Move sqrt and cbrt simplifications to match.pd

This patch moves the sqrt and cbrt simplification rules to match.pd.
builtins.c now only does the constant folding.

Bootstrapped & regression-tested on x86_64-linux-gnu.  OK to install?

Thanks,
Richard


gcc/
	* builtins.c (fold_builtin_sqrt, fold_builtin_cbrt): Delete.
	(fold_builtin_1): Update accordingly.  Handle constant arguments here.
	* match.pd: Add rules previously handled by fold_builtin_sqrt
	and fold_builtin_cbrt.

gcc/testsuite/
	* gcc.dg/builtins-47.c: Test the optimized dump instead.

On Mon, Oct 5, 2015 at 5:17 PM, Richard Sandiford
<richard.sandiford@arm.com> wrote:
> This patch moves the sqrt and cbrt simplification rules to match.pd.
> builtins.c now only does the constant folding.
>
> Bootstrapped & regression-tested on x86_64-linux-gnu.  OK to install?

Ok (once prerequesites are approved).

People may notice that on GENERIC we no longer simplify these - this is because
genmatch doesn't output a toplevel entry for simplifying calls (well,
I was lazy,
would need to have hooked into builtins.c folding somewhere but IMHO GENERIC
call folding should go).

Thanks,
Richard.

