flow.c (propagate_one_insn): Preserve live-at-end registers across tail calls.

        * flow.c (propagate_one_insn): Preserve live-at-end registers
        across tail calls.

From-SVN: r68544

gcc/ChangeLog

+2003-06-26  Richard Henderson  <rth@redhat.com>
+
+	* flow.c (propagate_one_insn): Preserve live-at-end registers
+	across tail calls.
+
 2003-06-26  J"orn Rennecke <joern.rennecke@superh.com>
 
 	* reload.c (can_reload_into): New function.

gcc/flow.c

@@ -1770,8 +1770,10 @@ propagate_one_insn (pbi, insn)
 
       if (GET_CODE (insn) == CALL_INSN)
 	{
-	  int i;
+	  regset live_at_end;
+	  bool sibcall_p;
 	  rtx note, cond;
+	  int i;
 
 	  cond = NULL_RTX;
 	  if (GET_CODE (PATTERN (insn)) == COND_EXEC)
@@ -1796,9 +1798,14 @@ propagate_one_insn (pbi, insn)
 	      mark_set_1 (pbi, CLOBBER, XEXP (XEXP (note, 0), 0),
 			  cond, insn, pbi->flags);
 
-	  /* Calls change all call-used and global registers.  */
+	  /* Calls change all call-used and global registers; sibcalls do not
+	     clobber anything that must be preserved at end-of-function.  */
+
+	  sibcall_p = SIBLING_CALL_P (insn);
+	  live_at_end = EXIT_BLOCK_PTR->global_live_at_start;
 	  for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
-	    if (TEST_HARD_REG_BIT (regs_invalidated_by_call, i))
+	    if (TEST_HARD_REG_BIT (regs_invalidated_by_call, i)
+		&& ! (sibcall_p && REGNO_REG_SET_P (live_at_end, i)))
 	      {
 		/* We do not want REG_UNUSED notes for these registers.  */
 		mark_set_1 (pbi, CLOBBER, regno_reg_rtx[i], cond, insn,