From: Jim Wilson <wilson@gcc.gnu.org>
Date: Fri, 5 Mar 1993 17:45:15 +0000 (-0800)
Subject: (note_mem_written): QImode varying structure memory accesses can alias scalars.
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=2d08d5b6566d4c019a85ee1ea957a1d59d4bc8f6;p=gcc.git

(note_mem_written): QImode varying structure memory accesses can alias scalars.

From-SVN: r3654
---

diff --git a/gcc/cse.c b/gcc/cse.c
index 4249af65e3b..855242d4c12 100644
--- a/gcc/cse.c
+++ b/gcc/cse.c
@@ -6885,9 +6885,12 @@ note_mem_written (written, writes_ptr)
 	{
 	  /* A varying address that is a sum indicates an array element,
 	     and that's just as good as a structure element
-	     in implying that we need not invalidate scalar variables.  */
-	  if (!(MEM_IN_STRUCT_P (written)
-		|| GET_CODE (XEXP (written, 0)) == PLUS))
+	     in implying that we need not invalidate scalar variables.
+	     However, we must allow QImode aliasing of scalars, because the
+	     ANSI C standard allows character pointers to alias anything.  */
+	  if (! ((MEM_IN_STRUCT_P (written)
+		  || GET_CODE (XEXP (written, 0)) == PLUS)
+		 && GET_MODE (written) != QImode))
 	    writes_ptr->all = 1;
 	  writes_ptr->nonscalar = 1;
 	}