213 lines
6.7 KiB
C++
213 lines
6.7 KiB
C++
/* Header file for SSA dominator optimizations.
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Copyright (C) 2013-2019 Free Software Foundation, Inc.
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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 it under
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the terms of the GNU General Public License as published by the Free
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Software Foundation; either version 3, or (at your option) any later
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version.
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GCC is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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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 GCC_TREE_SSA_SCOPED_TABLES_H
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#define GCC_TREE_SSA_SCOPED_TABLES_H
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/* Representation of a "naked" right-hand-side expression, to be used
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in recording available expressions in the expression hash table. */
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enum expr_kind
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{
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EXPR_SINGLE,
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EXPR_UNARY,
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EXPR_BINARY,
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EXPR_TERNARY,
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EXPR_CALL,
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EXPR_PHI
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};
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struct hashable_expr
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{
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tree type;
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enum expr_kind kind;
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union {
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struct { tree rhs; } single;
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struct { enum tree_code op; tree opnd; } unary;
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struct { enum tree_code op; tree opnd0, opnd1; } binary;
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struct { enum tree_code op; tree opnd0, opnd1, opnd2; } ternary;
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struct { gcall *fn_from; bool pure; size_t nargs; tree *args; } call;
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struct { size_t nargs; tree *args; } phi;
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} ops;
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};
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/* Structure for recording known value of a conditional expression.
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Clients build vectors of these objects to record known values
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that occur on edges. */
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struct cond_equivalence
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{
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/* The condition, in a HASHABLE_EXPR form. */
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struct hashable_expr cond;
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/* The result of the condition (true or false. */
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tree value;
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};
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/* Structure for entries in the expression hash table. */
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typedef class expr_hash_elt * expr_hash_elt_t;
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class expr_hash_elt
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{
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public:
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expr_hash_elt (gimple *, tree);
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expr_hash_elt (tree);
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expr_hash_elt (struct hashable_expr *, tree);
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expr_hash_elt (class expr_hash_elt &);
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~expr_hash_elt ();
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void print (FILE *);
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tree vop (void) { return m_vop; }
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tree lhs (void) { return m_lhs; }
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struct hashable_expr *expr (void) { return &m_expr; }
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expr_hash_elt *stamp (void) { return m_stamp; }
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hashval_t hash (void) { return m_hash; }
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private:
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/* The expression (rhs) we want to record. */
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struct hashable_expr m_expr;
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/* The value (lhs) of this expression. */
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tree m_lhs;
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/* The virtual operand associated with the nearest dominating stmt
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loading from or storing to expr. */
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tree m_vop;
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/* The hash value for RHS. */
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hashval_t m_hash;
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/* A unique stamp, typically the address of the hash
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element itself, used in removing entries from the table. */
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struct expr_hash_elt *m_stamp;
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/* We should never be making assignments between objects in this class.
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Though it might allow us to exploit C++11 move semantics if we
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defined the move constructor and move assignment operator. */
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expr_hash_elt& operator= (const expr_hash_elt&);
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};
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/* Hashtable helpers. */
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struct expr_elt_hasher : pointer_hash <expr_hash_elt>
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{
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static inline hashval_t hash (const value_type &p)
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{ return p->hash (); }
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static bool equal (const value_type &, const compare_type &);
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static inline void remove (value_type &element)
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{ delete element; }
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};
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/* This class defines a unwindable expression equivalence table
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layered on top of the expression hash table.
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Essentially it's just a stack of available expression value pairs with
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a special marker (NULL, NULL) to indicate unwind points. */
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class avail_exprs_stack
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{
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public:
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/* We need access to the AVAIL_EXPR hash table so that we can
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remove entries from the hash table when unwinding the stack. */
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avail_exprs_stack (hash_table<expr_elt_hasher> *table)
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{ m_stack.create (20); m_avail_exprs = table; }
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~avail_exprs_stack (void) { m_stack.release (); }
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/* Push the unwinding marker onto the stack. */
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void push_marker (void) { record_expr (NULL, NULL, 'M'); }
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/* Restore the AVAIL_EXPRs table to its state when the last marker
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was pushed. */
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void pop_to_marker (void);
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/* Record a single available expression that can be unwound. */
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void record_expr (expr_hash_elt_t, expr_hash_elt_t, char);
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/* Get the underlying hash table. Would this be better as
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class inheritance? */
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hash_table<expr_elt_hasher> *avail_exprs (void)
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{ return m_avail_exprs; }
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/* Lookup and conditionally insert an expression into the table,
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recording enough information to unwind as needed. */
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tree lookup_avail_expr (gimple *, bool, bool);
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void record_cond (cond_equivalence *);
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private:
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vec<std::pair<expr_hash_elt_t, expr_hash_elt_t> > m_stack;
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hash_table<expr_elt_hasher> *m_avail_exprs;
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/* For some assignments where the RHS is a binary operator, if we know
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a equality relationship between the operands, we may be able to compute
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a result, even if we don't know the exact value of the operands. */
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tree simplify_binary_operation (gimple *, class expr_hash_elt);
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/* We do not allow copying this object or initializing one
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from another. */
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avail_exprs_stack& operator= (const avail_exprs_stack&);
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avail_exprs_stack (class avail_exprs_stack &);
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};
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/* This class defines an unwindable const/copy equivalence table
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layered on top of SSA_NAME_VALUE/set_ssa_name_value.
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Essentially it's just a stack of name,prev value pairs with a
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special marker (NULL) to indicate unwind points. */
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class const_and_copies
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{
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public:
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const_and_copies (void) { m_stack.create (20); };
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~const_and_copies (void) { m_stack.release (); }
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/* Push the unwinding marker onto the stack. */
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void push_marker (void) { m_stack.safe_push (NULL_TREE); }
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/* Restore the const/copies table to its state when the last marker
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was pushed. */
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void pop_to_marker (void);
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/* Record a single const/copy pair that can be unwound. This version
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may follow the value chain for the RHS. */
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void record_const_or_copy (tree, tree);
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/* Special entry point when we want to provide an explicit previous
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value for the first argument. Try to get rid of this in the future.
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This version may also follow the value chain for the RHS. */
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void record_const_or_copy (tree, tree, tree);
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private:
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/* Record a single const/copy pair that can be unwound. This version
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does not follow the value chain for the RHS. */
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void record_const_or_copy_raw (tree, tree, tree);
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vec<tree> m_stack;
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const_and_copies& operator= (const const_and_copies&);
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const_and_copies (class const_and_copies &);
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};
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void initialize_expr_from_cond (tree cond, struct hashable_expr *expr);
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void record_conditions (vec<cond_equivalence> *p, tree, tree);
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#endif /* GCC_TREE_SSA_SCOPED_TABLES_H */
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