock>(ValueMap[PN->getIncomingBlock(pred)])) {
+ Value *InVal = MapValue(PN->getIncomingValue(pred), ValueMap);
+ assert(InVal && "Unknown input value?");
+ PN->setIncomingValue(pred, InVal);
+ PN->setIncomingBlock(pred, MappedBlock);
+ } else {
+ PN->removeIncomingValue(pred, false);
+ --pred, --e; // Revisit the next entry.
+ }
+ }
+ }
+
+ // The loop above has removed PHI entries for those blocks that are dead
+ // and has updated others. However, if a block is live (i.e. copied over)
+ // but its terminator has been changed to not go to this block, then our
+ // phi nodes will have invalid entries. Update the PHI nodes in this
+ // case.
+ PHINode *PN = cast<PHINode>(NewBB->begin());
+ NumPreds = std::distance(pred_begin(NewBB), pred_end(NewBB));
+ if (NumPreds != PN->getNumIncomingValues()) {
+ assert(NumPreds < PN->getNumIncomingValues());
+ // Count how many times each predecessor comes to this block.
+ std::map<BasicBlock*, unsigned> PredCount;
+ for (pred_iterator PI = pred_begin(NewBB), E = pred_end(NewBB);
+ PI != E; ++PI)
+ --PredCount[*PI];
+
+ // Figure out how many entries to remove from each PHI.
+ for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
+ ++PredCount[PN->getIncomingBlock(i)];
+
+ // At this point, the excess predecessor entries are positive in the
+ // map. Loop over all of the PHIs and remove excess predecessor
+ // entries.
+ BasicBlock::iterator I = NewBB->begin();
+ for (; (PN = dyn_cast<PHINode>(I)); ++I) {
+ for (std::map<BasicBlock*, unsigned>::iterator PCI =PredCount.begin(),
+ E = PredCount.end(); PCI != E; ++PCI) {
+ BasicBlock *Pred = PCI->first;
+ for (unsigned NumToRemove = PCI->second; NumToRemove; --NumToRemove)
+ PN->removeIncomingValue(Pred, false);
+ }
+ }
+ }
+
+ // If the loops above have made these phi nodes have 0 or 1 operand,
+ // replace them with undef or the input value. We must do this for
+ // correctness, because 0-operand phis are not valid.
+ PN = cast<PHINode>(NewBB->begin());
+ if (PN->getNumIncomingValues() == 0) {
+ BasicBlock::iterator I = NewBB->begin();
+ BasicBlock::const_iterator OldI = OldBB->begin();
+ while ((PN = dyn_cast<PHINode>(I++))) {
+ Value *NV = UndefValue::get(PN->getType());
+ PN->replaceAllUsesWith(NV);
+ assert(ValueMap[OldI] == PN && "ValueMap mismatch");
+ ValueMap[OldI] = NV;
+ PN->eraseFromParent();
+ ++OldI;
+ }
+ } else if (PN->getNumIncomingValues() == 1) {
+ BasicBlock::iterator I = NewBB->begin();
+ BasicBlock::const_iterator OldI = OldBB->begin();
+ while ((PN = dyn_cast<PHINode>(I++))) {
+ Value *NV = PN->getIncomingValue(0);
+ PN->replaceAllUsesWith(NV);
+ assert(ValueMap[OldI] == PN && "ValueMap mismatch");
+ ValueMap[OldI] = NV;
+ PN->eraseFromParent();
+ ++OldI;
+ }
+ }
+ }
}
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