*** empty log message ***

From-SVN: r666

1 files changed, 16 insertions, 2 deletions

diff --git a/gcc/optabs.c b/gcc/optabs.c
index b1578531a50..c345fc9d294 100644
--- a/gcc/optabs.c
+++ b/gcc/optabs.c
@@ -1315,6 +1315,16 @@ emit_no_conflict_block (insns, target, op0, op1, equiv)
    an insn to move RESULT to TARGET.  This last insn will have a REQ_EQUAL
    note with an operand of EQUIV.
 
+   Moving assignments to pseudos outside of the block is done to improve
+   the generated code, but is not required to generate correct code,
+   hence being unable to move an assignment is not grounds for not making
+   a libcall block.  There are two reasons why it is safe to leave these
+   insns inside the block: First, we know that these pseudos cannot be
+   used in generated RTL outside the block since they are created for
+   temporary purposes within the block.  Second, CSE will not record the
+   values of anything set inside a libcall block, so we know they must
+   be dead at the end of the block.
+
    Except for the first group of insns (the ones setting pseudos), the
    block is delimited by REG_RETVAL and REG_LIBCALL notes.  */
 
@@ -1328,7 +1338,9 @@ emit_libcall_block (insns, target, result, equiv)
   rtx prev, next, first, last, insn;
 
   /* First emit all insns that set pseudos.  Remove them from the list as
-     we go.  */
+     we go.  Avoid insns that set pseudo which were referenced in previous
+     insns.  These can be generated by move_by_pieces, for example,
+     to update an address.  */
 
   for (insn = insns; insn; insn = next)
     {
@@ -1337,7 +1349,9 @@ emit_libcall_block (insns, target, result, equiv)
       next = NEXT_INSN (insn);
 
       if (set != 0 && GET_CODE (SET_DEST (set)) == REG
-	  && REGNO (SET_DEST (set)) >= FIRST_PSEUDO_REGISTER)
+	  && REGNO (SET_DEST (set)) >= FIRST_PSEUDO_REGISTER
+	  && ! reg_mentioned_p (SET_DEST (set), PATTERN (insns))
+	  && ! reg_used_between_p (SET_DEST (set), insns, insn))
 	{
 	  if (PREV_INSN (insn))
 	    NEXT_INSN (PREV_INSN (insn)) = next;