On Tue, Nov 10, 2015 at 11:57 AM, Richard Sandiford
<richard.sandif...@arm.com> wrote:
> Richard Biener <richard.guent...@gmail.com> writes:
>> On Mon, Nov 9, 2015 at 5:21 PM, Richard Sandiford
>> <richard.sandif...@arm.com> wrote:
>>> In practice all targets that can vectorise sqrt define the appropriate
>>> sqrt<mode>2 optab. The only case where this isn't immediately obvious
>>> is the libmass support in rs6000.c, but Mike Meissner said that it shouldn't
>>> be exercised for sqrt.
>>>
>>> This patch therefore uses the internal function interface instead of
>>> going via the target hook.
>>>
>>>
>>> gcc/
>>> * tree-vect-patterns.c: Include internal-fn.h.
>>> (vect_recog_pow_pattern): Use IFN_SQRT instead of BUILT_IN_SQRT*.
>>>
>>> diff --git a/gcc/tree-vect-patterns.c b/gcc/tree-vect-patterns.c
>>> index bab9a4f..a803e8c 100644
>>> --- a/gcc/tree-vect-patterns.c
>>> +++ b/gcc/tree-vect-patterns.c
>>> @@ -39,6 +39,7 @@ along with GCC; see the file COPYING3. If not see
>>> #include "tree-vectorizer.h"
>>> #include "dumpfile.h"
>>> #include "builtins.h"
>>> +#include "internal-fn.h"
>>> #include "case-cfn-macros.h"
>>>
>>> /* Pattern recognition functions */
>>> @@ -1052,18 +1053,13 @@ vect_recog_pow_pattern (vec<gimple *> *stmts, tree
>>> *type_in,
>>> if (TREE_CODE (exp) == REAL_CST
>>> && real_equal (&TREE_REAL_CST (exp), &dconsthalf))
>>> {
>>> - tree newfn = mathfn_built_in (TREE_TYPE (base), BUILT_IN_SQRT);
>>> *type_in = get_vectype_for_scalar_type (TREE_TYPE (base));
>>> - if (*type_in)
>>> + if (*type_in && direct_internal_fn_supported_p (IFN_SQRT, *type_in))
>>> {
>>> - gcall *stmt = gimple_build_call (newfn, 1, base);
>>> - if (vectorizable_function (stmt, *type_in, *type_in)
>>> - != NULL_TREE)
>>> - {
>>> - var = vect_recog_temp_ssa_var (TREE_TYPE (base), stmt);
>>> - gimple_call_set_lhs (stmt, var);
>>> - return stmt;
>>> - }
>>> + gcall *stmt = gimple_build_call_internal (IFN_SQRT, 1, base);
>>> + var = vect_recog_temp_ssa_var (TREE_TYPE (base), stmt);
>>> + gimple_call_set_lhs (stmt, var);
>>> + return stmt;
>>
>> Looks ok but I wonder if this is dead code with
>>
>> (for pows (POW)
>> sqrts (SQRT)
>> cbrts (CBRT)
>> (simplify
>> (pows @0 REAL_CST@1)
>> (with {
>> const REAL_VALUE_TYPE *value = TREE_REAL_CST_PTR (@1);
>> REAL_VALUE_TYPE tmp;
>> }
>> (switch
>> ...
>> /* pow(x,0.5) -> sqrt(x). */
>> (if (flag_unsafe_math_optimizations
>> && canonicalize_math_p ()
>> && real_equal (value, &dconsthalf))
>> (sqrts @0))
>
> Yeah, I wondered that too, although I think it's more likely to be dead
> because of sincos. In the end it just seemed like a rabiit hole too far
> though.
Indeed. sincos should also fix the pow(x, 2.) case handled.
Richard.
>> Anyway, patch is ok.
>
> Thanks,
> Richard
>
