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Fix a case where UnswitchTrivialCondition broke critical edges with

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phi's in the successors


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@26108 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2006-02-10 19:08:15 +00:00
parent ad7a3e6208
commit 81be2e961b
1 changed files with 24 additions and 1 deletions
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25
lib/Transforms/Scalar/LoopUnswitch.cpp
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@ -34,6 +34,7 @@
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Transforms/Utils/Cloning.h"
#include "llvm/Transforms/Utils/Local.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/CommandLine.h"
@ -255,6 +256,8 @@ bool LoopUnswitch::visitLoop(Loop *L) {
// loop.
for (Loop::block_iterator I = L->block_begin(), E = L->block_end();
I != E; ++I) {
for (BasicBlock::iterator BBI = (*I)->begin(), E = (*I)->end();
BBI != E; ++BBI)
TerminatorInst *TI = (*I)->getTerminator();
// FIXME: Handle invariant select instructions.
@ -415,7 +418,27 @@ void LoopUnswitch::UnswitchTrivialCondition(Loop *L, Value *Cond,
// Split this block now, so that the loop maintains its exit block.
assert(!L->contains(ExitBlock) && "Exit block is in the loop?");
BasicBlock *NewExit = SplitBlock(ExitBlock, true);
BasicBlock *NewExit;
if (BasicBlock *SinglePred = ExitBlock->getSinglePredecessor()) {
assert(SinglePred == L->getLoopLatch() && "Unexpected case");
NewExit = SplitBlock(ExitBlock, true);
} else {
// Otherwise, this is a critical edge. Split block would split the wrong
// edge here, so we use SplitCriticalEdge, which allows us to specify the
// edge to split, not just the block.
TerminatorInst *LatchTerm = L->getLoopLatch()->getTerminator();
unsigned SuccNum = 0;
for (unsigned i = 0, e = LatchTerm->getNumSuccessors(); ; ++i) {
assert(i != e && "Didn't find edge?");
if (LatchTerm->getSuccessor(i) == ExitBlock) {
SuccNum = i;
break;
}
}
SplitCriticalEdge(LatchTerm, SuccNum, this);
NewExit = LatchTerm->getSuccessor(SuccNum);
assert(NewExit != ExitBlock && "Edge not split!");
}
// Okay, now we have a position to branch from and a position to branch to,
// insert the new conditional branch.