[PATCH, PR58066] preferred_stack_boundary update for tls expanded call

[Wei Mi]

Yes, x32 has the same problem. It should be tested. Fixed.

Thanks,
Wei.


On Fri, Mar 7, 2014 at 2:06 PM, H.J. Lu <hjl.tools@gmail.com> wrote:
> On Fri, Mar 7, 2014 at 1:26 PM, Wei Mi <wmi@google.com> wrote:
>> Hi,
>>
>> This patch is to fix the problem described here:
>> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58066
>>
>> I follow Ian's suggestion and set
>> ix86_tls_descriptor_calls_expanded_in_cfun in
>> tls_global_dynamic_64_<mode> and tls_local_dynamic_base_64_<mode>.
>> Although 32bit doesn't have the problem,
>> ix86_tls_descriptor_calls_expanded_in_cfun is also set for
>> tls_global_dynamic_32 and tls_local_dynamic_base_32 to make
>> ix86_tls_descriptor_calls_expanded_in_cfun setting consistent across
>> 32bits and 64bits.
>>
>> If ix86_current_function_calls_tls_descriptor is set, we know that
>> there is tls expanded call in current function. Update
>> crtl->preferred_stack_boundary and crtl->stack_alignment_needed to be
>> no less than PREFERED_STACK_ALIGNMENT at the start of
>> ix86_compute_frame_layout. We don't do the update in
>> legitimize_tls_address in cfgexpand stage, which is too early because
>> according to the comments before
>> ix86_current_function_calls_tls_descriptor, tls call may be optimized
>> away. ix86_compute_frame_layout is the latest place to do the update.
>>
>> bootstrap on x86_64-linux-gnu is ok. regression test is going on. Ok
>> for trunk if tests pass?
>>
>> Thanks,
>> Wei.
>>
>> gcc/ChangeLog:
>>
>> 2014-03-07  Wei Mi  <wmi@google.com>
>>
>>         * config/i386/i386.c (ix86_compute_frame_layout): Update
>>         preferred_stack_boundary when there is tls expanded call.
>>         * config/i386/i386.md: Set
>>         ix86_tls_descriptor_calls_expanded_in_cfun.
>>
>> gcc/testsuite/ChangeLog:
>>
>> 2014-03-07  Wei Mi  <wmi@google.com>
>>
>>         * g++.dg/pr58066.C: New test.
>>
>>
>> Index: gcc/config/i386/i386.c
>> ===================================================================
>> --- gcc/config/i386/i386.c      (revision 208410)
>> +++ gcc/config/i386/i386.c      (working copy)
>> @@ -9504,6 +9504,19 @@ ix86_compute_frame_layout (struct ix86_f
>>        crtl->preferred_stack_boundary = 128;
>>        crtl->stack_alignment_needed = 128;
>>      }
>> +  /* For 64-bit target, preferred_stack_boundary is never updated for call
>> +     expanded from tls descriptor. Update it here. We don't update it in
>> +     expand stage because according to the comments before
>> +     ix86_current_function_calls_tls_descriptor, tls calls may be optimized
>> +     away.  */
>> +  else if (TARGET_64BIT
>> +          && ix86_current_function_calls_tls_descriptor
>> +          && crtl->preferred_stack_boundary < PREFERRED_STACK_BOUNDARY)
>> +    {
>> +      crtl->preferred_stack_boundary = PREFERRED_STACK_BOUNDARY;
>> +      if (crtl->stack_alignment_needed < PREFERRED_STACK_BOUNDARY)
>> +       crtl->stack_alignment_needed = PREFERRED_STACK_BOUNDARY;
>> +    }
>>
>>    gcc_assert (!size || stack_alignment_needed);
>>    gcc_assert (preferred_alignment >= STACK_BOUNDARY / BITS_PER_UNIT);
>> Index: gcc/config/i386/i386.md
>> ===================================================================
>> --- gcc/config/i386/i386.md     (revision 208410)
>> +++ gcc/config/i386/i386.md     (working copy)
>> @@ -12891,7 +12891,11 @@
>>                      UNSPEC_TLS_GD))
>>       (clobber (match_scratch:SI 4))
>>       (clobber (match_scratch:SI 5))
>> -     (clobber (reg:CC FLAGS_REG))])])
>> +     (clobber (reg:CC FLAGS_REG))])]
>> +  ""
>> +{
>> +  ix86_tls_descriptor_calls_expanded_in_cfun = true;
>> +})
>>
>>  (define_insn "*tls_global_dynamic_64_<mode>"
>>    [(set (match_operand:P 0 "register_operand" "=a")
>> @@ -12946,7 +12950,10 @@
>>            (const_int 0)))
>>       (unspec:P [(match_operand 1 "tls_symbolic_operand")]
>>                UNSPEC_TLS_GD)])]
>> -  "TARGET_64BIT")
>> +  "TARGET_64BIT"
>> +{
>> +  ix86_tls_descriptor_calls_expanded_in_cfun = true;
>> +})
>>
>>  (define_insn "*tls_local_dynamic_base_32_gnu"
>>    [(set (match_operand:SI 0 "register_operand" "=a")
>> @@ -12982,7 +12989,11 @@
>>             UNSPEC_TLS_LD_BASE))
>>        (clobber (match_scratch:SI 3))
>>        (clobber (match_scratch:SI 4))
>> -      (clobber (reg:CC FLAGS_REG))])])
>> +      (clobber (reg:CC FLAGS_REG))])]
>> +  ""
>> +{
>> +  ix86_tls_descriptor_calls_expanded_in_cfun = true;
>> +})
>>
>>  (define_insn "*tls_local_dynamic_base_64_<mode>"
>>    [(set (match_operand:P 0 "register_operand" "=a")
>> @@ -13029,7 +13040,10 @@
>>             (mem:QI (match_operand 1))
>>             (const_int 0)))
>>        (unspec:P [(const_int 0)] UNSPEC_TLS_LD_BASE)])]
>> -  "TARGET_64BIT")
>> +  "TARGET_64BIT"
>> +{
>> +  ix86_tls_descriptor_calls_expanded_in_cfun = true;
>> +})
>>
>>  ;; Local dynamic of a single variable is a lose.  Show combine how
>>  ;; to convert that back to global dynamic.
>> Index: gcc/testsuite/g++.dg/pr58066.C
>> ===================================================================
>> --- gcc/testsuite/g++.dg/pr58066.C      (revision 0)
>> +++ gcc/testsuite/g++.dg/pr58066.C      (revision 0)
>> @@ -0,0 +1,12 @@
>> +/* { dg-do compile { target {{ i?86-*-* x86_64-*-* } && lp64 } } } */
>
>          ^^^^^ It should be not ia32.
> since we also want to test it for x32.
>
>> +/* { dg-options "-fPIC -O2 -m64" } */
>                                          ^^^^^^^^  No need to add -m64.
>> +
>> +/* Check whether the stack frame starting address of tls expanded call
>> +   in __cxa_get_globals() is 16bytes aligned.  */
>> +static __thread char ccc;
>> +extern "C" void* __cxa_get_globals() throw()
>> +{
>> + return &ccc;
>> +}
>> +
>> +/* { dg-final { scan-assembler ".cfi_def_cfa_offset 16" } } */
>
>
>
> --
> H.J.