Author: resistor
Date: Mon Jan 21 16:03:00 2008
New Revision: 46218
URL: http://llvm.org/viewvc/llvm-project?rev=46218&view=rev
Log:
Clarify a deviation from the original algorithm.
Modified:
llvm/trunk/lib/CodeGen/StrongPHIElimination.cpp
Modified: llvm/trunk/lib/CodeGen/StrongPHIElimination.cpp
URL:
http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/StrongPHIElimination.cpp?rev=46218&r1=46217&r2=46218&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/StrongPHIElimination.cpp (original)
+++ llvm/trunk/lib/CodeGen/StrongPHIElimination.cpp Mon Jan 21 16:03:00 2008
@@ -552,7 +552,10 @@
DomForestNode* child = *CI;
// If the current node is live-out of the defining block of one of its
- // children, insert a copy for it
+ // children, insert a copy for it. NOTE: The paper actually calls for
+ // a more elaborate heuristic for determining whether to insert copies
+ // for the child or the parent. In the interest of simplicity, we're
+ // just always choosing the parent.
if (isLiveOut(DFNode->getReg(),
MRI.getVRegDef(child->getReg())->getParent(), MRI, LV)) {
// Insert copies for parent
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