> Thanks,
> Richard
>
>
> gcc/
>         * builtins.c (fold_builtin_sqrt, fold_builtin_cbrt): Delete.
>         (fold_builtin_1): Update accordingly.  Handle constant arguments here.
>         * match.pd: Add rules previously handled by fold_builtin_sqrt
>         and fold_builtin_cbrt.
>
> gcc/testsuite/
>         * gcc.dg/builtins-47.c: Test the optimized dump instead.
>
> diff --git a/gcc/builtins.c b/gcc/builtins.c
> index 85ba6dd..3df60e8 100644
> --- a/gcc/builtins.c
> +++ b/gcc/builtins.c
> @@ -158,8 +158,6 @@ static bool integer_valued_real_p (tree);
>  static tree fold_trunc_transparent_mathfn (location_t, tree, tree);
>  static rtx expand_builtin_fabs (tree, rtx, rtx);
>  static rtx expand_builtin_signbit (tree, rtx);
> -static tree fold_builtin_sqrt (location_t, tree, tree);
> -static tree fold_builtin_cbrt (location_t, tree, tree);
>  static tree fold_builtin_pow (location_t, tree, tree, tree, tree);
>  static tree fold_builtin_powi (location_t, tree, tree, tree, tree);
>  static tree fold_builtin_cos (location_t, tree, tree, tree);
> @@ -7706,145 +7704,6 @@ fold_builtin_cproj (location_t loc, tree arg, tree type)
>    return NULL_TREE;
>  }
>
> -/* Fold a builtin function call to sqrt, sqrtf, or sqrtl with argument ARG.
> -   Return NULL_TREE if no simplification can be made.  */
> -
> -static tree
> -fold_builtin_sqrt (location_t loc, tree arg, tree type)
> -{
> -
> -  enum built_in_function fcode;
> -  tree res;
> -
> -  if (!validate_arg (arg, REAL_TYPE))
> -    return NULL_TREE;
> -
> -  /* Calculate the result when the argument is a constant.  */
> -  if ((res = do_mpfr_arg1 (arg, type, mpfr_sqrt, &dconst<0> (), NULL, true)))
> -    return res;
> -
> -  /* Optimize sqrt(expN(x)) = expN(x*0.5).  */
> -  fcode = builtin_mathfn_code (arg);
> -  if (flag_unsafe_math_optimizations && BUILTIN_EXPONENT_P (fcode))
> -    {
> -      tree expfn = TREE_OPERAND (CALL_EXPR_FN (arg), 0);
> -      arg = fold_build2_loc (loc, MULT_EXPR, type,
> -                        CALL_EXPR_ARG (arg, 0),
> -                        build_real (type, dconst<1, 2> ()));
> -      return build_call_expr_loc (loc, expfn, 1, arg);
> -    }
> -
> -  /* Optimize sqrt(Nroot(x)) -> pow(x,1/(2*N)).  */
> -  if (flag_unsafe_math_optimizations && BUILTIN_ROOT_P (fcode))
> -    {
> -      tree powfn = mathfn_built_in (type, BUILT_IN_POW);
> -
> -      if (powfn)
> -       {
> -         tree arg0 = CALL_EXPR_ARG (arg, 0);
> -         tree arg1 = (BUILTIN_SQRT_P (fcode)
> -                      ? build_real (type, dconst<1, 4> ())
> -                      : build_real_truncate (type, dconst<1, 6> ()));
> -         return build_call_expr_loc (loc, powfn, 2, arg0, arg1);
> -       }
> -    }
> -
> -  /* Optimize sqrt(pow(x,y)) = pow(|x|,y*0.5).  */
> -  if (flag_unsafe_math_optimizations
> -      && (fcode == BUILT_IN_POW
> -         || fcode == BUILT_IN_POWF
> -         || fcode == BUILT_IN_POWL))
> -    {
> -      tree powfn = TREE_OPERAND (CALL_EXPR_FN (arg), 0);
> -      tree arg0 = CALL_EXPR_ARG (arg, 0);
> -      tree arg1 = CALL_EXPR_ARG (arg, 1);
> -      tree narg1;
> -      if (!tree_expr_nonnegative_p (arg0))
> -       arg0 = build1 (ABS_EXPR, type, arg0);
> -      narg1 = fold_build2_loc (loc, MULT_EXPR, type, arg1,
> -                          build_real (type, dconst<1, 2> ()));
> -      return build_call_expr_loc (loc, powfn, 2, arg0, narg1);
> -    }
> -
> -  return NULL_TREE;
> -}
> -
> -/* Fold a builtin function call to cbrt, cbrtf, or cbrtl with argument ARG.
> -   Return NULL_TREE if no simplification can be made.  */
> -
> -static tree
> -fold_builtin_cbrt (location_t loc, tree arg, tree type)
> -{
> -  const enum built_in_function fcode = builtin_mathfn_code (arg);
> -  tree res;
> -
> -  if (!validate_arg (arg, REAL_TYPE))
> -    return NULL_TREE;
> -
> -  /* Calculate the result when the argument is a constant.  */
> -  if ((res = do_mpfr_arg1 (arg, type, mpfr_cbrt, NULL, NULL, 0)))
> -    return res;
> -
> -  if (flag_unsafe_math_optimizations)
> -    {
> -      /* Optimize cbrt(expN(x)) -> expN(x/3).  */
> -      if (BUILTIN_EXPONENT_P (fcode))
> -       {
> -         tree expfn = TREE_OPERAND (CALL_EXPR_FN (arg), 0);
> -         arg = fold_build2_loc (loc, MULT_EXPR, type,
> -                                CALL_EXPR_ARG (arg, 0),
> -                                build_real_truncate (type, dconst<1, 3> ()));
> -         return build_call_expr_loc (loc, expfn, 1, arg);
> -       }
> -
> -      /* Optimize cbrt(sqrt(x)) -> pow(x,1/6).  */
> -      if (BUILTIN_SQRT_P (fcode))
> -       {
> -         tree powfn = mathfn_built_in (type, BUILT_IN_POW);
> -
> -         if (powfn)
> -           {
> -             tree arg0 = CALL_EXPR_ARG (arg, 0);
> -             tree tree_root = build_real_truncate (type, dconst<1, 6> ());
