[llvm-commits] [llvm] r46217 - /llvm/trunk/lib/CodeGen/StrongPHIElimination.cpp

[Owen Anderson]

Author: resistor
Date: Mon Jan 21 16:01:01 2008
New Revision: 46217

URL: http://llvm.org/viewvc/llvm-project?rev=46217&view=rev
Log:
Improve a few comments.

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=46217&r1=46216&r2=46217&view=diff

==============================================================================
--- llvm/trunk/lib/CodeGen/StrongPHIElimination.cpp (original)
+++ llvm/trunk/lib/CodeGen/StrongPHIElimination.cpp Mon Jan 21 16:01:01 2008
@@ -550,7 +550,9 @@
     for (DomForestNode::iterator CI = DFNode->begin(), CE = DFNode->end();
          CI != CE; ++CI) {
       DomForestNode* child = *CI;   
-        
+      
+      // If the current node is live-out of the defining block of one of its
+      // children, insert a copy for it
       if (isLiveOut(DFNode->getReg(),
           MRI.getVRegDef(child->getReg())->getParent(), MRI, LV)) {
         // Insert copies for parent
@@ -565,6 +567,9 @@
             PHIUnion.erase(SrcReg);
           }
         }
+      
+      // If a node is live-in to the defining block of one of its children, but
+      // not live-out, then we need to scan that block for local interferences.
       } else if (isLiveIn(DFNode->getReg(),
                           MRI.getVRegDef(child->getReg())->getParent(),
                           MRI, LV) ||