From 44d5c064888aedd70a8f994bd379372d532ab46f Mon Sep 17 00:00:00 2001 From: Nuno Lopes Date: Tue, 3 Jul 2012 17:10:28 +0000 Subject: [PATCH] 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 --- lib/VMCore/Instructions.cpp | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/lib/VMCore/Instructions.cpp b/lib/VMCore/Instructions.cpp index 383994554db..5aef4592501 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; } -- 2.34.1