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| author | Nuno Lopes <nunoplopes@sapo.pt> | 2012-07-03 17:10:28 +0000 |
|---|---|---|
| committer | Nuno Lopes <nunoplopes@sapo.pt> | 2012-07-03 17:10:28 +0000 |
| commit | 44d5c064888aedd70a8f994bd379372d532ab46f (patch) | |
| tree | dc80f11c102099956b4a05db1076178e3dc33234 /lib/VMCore/Instructions.cpp | |
| parent | 9ccc83e7f70e63b746cbc7eef9fb06022e758677 (diff) | |
| download | llvm-44d5c064888aedd70a8f994bd379372d532ab46f.tar.gz llvm-44d5c064888aedd70a8f994bd379372d532ab46f.tar.bz2 llvm-44d5c064888aedd70a8f994bd379372d532ab46f.tar.xz | |
improve PHINode::hasConstantValue() to detect recursive cases like %phi = phi(%phi,42) as constant
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@159666 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/VMCore/Instructions.cpp')
| -rw-r--r-- | lib/VMCore/Instructions.cpp | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/lib/VMCore/Instructions.cpp b/lib/VMCore/Instructions.cpp index 383994554d..5aef459250 100644 --- a/lib/VMCore/Instructions.cpp +++ b/lib/VMCore/Instructions.cpp @@ -161,8 +161,12 @@ Value *PHINode::hasConstantValue() const { // 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; } |