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
>
> ------------------------------------------------------------------------------
> EditLive Enterprise is the world's most technically advanced content
> authoring tool. Experience the power of Track Changes, Inline Image
> Editing and ensure content is compliant with Accessibility Checking.
> http://p.sf.net/sfu/ephox-dev2dev
> _______________________________________________
> Open64-devel mailing list
> Open64-devel@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/open64-devel
>
>
------------------------------------------------------------------------------
EditLive Enterprise is the world's most technically advanced content
authoring tool. Experience the power of Track Changes, Inline Image
Editing and ensure content is compliant with Accessibility Checking.
http://p.sf.net/sfu/ephox-dev2dev
_______________________________________________
Open64-devel mailing list
Open64-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/open64-devel
