-/* Forward propagation of single use variables.
- Copyright (C) 2004, 2005 Free Software Foundation, Inc.
+/* Forward propagation of expressions for single use variables.
+ Copyright (C) 2004, 2005, 2007, 2008 Free Software Foundation, Inc.
This file is part of GCC.
GCC is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2, or (at your option)
+the Free Software Foundation; either version 3, or (at your option)
any later version.
GCC is distributed in the hope that it will be useful,
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
-along with GCC; see the file COPYING. If not, write to
-the Free Software Foundation, 59 Temple Place - Suite 330,
-Boston, MA 02111-1307, USA. */
+along with GCC; see the file COPYING3. If not see
+<http://www.gnu.org/licenses/>. */
#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tm.h"
-#include "errors.h"
#include "ggc.h"
#include "tree.h"
#include "rtl.h"
#include "tree-flow.h"
#include "tree-pass.h"
#include "tree-dump.h"
+#include "langhooks.h"
+#include "flags.h"
+#include "gimple.h"
-/* This pass performs simple forward propagation of single use variables
- from their definition site into their single use site.
+/* This pass propagates the RHS of assignment statements into use
+ sites of the LHS of the assignment. It's basically a specialized
+ form of tree combination. It is hoped all of this can disappear
+ when we have a generalized tree combiner.
- Right now we only bother forward propagating into COND_EXPRs since those
- are relatively common cases where forward propagation creates valid
- gimple code without the expression needing to fold. i.e.
+ One class of common cases we handle is forward propagating a single use
+ variable into a COND_EXPR.
bb0:
x = a COND b;
a statement, we put it back on the worklist to examine on the next
iteration of the main loop.
+ A second class of propagation opportunities arises for ADDR_EXPR
+ nodes.
+
+ ptr = &x->y->z;
+ res = *ptr;
+
+ Will get turned into
+
+ res = x->y->z;
+
+ Or
+ ptr = (type1*)&type2var;
+ res = *ptr
+
+ Will get turned into (if type1 and type2 are the same size
+ and neither have volatile on them):
+ res = VIEW_CONVERT_EXPR<type1>(type2var)
+
+ Or
+
+ ptr = &x[0];
+ ptr2 = ptr + <constant>;
+
+ Will get turned into
+
+ ptr2 = &x[constant/elementsize];
+
+ Or
+
+ ptr = &x[0];
+ offset = index * element_size;
+ offset_p = (pointer) offset;
+ ptr2 = ptr + offset_p
+
+ Will get turned into:
+
+ ptr2 = &x[index];
+
+ We also propagate casts into SWITCH_EXPR and COND_EXPR conditions to
+ allow us to remove the cast and {NOT_EXPR,NEG_EXPR} into a subsequent
+ {NOT_EXPR,NEG_EXPR}.
+
This will (of course) be extended as other needs arise. */
-/* Given an SSA_NAME VAR, return true if and only if VAR is defined by
- a comparison. */
+static bool forward_propagate_addr_expr (tree name, tree rhs);
-static bool
-ssa_name_defined_by_comparison_p (tree var)
+/* Set to true if we delete EH edges during the optimization. */
+static bool cfg_changed;
+
+static tree rhs_to_tree (tree type, gimple stmt);
+
+/* Get the next statement we can propagate NAME's value into skipping
+ trivial copies. Returns the statement that is suitable as a
+ propagation destination or NULL_TREE if there is no such one.
+ This only returns destinations in a single-use chain. FINAL_NAME_P
+ if non-NULL is written to the ssa name that represents the use. */
+
+static gimple
+get_prop_dest_stmt (tree name, tree *final_name_p)
{
- tree def = SSA_NAME_DEF_STMT (var);
+ use_operand_p use;
+ gimple use_stmt;
+
+ do {
+ /* If name has multiple uses, bail out. */
+ if (!single_imm_use (name, &use, &use_stmt))
+ return NULL;
+
+ /* If this is not a trivial copy, we found it. */
+ if (!gimple_assign_copy_p (use_stmt)
+ || TREE_CODE (gimple_assign_lhs (use_stmt)) != SSA_NAME
+ || gimple_assign_rhs1 (use_stmt) != name)
+ break;
- if (TREE_CODE (def) == MODIFY_EXPR)
+ /* Continue searching uses of the copy destination. */
+ name = gimple_assign_lhs (use_stmt);
+ } while (1);
+
+ if (final_name_p)
+ *final_name_p = name;
+
+ return use_stmt;
+}
+
+/* Get the statement we can propagate from into NAME skipping
+ trivial copies. Returns the statement which defines the
+ propagation source or NULL_TREE if there is no such one.
