Author: lattner
Date: Tue Feb 5 15:26:23 2008
New Revision: 46767
URL: http://llvm.org/viewvc/llvm-project?rev=46767&view=rev
Log:
Make RenamePass faster by making the 'is this a new phi node'
check more intelligent. This speeds up mem2reg from 5.29s to
0.79s on a synthetic testcase with tons of predecessors and
phi nodes.
Modified:
llvm/trunk/lib/Transforms/Utils/PromoteMemoryToRegister.cpp
Modified: llvm/trunk/lib/Transforms/Utils/PromoteMemoryToRegister.cpp
URL:
http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/PromoteMemoryToRegister.cpp?rev=46767&r1=46766&r2=46767&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Utils/PromoteMemoryToRegister.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/PromoteMemoryToRegister.cpp Tue Feb 5
15:26:23 2008
@@ -849,7 +849,6 @@
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 @@
// 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 @@
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);
}
}
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