Re: [PATCH] PowerPC: Implement TARGET_ATOMIC_ASSIGN_EXPAND_FENV

[Adhemerval Zanella <azanella@linux.vnet.ibm.com>]

Ping.

On 06-08-2014 17:21, Adhemerval Zanella wrote:
> On 01-08-2014 12:31, Joseph S. Myers wrote:
>> On Thu, 31 Jul 2014, David Edelsohn wrote:
>>
>>> Thanks for implementing the FENV support.  The patch generally looks 
>>> good to me.
>>>
>>> My one concern is a detail in the implementation of "update". I do not
>>> have enough experience with GENERIC to verify the details and it seems
>>> like it is missing building an outer COMPOUND_EXPR containing
>>> update_mffs and the CALL_EXPR for update mtfsf.
>> I suppose what's actually odd there is that you have
>>
>> +  tree update_mffs = build2 (MODIFY_EXPR, void_type_node, old_fenv, call_mffs);
>> +
>> +  tree old_llu = build1 (VIEW_CONVERT_EXPR, uint64_type_node, update_mffs);
>>
>> so you build a MODIFY_EXPR in void_type_node but then convert it with a 
>> VIEW_CONVERT_EXPR.  If you'd built the MODIFY_EXPR in double_type_node 
>> then the VIEW_CONVERT_EXPR would be meaningful (the value of an assignment 
>> a = b being the new value of a), but reinterpreting a void value doesn't 
>> make sense.  Or you could probably just use call_mffs directly in the 
>> VIEW_CONVERT_EXPR without explicitly creating the old_fenv variable.
>>
> Thanks for the review Josephm.  I have changed to avoid the void reinterpretation
> and use call_mffs directly.  I have also removed the the mask generation in 'clear'
> from your previous message, it is now reusing the mas used in feholdexcept.  The 
> testcase patch is the same as before.
>
> Checked on both linux-powerpc64/powerpc64le and no regressions found.
>
> --
>
> 2014-08-06  Adhemerval Zanella  <azanella@linux.vnet.ibm.com>
>
> gcc:
> 	* config/rs6000/rs6000.c (rs6000_atomic_assign_expand_fenv): New
> 	function.
>
> gcc/testsuite:
> 	* gcc.dg/atomic/c11-atomic-exec-5.c
> 	(test_main_long_double_add_overflow): Define and run only for
> 	LDBL_MANT_DIG != 106.
> 	(test_main_complex_long_double_add_overflow): Likewise.
> 	(test_main_long_double_sub_overflow): Likewise.
> 	(test_main_complex_long_double_sub_overflow): Likewise.
>
> ---
>
> diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
> index d088ff6..7d66eb1 100644
> --- a/gcc/config/rs6000/rs6000.c
> +++ b/gcc/config/rs6000/rs6000.c
> @@ -1631,6 +1631,9 @@ static const struct attribute_spec rs6000_attribute_table[] =
>
>  #undef TARGET_CAN_USE_DOLOOP_P
>  #define TARGET_CAN_USE_DOLOOP_P can_use_doloop_if_innermost
> +
> +#undef TARGET_ATOMIC_ASSIGN_EXPAND_FENV
> +#define TARGET_ATOMIC_ASSIGN_EXPAND_FENV rs6000_atomic_assign_expand_fenv
>  \f
>
>  /* Processor table.  */
> @@ -33337,6 +33340,80 @@ emit_fusion_gpr_load (rtx *operands)
>    return "";
>  }
>
> +/* Implement TARGET_ATOMIC_ASSIGN_EXPAND_FENV hook.  */
> +
> +static void
> +rs6000_atomic_assign_expand_fenv (tree *hold, tree *clear, tree *update)
> +{
> +  if (!TARGET_HARD_FLOAT || !TARGET_FPRS)
> +    return;
> +
> +  tree mffs = rs6000_builtin_decls[RS6000_BUILTIN_MFFS];
> +  tree mtfsf = rs6000_builtin_decls[RS6000_BUILTIN_MTFSF];