+ If SINGLE_USE_ONLY is set considers only sources which have
+ a single use chain up to NAME. If SINGLE_USE_P is non-null,
+ it is set to whether the chain to NAME is a single use chain
+ or not. SINGLE_USE_P is not written to if SINGLE_USE_ONLY is set. */
+
+static gimple
+get_prop_source_stmt (tree name, bool single_use_only, bool *single_use_p)
+{
+ bool single_use = true;
+
+ do {
+ gimple def_stmt = SSA_NAME_DEF_STMT (name);
+
+ if (!has_single_use (name))
+ {
+ single_use = false;
+ if (single_use_only)
+ return NULL;
+ }
+
+ /* If name is defined by a PHI node or is the default def, bail out. */
+ if (gimple_code (def_stmt) != GIMPLE_ASSIGN)
+ return NULL;
+
+ /* If name is not a simple copy destination, we found it. */
+ if (!gimple_assign_copy_p (def_stmt)
+ || TREE_CODE (gimple_assign_rhs1 (def_stmt)) != SSA_NAME)
+ {
+ tree rhs;
+
+ if (!single_use_only && single_use_p)
+ *single_use_p = single_use;
+
+ /* We can look through pointer conversions in the search
+ for a useful stmt for the comparison folding. */
+ rhs = gimple_assign_rhs1 (def_stmt);
+ if (CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (def_stmt))
+ && TREE_CODE (rhs) == SSA_NAME
+ && POINTER_TYPE_P (TREE_TYPE (gimple_assign_lhs (def_stmt)))
+ && POINTER_TYPE_P (TREE_TYPE (rhs)))
+ name = rhs;
+ else
+ return def_stmt;
+ }
+ else
+ {
+ /* Continue searching the def of the copy source name. */
+ name = gimple_assign_rhs1 (def_stmt);
+ }
+ } while (1);
+}
+
+/* Checks if the destination ssa name in DEF_STMT can be used as
+ propagation source. Returns true if so, otherwise false. */
+
+static bool
+can_propagate_from (gimple def_stmt)
+{
+ use_operand_p use_p;
+ ssa_op_iter iter;
+
+ gcc_assert (is_gimple_assign (def_stmt));
+ /* If the rhs has side-effects we cannot propagate from it. */
+ if (gimple_has_volatile_ops (def_stmt))
+ return false;
+
+ /* If the rhs is a load we cannot propagate from it. */
+ if (TREE_CODE_CLASS (gimple_assign_rhs_code (def_stmt)) == tcc_reference
+ || TREE_CODE_CLASS (gimple_assign_rhs_code (def_stmt)) == tcc_declaration)
+ return false;
+
+ /* Constants can be always propagated. */
+ if (is_gimple_min_invariant
+ (rhs_to_tree (TREE_TYPE (gimple_assign_lhs (def_stmt)), def_stmt)))
+ return true;
+
+ /* We cannot propagate ssa names that occur in abnormal phi nodes. */
+ FOR_EACH_SSA_USE_OPERAND (use_p, def_stmt, iter, SSA_OP_USE)
+ if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (USE_FROM_PTR (use_p)))
+ return false;
+
+ /* If the definition is a conversion of a pointer to a function type,
+ then we can not apply optimizations as some targets require
+ function pointers to be canonicalized and in this case this
+ optimization could eliminate a necessary canonicalization. */
+ if (is_gimple_assign (def_stmt)
+ && (CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (def_stmt))))
{
- tree rhs = TREE_OPERAND (def, 1);
- return COMPARISON_CLASS_P (rhs);
+ tree rhs = gimple_assign_rhs1 (def_stmt);
+ if (POINTER_TYPE_P (TREE_TYPE (rhs))
+ && TREE_CODE (TREE_TYPE (TREE_TYPE (rhs))) == FUNCTION_TYPE)
+ return false;
}
+ return true;
+}
+
+/* Remove a copy chain ending in NAME along the defs but not
+ further or including UP_TO_STMT. If NAME was replaced in
+ its only use then this function can be used to clean up
+ dead stmts. Returns true if UP_TO_STMT can be removed
+ as well, otherwise false. */
+
+static bool
+remove_prop_source_from_use (tree name, gimple up_to_stmt)
+{
+ gimple_stmt_iterator gsi;
+ gimple stmt;
+
+ do {
+ if (!has_zero_uses (name))
+ return false;
+
+ stmt = SSA_NAME_DEF_STMT (name);
+ if (stmt == up_to_stmt)
+ return true;
+
+ gsi = gsi_for_stmt (stmt);
+ release_defs (stmt);
+ gsi_remove (&gsi, true);
+
+ name = (gimple_assign_copy_p (stmt)) ? gimple_assign_rhs1 (stmt) : NULL;
+ } while (name && TREE_CODE (name) == SSA_NAME);
+
+ return false;
+}
- return 0;
+/* Return the rhs of a gimple_assign STMT in a form of a single tree,
+ converted to type TYPE.
