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Use the new SplitBlockPredecessors to implement a todo. 

llvm-svn: 50022
This commit is contained in:
Chris Lattner 2008-04-21 02:57:57 +00:00
parent 89f238cbe1
commit f6236cc2e9
1 changed files with 16 additions and 4 deletions
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20
llvm/lib/Transforms/Scalar/JumpThreading.cpp
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@ -17,6 +17,7 @@
#include "llvm/Pass.h" #include "llvm/Pass.h"
#include "llvm/ADT/DenseMap.h" #include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/Statistic.h" #include "llvm/ADT/Statistic.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/Local.h" #include "llvm/Transforms/Utils/Local.h"
#include "llvm/Support/CommandLine.h" #include "llvm/Support/CommandLine.h"
#include "llvm/Support/Compiler.h" #include "llvm/Support/Compiler.h"
@ -194,10 +195,21 @@ bool JumpThreading::ThreadBlock(BasicBlock *BB) {
SuccBB = SI->getSuccessor(SI->findCaseValue(PredCst)); SuccBB = SI->getSuccessor(SI->findCaseValue(PredCst));
} }
// TODO: If there are multiple preds with the same incoming value for the PHI, // If there are multiple preds with the same incoming value for the PHI,
// factor them together so we get one thread block for the whole group. This // factor them together so we get one block to thread for the whole group.
// is important for things like "phi i1 [true, true, false, true, x]" where // This is important for things like "phi i1 [true, true, false, true, x]"
// we only need to clone the block for the true blocks once. // where we only need to clone the block for the true blocks once.
SmallVector<BasicBlock*, 16> CommonPreds;
for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
if (PN->getIncomingValue(i) == PredCst)
CommonPreds.push_back(PN->getIncomingBlock(i));
if (CommonPreds.size() != 1) {
DOUT << " Factoring out " << CommonPreds.size()
<< " common predecessors.\n";
PredBB = SplitBlockPredecessors(BB, &CommonPreds[0], CommonPreds.size(),
".thr_comm", this);
}
DOUT << " Threading edge from '" << PredBB->getNameStart() << "' to '" DOUT << " Threading edge from '" << PredBB->getNameStart() << "' to '"
<< SuccBB->getNameStart() << "' with cost: " << JumpThreadCost << SuccBB->getNameStart() << "' with cost: " << JumpThreadCost