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Make RenamePass faster by making the 'is this a new phi node'

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check more intelligent.  This speeds up mem2reg from 5.29s to 
0.79s on a synthetic testcase with tons of predecessors and
phi nodes.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@46767 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2008-02-05 21:26:23 +00:00
parent e672af15d6
commit 2663ffe751
1 changed files with 11 additions and 11 deletions
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22
lib/Transforms/Utils/PromoteMemoryToRegister.cpp
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@ -849,7 +849,6 @@ bool PromoteMem2Reg::QueuePhiNode(BasicBlock *BB, unsigned AllocaNo,
return true;
}
// RenamePass - Recursively traverse the CFG of the function, renaming loads and
// stores to the allocas which we are promoting. IncomingVals indicates what
// value each Alloca contains on exit from the predecessor block Pred.
@ -877,6 +876,14 @@ NextIteration:
// If we have PHI nodes to update, compute the number of edges from Pred to
// BB.
if (!HasPredEntries) {
// We want to be able to distinguish between PHI nodes being inserted by
// this invocation of mem2reg from those phi nodes that already existed in
// the IR before mem2reg was run. We determine that APN is being inserted
// because it is missing incoming edges. All other PHI nodes being
// inserted by this pass of mem2reg will have the same number of incoming
// operands so far. Remember this count.
unsigned NewPHINumOperands = APN->getNumOperands();
TerminatorInst *PredTerm = Pred->getTerminator();
unsigned NumEdges = 0;
for (unsigned i = 0, e = PredTerm->getNumSuccessors(); i != e; ++i) {
@ -902,16 +909,9 @@ NextIteration:
APN = dyn_cast<PHINode>(PNI);
if (APN == 0) break;
// Verify it doesn't already have entries for Pred. If it does, it is
// not being inserted by this mem2reg invocation.
HasPredEntries = false;
for (unsigned i = 0, e = APN->getNumIncomingValues(); i != e; ++i) {
if (APN->getIncomingBlock(i) == Pred) {
HasPredEntries = true;
break;
}
}
} while (!HasPredEntries);
// Verify that it is missing entries. If not, it is not being inserted
// by this mem2reg invocation so we want to ignore it.
} while (APN->getNumOperands() == NewPHINumOperands);
}
}