+
+ This should disappear, but is needed so we can combine expressions and use
+ the fold() interfaces. Long term, we need to develop folding and combine
+ routines that deal with gimple exclusively . */
+
+static tree
+rhs_to_tree (tree type, gimple stmt)
+{
+ enum tree_code code = gimple_assign_rhs_code (stmt);
+ if (get_gimple_rhs_class (code) == GIMPLE_BINARY_RHS)
+ return fold_build2 (code, type, gimple_assign_rhs1 (stmt),
+ gimple_assign_rhs2 (stmt));
+ else if (get_gimple_rhs_class (code) == GIMPLE_UNARY_RHS)
+ return build1 (code, type, gimple_assign_rhs1 (stmt));
+ else if (get_gimple_rhs_class (code) == GIMPLE_SINGLE_RHS)
+ return gimple_assign_rhs1 (stmt);
+ else
+ gcc_unreachable ();
}
-/* Forward propagate a single-use variable into COND once. Return a
- new condition if successful. Return NULL_TREE otherwise. */
+/* Combine OP0 CODE OP1 in the context of a COND_EXPR. Returns
+ the folded result in a form suitable for COND_EXPR_COND or
+ NULL_TREE, if there is no suitable simplified form. If
+ INVARIANT_ONLY is true only gimple_min_invariant results are
+ considered simplified. */
static tree
-forward_propagate_into_cond_1 (tree cond, tree *test_var_p)
+combine_cond_expr_cond (enum tree_code code, tree type,
+ tree op0, tree op1, bool invariant_only)
{
- tree new_cond = NULL_TREE;
- enum tree_code cond_code = TREE_CODE (cond);
- tree test_var = NULL_TREE;
- tree def;
- tree def_rhs;
-
- /* If the condition is not a lone variable or an equality test of an
- SSA_NAME against an integral constant, then we do not have an
- optimizable case.
-
- Note these conditions also ensure the COND_EXPR has no
- virtual operands or other side effects. */
- if (cond_code != SSA_NAME
- && !((cond_code == EQ_EXPR || cond_code == NE_EXPR)
- && TREE_CODE (TREE_OPERAND (cond, 0)) == SSA_NAME
- && CONSTANT_CLASS_P (TREE_OPERAND (cond, 1))
- && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (cond, 1)))))
+ tree t;
+
+ gcc_assert (TREE_CODE_CLASS (code) == tcc_comparison);
+
+ t = fold_binary (code, type, op0, op1);
+ if (!t)
return NULL_TREE;
- /* Extract the single variable used in the test into TEST_VAR. */
- if (cond_code == SSA_NAME)
- test_var = cond;
- else
- test_var = TREE_OPERAND (cond, 0);
+ /* Require that we got a boolean type out if we put one in. */
+ gcc_assert (TREE_CODE (TREE_TYPE (t)) == TREE_CODE (type));
+
+ /* Canonicalize the combined condition for use in a COND_EXPR. */
+ t = canonicalize_cond_expr_cond (t);
- /* Now get the defining statement for TEST_VAR. Skip this case if
- it's not defined by some MODIFY_EXPR. */
- def = SSA_NAME_DEF_STMT (test_var);
- if (TREE_CODE (def) != MODIFY_EXPR)
+ /* Bail out if we required an invariant but didn't get one. */
+ if (!t || (invariant_only && !is_gimple_min_invariant (t)))
return NULL_TREE;
- def_rhs = TREE_OPERAND (def, 1);
+ return t;
+}
+
+/* Propagate from the ssa name definition statements of COND_EXPR
+ in GIMPLE_COND statement STMT into the conditional if that simplifies it.
