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PHIs don't need to be postprocessed 

llvm-svn: 244275
This commit is contained in:
David Majnemer 2015-08-06 21:08:34 +00:00
parent ac6b298850
commit a102e6a0e3
1 changed files with 6 additions and 31 deletions
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37
llvm/lib/CodeGen/WinEHPrepare.cpp
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@ -3190,6 +3190,9 @@ bool WinEHPrepare::prepareExplicitEH(Function &F) {
if (NumColorsForBB == 1) if (NumColorsForBB == 1)
continue; continue;
assert(!isa<PHINode>(BB->front()) &&
"Polychromatic PHI nodes should have been demoted!");
// Create a new basic block and copy instructions into it! // Create a new basic block and copy instructions into it!
BasicBlock *CBB = CloneBasicBlock( BasicBlock *CBB = CloneBasicBlock(
BB, VMap, Twine(".for.", FuncletPadBB->getName()), &F); BB, VMap, Twine(".for.", FuncletPadBB->getName()), &F);
@ -3220,43 +3223,15 @@ bool WinEHPrepare::prepareExplicitEH(Function &F) {
// Loop over all instructions, fixing each one as we find it... // Loop over all instructions, fixing each one as we find it...
for (Instruction &I : *BB) for (Instruction &I : *BB)
RemapInstruction(&I, VMap, RF_IgnoreMissingEntries); RemapInstruction(&I, VMap, RF_IgnoreMissingEntries);
// Our PHI nodes have stale predecessors after we have cloned our new blocks
// into the CFG. Fix this by removing the stale predecessors.
for (BasicBlock *BB : BlocksInFunclet) {
for (BasicBlock::iterator BI = BB->begin(), BE = BB->end(); BI != BE;) {
Instruction *I = BI++;
auto *PN = dyn_cast<PHINode>(I);
// All the PHI nodes are bunched together at the start of the BB.
// Stop once we've hit a non-PHI.
if (!PN)
break;
// Create a list of all the incoming PHI values we'd like to remove.
// This is done in two steps to avoid iterator invalidation issues.
std::vector<unsigned> IndicesToRemove;
for (unsigned Idx = 0, E = PN->getNumIncomingValues(); Idx != E;
++Idx) {
BasicBlock *PredBB = PN->getIncomingBlock(Idx);
if (BlockColors[PredBB].count(FuncletPadBB) == 0)
IndicesToRemove.push_back(Idx);
}
// Remove incoming values in the reverse order to prevent invalidating
// *successive* index.
for (auto I = IndicesToRemove.rbegin(), E = IndicesToRemove.rend();
I != E; ++I)
PN->removeIncomingValue(*I);
}
}
} }
// Clean-up some of the mess we made by removing useles PHI nodes, trivial // Clean-up some of the mess we made by removing useles PHI nodes, trivial
// branches, etc. // branches, etc.
for (Function::iterator FI = F.begin(), FE = F.end(); FI != FE;) { for (Function::iterator FI = F.begin(), FE = F.end(); FI != FE;) {
BasicBlock *BB = FI++; BasicBlock *BB = FI++;
//SimplifyInstructionsInBlock(BB); SimplifyInstructionsInBlock(BB);
//ConstantFoldTerminator(BB, /*DeleteDeadConditions=*/true); ConstantFoldTerminator(BB, /*DeleteDeadConditions=*/true);
//MergeBlockIntoPredecessor(BB); MergeBlockIntoPredecessor(BB);
} }
// TODO: Do something about cleanupblocks which branch to implausible // TODO: Do something about cleanupblocks which branch to implausible