On Wed, Nov 12, 2014 at 11:34 PM, Ard Biesheuvel
<ard.biesheuvel@xxxxxxxxxx> wrote:
>
> Well, I spent some time playing around with this:
>
> This one is accepted:
>
> static __attribute__((__pure__)) int pure1(void)
> {
> int i = 0;
> return i;
> }
>
> This one is not accepted:
>
> static __attribute__((__pure__)) void *pure2(void)
> {
> void *i = (void *)0;
> return i;
> }
>
Thanks for the test case. I have commit your test case with a bit more
test case regarding function pointer assign.
The change is in chrisl repository reveiw-pure-attr branch:
https://git.kernel.org/cgit/devel/sparse/chrisl/sparse.git/log/?h=review-pure-attr
I purpose this fix for it. It can pass your test case.
This patch limit the pure attribute to functions.
The pure bit should not be a modifier in the first place.
But that is a much bigger change.
Can you please help me test and review the change?
Chris
diff --git a/evaluate.c b/evaluate.c
index 035e448..4c8b64a 100644
--- a/evaluate.c
+++ b/evaluate.c
@@ -632,6 +632,8 @@ const char *type_difference(struct ctype *c1,
struct ctype *c2,
struct symbol *t1 = c1->base_type;
struct symbol *t2 = c2->base_type;
int move1 = 1, move2 = 1;
+ unsigned long ignore = ~MOD_PURE;
+
mod1 |= c1->modifiers;
mod2 |= c2->modifiers;
for (;;) {
@@ -728,6 +730,7 @@ const char *type_difference(struct ctype *c1,
struct ctype *c2,
as1 = t1->ctype.as;
mod2 = t2->ctype.modifiers;
as2 = t2->ctype.as;
+ ignore = ~0;
if (base1->variadic != base2->variadic)
return "incompatible variadic arguments";
@@ -778,7 +781,7 @@ const char *type_difference(struct ctype *c1,
struct ctype *c2,
}
if (as1 != as2)
return "different address spaces";
- if ((mod1 ^ mod2) & ~MOD_IGNORE & ~MOD_SIGNEDNESS)
+ if ((mod1 ^ mod2) & ~MOD_IGNORE & ~MOD_SIGNEDNESS & ignore)
return "different modifiers";
return NULL;
}
diff --git a/show-parse.c b/show-parse.c
index fb54375..f274431 100644
--- a/show-parse.c
+++ b/show-parse.c
@@ -326,6 +326,7 @@ deeper:
was_ptr = 0;
}
append(name, "( ... )");
+ mod = sym->ctype.modifiers;
break;
case SYM_STRUCT:
--
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