From: Richard Henderson <rth@redhat.com>
Date: Thu, 20 Jun 2002 07:35:46 +0000 (-0700)
Subject: c-common.c (c_common_get_alias_set): Correctly handle characters.
X-Git-Tag: releases/gcc-3.1.1~125
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=71c0a5fe74ff1014b4f1d2526957ca0777f65ed7;p=thirdparty%2Fgcc.git

c-common.c (c_common_get_alias_set): Correctly handle characters.

        * c-common.c (c_common_get_alias_set): Correctly handle characters.
        Rearrange order of expressions; don't handle vectors here.
        * alias.c (get_alias_set): Let vectors match their components.

From-SVN: r54823
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 3c59ce489777..4a2f57fb6cd5 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2002-06-20  Richard Henderson  <rth@redhat.com>
+
+	* c-common.c (c_common_get_alias_set): Correctly handle characters.
+	Rearrange order of expressions; don't handle vectors here.
+	* alias.c (get_alias_set): Let vectors match their components.
+
 2002-06-17  Hans-Peter Nilsson  <hp@axis.com>
 
 	PR target/7042
diff --git a/gcc/alias.c b/gcc/alias.c
index c5a626516032..6d4104e640b5 100644
--- a/gcc/alias.c
+++ b/gcc/alias.c
@@ -564,6 +564,14 @@ get_alias_set (t)
      and references to functions, but that's different.)  */
   else if (TREE_CODE (t) == FUNCTION_TYPE)
     set = 0;
+
+  /* Unless the language specifies otherwise, let vector types alias
+     their components.  This avoids some nasty type punning issues in
+     normal usage.  And indeed lets vectors be treated more like an
+     array slice.  */
+  else if (TREE_CODE (t) == VECTOR_TYPE)
+    set = get_alias_set (TREE_TYPE (t));
+
   else
     /* Otherwise make a new alias set for this type.  */
     set = new_alias_set ();
diff --git a/gcc/c-common.c b/gcc/c-common.c
index 5b8b56546268..f9e593057a9b 100644
--- a/gcc/c-common.c
+++ b/gcc/c-common.c
@@ -2326,10 +2326,6 @@ c_common_get_alias_set (t)
 {
   tree u;
   
-  /* We know nothing about vector types */
-  if (TREE_CODE (t) == VECTOR_TYPE)
-    return 0;          
-  
   /* Permit type-punning when accessing a union, provided the access
      is directly through the union.  For example, this code does not
      permit taking the address of a union member and then storing
@@ -2343,17 +2339,17 @@ c_common_get_alias_set (t)
 	&& TREE_CODE (TREE_TYPE (TREE_OPERAND (u, 0))) == UNION_TYPE)
       return 0;
 
-  /* If this is a char *, the ANSI C standard says it can alias
-     anything.  Note that all references need do this.  */
-  if (TREE_CODE_CLASS (TREE_CODE (t)) == 'r'
-      && TREE_CODE (TREE_TYPE (t)) == INTEGER_TYPE
-      && TYPE_PRECISION (TREE_TYPE (t)) == TYPE_PRECISION (char_type_node))
-    return 0;
-
   /* That's all the expressions we handle specially.  */
   if (! TYPE_P (t))
     return -1;
 
+  /* The C standard guarantess that any object may be accessed via an
+     lvalue that has character type.  */
+  if (t == char_type_node
+      || t == signed_char_type_node
+      || t == unsigned_char_type_node)
+    return 0;
+  
   /* The C standard specifically allows aliasing between signed and
      unsigned variants of the same type.  We treat the signed
      variant as canonical.  */