diff options
Diffstat (limited to 'gcc/c-common.c')
| -rw-r--r-- | gcc/c-common.c | 30 |
1 files changed, 18 insertions, 12 deletions
diff --git a/gcc/c-common.c b/gcc/c-common.c index 30985b5..4631417 100644 --- a/gcc/c-common.c +++ b/gcc/c-common.c @@ -3332,21 +3332,20 @@ c_get_alias_set (t) if (t == error_mark_node) return 0; - type = (TYPE_P (t)) ? t : TREE_TYPE (t); + /* For a bit field reference that's not to a specific field, + all we can say is the aliasing information for the underlying object. */ + if (TREE_CODE (t) == BIT_FIELD_REF) + t = TREE_OPERAND (t, 0); + /* If this is a type, use it, otherwise get the type of the expression. + If the type is an error type, say this may alias anything. */ + type = TYPE_P (t) ? t : TREE_TYPE (t); if (type == error_mark_node) return 0; /* Deal with special cases first; for certain kinds of references we're interested in more than just the type. */ - if (TREE_CODE (t) == BIT_FIELD_REF) - /* Perhaps reads and writes to this piece of data alias fields - neighboring the bitfield. Perhaps that's impossible. For now, - let's just assume that bitfields can alias everything, which is - the conservative assumption. */ - 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 @@ -3363,11 +3362,19 @@ c_get_alias_set (t) if (TREE_CODE (t) == INDIRECT_REF) { /* Check for accesses through restrict-qualified pointers. */ - tree decl = c_find_base_decl (TREE_OPERAND (t, 0)); + tree op = TREE_OPERAND (t, 0); + tree decl = c_find_base_decl (op); if (decl && DECL_POINTER_ALIAS_SET_KNOWN_P (decl)) /* We use the alias set indicated in the declaration. */ return DECL_POINTER_ALIAS_SET (decl); + + /* If this is a char *, the ANSI C standard says it can alias + anything. */ + if (TREE_CODE (TREE_TYPE (op)) == INTEGER_TYPE + && (TYPE_PRECISION (TREE_TYPE (op)) + == TYPE_PRECISION (char_type_node))) + return 0; } /* From here on, only the type matters. */ @@ -3424,8 +3431,7 @@ c_get_alias_set (t) whose type is the same as one of the fields, recursively, but we don't yet make any use of that information.) */ TYPE_ALIAS_SET (type) = 0; - else if (TREE_CODE (type) == POINTER_TYPE - || TREE_CODE (type) == REFERENCE_TYPE) + else if (POINTER_TYPE_P (type)) { tree t; @@ -3459,7 +3465,7 @@ c_get_alias_set (t) TYPE_ALIAS_SET (type) = c_get_alias_set (t); } - if (!TYPE_ALIAS_SET_KNOWN_P (type)) + if (! TYPE_ALIAS_SET_KNOWN_P (type)) /* TYPE is something we haven't seen before. Put it in a new alias set. */ TYPE_ALIAS_SET (type) = new_alias_set (); |