+ Returns zero if no statement was changed, one if there were
+ changes and two if cfg_cleanup needs to run.
+
+ This must be kept in sync with forward_propagate_into_cond. */
+
+static int
+forward_propagate_into_gimple_cond (gimple stmt)
+{
+ int did_something = 0;
+
+ do {
+ tree tmp = NULL_TREE;
+ tree name, rhs0 = NULL_TREE, rhs1 = NULL_TREE;
+ gimple def_stmt;
+ bool single_use0_p = false, single_use1_p = false;
+ enum tree_code code = gimple_cond_code (stmt);
+
+ /* We can do tree combining on SSA_NAME and comparison expressions. */
+ if (TREE_CODE_CLASS (gimple_cond_code (stmt)) == tcc_comparison
+ && TREE_CODE (gimple_cond_lhs (stmt)) == SSA_NAME)
+ {
+ /* For comparisons use the first operand, that is likely to
+ simplify comparisons against constants. */
+ name = gimple_cond_lhs (stmt);
+ def_stmt = get_prop_source_stmt (name, false, &single_use0_p);
+ if (def_stmt && can_propagate_from (def_stmt))
+ {
+ tree op1 = gimple_cond_rhs (stmt);
+ rhs0 = rhs_to_tree (TREE_TYPE (op1), def_stmt);
+ tmp = combine_cond_expr_cond (code, boolean_type_node, rhs0,
+ op1, !single_use0_p);
+ }
+ /* If that wasn't successful, try the second operand. */
+ if (tmp == NULL_TREE
+ && TREE_CODE (gimple_cond_rhs (stmt)) == SSA_NAME)
+ {
+ tree op0 = gimple_cond_lhs (stmt);
+ name = gimple_cond_rhs (stmt);
+ def_stmt = get_prop_source_stmt (name, false, &single_use1_p);
+ if (!def_stmt || !can_propagate_from (def_stmt))
+ return did_something;
+
+ rhs1 = rhs_to_tree (TREE_TYPE (op0), def_stmt);
+ tmp = combine_cond_expr_cond (code, boolean_type_node, op0, rhs1,
+ !single_use1_p);
+ }
+ /* If that wasn't successful either, try both operands. */
+ if (tmp == NULL_TREE
+ && rhs0 != NULL_TREE
+ && rhs1 != NULL_TREE)
+ tmp = combine_cond_expr_cond (code, boolean_type_node, rhs0,
+ fold_convert (TREE_TYPE (rhs0), rhs1),
+ !(single_use0_p && single_use1_p));
+ }
+
+ if (tmp)
+ {
+ if (dump_file && tmp)
+ {
+ tree cond = build2 (gimple_cond_code (stmt),
+ boolean_type_node,
+ gimple_cond_lhs (stmt),
+ gimple_cond_rhs (stmt));
+ fprintf (dump_file, " Replaced '");
+ print_generic_expr (dump_file, cond, 0);
+ fprintf (dump_file, "' with '");
+ print_generic_expr (dump_file, tmp, 0);
+ fprintf (dump_file, "'\n");
+ }
+
+ gimple_cond_set_condition_from_tree (stmt, unshare_expr (tmp));
+ update_stmt (stmt);
+
+ /* Remove defining statements. */
+ remove_prop_source_from_use (name, NULL);
+
+ if (is_gimple_min_invariant (tmp))
+ did_something = 2;
+ else if (did_something == 0)
+ did_something = 1;
+
+ /* Continue combining. */
+ continue;
+ }
+
+ break;
+ } while (1);
+
+ return did_something;
+}
+
+
+/* Propagate from the ssa name definition statements of COND_EXPR
+ in the rhs of statement STMT into the conditional if that simplifies it.
+ Returns zero if no statement was changed, one if there were
+ changes and two if cfg_cleanup needs to run.
