* config/i386/i386.c (ix86_split_ashrdi): Optimize shift by 63.

From-SVN: r79397

gcc/ChangeLog

+2004-03-12  Roger Sayle  <roger@eyesopen.com>
+
+	* config/i386/i386.c (ix86_split_ashrdi): Optimize shift by 63.
+
 2004-03-12  Matt Austern  <austern@apple.com>
 
 	* target.h (struct gcc_target): New target hook, unwind_label.

gcc/config/i386/i386.c

@@ -10873,7 +10873,14 @@ ix86_split_ashrdi (rtx *operands, rtx scratch)
       split_di (operands, 2, low, high);
       count = INTVAL (operands[2]) & 63;
 
-      if (count >= 32)
+      if (count == 63)
+	{
+	  emit_move_insn (high[0], high[1]);
+	  emit_insn (gen_ashrsi3 (high[0], high[0], GEN_INT (31)));
+	  emit_move_insn (low[0], high[0]);
+
+	}
+      else if (count >= 32)
 	{
 	  emit_move_insn (low[0], high[1]);