1 //===- CloneTrace.cpp - Clone a trace -------------------------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the CloneTrace interface, which is used
11 // when writing runtime optimizations. It takes a vector of basic blocks
12 // clones the basic blocks, removes internal phi nodes, adds it to the
13 // same function as the original (although there is no jump to it) and
14 // returns the new vector of basic blocks.
16 //===----------------------------------------------------------------------===//
18 #include "llvm/Transforms/Utils/Cloning.h"
19 #include "llvm/iPHINode.h"
20 #include "llvm/Function.h"
25 //Clones the trace (a vector of basic blocks)
26 std::vector<BasicBlock *> CloneTrace(const std::vector<BasicBlock*> &origTrace) {
28 std::vector<BasicBlock *> clonedTrace;
29 std::map<const Value*, Value*> ValueMap;
31 //First, loop over all the Basic Blocks in the trace and copy
32 //them using CloneBasicBlock. Also fix the phi nodes during
33 //this loop. To fix the phi nodes, we delete incoming branches
34 //that are not in the trace.
35 for(std::vector<BasicBlock *>::const_iterator T = origTrace.begin(),
36 End = origTrace.end(); T != End; ++T) {
39 BasicBlock *clonedBlock = CloneBasicBlock(*T, ValueMap);
41 //Add it to our new trace
42 clonedTrace.push_back(clonedBlock);
44 //Add this new mapping to our Value Map
45 ValueMap[*T] = clonedBlock;
47 //Add this cloned BB to the old BB's function
48 (*T)->getParent()->getBasicBlockList().push_back(clonedBlock);
50 //Loop over the phi instructions and delete operands
51 //that are from blocks not in the trace
52 //only do this if we are NOT the first block
53 if(T != origTrace.begin()) {
54 for (BasicBlock::iterator I = clonedBlock->begin();
55 PHINode *PN = dyn_cast<PHINode>(I); ++I) {
56 //get incoming value for the previous BB
57 Value *V = PN->getIncomingValueForBlock(*(T-1));
58 assert(V && "No incoming value from a BasicBlock in our trace!");
60 //remap our phi node to point to incoming value
64 clonedBlock->getInstList().erase(PN);
69 //Second loop to do the remapping
70 for(std::vector<BasicBlock *>::const_iterator BB = clonedTrace.begin(),
71 BE = clonedTrace.end(); BB != BE; ++BB) {
72 for(BasicBlock::iterator I = (*BB)->begin(); I != (*BB)->end(); ++I) {
74 //Loop over all the operands of the instruction
75 for(unsigned op=0, E = I->getNumOperands(); op != E; ++op) {
76 const Value *Op = I->getOperand(op);
78 //Get it out of the value map
79 Value *V = ValueMap[Op];
81 //If not in the value map, then its outside our trace so ignore
88 //return new vector of basic blocks
92 } // End llvm namespace