159 lines
4.6 KiB
C
159 lines
4.6 KiB
C
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/* Support for simple predicate analysis.
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Copyright (C) 2021-2022 Free Software Foundation, Inc.
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Contributed by Martin Sebor <msebor@redhat.com>
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This file is part of GCC.
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GCC is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3, or (at your option)
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any later version.
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GCC is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GCC; see the file COPYING3. If not see
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<http://www.gnu.org/licenses/>. */
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#ifndef GIMPLE_PREDICATE_ANALYSIS_H_INCLUDED
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#define GIMPLE_PREDICATE_ANALYSIS_H_INCLUDED
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#define MAX_NUM_CHAINS 8
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#define MAX_CHAIN_LEN 5
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#define MAX_POSTDOM_CHECK 8
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#define MAX_SWITCH_CASES 40
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/* Represents a simple Boolean predicate. */
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struct pred_info
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{
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tree pred_lhs;
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tree pred_rhs;
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enum tree_code cond_code;
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bool invert;
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};
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/* The type to represent a sequence of predicates grouped
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with .AND. operation. */
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typedef vec<pred_info, va_heap, vl_ptr> pred_chain;
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/* The type to represent a sequence of pred_chains grouped
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with .OR. operation. */
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typedef vec<pred_chain, va_heap, vl_ptr> pred_chain_union;
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/* Represents a complex Boolean predicate expression. */
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class predicate
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{
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public:
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/* Base function object type used to determine whether an expression
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is of interest. */
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struct func_t
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{
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typedef unsigned phi_arg_set_t;
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/* Return true if the argument is an expression of interest. */
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virtual bool operator()(tree) = 0;
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/* Return a bitset of PHI arguments of interest. By default returns
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bitset with a bit set for each argument. Should be called in
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the overriden function first and, if nonzero, the result then
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refined as appropriate. */
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virtual phi_arg_set_t phi_arg_set (gphi *);
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/* Maximum number of PHI arguments supported by phi_arg_set(). */
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static constexpr unsigned max_phi_args =
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sizeof (phi_arg_set_t) * CHAR_BIT;
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};
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/* Construct with the specified EVAL object. */
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predicate (func_t &eval)
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: m_preds (vNULL), m_eval (eval), m_use_expr () { }
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/* Copy. */
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predicate (const predicate &rhs)
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: m_preds (vNULL), m_eval (rhs.m_eval), m_use_expr ()
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{
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*this = rhs;
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}
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predicate (basic_block, basic_block, func_t &);
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~predicate ();
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/* Assign. */
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predicate& operator= (const predicate &);
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bool is_empty () const
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{
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return m_preds.is_empty ();
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}
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const pred_chain_union chain () const
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{
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return m_preds;
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}
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/* Return true if the use by a statement in the basic block of
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a PHI operand is ruled out (i.e., guarded) by *THIS. */
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bool is_use_guarded (gimple *, basic_block, gphi *, unsigned);
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void init_from_control_deps (const vec<edge> *, unsigned);
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void dump (gimple *, const char *) const;
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void normalize (gimple * = NULL, bool = false);
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void simplify (gimple * = NULL, bool = false);
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bool is_use_guarded (gimple *, basic_block, gphi *, unsigned,
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hash_set<gphi *> *);
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/* Return the predicate expression guarding the definition of
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the interesting variable, optionally inverted. */
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tree def_expr (bool = false) const;
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/* Return the predicate expression guarding the use of the interesting
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variable. */
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tree use_expr () const;
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tree expr (bool = false) const;
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private:
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bool includes (const pred_chain &) const;
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bool superset_of (const predicate &) const;
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bool overlap (gphi *, unsigned, hash_set<gphi *> *);
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bool use_cannot_happen (gphi *, unsigned);
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bool init_from_phi_def (gphi *);
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void push_pred (const pred_info &);
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/* Normalization functions. */
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void normalize (pred_chain *, pred_info, tree_code, pred_chain *,
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hash_set<tree> *);
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void normalize (const pred_info &);
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void normalize (const pred_chain &);
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/* Simplification functions. */
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bool simplify_2 ();
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bool simplify_3 ();
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bool simplify_4 ();
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private:
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/* Representation of the predicate expression(s). */
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pred_chain_union m_preds;
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/* Callback to evaluate an operand. Return true if it's interesting. */
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func_t &m_eval;
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/* The predicate expression guarding the use of the interesting
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variable. */
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tree m_use_expr;
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};
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/* Bit mask handling macros. */
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#define MASK_SET_BIT(mask, pos) mask |= (1 << pos)
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#define MASK_TEST_BIT(mask, pos) (mask & (1 << pos))
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#define MASK_EMPTY(mask) (mask == 0)
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#endif // GIMPLE_PREDICATE_ANALYSIS_H_INCLUDED
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