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//===- CloneTrace.cpp - Clone a trace -------------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the CloneTrace interface, which is used
// when writing runtime optimizations. It takes a vector of basic blocks
// clones the basic blocks, removes internal phi nodes, adds it to the
// same function as the original (although there is no jump to it) and
// returns the new vector of basic blocks.
//
//===----------------------------------------------------------------------===//
#include "llvm/Transforms/Utils/Cloning.h"
#include "llvm/iPHINode.h"
#include "llvm/Function.h"
using namespace llvm;
//Clones the trace (a vector of basic blocks)
std::vector<BasicBlock *>
llvm::CloneTrace(const std::vector<BasicBlock*> &origTrace) {
std::vector<BasicBlock *> clonedTrace;
std::map<const Value*, Value*> ValueMap;
//First, loop over all the Basic Blocks in the trace and copy
//them using CloneBasicBlock. Also fix the phi nodes during
//this loop. To fix the phi nodes, we delete incoming branches
//that are not in the trace.
for(std::vector<BasicBlock *>::const_iterator T = origTrace.begin(),
End = origTrace.end(); T != End; ++T) {
//Clone Basic Block
BasicBlock *clonedBlock = CloneBasicBlock(*T, ValueMap);
//Add it to our new trace
clonedTrace.push_back(clonedBlock);
//Add this new mapping to our Value Map
ValueMap[*T] = clonedBlock;
//Add this cloned BB to the old BB's function
(*T)->getParent()->getBasicBlockList().push_back(clonedBlock);
//Loop over the phi instructions and delete operands
//that are from blocks not in the trace
//only do this if we are NOT the first block
if(T != origTrace.begin()) {
for (BasicBlock::iterator I = clonedBlock->begin();
PHINode *PN = dyn_cast<PHINode>(I); ++I) {
//get incoming value for the previous BB
Value *V = PN->getIncomingValueForBlock(*(T-1));
assert(V && "No incoming value from a BasicBlock in our trace!");
//remap our phi node to point to incoming value
ValueMap[*&I] = V;
//remove phi node
clonedBlock->getInstList().erase(PN);
}
}
}
//Second loop to do the remapping
for(std::vector<BasicBlock *>::const_iterator BB = clonedTrace.begin(),
BE = clonedTrace.end(); BB != BE; ++BB) {
for(BasicBlock::iterator I = (*BB)->begin(); I != (*BB)->end(); ++I) {
//Loop over all the operands of the instruction
for(unsigned op=0, E = I->getNumOperands(); op != E; ++op) {
const Value *Op = I->getOperand(op);
//Get it out of the value map
Value *V = ValueMap[Op];
//If not in the value map, then its outside our trace so ignore
if(V != 0)
I->setOperand(op,V);
}
}
}
//return new vector of basic blocks
return clonedTrace;
}
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