+
+ This must be kept in sync with forward_propagate_into_gimple_cond. */
+
+static int
+forward_propagate_into_cond (gimple_stmt_iterator *gsi_p)
+{
+ gimple stmt = gsi_stmt (*gsi_p);
+ int did_something = 0;
+
+ do {
+ tree tmp = NULL_TREE;
+ tree cond = gimple_assign_rhs1 (stmt);
+ tree name, rhs0 = NULL_TREE, rhs1 = NULL_TREE;
+ gimple def_stmt;
+ bool single_use0_p = false, single_use1_p = false;
+
+ /* We can do tree combining on SSA_NAME and comparison expressions. */
+ if (COMPARISON_CLASS_P (cond)
+ && TREE_CODE (TREE_OPERAND (cond, 0)) == SSA_NAME)
+ {
+ /* For comparisons use the first operand, that is likely to
+ simplify comparisons against constants. */
+ name = TREE_OPERAND (cond, 0);
+ def_stmt = get_prop_source_stmt (name, false, &single_use0_p);
+ if (def_stmt && can_propagate_from (def_stmt))
+ {
+ tree op1 = TREE_OPERAND (cond, 1);
+ rhs0 = rhs_to_tree (TREE_TYPE (op1), def_stmt);
+ tmp = combine_cond_expr_cond (TREE_CODE (cond), boolean_type_node,
+ rhs0, op1, !single_use0_p);
+ }
+ /* If that wasn't successful, try the second operand. */
+ if (tmp == NULL_TREE
+ && TREE_CODE (TREE_OPERAND (cond, 1)) == SSA_NAME)
+ {
+ tree op0 = TREE_OPERAND (cond, 0);
+ name = TREE_OPERAND (cond, 1);
+ def_stmt = get_prop_source_stmt (name, false, &single_use1_p);
+ if (!def_stmt || !can_propagate_from (def_stmt))
+ return did_something;
+
+ rhs1 = rhs_to_tree (TREE_TYPE (op0), def_stmt);
+ tmp = combine_cond_expr_cond (TREE_CODE (cond), boolean_type_node,
+ op0, rhs1, !single_use1_p);
+ }
+ /* If that wasn't successful either, try both operands. */
+ if (tmp == NULL_TREE
+ && rhs0 != NULL_TREE
+ && rhs1 != NULL_TREE)
+ tmp = combine_cond_expr_cond (TREE_CODE (cond), boolean_type_node,
+ rhs0, fold_convert (TREE_TYPE (rhs0),
+ rhs1),
+ !(single_use0_p && single_use1_p));
+ }
+ else if (TREE_CODE (cond) == SSA_NAME)
+ {
+ name = cond;
+ def_stmt = get_prop_source_stmt (name, true, NULL);
+ if (def_stmt || !can_propagate_from (def_stmt))
+ return did_something;
+
+ rhs0 = gimple_assign_rhs1 (def_stmt);
+ tmp = combine_cond_expr_cond (NE_EXPR, boolean_type_node, rhs0,
+ build_int_cst (TREE_TYPE (rhs0), 0),
+ false);
+ }
+
+ if (tmp)
+ {
+ if (dump_file && tmp)
+ {
+ fprintf (dump_file, " Replaced '");
+ print_generic_expr (dump_file, cond, 0);
+ fprintf (dump_file, "' with '");
+ print_generic_expr (dump_file, tmp, 0);
+ fprintf (dump_file, "'\n");
+ }
+
+ gimple_assign_set_rhs_from_tree (gsi_p, unshare_expr (tmp));
+ stmt = gsi_stmt (*gsi_p);
+ update_stmt (stmt);
+
+ /* Remove defining statements. */
+ remove_prop_source_from_use (name, NULL);
+
+ if (is_gimple_min_invariant (tmp))
+ did_something = 2;
+ else if (did_something == 0)
+ did_something = 1;
+
+ /* Continue combining. */
+ continue;
+ }
+
+ break;
+ } while (1);
+
+ return did_something;
+}
+
+/* We've just substituted an ADDR_EXPR into stmt. Update all the
+ relevant data structures to match. */
+
+static void
+tidy_after_forward_propagate_addr (gimple stmt)
+{
+ /* We may have turned a trapping insn into a non-trapping insn. */
+ if (maybe_clean_or_replace_eh_stmt (stmt, stmt)
+ && gimple_purge_dead_eh_edges (gimple_bb (stmt)))
+ cfg_changed = true;
+
+ if (TREE_CODE (gimple_assign_rhs1 (stmt)) == ADDR_EXPR)
+ recompute_tree_invariant_for_addr_expr (gimple_assign_rhs1 (stmt));
+
+ mark_symbols_for_renaming (stmt);
+}
+
+/* DEF_RHS contains the address of the 0th element in an array.
