[PATCH 21/50] Faster for_each_rtx-like iterators

[Richard Sandiford]

The switch statement in the old code seemed overly cautious.  It's well
established elsewhere that the first operand of an RTX_AUTOINC is the
automodified register.  If anyone wanted to add a new code for which that
wasn't true they should (a) reconsider or (b) go through all RTX_AUTOINCs
as a precaution.


gcc/
        * emit-rtl.c: Include rtl-iter.h.
        (find_auto_inc): Turn from being a for_each_rtx callback to being
        a function that examines each subrtx itself.  Assume the first operand
        to an RTX_AUTOINC is the automodified register.
        (try_split): Update call accordingly.

Index: gcc/emit-rtl.c
===================================================================
--- gcc/emit-rtl.c      2014-08-03 11:25:10.047955517 +0100
+++ gcc/emit-rtl.c      2014-08-03 11:25:26.062113842 +0100
@@ -58,6 +58,7 @@ Software Foundation; either version 3, o
 #include "params.h"
 #include "target.h"
 #include "builtins.h"
+#include "rtl-iter.h"
 
 struct target_rtl default_target_rtl;
 #if SWITCHABLE_TARGET
@@ -3485,30 +3486,17 @@ prev_cc0_setter (rtx insn)
 /* Find a RTX_AUTOINC class rtx which matches DATA.  */
 
 static int
-find_auto_inc (rtx *xp, void *data)
+find_auto_inc (const_rtx x, const_rtx reg)
 {
-  rtx x = *xp;
-  rtx reg = (rtx) data;
-
-  if (GET_RTX_CLASS (GET_CODE (x)) != RTX_AUTOINC)
-    return 0;
-
-  switch (GET_CODE (x))
+  subrtx_iterator::array_type array;
+  FOR_EACH_SUBRTX (iter, array, x, NONCONST)
     {
-      case PRE_DEC:
-      case PRE_INC:
-      case POST_DEC:
-      case POST_INC:
-      case PRE_MODIFY:
-      case POST_MODIFY:
-       if (rtx_equal_p (reg, XEXP (x, 0)))
-         return 1;
-       break;
-
-      default:
-       gcc_unreachable ();
+      const_rtx x = *iter;
+      if (GET_RTX_CLASS (GET_CODE (x)) == RTX_AUTOINC
+         && rtx_equal_p (reg, XEXP (x, 0)))
+       return true;
     }
-  return -1;
+  return false;
 }
 #endif
 
@@ -3695,7 +3683,7 @@ try_split (rtx pat, rtx trial, int last)
            {
              rtx reg = XEXP (note, 0);
              if (!FIND_REG_INC_NOTE (insn, reg)
-                 && for_each_rtx (&PATTERN (insn), find_auto_inc, reg) > 0)
+                 && find_auto_inc (PATTERN (insn), reg))
                add_reg_note (insn, REG_INC, reg);
            }
          break;