* regmove.c (regmove_optimize): Avoid increasing of register pressure.

From-SVN: r49864

gcc/ChangeLog

+Tue Feb 19 12:37:23 CET 2002  Jan Hubicka  <jh@suse.cz>
+
+	* regmove.c (regmove_optimize): Avoid increasing of register pressure.
+
 2002-02-19  Neil Booth  <neil@daikokuya.demon.co.uk>
 
 	PR other/5718

gcc/regmove.c

@@ -1328,19 +1328,22 @@ regmove_optimize (f, nregs, regmove_dump_file)
 		}
 	      src_class = reg_preferred_class (REGNO (src));
 	      dst_class = reg_preferred_class (REGNO (dst));
-	      if (! regclass_compatible_p (src_class, dst_class))
-		{
-		  if (!copy_src)
+
+	      if (! (src_note = find_reg_note (insn, REG_DEAD, src)))
 		{
-		      copy_src = src;
-		      copy_dst = dst;
-		    }
+		  /* We used to force the copy here like in other cases, but
+		     it produces worse code, as it eliminates no copy
+		     instructions and the copy emitted will be produced by
+		     reload anyway.  On patterns with multiple alternatives,
+		     there may be better sollution availble.
+
+		     In particular this change produced slower code for numeric
+		     i387 programs.  */
+
 		  continue;
 		}
 
-	      /* Can not modify an earlier insn to set dst if this insn
-		 uses an old value in the source.  */
-	      if (reg_overlap_mentioned_p (dst, SET_SRC (set)))
+	      if (! regclass_compatible_p (src_class, dst_class))
 		{
 		  if (!copy_src)
 		    {
@@ -1350,7 +1353,9 @@ regmove_optimize (f, nregs, regmove_dump_file)
 		  continue;
 		}
 
-	      if (! (src_note = find_reg_note (insn, REG_DEAD, src)))
+	      /* Can not modify an earlier insn to set dst if this insn
+		 uses an old value in the source.  */
+	      if (reg_overlap_mentioned_p (dst, SET_SRC (set)))
 		{
 		  if (!copy_src)
 		    {
@@ -1360,7 +1365,6 @@ regmove_optimize (f, nregs, regmove_dump_file)
 		  continue;
 		}
 
-
 	      /* If src is set once in a different basic block,
 		 and is set equal to a constant, then do not use
 		 it for this optimization, as this would make it