+ USE_STMT uses type of DEF_RHS to compute the address of an
+ arbitrary element within the array. The (variable) byte offset
+ of the element is contained in OFFSET.
+
+ We walk back through the use-def chains of OFFSET to verify that
+ it is indeed computing the offset of an element within the array
+ and extract the index corresponding to the given byte offset.
+
+ We then try to fold the entire address expression into a form
+ &array[index].
+
+ If we are successful, we replace the right hand side of USE_STMT
+ with the new address computation. */
+
+static bool
+forward_propagate_addr_into_variable_array_index (tree offset,
+ tree def_rhs,
+ gimple_stmt_iterator *use_stmt_gsi)
+{
+ tree index;
+ gimple offset_def, use_stmt = gsi_stmt (*use_stmt_gsi);
+
+ /* Get the offset's defining statement. */
+ offset_def = SSA_NAME_DEF_STMT (offset);
+
+ /* Try to find an expression for a proper index. This is either a
+ multiplication expression by the element size or just the ssa name we came
+ along in case the element size is one. In that case, however, we do not
+ allow multiplications because they can be computing index to a higher
+ level dimension (PR 37861). */
+ if (integer_onep (TYPE_SIZE_UNIT (TREE_TYPE (TREE_TYPE (def_rhs)))))
+ {
+ if (is_gimple_assign (offset_def)
+ && gimple_assign_rhs_code (offset_def) == MULT_EXPR)
+ return false;
+
+ index = offset;
+ }
+ else
+ {
+ /* The statement which defines OFFSET before type conversion
+ must be a simple GIMPLE_ASSIGN. */
+ if (!is_gimple_assign (offset_def))
+ return false;
+
+ /* The RHS of the statement which defines OFFSET must be a
+ multiplication of an object by the size of the array elements.
+ This implicitly verifies that the size of the array elements
+ is constant. */
+ offset = gimple_assign_rhs1 (offset_def);
+ if (gimple_assign_rhs_code (offset_def) != MULT_EXPR
+ || TREE_CODE (gimple_assign_rhs2 (offset_def)) != INTEGER_CST
+ || !simple_cst_equal (gimple_assign_rhs2 (offset_def),
+ TYPE_SIZE_UNIT (TREE_TYPE (TREE_TYPE (def_rhs)))))
+ return false;
+
+ /* The first operand to the MULT_EXPR is the desired index. */
+ index = offset;
+ }
+
+ /* Replace the pointer addition with array indexing. */
+ gimple_assign_set_rhs_from_tree (use_stmt_gsi, unshare_expr (def_rhs));
+ use_stmt = gsi_stmt (*use_stmt_gsi);
+ TREE_OPERAND (TREE_OPERAND (gimple_assign_rhs1 (use_stmt), 0), 1)
+ = index;
+
+ /* That should have created gimple, so there is no need to
+ record information to undo the propagation. */
+ fold_stmt_inplace (use_stmt);
+ tidy_after_forward_propagate_addr (use_stmt);
+ return true;
+}
+
+/* NAME is a SSA_NAME representing DEF_RHS which is of the form
+ ADDR_EXPR <whatever>.
+
+ Try to forward propagate the ADDR_EXPR into the use USE_STMT.
+ Often this will allow for removal of an ADDR_EXPR and INDIRECT_REF
+ node or for recovery of array indexing from pointer arithmetic.
