Re: [PATCH V5 1/2] Add overflow API for plus minus mult on range

[Jiufu Guo <guojiufu@linux.ibm.com>]

Hi,

I would like to have a ping on this patch.

BR,
Jeff (Jiufu Guo)


Jiufu Guo <guojiufu@linux.ibm.com> writes:

> Hi,
>
> As discussed in previous reviews, adding overflow APIs to range-op
> would be useful. Those APIs could help to check if overflow happens
> when operating between two 'range's, like: plus, minus, and mult.
>
> Previous discussions are here:
> https://gcc.gnu.org/pipermail/gcc-patches/2023-July/624067.html
> https://gcc.gnu.org/pipermail/gcc-patches/2023-July/624701.html
>
> Bootstrap & regtest pass on ppc64{,le} and x86_64.
> Is this patch ok for trunk?
>
> BR,
> Jeff (Jiufu Guo)
>
> gcc/ChangeLog:
>
> 	* range-op-mixed.h (operator_plus::overflow_free_p): New declare.
> 	(operator_minus::overflow_free_p): New declare.
> 	(operator_mult::overflow_free_p): New declare.
> 	* range-op.cc (range_op_handler::overflow_free_p): New function.
> 	(range_operator::overflow_free_p): New default function.
> 	(operator_plus::overflow_free_p): New function.
> 	(operator_minus::overflow_free_p): New function.
> 	(operator_mult::overflow_free_p): New function.
> 	* range-op.h (range_op_handler::overflow_free_p): New declare.
> 	(range_operator::overflow_free_p): New declare.
> 	* value-range.cc (irange::nonnegative_p): New function.
> 	(irange::nonpositive_p): New function.
> 	* value-range.h (irange::nonnegative_p): New declare.
> 	(irange::nonpositive_p): New declare.
>
> ---
>  gcc/range-op-mixed.h |  11 ++++
>  gcc/range-op.cc      | 124 +++++++++++++++++++++++++++++++++++++++++++
>  gcc/range-op.h       |   5 ++
>  gcc/value-range.cc   |  12 +++++
>  gcc/value-range.h    |   2 +
>  5 files changed, 154 insertions(+)
>
> diff --git a/gcc/range-op-mixed.h b/gcc/range-op-mixed.h
> index 6944742ecbc..42157ed9061 100644
> --- a/gcc/range-op-mixed.h
> +++ b/gcc/range-op-mixed.h
> @@ -383,6 +383,10 @@ public:
>  				  relation_kind rel) const final override;
>    void update_bitmask (irange &r, const irange &lh,
>  		       const irange &rh) const final override;
> +
> +  virtual bool overflow_free_p (const irange &lh, const irange &rh,
> +				relation_trio = TRIO_VARYING) const;
> +
>  private:
>    void wi_fold (irange &r, tree type, const wide_int &lh_lb,
>  		const wide_int &lh_ub, const wide_int &rh_lb,
> @@ -446,6 +450,10 @@ public:
>  				relation_kind rel) const final override;
>    void update_bitmask (irange &r, const irange &lh,
>  		       const irange &rh) const final override;
> +
> +  virtual bool overflow_free_p (const irange &lh, const irange &rh,
> +				relation_trio = TRIO_VARYING) const;
> +
>  private:
>    void wi_fold (irange &r, tree type, const wide_int &lh_lb,
>  		const wide_int &lh_ub, const wide_int &rh_lb,
> @@ -525,6 +533,9 @@ public:
>  		const REAL_VALUE_TYPE &lh_lb, const REAL_VALUE_TYPE &lh_ub,
>  		const REAL_VALUE_TYPE &rh_lb, const REAL_VALUE_TYPE &rh_ub,
>  		relation_kind kind) const final override;
> +  virtual bool overflow_free_p (const irange &lh, const irange &rh,
> +				relation_trio = TRIO_VARYING) const;
> +
>  };
>  
>  class operator_addr_expr : public range_operator
> diff --git a/gcc/range-op.cc b/gcc/range-op.cc
> index cb584314f4c..632b044331b 100644
> --- a/gcc/range-op.cc
> +++ b/gcc/range-op.cc
> @@ -366,6 +366,22 @@ range_op_handler::op1_op2_relation (const vrange &lhs) const
>      }
>  }
>  
> +bool
> +range_op_handler::overflow_free_p (const vrange &lh,
> +				   const vrange &rh,
> +				   relation_trio rel) const
> +{
> +  gcc_checking_assert (m_operator);
> +  switch (dispatch_kind (lh, lh, rh))
> +    {
> +      case RO_III:
> +	return m_operator->overflow_free_p(as_a <irange> (lh),
> +					   as_a <irange> (rh),
> +					   rel);
> +      default:
> +	return false;
> +    }
> +}
>  
>  // Convert irange bitmasks into a VALUE MASK pair suitable for calling CCP.
>  
> @@ -688,6 +704,13 @@ range_operator::op1_op2_relation_effect (irange &lhs_range ATTRIBUTE_UNUSED,
>    return false;
>  }
>  
> +bool
> +range_operator::overflow_free_p (const irange &, const irange &,
> +				 relation_trio) const
> +{
> +  return false;
> +}
> +
>  // Apply any known bitmask updates based on this operator.
>  
>  void
> @@ -4311,6 +4334,107 @@ range_op_table::initialize_integral_ops ()
>  
>  }
>  
> +bool
> +operator_plus::overflow_free_p (const irange &lh, const irange &rh,
> +				relation_trio) const
> +{