> +  tree call_mffs = build_call_expr (mffs, 0);
> +
> +  /* Generates the equivalent of feholdexcept (&fenv_var)
> +
> +     *fenv_var = __builtin_mffs ();
> +     double fenv_hold;
> +     *(uint64_t*)&fenv_hold = *(uint64_t*)fenv_var & 0xffffffff00000007LL;
> +     __builtin_mtfsf (0xff, fenv_hold);  */
> +
> +  /* Mask to clear everything except for the rounding modes and non-IEEE
> +     arithmetic flag.  */
> +  const unsigned HOST_WIDE_INT hold_exception_mask =
> +    HOST_WIDE_INT_UC (0xffffffff00000007);
> +
> +  tree fenv_var = create_tmp_var (double_type_node, NULL);
> +
> +  tree hold_mffs = build2 (MODIFY_EXPR, void_type_node, fenv_var, call_mffs);
> +
> +  tree fenv_llu = build1 (VIEW_CONVERT_EXPR, uint64_type_node, fenv_var);
> +  tree fenv_llu_and = build2 (BIT_AND_EXPR, uint64_type_node, fenv_llu,
> +    build_int_cst (uint64_type_node, hold_exception_mask));
> +
> +  tree fenv_mtfsf = build1 (VIEW_CONVERT_EXPR, double_type_node, fenv_llu_and);
> +
> +  tree hold_mtfsf = build_call_expr (mtfsf, 2,
> +    build_int_cst (unsigned_type_node, 0xff), fenv_mtfsf);
> +
> +  *hold = build2 (COMPOUND_EXPR, void_type_node, hold_mffs, hold_mtfsf);
> +
> +  /* Reload the value of fenv_hold to clear the exceptions.  */
> +
> +  *clear = build_call_expr (mtfsf, 2,
> +    build_int_cst (unsigned_type_node, 0xff), fenv_mtfsf);
> +
> +  /* Generates the equivalent of feupdateenv (&fenv_var)
> +
> +     double old_fenv = __builtin_mffs ();
> +     double fenv_update;
> +     *(uint64_t*)&fenv_update = (*(uint64_t*)&old & 0xffffffff1fffff00LL) |
> +                                (*(uint64_t*)fenv_var 0x1ff80fff);
> +     __builtin_mtfsf (0xff, fenv_update);  */
> +
> +  const unsigned HOST_WIDE_INT update_exception_mask =
> +    HOST_WIDE_INT_UC (0xffffffff1fffff00);
> +  const unsigned HOST_WIDE_INT new_exception_mask =
> +    HOST_WIDE_INT_UC (0x1ff80fff);
> +
> +  tree old_llu = build1 (VIEW_CONVERT_EXPR, uint64_type_node, call_mffs);
> +  tree old_llu_and = build2 (BIT_AND_EXPR, uint64_type_node,
> +    old_llu, build_int_cst (uint64_type_node, update_exception_mask));
> +
> +  tree new_llu_and = build2 (BIT_AND_EXPR, uint64_type_node, fenv_llu,
> +    build_int_cst (uint64_type_node, new_exception_mask));
> +
> +  tree new_llu_mask = build2 (BIT_IOR_EXPR, uint64_type_node,
> +    old_llu_and, new_llu_and);
> +
> +  tree fenv_mtfsf_update = build1 (VIEW_CONVERT_EXPR, double_type_node,
> +    new_llu_mask);
> +  
> +  *update = build_call_expr (mtfsf, 2,
> +    build_int_cst (unsigned_type_node, 0xff), fenv_mtfsf_update);
> +}
> +
>  \f
>  struct gcc_target targetm = TARGET_INITIALIZER;
>
> diff --git a/gcc/testsuite/gcc.dg/atomic/c11-atomic-exec-5.c b/gcc/testsuite/gcc.dg/atomic/c11-atomic-exec-5.c
> index b47a228..6bcb302 100644
> --- a/gcc/testsuite/gcc.dg/atomic/c11-atomic-exec-5.c
> +++ b/gcc/testsuite/gcc.dg/atomic/c11-atomic-exec-5.c
> @@ -331,11 +331,11 @@ TEST_FUNCS (complex_double_div_overflow, _Complex double, , /= DBL_MIN, 0,
>  TEST_FUNCS (long_double_add_invalid, long double, , += __builtin_infl (), 0,
>  	    0, __builtin_isinf, 0,
>  	    -__builtin_infl (), FE_INVALID)
