Re: [PATCH] gimple-range-op: Handle sqrt (basic bounds only)

[Aldy Hernandez <aldyh@redhat.com>]

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Ok

On Thu, Apr 27, 2023, 15:30 Jakub Jelinek <jakub@redhat.com> wrote:

> Hi!
>
> The following patch adds sqrt support (but similarly to sincos, only
> dumb basic ranges only).
>
> Ok for trunk if it passes bootstrap/regtest?
>
> Will improve this incrementally and sin/cos as well.
>
> 2023-04-27  Jakub Jelinek  <jakub@redhat.com>
>
>         * gimple-range-op.cc (class cfn_sqrt): New type.
>         (op_cfn_sqrt): New variable.
>         (gimple_range_op_handler::maybe_builtin_call): Handle
>         CASE_CFN_SQRT{,_FN}.
>
>         * gcc.dg/tree-ssa/range-sqrt.c: New test.
>
> --- gcc/gimple-range-op.cc.jj   2023-04-27 11:57:09.865879982 +0200
> +++ gcc/gimple-range-op.cc      2023-04-27 15:15:05.089787859 +0200
> @@ -400,6 +400,83 @@ public:
>    }
>  } op_cfn_copysign;
>
> +class cfn_sqrt : public range_operator_float
> +{
> +public:
> +  using range_operator_float::fold_range;
> +  using range_operator_float::op1_range;
> +  virtual bool fold_range (frange &r, tree type,
> +                          const frange &lh, const frange &,
> +                          relation_trio) const final override
> +  {
> +    if (lh.undefined_p ())
> +      return false;
> +    if (lh.known_isnan () || real_less (&lh.upper_bound (), &dconstm0))
> +      {
> +       r.set_nan (type);
> +       return true;
> +      }
> +    unsigned bulps
> +      = targetm.libm_function_max_error (CFN_SQRT, TYPE_MODE (type),
> true);
> +    if (bulps == ~0U)
> +      r.set_varying (type);
> +    else if (bulps == 0)
> +      r.set (type, dconstm0, dconstinf);
> +    else
> +      {
> +       REAL_VALUE_TYPE boundmin = dconstm0;
> +       while (bulps--)
> +         frange_nextafter (TYPE_MODE (type), boundmin, dconstninf);
> +       r.set (type, boundmin, dconstinf);
> +      }
> +    if (!lh.maybe_isnan () && !real_less (&lh.lower_bound (), &dconst0))
> +      r.clear_nan ();
> +    return true;
> +  }
> +  virtual bool op1_range (frange &r, tree type,
> +                         const frange &lhs, const frange &,
> +                         relation_trio) const final override
> +  {
> +    if (lhs.undefined_p ())
> +      return false;
> +
> +    // A known NAN means the input is [-INF,-0.) U +-NAN.
> +    if (lhs.known_isnan ())
> +      {
> +      known_nan:
> +       REAL_VALUE_TYPE ub = dconstm0;
> +       frange_nextafter (TYPE_MODE (type), ub, dconstninf);
> +       r.set (type, dconstninf, ub);
> +       // No r.flush_denormals_to_zero (); here - it is a reverse op.
> +       return true;
> +      }
> +
> +    // Results outside of [-0.0, +Inf] are impossible.
> +    const REAL_VALUE_TYPE &ub = lhs.upper_bound ();
> +    if (real_less (&ub, &dconstm0))
> +      {
> +       if (!lhs.maybe_isnan ())
> +         r.set_undefined ();
> +       else
> +         // If lhs could be NAN and finite result is impossible,
> +         // the range is like lhs.known_isnan () above.
> +         goto known_nan;
> +       return true;
> +      }
> +
> +    if (!lhs.maybe_isnan ())
> +      {
> +       // If NAN is not valid result, the input cannot include either
> +       // a NAN nor values smaller than -0.
> +       r.set (type, dconstm0, dconstinf, nan_state (false, false));
> +       return true;
> +      }
> +
> +    r.set_varying (type);
> +    return true;
> +  }
> +} op_cfn_sqrt;
> +
>  class cfn_sincos : public range_operator_float
>  {
>  public:
> @@ -961,6 +1038,13 @@ gimple_range_op_handler::maybe_builtin_c
>        m_valid = true;
>        break;
>
> +    CASE_CFN_SQRT:
> +    CASE_CFN_SQRT_FN:
> +      m_op1 = gimple_call_arg (call, 0);
> +      m_float = &op_cfn_sqrt;
> +      m_valid = true;
> +      break;
> +
>      CASE_CFN_SIN:
>      CASE_CFN_SIN_FN:
>        m_op1 = gimple_call_arg (call, 0);
> --- gcc/testsuite/gcc.dg/tree-ssa/range-sqrt.c.jj       2023-04-27
> 15:10:09.285102144 +0200
> +++ gcc/testsuite/gcc.dg/tree-ssa/range-sqrt.c  2023-04-27
> 15:12:01.478465821 +0200
> @@ -0,0 +1,41 @@
> +// { dg-do compile }
> +// { dg-options "-O2 -fdump-tree-evrp -fno-thread-jumps" }
> +
> +#include <math.h>
> +
> +void use (double);
> +void link_error ();
> +
> +void
> +foo (double x)
> +{
> +  if (__builtin_isnan (x))
> +    __builtin_unreachable ();
> +  x = sqrt (x);
> +  if (x < -0.0)
> +    link_error ();
> +  use (x);
> +}
> +
> +void
> +bar (double x)
> +{
> +  if (!__builtin_isnan (sqrt (x)))
> +    {
> +      if (__builtin_isnan (x))
> +       link_error ();
> +      if (x < -0.0)
> +       link_error ();
> +    }
> +}
> +
> +void
> +stool (double x)
> +{
> +  double res1 = sqrt (x);
> +  double res2 = __builtin_sqrt (x);
> +  if (res1 < -0.0 || res2 < -0.0)
> +    link_error ();
> +}
> +
> +// { dg-final { scan-tree-dump-not "link_error" "evrp" { target { {
> *-*-linux* } && { glibc } } } } }
>
>         Jakub
>
>