> +  if (lh.undefined_p () || rh.undefined_p ())
> +    return false;
> +
> +  tree type = lh.type ();
> +  if (TYPE_OVERFLOW_UNDEFINED (type))
> +    return true;
> +
> +  wi::overflow_type ovf;
> +  signop sgn = TYPE_SIGN (type);
> +  wide_int wmax0 = lh.upper_bound ();
> +  wide_int wmax1 = rh.upper_bound ();
> +  wi::add (wmax0, wmax1, sgn, &ovf);
> +  if (ovf != wi::OVF_NONE)
> +    return false;
> +
> +  if (TYPE_UNSIGNED (type))
> +    return true;
> +
> +  wide_int wmin0 = lh.lower_bound ();
> +  wide_int wmin1 = rh.lower_bound ();
> +  wi::add (wmin0, wmin1, sgn, &ovf);
> +  if (ovf != wi::OVF_NONE)
> +    return false;
> +
> +  return true;
> +}
> +
> +bool
> +operator_minus::overflow_free_p (const irange &lh, const irange &rh,
> +				 relation_trio) const
> +{
> +  if (lh.undefined_p () || rh.undefined_p ())
> +    return false;
> +
> +  tree type = lh.type ();
> +  if (TYPE_OVERFLOW_UNDEFINED (type))
> +    return true;
> +
> +  wi::overflow_type ovf;
> +  signop sgn = TYPE_SIGN (type);
> +  wide_int wmin0 = lh.lower_bound ();
> +  wide_int wmax1 = rh.upper_bound ();
> +  wi::sub (wmin0, wmax1, sgn, &ovf);
> +  if (ovf != wi::OVF_NONE)
> +    return false;
> +
> +  if (TYPE_UNSIGNED (type))
> +    return true;
> +
> +  wide_int wmax0 = lh.upper_bound ();
> +  wide_int wmin1 = rh.lower_bound ();
> +  wi::sub (wmax0, wmin1, sgn, &ovf);
> +  if (ovf != wi::OVF_NONE)
> +    return false;
> +
> +  return true;
> +}
> +
> +bool
> +operator_mult::overflow_free_p (const irange &lh, const irange &rh,
> +				relation_trio) const
> +{
> +  if (lh.undefined_p () || rh.undefined_p ())
> +    return false;
> +
> +  tree type = lh.type ();
> +  if (TYPE_OVERFLOW_UNDEFINED (type))
> +    return true;
> +
> +  wi::overflow_type ovf;
> +  signop sgn = TYPE_SIGN (type);
> +  wide_int wmax0 = lh.upper_bound ();
> +  wide_int wmax1 = rh.upper_bound ();
> +  wi::mul (wmax0, wmax1, sgn, &ovf);
> +  if (ovf != wi::OVF_NONE)
> +    return false;
> +
> +  if (TYPE_UNSIGNED (type))
> +    return true;
> +
> +  wide_int wmin0 = lh.lower_bound ();
> +  wide_int wmin1 = rh.lower_bound ();
> +  wi::mul (wmin0, wmin1, sgn, &ovf);
> +  if (ovf != wi::OVF_NONE)
> +    return false;
> +
> +  wi::mul (wmin0, wmax1, sgn, &ovf);
> +  if (ovf != wi::OVF_NONE)
> +    return false;
> +
> +  wi::mul (wmax0, wmin1, sgn, &ovf);
> +  if (ovf != wi::OVF_NONE)
> +    return false;
> +
> +  return true;
> +}
> +
>  #if CHECKING_P
>  #include "selftest.h"
>  
> diff --git a/gcc/range-op.h b/gcc/range-op.h
> index af94c2756a7..db3b03f28a5 100644
> --- a/gcc/range-op.h
> +++ b/gcc/range-op.h
> @@ -147,6 +147,9 @@ public:
>  
>    virtual relation_kind op1_op2_relation (const irange &lhs) const;
>    virtual relation_kind op1_op2_relation (const frange &lhs) const;
> +
> +  virtual bool overflow_free_p (const irange &lh, const irange &rh,
> +				relation_trio = TRIO_VARYING) const;
>  protected:
>    // Perform an integral operation between 2 sub-ranges and return it.
>    virtual void wi_fold (irange &r, tree type,
> @@ -214,6 +217,8 @@ public:
>  				  const vrange &op2,
>  				  relation_kind = VREL_VARYING) const;
>    relation_kind op1_op2_relation (const vrange &lhs) const;
> +  bool overflow_free_p (const vrange &lh, const vrange &rh,
> +			relation_trio = TRIO_VARYING) const;
>  protected:
>    unsigned dispatch_kind (const vrange &lhs, const vrange &op1,
>  			  const vrange& op2) const;
> diff --git a/gcc/value-range.cc b/gcc/value-range.cc
> index 011bdbdeae6..5ae4e044194 100644
> --- a/gcc/value-range.cc
> +++ b/gcc/value-range.cc
> @@ -313,6 +313,18 @@ add_vrange (const vrange &v, inchash::hash &hstate,
>  
>  } //namespace inchash
>  
> +bool
> +irange::nonnegative_p () const
> +{
> +  return wi::ge_p (lower_bound (), 0, TYPE_SIGN (type ()));
> +}
> +
> +bool
> +irange::nonpositive_p () const
> +{
> +  return wi::le_p (upper_bound (), 0, TYPE_SIGN (type ()));
> +}
> +
>  bool
>  irange::supports_type_p (const_tree type) const
>  {
> diff --git a/gcc/value-range.h b/gcc/value-range.h
> index 0170188201b..a12dea514e4 100644
> --- a/gcc/value-range.h
> +++ b/gcc/value-range.h
> @@ -280,6 +280,8 @@ public:
>    virtual bool singleton_p (tree *result = NULL) const override;
>    bool singleton_p (wide_int &) const;
>    bool contains_p (const wide_int &) const;
> +  bool nonnegative_p () const;
> +  bool nonpositive_p () const;
>  
>    // In-place operators.
>    virtual bool union_ (const vrange &) override;