> +#if LDBL_MANT_DIG != 106
>  TEST_FUNCS (long_double_add_overflow, long double, , += LDBL_MAX, 0,
>  	    LDBL_MAX, __builtin_isinf, FE_OVERFLOW | FE_INEXACT,
>  	    0, 0)
>  #define NOT_LDBL_EPSILON_2(X) ((X) != LDBL_EPSILON / 2)
> -#if LDBL_MANT_DIG != 106
>  TEST_FUNCS (long_double_add_inexact, long double, , += LDBL_EPSILON / 2, 0,
>  	    1.0L, NOT_LDBL_EPSILON_2, FE_INEXACT,
>  	    0, 0)
> @@ -348,18 +348,18 @@ TEST_FUNCS (long_double_preinc_inexact, long double, ++, , 0,
>  TEST_FUNCS (long_double_postinc_inexact, long double, , ++, 0,
>  	    LDBL_EPSILON / 2, NOT_MINUS_1, FE_INEXACT,
>  	    -1, 0)
> -#endif
>  TEST_FUNCS (complex_long_double_add_overflow, _Complex long double, , += LDBL_MAX, 0,
>  	    LDBL_MAX, REAL_ISINF, FE_OVERFLOW | FE_INEXACT,
>  	    0, 0)
> +#endif
>  TEST_FUNCS (long_double_sub_invalid, long double, , -= __builtin_infl (), 0,
>  	    0, __builtin_isinf, 0,
>  	    __builtin_infl (), FE_INVALID)
> +#if LDBL_MANT_DIG != 106
>  TEST_FUNCS (long_double_sub_overflow, long double, , -= LDBL_MAX, 0,
>  	    -LDBL_MAX, __builtin_isinf, FE_OVERFLOW | FE_INEXACT,
>  	    0, 0)
>  #define NOT_MINUS_LDBL_EPSILON_2(X) ((X) != -LDBL_EPSILON / 2)
> -#if LDBL_MANT_DIG != 106
>  TEST_FUNCS (long_double_sub_inexact, long double, , -= LDBL_EPSILON / 2, 0,
>  	    -1.0L, NOT_MINUS_LDBL_EPSILON_2, FE_INEXACT,
>  	    0, 0)
> @@ -372,10 +372,10 @@ TEST_FUNCS (long_double_predec_inexact, long double, --, , 0,
>  TEST_FUNCS (long_double_postdec_inexact, long double, , --, 0,
>  	    -LDBL_EPSILON / 2, NOT_1, FE_INEXACT,
>  	    1, 0)
> -#endif
>  TEST_FUNCS (complex_long_double_sub_overflow, _Complex long double, , -= LDBL_MAX, 0,
>  	    -LDBL_MAX, REAL_ISINF, FE_OVERFLOW | FE_INEXACT,
>  	    0, 0)
> +#endif
>  TEST_FUNCS (long_double_mul_invalid, long double, , *= __builtin_infl (), 0,
>  	    __builtin_infl (), __builtin_isinf, 0,
>  	    0, FE_INVALID)
> @@ -507,23 +507,23 @@ main (void)
>    ret |= test_main_int_div_double_inexact ();
>    ret |= test_main_complex_double_div_overflow ();
>    ret |= test_main_long_double_add_invalid ();
> -  ret |= test_main_long_double_add_overflow ();
>  #if LDBL_MANT_DIG != 106
> +  ret |= test_main_long_double_add_overflow ();
>    ret |= test_main_long_double_add_inexact ();
>    ret |= test_main_long_double_add_inexact_int ();
>    ret |= test_main_long_double_preinc_inexact ();
>    ret |= test_main_long_double_postinc_inexact ();
> -#endif
>    ret |= test_main_complex_long_double_add_overflow ();
> +#endif
>    ret |= test_main_long_double_sub_invalid ();
> -  ret |= test_main_long_double_sub_overflow ();
>  #if LDBL_MANT_DIG != 106
> +  ret |= test_main_long_double_sub_overflow ();
>    ret |= test_main_long_double_sub_inexact ();
>    ret |= test_main_long_double_sub_inexact_int ();
>    ret |= test_main_long_double_predec_inexact ();
>    ret |= test_main_long_double_postdec_inexact ();
> -#endif
>    ret |= test_main_complex_long_double_sub_overflow ();
> +#endif
>    ret |= test_main_long_double_mul_invalid ();
>    ret |= test_main_long_double_mul_overflow ();
>    ret |= test_main_long_double_mul_overflow_float ();
>