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Two things. Preserve the unwind_to when splitting a BB.

Browse Source 
Add the ability to remove just one instance of a BB from a phi node. This fixes
the compile error in the tree now.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@48085 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nick Lewycky 2008-03-09 05:04:48 +00:00
parent c0d025f54f
commit c6694228fa
3 changed files with 19 additions and 7 deletions
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6
include/llvm/BasicBlock.h
View File

@ -185,7 +185,11 @@ public:
/// DontDeleteUselessPHIs will keep PHIs that have one value or the same
/// value for all entries.
///
void removePredecessor(BasicBlock *Pred, bool DontDeleteUselessPHIs = false);
/// OnlyDeleteOne will only remove one entry from a PHI, in case there were
/// duplicate entries for the Pred.
///
void removePredecessor(BasicBlock *Pred, bool DontDeleteUselessPHIs = false,
bool OnlyDeleteOne = false);
/// splitBasicBlock - This splits a basic block into two at the specified
/// instruction. Note that all instructions BEFORE the specified iterator

1
lib/Transforms/Utils/BasicBlockUtils.cpp
View File

@ -160,6 +160,7 @@ BasicBlock *llvm::SplitBlock(BasicBlock *Old, Instruction *SplitPt, Pass *P) {
while (isa<PHINode>(SplitIt))
++SplitIt;
BasicBlock *New = Old->splitBasicBlock(SplitIt, Old->getName()+".split");
New->setUnwindDest(Old->getUnwindDest());
// The new block lives in whichever loop the old one did.
if (Loop *L = LI.getLoopFor(Old))

19
lib/VMCore/BasicBlock.cpp
View File

@ -188,14 +188,12 @@ BasicBlock *BasicBlock::getSinglePredecessor() {
/// called while the predecessor still refers to this block.
///
void BasicBlock::removePredecessor(BasicBlock *Pred,
bool DontDeleteUselessPHIs) {
bool DontDeleteUselessPHIs,
bool OnlyDeleteOne) {
assert((hasNUsesOrMore(16)||// Reduce cost of this assertion for complex CFGs.
find(pred_begin(this), pred_end(this), Pred) != pred_end(this)) &&
"removePredecessor: BB is not a predecessor!");
if (Pred == getUnwindDest())
setUnwindDest(NULL);
if (InstList.empty()) return;
PHINode *APN = dyn_cast<PHINode>(&front());
if (!APN) return; // Quick exit.
@ -226,7 +224,11 @@ void BasicBlock::removePredecessor(BasicBlock *Pred,
// Yup, loop through and nuke the PHI nodes
while (PHINode *PN = dyn_cast<PHINode>(&front())) {
// Remove the predecessor first.
PN->removeIncomingValue(Pred, !DontDeleteUselessPHIs);
if (OnlyDeleteOne) {
int idx = PN->getBasicBlockIndex(Pred);
PN->removeIncomingValue(idx, !DontDeleteUselessPHIs);
} else
PN->removeIncomingValue(Pred, !DontDeleteUselessPHIs);
// If the PHI _HAD_ two uses, replace PHI node with its now *single* value
if (max_idx == 2) {
@ -247,7 +249,12 @@ void BasicBlock::removePredecessor(BasicBlock *Pred,
PHINode *PN;
for (iterator II = begin(); (PN = dyn_cast<PHINode>(II)); ) {
++II;
PN->removeIncomingValue(Pred, false);
if (OnlyDeleteOne) {
int idx = PN->getBasicBlockIndex(Pred);
PN->removeIncomingValue(idx, false);
} else
PN->removeIncomingValue(Pred, false);
// If all incoming values to the Phi are the same, we can replace the Phi
// with that value.
Value* PNV = 0;