(try_combine): Only use I2DEST as a scratch reg for

a split if it does not overlap any inputs of NEWPAT.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@2857 138bc75d-0d04-0410-961f-82ee72b054a4

diff --git a/gcc/combine.c b/gcc/combine.c
index 9632ab2..269c02c 100644 (file)
--- a/gcc/combine.c
+++ b/gcc/combine.c
@@ -1535,7 +1535,15 @@ try_combine (i3, i2, i1)
         convert I2DEST to the mode of the source of NEWPAT if we can.  */
 
       m_split = split_insns (newpat, i3);
-      if (m_split == 0)
+
+      /* We can only use I2DEST as a scratch reg if it doesn't overlap any
+        inputs of NEWPAT.  */
+
+      /* ??? If I2DEST is not safe, and I1DEST exists, then it would be
+        possible to try that as a scratch reg.  This would require adding
+        more code to make it work though.  */
+
+      if (m_split == 0 && ! reg_overlap_mentioned_p (ni2dest, newpat))
        {
          /* If I2DEST is a hard register or the only use of a pseudo,
             we can change its mode.  */