+
+ Return true if the propagation was successful (the propagation can
+ be not totally successful, yet things may have been changed). */
+
+static bool
+forward_propagate_addr_expr_1 (tree name, tree def_rhs,
+ gimple_stmt_iterator *use_stmt_gsi,
+ bool single_use_p)
+{
+ tree lhs, rhs, rhs2, array_ref;
+ tree *rhsp, *lhsp;
+ gimple use_stmt = gsi_stmt (*use_stmt_gsi);
+ enum tree_code rhs_code;
+
+ gcc_assert (TREE_CODE (def_rhs) == ADDR_EXPR);
+
+ lhs = gimple_assign_lhs (use_stmt);
+ rhs_code = gimple_assign_rhs_code (use_stmt);
+ rhs = gimple_assign_rhs1 (use_stmt);
+
+ /* Trivial cases. The use statement could be a trivial copy or a
+ useless conversion. Recurse to the uses of the lhs as copyprop does
+ not copy through different variant pointers and FRE does not catch
+ all useless conversions. Treat the case of a single-use name and
+ a conversion to def_rhs type separate, though. */
+ if (TREE_CODE (lhs) == SSA_NAME
+ && ((rhs_code == SSA_NAME && rhs == name)
+ || CONVERT_EXPR_CODE_P (rhs_code)))
+ {
+ /* Only recurse if we don't deal with a single use or we cannot
+ do the propagation to the current statement. In particular
+ we can end up with a conversion needed for a non-invariant
+ address which we cannot do in a single statement. */
+ if (!single_use_p
+ || (!useless_type_conversion_p (TREE_TYPE (lhs), TREE_TYPE (def_rhs))
+ && !is_gimple_min_invariant (def_rhs)))
+ return forward_propagate_addr_expr (lhs, def_rhs);
+
+ gimple_assign_set_rhs1 (use_stmt, unshare_expr (def_rhs));
+ if (useless_type_conversion_p (TREE_TYPE (lhs), TREE_TYPE (def_rhs)))
+ gimple_assign_set_rhs_code (use_stmt, TREE_CODE (def_rhs));
+ else
+ gimple_assign_set_rhs_code (use_stmt, NOP_EXPR);
+ return true;
+ }
+
+ /* Now strip away any outer COMPONENT_REF/ARRAY_REF nodes from the LHS.
+ ADDR_EXPR will not appear on the LHS. */
+ lhsp = gimple_assign_lhs_ptr (use_stmt);
+ while (handled_component_p (*lhsp))
+ lhsp = &TREE_OPERAND (*lhsp, 0);
+ lhs = *lhsp;
+
+ /* Now see if the LHS node is an INDIRECT_REF using NAME. If so,
+ propagate the ADDR_EXPR into the use of NAME and fold the result. */
+ if (TREE_CODE (lhs) == INDIRECT_REF
+ && TREE_OPERAND (lhs, 0) == name
+ && may_propagate_address_into_dereference (def_rhs, lhs)
+ && (lhsp != gimple_assign_lhs_ptr (use_stmt)
+ || useless_type_conversion_p (TREE_TYPE (TREE_OPERAND (def_rhs, 0)),
+ TREE_TYPE (rhs))))
+ {
+ *lhsp = unshare_expr (TREE_OPERAND (def_rhs, 0));
+ fold_stmt_inplace (use_stmt);
+ tidy_after_forward_propagate_addr (use_stmt);
- /* If TEST_VAR is set by adding or subtracting a constant
- from an SSA_NAME, then it is interesting to us as we
- can adjust the constant in the conditional and thus
- eliminate the arithmetic operation. */
- if (TREE_CODE (def_rhs) == PLUS_EXPR
- || TREE_CODE (def_rhs) == MINUS_EXPR)
+ /* Continue propagating into the RHS if this was not the only use. */
+ if (single_use_p)
+ return true;
+ }
+
+ /* Strip away any outer COMPONENT_REF, ARRAY_REF or ADDR_EXPR
+ nodes from the RHS. */
+ rhsp = gimple_assign_rhs1_ptr (use_stmt);
+ while (handled_component_p (*rhsp)
+ || TREE_CODE (*rhsp) == ADDR_EXPR)
+ rhsp = &TREE_OPERAND (*rhsp, 0);
+ rhs = *rhsp;
+
+ /* Now see if the RHS node is an INDIRECT_REF using NAME. If so,
+ propagate the ADDR_EXPR into the use of NAME and fold the result. */
+ if (TREE_CODE (rhs) == INDIRECT_REF
+ && TREE_OPERAND (rhs, 0) == name
+ && may_propagate_address_into_dereference (def_rhs, rhs))
