[llvm-commits] [llvm] r159666 - /llvm/trunk/lib/VMCore/Instructions.cpp
Nuno Lopes
nunoplopes at sapo.pt
Tue Jul 3 10:10:28 PDT 2012
Author: nlopes
Date: Tue Jul 3 12:10:28 2012
New Revision: 159666
URL: http://llvm.org/viewvc/llvm-project?rev=159666&view=rev
Log:
improve PHINode::hasConstantValue() to detect recursive cases like %phi = phi(%phi,42) as constant
Modified:
llvm/trunk/lib/VMCore/Instructions.cpp
Modified: llvm/trunk/lib/VMCore/Instructions.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/VMCore/Instructions.cpp?rev=159666&r1=159665&r2=159666&view=diff
==============================================================================
--- llvm/trunk/lib/VMCore/Instructions.cpp (original)
+++ llvm/trunk/lib/VMCore/Instructions.cpp Tue Jul 3 12:10:28 2012
@@ -161,8 +161,12 @@
// Exploit the fact that phi nodes always have at least one entry.
Value *ConstantValue = getIncomingValue(0);
for (unsigned i = 1, e = getNumIncomingValues(); i != e; ++i)
- if (getIncomingValue(i) != ConstantValue)
- return 0; // Incoming values not all the same.
+ if (getIncomingValue(i) != ConstantValue && getIncomingValue(i) != this) {
+ if (ConstantValue != this)
+ return 0; // Incoming values not all the same.
+ // The case where the first value is this PHI.
+ ConstantValue = getIncomingValue(i);
+ }
return ConstantValue;
}
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