From: Wei Guozhi <carrot@google.com>
Date: Fri, 14 Sep 2012 23:00:45 +0000 (+0000)
Subject: cselib.c (expand_loc): Return sp, fp, hfp or cfa base reg right away if seen.
X-Git-Tag: releases/gcc-4.6.4~367
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=02c9173bca2031296bd4acffb3a53ebe5f732622;p=thirdparty%2Fgcc.git

cselib.c (expand_loc): Return sp, fp, hfp or cfa base reg right away if seen.

	* cselib.c (expand_loc): Return sp, fp, hfp or cfa base reg right
	away if seen.

From-SVN: r191315
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 8ff1ac63ccc3..e381f2e80849 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,10 @@
+2012-09-14  Wei Guozhi  <carrot@google.com>
+
+	Backport from 2012-02-13 mainline r184169.
+
+	* cselib.c (expand_loc): Return sp, fp, hfp or cfa base reg right
+	away if seen.
+
 2012-09-10  Georg-Johann Lay  <avr@gjlay.de>
 
 	Backport from 2012-09-10 mainline r191132.
diff --git a/gcc/cselib.c b/gcc/cselib.c
index a2fdef7dbe3f..d060c274562b 100644
--- a/gcc/cselib.c
+++ b/gcc/cselib.c
@@ -1237,8 +1237,18 @@ expand_loc (struct elt_loc_list *p, struct expand_value_data *evd,
   unsigned int regno = UINT_MAX;
   struct elt_loc_list *p_in = p;
 
-  for (; p; p = p -> next)
+  for (; p; p = p->next)
     {
+      /* Return these right away to avoid returning stack pointer based
+	 expressions for frame pointer and vice versa, which is something
+	 that would confuse DSE.  See the comment in cselib_expand_value_rtx_1
+	 for more details.  */
+      if (REG_P (p->loc)
+	  && (REGNO (p->loc) == STACK_POINTER_REGNUM
+	      || REGNO (p->loc) == FRAME_POINTER_REGNUM
+	      || REGNO (p->loc) == HARD_FRAME_POINTER_REGNUM
+	      || REGNO (p->loc) == cfa_base_preserved_regno))
+	return p->loc;
       /* Avoid infinite recursion trying to expand a reg into a
 	 the same reg.  */
       if ((REG_P (p->loc))