> -             return build_call_expr_loc (loc, powfn, 2, arg0, tree_root);
> -           }
> -       }
> -
> -      /* Optimize cbrt(cbrt(x)) -> pow(x,1/9) iff x is nonnegative.  */
> -      if (BUILTIN_CBRT_P (fcode))
> -       {
> -         tree arg0 = CALL_EXPR_ARG (arg, 0);
> -         if (tree_expr_nonnegative_p (arg0))
> -           {
> -             tree powfn = mathfn_built_in (type, BUILT_IN_POW);
> -
> -             if (powfn)
> -               {
> -                 tree tree_root = build_real_truncate (type, dconst<1, 9> ());
> -                 return build_call_expr_loc (loc, powfn, 2, arg0, tree_root);
> -               }
> -           }
> -       }
> -
> -      /* Optimize cbrt(pow(x,y)) -> pow(x,y/3) iff x is nonnegative.  */
> -      if (fcode == BUILT_IN_POW
> -          || fcode == BUILT_IN_POWF
> -         || fcode == BUILT_IN_POWL)
> -       {
> -         tree arg00 = CALL_EXPR_ARG (arg, 0);
> -         tree arg01 = CALL_EXPR_ARG (arg, 1);
> -         if (tree_expr_nonnegative_p (arg00))
> -           {
> -             tree powfn = TREE_OPERAND (CALL_EXPR_FN (arg), 0);
> -             tree c = build_real_truncate (type, dconst<1, 3> ());
> -             tree narg01 = fold_build2_loc (loc, MULT_EXPR, type, arg01, c);
> -             return build_call_expr_loc (loc, powfn, 2, arg00, narg01);
> -           }
> -       }
> -    }
> -  return NULL_TREE;
> -}
> -
>  /* Fold function call to builtin cos, cosf, or cosl with argument ARG.
>     TYPE is the type of the return value.  Return NULL_TREE if no
>     simplification can be made.  */
> @@ -9943,10 +9802,14 @@ fold_builtin_1 (location_t loc, tree fndecl, tree arg0)
>        return fold_builtin_carg (loc, arg0, type);
>
>      CASE_FLT_FN (BUILT_IN_SQRT):
> -      return fold_builtin_sqrt (loc, arg0, type);
> +      if (validate_arg (arg0, REAL_TYPE))
> +       return do_mpfr_arg1 (arg0, type, mpfr_sqrt, &dconst<0> (), NULL, true);
> +      break;
>
>      CASE_FLT_FN (BUILT_IN_CBRT):
> -      return fold_builtin_cbrt (loc, arg0, type);
> +      if (validate_arg (arg0, REAL_TYPE))
> +       return do_mpfr_arg1 (arg0, type, mpfr_cbrt, NULL, NULL, 0);
> +      break;
>
>      CASE_FLT_FN (BUILT_IN_ASIN):
>        if (validate_arg (arg0, REAL_TYPE))
> diff --git a/gcc/match.pd b/gcc/match.pd
> index 5ab8c06..db8b731 100644
> --- a/gcc/match.pd
> +++ b/gcc/match.pd
> @@ -2315,3 +2315,44 @@ along with GCC; see the file COPYING3.  If not see
>      (with { tree utype = unsigned_type_for (TREE_TYPE (@0)); }
>       (convert (bit_and (op (convert:utype @0) (convert:utype @1))
>                (convert:utype @4))))))))
> +
> +(if (flag_unsafe_math_optimizations)
> + (for sqrts (SQRT)
> +      cbrts (CBRT)
> +      exps (EXP EXP2 EXP10 POW10)
> +  /* sqrt(expN(x)) -> expN(x*0.5).  */
> +  (simplify
> +   (sqrts (exps @0))
> +   (exps (mult @0 { build_real (type, dconst<1, 2> ()); })))
> +  /* cbrt(expN(x)) -> expN(x/3).  */
> +  (simplify
> +   (cbrts (exps @0))
> +   (exps (mult @0 { build_real_truncate (type, dconst<1, 3> ()); }))))
> +
> + (for sqrts (SQRT)
> +      cbrts (CBRT)
> +      pows (POW)
> +  /* sqrt(sqrt(x)) -> pow(x,1/4).  */
> +  (simplify
> +   (sqrts (sqrts @0))
> +   (pows @0 { build_real (type, dconst<1, 4> ()); }))
> +  /* cbrt(sqrt(x)) -> pow(x,1/6).  */
> +  (simplify
> +   (sqrts (cbrts @0))
> +   (pows @0 { build_real_truncate (type, dconst<1, 6> ()); }))
> +  /* sqrt(cbrt(x)) -> pow(x,1/6).  */
> +  (simplify
> +   (cbrts (sqrts @0))
> +   (pows @0 { build_real_truncate (type, dconst<1, 6> ()); }))
> +  /* cbrt(cbrt(x)) -> pow(x,1/9), iff x is nonnegative.  */
> +  (simplify
> +   (cbrts (cbrts nonnegative_p@0))
> +   (pows @0 { build_real_truncate (type, dconst<1, 9> ()); }))
> +  /* sqrt(pow(x,y)) -> pow(|x|,y*0.5).  */
> +  (simplify
> +   (sqrts (pows @0 @1))
> +   (pows (abs @0) (mult @1 { build_real (type, dconst<1, 2> ()); })))
> +  /* cbrt(pow(x,y)) -> pow(x,y/3), iff x is nonnegative.  */
> +  (simplify
> +   (cbrts (pows nonnegative_p@0 @1))
> +   (pows @0 (mult @1 { build_real_truncate (type, dconst<1, 3> ()); })))))
> diff --git a/gcc/testsuite/gcc.dg/builtins-47.c b/gcc/testsuite/gcc.dg/builtins-47.c
> index 024d7ee..fbe9d21 100644
> --- a/gcc/testsuite/gcc.dg/builtins-47.c
> +++ b/gcc/testsuite/gcc.dg/builtins-47.c
> @@ -1,5 +1,5 @@
>  /* { dg-do run } */
> -/* { dg-options "-O -ffast-math -fdump-tree-gimple" } */
> +/* { dg-options "-O -ffast-math -fdump-tree-optimized" } */
>
>  extern double sqrt (double);
>  extern double pow (double, double);
> @@ -15,5 +15,5 @@ int main ()
>    return 0;
>  }
>
> -/* { dg-final { scan-tree-dump-times "sqrt" 0 "gimple" } } */
> -/* { dg-final { scan-tree-dump-times "pow" 0 "gimple" } } */
> +/* { dg-final { scan-tree-dump-times "sqrt" 0 "optimized" } } */
> +/* { dg-final { scan-tree-dump-times "pow" 0 "optimized" } } */
>

