Stack Coloring: Handle the case where END markers come before BEGIN markers properly.

[oota-llvm.git] / lib / CodeGen / StackColoring.cpp

diff --git a/lib/CodeGen/StackColoring.cpp b/lib/CodeGen/StackColoring.cpp
index 462a134ace3156da6c0fd15128da8f1789820b90..927ecef17160ba8971397e156acf4bc6d520d049 100644 (file)
--- a/lib/CodeGen/StackColoring.cpp
+++ b/lib/CodeGen/StackColoring.cpp
@@ -315,6 +315,18 @@ void StackColoring::calculateLocalLiveness() {
       LocalLiveOut.reset(BlockLiveness[BB].End);
       LocalLiveIn.reset(BlockLiveness[BB].Begin);
 
+      // If we have both BEGIN and END markers in the same basic block then
+      // we know that the BEGIN marker comes after the END, because we already
+      // handle the case where the BEGIN comes before the END when collecting
+      // the markers (and building the BEGIN/END vectore).
+      // Want to enable the LIVE_IN and LIVE_OUT of slots that have both
+      // BEGIN and END because it means that the value lives before and after
+      // this basic block.
+      BitVector LocalEndBegin = BlockLiveness[BB].End;
+      LocalEndBegin &= BlockLiveness[BB].Begin;
+      LocalLiveIn |= LocalEndBegin;
+      LocalLiveOut |= LocalEndBegin;
+
       if (LocalLiveIn.test(BlockLiveness[BB].LiveIn)) {
         changed = true;
         BlockLiveness[BB].LiveIn |= LocalLiveIn;