I can confirm this is the right fix. I have tested all the test cases on
bug897, no doubltly right.
So, what traces do you want?
Regards
Gang
On Sat, Dec 17, 2011 at 5:22 PM, Sun Chan <sun.c...@gmail.com> wrote:
> I highly doubt you have the right fix. OTOH, I can't follow your
> explaination either. Can you further cut down the example? Also, try to use
> something less confusing in names because it gets mixed up with versioning
> of stmt, symbol etc.
> Once you have a minimum case, we can look at some trace first
> Sun
>
> On Sat, Dec 17, 2011 at 5:11 PM, Gang Yu <yugang...@gmail.com> wrote:
>
>> Hi,
>>
>> Could a gatekeeper please help review the fix for bug897(
>> https://bugs.open64.net/show_bug.cgi?id=897)?
>>
>> when we use csmith to test the compiler stability, we find the DCE always
>> trapped into segment fault.
>>
>> A typical case:
>> int32_t g_46 = 0L;
>> int32_t g_71 = 0L;
>> int32_t *g_311 = &g_46;
>> int32_t * func_19(int32_t * p_20, int16_t p_21, int32_t * p_22, const
>> uint8_t
>> p_23, int32_t * p_24) {
>> int32_t **l_426 = &g_311;
>> const uint64_t l_440 = 0x2A1DFCF9L;
>> for (p_21 = (-24);
>> (p_21 < 1);
>> p_21 = safe_add_func_int16_t_s_s(p_21, 3)) {
>> int32_t ***l_428 = &l_426;
>> (*l_428) = &g_311;
>> if ((*p_20)) {
>> if (l_440) {
>> }
>> else {
>> uint32_t l_445 = 4U;
>> if ((*g_311)) {
>> if ((safe_rshift_func_uint16_t_u_s(func_124((&p_22 !=
>> &p_24)), 10))) {
>> (*g_311) |= l_445;
>> (**l_426) |= (*p_24);
>> g_311 = &g_71;
>> }
>> }
>> }
>> }
>> }
>> }
>> Analysis:
>>
>> the segment fault always occurs at the dead_store_elim phase of DCE, i.e,
>> after the Unreachable_code_elim, and the backtrace shows the DCE tries to
>> mark call statement func_124 live, this is a wrong operation. the branch
>> else {
>> uint32_t l_445 = 4U;
>> if ((*g_311)) {
>> if ((safe_rshift_func_uint16_t_u_s(func_124((&p_22 !=
>> &p_24)), 10))) {
>> (*g_311) |= l_445;
>> (**l_426) |= (*p_24);
>> g_311 = &g_71;
>> }
>> }
>> }
>> has already been deleted by DCE at this point, more investigation shows,
>> when mark safe_add_func_int16_t_s_s(p_21, 3) live, DCE will also mark the
>> mu node g_311 live, which then marks the sym10v0(g_311) version live.
>> The sym10v0 is resurrected chi to (*g311) |= l_445, so (*g_311) |= l_445
>> should be marked live(at this case it should already been marked live
>> although removed[in deleted block]). However it is not the case, DCE tries
>> to mark that statement live...
>>
>> the problem is we do unexpected at Remove_stmtrep:
>> 720// remove the given statement from this block
>> 721void
>> 722BB_NODE::Remove_stmtrep( STMTREP *stmt )
>> 723{
>> ...
>> 735 _stmtlist.Remove(stmt);
>> 736 stmt->Reset_live_stmt(); // WHIRL SSA: mark stmt dead
>> 737}
>>
>> 736 is the cause of this fault.
>>
>> Suggested fix:
>> --- a/osprey/be/opt/opt_bb.cxx
>> +++ b/osprey/be/opt/opt_bb.cxx
>> @@ -733,7 +733,6 @@ BB_NODE::Remove_stmtrep( STMTREP *stmt )
>> }
>> _stmtlist.Remove(stmt);
>> - stmt->Reset_live_stmt(); // WHIRL SSA: mark stmt dead
>> }
>>
>>
>> Regards
>> Gang
>>
>>
>> ------------------------------------------------------------------------------
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>>
>
------------------------------------------------------------------------------
Learn Windows Azure Live! Tuesday, Dec 13, 2011
Microsoft is holding a special Learn Windows Azure training event for
developers. It will provide a great way to learn Windows Azure and what it
provides. You can attend the event by watching it streamed LIVE online.
Learn more at http://p.sf.net/sfu/ms-windowsazure
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