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