[PATCH] [ARC] PR 88409: miscompilation due to missing cc clobber in longlong.h macros

[Vineet Gupta]

On 4/3/19 2:53 AM, Claudiu Zissulescu wrote:
> Pushed, thank you for your contribution,
> Claudiu

Thx, can this be backported to gcc-8-stable please which is what glibc folks use
for testing !

-Vineet

>
> On Tue, Apr 2, 2019 at 9:27 PM Vineet Gupta <vineet.gupta1@synopsys.com> wrote:
>> simple test such as below was failing.
>>
>> | void main(int argc, char *argv[])
>> | {
>> |    size_t total_time = 115424;                       // expected 115.424
>> |    double secs = (double)total_time/(double)1000;
>> |    printf("%s %d %lf\n", "secs", total_time, secs);  // prints 113.504
>> |    printf("%d\n", (size_t)secs);
>> | }
>>
>> The printf eventually called into glibc stdlib/divrem.c:__mpn_divrem()
>> which uses the __arc__ specific inline asm macros from longlong.h which
>> were causing miscompilation.
>>
>> include/
>> 2019-03-28  Vineet Gupta <vgupta@synopsys.com>
>>
>>         PR 89877
>>
>>         * longlong.h [__arc__] (add_ssaaaa): Add cc clobber
>>         (sub_ddmmss): Likewise.
>>
>> Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
>> ---
>>  include/ChangeLog  | 7 +++++++
>>  include/longlong.h | 6 ++++--
>>  2 files changed, 11 insertions(+), 2 deletions(-)
>>
>> diff --git a/include/ChangeLog b/include/ChangeLog
>> index be08141deeb9..96d967d10a52 100644
>> --- a/include/ChangeLog
>> +++ b/include/ChangeLog
>> @@ -1,3 +1,10 @@
>> +2019-03-28  Vineet Gupta <vgupta@synopsys.com>
>> +
>> +       PR 89877
>> +
>> +       * longlong.h [__arc__] (add_ssaaaa): Add cc clobber
>> +       (sub_ddmmss): Likewise.
>> +
>>  2019-02-11  Philippe Waroquiers  <philippe.waroquiers@skynet.be>
>>
>>         * splay-tree.h (splay_tree_delete_key_fn): Update comment.
>> diff --git a/include/longlong.h b/include/longlong.h
>> index 3dd8dc3aa80c..1f0ce4204255 100644
>> --- a/include/longlong.h
>> +++ b/include/longlong.h
>> @@ -199,7 +199,8 @@ extern UDItype __udiv_qrnnd (UDItype *, UDItype, UDItype, UDItype);
>>            : "%r" ((USItype) (ah)),                                     \
>>              "rICal" ((USItype) (bh)),                                  \
>>              "%r" ((USItype) (al)),                                     \
>> -            "rICal" ((USItype) (bl)))
>> +            "rICal" ((USItype) (bl))                                   \
>> +          : "cc")
>>  #define sub_ddmmss(sh, sl, ah, al, bh, bl) \
>>    __asm__ ("sub.f      %1, %4, %5\n\tsbc       %0, %2, %3"             \
>>            : "=r" ((USItype) (sh)),                                     \
>> @@ -207,7 +208,8 @@ extern UDItype __udiv_qrnnd (UDItype *, UDItype, UDItype, UDItype);
>>            : "r" ((USItype) (ah)),                                      \
>>              "rICal" ((USItype) (bh)),                                  \
>>              "r" ((USItype) (al)),                                      \
>> -            "rICal" ((USItype) (bl)))
>> +            "rICal" ((USItype) (bl))                                   \
>> +          : "cc")
>>
>>  #define __umulsidi3(u,v) ((UDItype)(USItype)u*(USItype)v)
>>  #ifdef __ARC_NORM__
>> --
>> 2.7.4
>>