Does this mean you are volunteering? I suspect the only sure way
(although slow) is simply remove them while people fixing/changing
things. Else, it can only get worst
Sun
On Wed, Jun 15, 2011 at 9:59 PM, Jian-Xin Lai <laij...@gmail.com> wrote:
> It seems combining the code cleanup with bug fix is not a good practice. If
> #ifdef KEY is not used anymore, we can initiate another round of code
> cleanup to remove this macro.
>
> 2011/6/14 Sun Chan <sun.c...@gmail.com>
>>
>> 1. WOPT does not allow static objects, can you put your new routines
>> inside the right class?
>> 2. please remove the #ifdef KEY, I think we can start removing this
>> KEY thing now, everyone assumes this as default now
>>
>> Sun
>>
>> On Mon, Jun 13, 2011 at 7:52 PM, Wu Yongchong <wuyongch...@gmail.com>
>> wrote:
>> > Hi
>> > can a gatekeeper help review this patch
>> >
>> > This patch tries to fix various C standard compliant problems related
>> > to volatile in open64. Here is the list of the problems:
>> >
>> > 1. Incorrect simplification in the following case:
>> >
>> > volatile int x;
>> > return x - x;
>> >
>> > The expression (x - x) cannot be simplified to 0 because x is volatile.
>> >
>> > int v; volatile int val;
>> > val = *(volatile int*)(&v); /* should not be simplified to LDID v */
>> >
>> > According to C standard, the *(volatile int*)(&v) should be converted
>> > into an ILOAD expression in WHIRL. However, the simplifier folds the
>> > whole expression into LDID v.
>> >
>> > 2. Incorrect simplification related to pointers:
>> >
>> > int test_volatile_ptrs1(){
>> > volatile int *p;
>> > int val;
>> >
>> > val = p - p; /* can be folded to zero */
>> > val += (*p) - (*p); /* cannot be folded */
>> >
>> > return val;
>> > }
>> >
>> > The expression (*p) - (*p) cannot be simplified since p is a pointer
>> > to volatile int. However, WN simplifier fails to check for this.
>> >
>> > 3. Incorrect Boolean expression simplification
>> >
>> > The VHO lowering code tries to simplify certain Boolean operations
>> > because of short circuiting in C99 semantics. However, it fails to
>> > consider volatile in the case. For example: (x && 0) cannot be
>> > simplified to 0 when (x) is a volatile.
>> >
>> > 4. Bugs related to aggregates that are volatile or have volatile members
>> >
>> > int test_volatile_struct() {
>> > struct struct_typ {
>> > int foo;
>> > int bar;
>> > };
>> > struct vol_struct_typ {
>> > volatile int foo;
>> > volatile int bar;
>> > };
>> >
>> > volatile struct struct_typ val;
>> > struct vol_struct_typ vol_val;
>> >
>> > val = val; /* should not be deleted because val is volatile*/
>> > vol_val = vol_val; /* should not be deleted because its members
>> > are volatile */
>> >
>> > return 0;
>> > }
>> >
>> > void test_volatile_partial_struct() {
>> > struct foo {
>> > volatile int bar;
>> > float baz;
>> > } v;
>> >
>> > v = v; /* can be optimized to v.bar = v.bar only */
>> > }
>> >
>> > void test_volatile_nested_struct() {
>> > struct foo {
>> > struct {
>> > volatile int val;
>> > int var;
>> > } bar;
>> > float baz;
>> > };
>> >
>> > struct foo v;
>> > v = v;
>> > }
>> >
>> > int test_volatile_arg_5(volatile struct foo_t *foop) {
>> > return foop->bar - foop->bar; /* should not be simplified to 0 */
>> > }
>> >
>> > In wn_lower.cxx, expression like struct_val = struct_val may have side
>> > effects. Therefore, we need to traverse its fields and look for
>> > volatile. The function is implemented as TY_has_volatile.
>> >
>> > WN_Is_Volatile_Mem checks for accessing volatile memories. However, it
>> > only looks at WN_ty and WN_load_addr_ty. However, in the case of
>> > aggregate type, the WN_ty does not reflect the type of the field being
>> > accessed. We need to use WN_object_ty to get the type. However, adding
>> > this code causes circular dependency between wn_util.h and wn_core.h.
>> > The solution is to move WN_Is_Volatile_Mem to wn_util.h
>> >
>> > Failure to check for WN_object_ty also causes problems in WN
>> > simplifier and WN_has_side_effects (which should return TRUE for
>> > accessing a volatile field of a struct and FALSE otherwise).
>> >
>> >
>> > --
>> > yongchong
>> >
>> >
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>> >
>> >
>>
>>
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>
>
>
> --
> Regards,
> Lai Jian-Xin
>
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