On Mon, 5 Oct 2015, Richard Sandiford wrote:

> +  /* cbrt(sqrt(x)) -> pow(x,1/6).  */
> +  (simplify
> +   (sqrts (cbrts @0))
> +   (pows @0 { build_real_truncate (type, dconst<1, 6> ()); }))
> +  /* sqrt(cbrt(x)) -> pow(x,1/6).  */
> +  (simplify
> +   (cbrts (sqrts @0))
> +   (pows @0 { build_real_truncate (type, dconst<1, 6> ()); }))

I think you swapped the comments (not that it matters).

Marc Glisse <marc.glisse@inria.fr> writes:
> On Mon, 5 Oct 2015, Richard Sandiford wrote:
>
>> +  /* cbrt(sqrt(x)) -> pow(x,1/6).  */
>> +  (simplify
>> +   (sqrts (cbrts @0))
>> +   (pows @0 { build_real_truncate (type, dconst<1, 6> ()); }))
>> +  /* sqrt(cbrt(x)) -> pow(x,1/6).  */
>> +  (simplify
>> +   (cbrts (sqrts @0))
>> +   (pows @0 { build_real_truncate (type, dconst<1, 6> ()); }))
>
> I think you swapped the comments (not that it matters).

Thanks, fixed in the committed version.

Richard

On 8 October 2015 at 18:55, Richard Sandiford <richard.sandiford@arm.com> wrote:
> Marc Glisse <marc.glisse@inria.fr> writes:
>> On Mon, 5 Oct 2015, Richard Sandiford wrote:
>>
>>> +  /* cbrt(sqrt(x)) -> pow(x,1/6).  */
>>> +  (simplify
>>> +   (sqrts (cbrts @0))
>>> +   (pows @0 { build_real_truncate (type, dconst<1, 6> ()); }))
>>> +  /* sqrt(cbrt(x)) -> pow(x,1/6).  */
>>> +  (simplify
>>> +   (cbrts (sqrts @0))
>>> +   (pows @0 { build_real_truncate (type, dconst<1, 6> ()); }))
>>
>> I think you swapped the comments (not that it matters).
>
> Thanks, fixed in the committed version.
>
> Richard
>
Hi Richard,

Since you committed this patch, I've noticed that gcc.dg/builtins-10.c fails
on arm-none-linux-gnueabi targets (as opposed to arm-none-linux-gnueabihf).

gcc.log shows:
/cchfHDHc.o: In function `test':
builtins-10.c:(.text+0x60): undefined reference to `link_error'
collect2: error: ld returned 1 exit status

Does this ring a bell?

Christophe.

Christophe Lyon <christophe.lyon@linaro.org> writes:
> On 8 October 2015 at 18:55, Richard Sandiford <richard.sandiford@arm.com> wrote:
>> Marc Glisse <marc.glisse@inria.fr> writes:
>>> On Mon, 5 Oct 2015, Richard Sandiford wrote:
>>>
>>>> +  /* cbrt(sqrt(x)) -> pow(x,1/6).  */
>>>> +  (simplify
>>>> +   (sqrts (cbrts @0))
>>>> +   (pows @0 { build_real_truncate (type, dconst<1, 6> ()); }))
>>>> +  /* sqrt(cbrt(x)) -> pow(x,1/6).  */
>>>> +  (simplify
>>>> +   (cbrts (sqrts @0))
>>>> +   (pows @0 { build_real_truncate (type, dconst<1, 6> ()); }))
>>>
>>> I think you swapped the comments (not that it matters).
>>
>> Thanks, fixed in the committed version.
>>
>> Richard
>>
> Hi Richard,
>
> Since you committed this patch, I've noticed that gcc.dg/builtins-10.c fails
> on arm-none-linux-gnueabi targets (as opposed to arm-none-linux-gnueabihf).
>
> gcc.log shows:
> /cchfHDHc.o: In function `test':
> builtins-10.c:(.text+0x60): undefined reference to `link_error'
> collect2: error: ld returned 1 exit status

Looks like this is the same fold_strip_sign_ops problem that I was seeing
with some WIP follow-on patches.  We don't fold pow(abs(x), 4) to pow(x, 4).

Hope to have a fix soon.

Thanks,
Richard