On Wed, Dec 24, 2008 at 4:15 PM, Christopher Li <sparse@xxxxxxxxxxx> wrote:
> On Wed, Dec 24, 2008 at 3:35 PM, Tommy Thorn <tommy@xxxxxxxxxxxx> wrote:
>>
>> You can't have one without the other as you will break identities like
>>
>> (uintptr_t) (x + k) === (uintptr_t) x + sizeof (typeof (x)) * k
>>
>> which could appear in a macro.
>
> Right. That is exactly the place I actuall want to know. We should
> consider fix that in the source to have proper type. I expect there is
> not much place in the kernel use that.
I think you do have a point that from the "spase as a compiler" point
of view, there is need to maintain the compatibility with gcc. And I do
care about the current patch breaking the assumption of using
void_ctype.bit_size.
So here is what I got. A patch address both of our need. It gives warning
of using sizeof(void) explicitly. void* + offset will continue to work without
warnings. It will also make is_byte_type() continue to work as it was
before.
Here is my test script:
void *p;
int i = sizeof(void);
int j = sizeof(*p);
void* foo(void)
{
return p + 1;
}
I run the kernel compile with C=2, guess what. None of the current
kernel code use sizeof(void) explicitly. So that is good news.
Every one happy?
Chris
============================================================
Warn about explicit usage of sizeof(void)
sizeof(void) still evaluate as 1 after the warning.
void_ctype.bit_size remain zero so is_byte_type()
will continue to work.
Signed-Off-By: Christopher Li <sparse@xxxxxxxxxxx>
Index: sparse.chrisl/evaluate.c
===================================================================
--- sparse.chrisl.orig/evaluate.c
+++ sparse.chrisl/evaluate.c
@@ -584,7 +584,7 @@ static struct symbol *evaluate_ptr_add(s
}
/* Get the size of whatever the pointer points to */
- multiply = bits_to_bytes(base->bit_size);
+ multiply = (base == &void_ctype) ? 1 : bits_to_bytes(base->bit_size);
if (ctype == &null_ctype)
ctype = &ptr_ctype;
@@ -2049,8 +2049,14 @@ static struct symbol *evaluate_sizeof(st
return NULL;
size = type->bit_size;
+
+ if (type->ctype.base_type == &void_ctype) {
+ warning(expr->pos, "expression using sizeof(void)");
+ size = bits_in_char;
+ }
if ((size < 0) || (size & (bits_in_char - 1)))
expression_error(expr, "cannot size expression");
+
expr->type = EXPR_VALUE;
expr->value = bits_to_bytes(size);
expr->taint = 0;
Index: sparse.chrisl/symbol.c
===================================================================
--- sparse.chrisl.orig/symbol.c
+++ sparse.chrisl/symbol.c
@@ -834,7 +834,7 @@ static const struct ctype_declare {
struct symbol *base_type;
} ctype_declaration[] = {
{ &bool_ctype, SYM_BASETYPE, MOD_UNSIGNED, &bits_in_bool,
&max_int_alignment, &int_type },
- { &void_ctype, SYM_BASETYPE, 0, &bits_in_char, NULL, NULL },
+ { &void_ctype, SYM_BASETYPE, 0, NULL, NULL, NULL },
{ &type_ctype, SYM_BASETYPE, MOD_TYPE, NULL, NULL, NULL },
{ &incomplete_ctype,SYM_BASETYPE, 0, NULL, NULL, NULL },
{ &bad_ctype, SYM_BASETYPE, 0, NULL, NULL, NULL },
--
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