+ {
+ *rhsp = unshare_expr (TREE_OPERAND (def_rhs, 0));
+ fold_stmt_inplace (use_stmt);
+ tidy_after_forward_propagate_addr (use_stmt);
+ return true;
+ }
+
+ /* Now see if the RHS node is an INDIRECT_REF using NAME. If so,
+ propagate the ADDR_EXPR into the use of NAME and try to
+ create a VCE and fold the result. */
+ if (TREE_CODE (rhs) == INDIRECT_REF
+ && TREE_OPERAND (rhs, 0) == name
+ && TYPE_SIZE (TREE_TYPE (rhs))
+ && TYPE_SIZE (TREE_TYPE (TREE_OPERAND (def_rhs, 0)))
+ /* Function decls should not be used for VCE either as it could be a
+ function descriptor that we want and not the actual function code. */
+ && TREE_CODE (TREE_OPERAND (def_rhs, 0)) != FUNCTION_DECL
+ /* We should not convert volatile loads to non volatile loads. */
+ && !TYPE_VOLATILE (TREE_TYPE (rhs))
+ && !TYPE_VOLATILE (TREE_TYPE (TREE_OPERAND (def_rhs, 0)))
+ && operand_equal_p (TYPE_SIZE (TREE_TYPE (rhs)),
+ TYPE_SIZE (TREE_TYPE (TREE_OPERAND (def_rhs, 0))), 0))
+ {
+ tree def_rhs_base, new_rhs = unshare_expr (TREE_OPERAND (def_rhs, 0));
+ new_rhs = fold_build1 (VIEW_CONVERT_EXPR, TREE_TYPE (rhs), new_rhs);
+ if (TREE_CODE (new_rhs) != VIEW_CONVERT_EXPR)
+ {
+ /* If we have folded the VIEW_CONVERT_EXPR then the result is only
+ valid if we can replace the whole rhs of the use statement. */
+ if (rhs != gimple_assign_rhs1 (use_stmt))
+ return false;
+ new_rhs = force_gimple_operand_gsi (use_stmt_gsi, new_rhs, true, NULL,
+ true, GSI_NEW_STMT);
+ gimple_assign_set_rhs1 (use_stmt, new_rhs);
+ tidy_after_forward_propagate_addr (use_stmt);
+ return true;
+ }
+ /* If the defining rhs comes from an indirect reference, then do not
+ convert into a VIEW_CONVERT_EXPR. */
+ def_rhs_base = TREE_OPERAND (def_rhs, 0);
+ while (handled_component_p (def_rhs_base))
+ def_rhs_base = TREE_OPERAND (def_rhs_base, 0);
+ if (!INDIRECT_REF_P (def_rhs_base))
+ {
+ /* We may have arbitrary VIEW_CONVERT_EXPRs in a nested component
+ reference. Place it there and fold the thing. */
+ *rhsp = new_rhs;
+ fold_stmt_inplace (use_stmt);
+ tidy_after_forward_propagate_addr (use_stmt);
+ return true;
+ }
+ }
+
+ /* If the use of the ADDR_EXPR is not a POINTER_PLUS_EXPR, there
+ is nothing to do. */
+ if (gimple_assign_rhs_code (use_stmt) != POINTER_PLUS_EXPR
+ || gimple_assign_rhs1 (use_stmt) != name)
+ return false;
+
+ /* The remaining cases are all for turning pointer arithmetic into
+ array indexing. They only apply when we have the address of
+ element zero in an array. If that is not the case then there
+ is nothing to do. */
+ array_ref = TREE_OPERAND (def_rhs, 0);
+ if (TREE_CODE (array_ref) != ARRAY_REF
+ || TREE_CODE (TREE_TYPE (TREE_OPERAND (array_ref, 0))) != ARRAY_TYPE
+ || !integer_zerop (TREE_OPERAND (array_ref, 1)))
+ return false;
+
+ rhs2 = gimple_assign_rhs2 (use_stmt);
+ /* Try to optimize &x[0] p+ C where C is a multiple of the size
+ of the elements in X into &x[C/element size]. */
+ if (TREE_CODE (rhs2) == INTEGER_CST)
{
- tree op0 = TREE_OPERAND (def_rhs, 0);
- tree op1 = TREE_OPERAND (def_rhs, 1);
-
- /* The first operand must be an SSA_NAME and the second
- operand must be a constant. */
- if (TREE_CODE (op0) != SSA_NAME
- || !CONSTANT_CLASS_P (op1)
- || !INTEGRAL_TYPE_P (TREE_TYPE (op1)))
- return NULL_TREE;
-
- /* Don't propagate if the first operand occurs in
- an abnormal PHI. */
- if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op0))
- return NULL_TREE;
-
- if (has_single_use (test_var))
+ tree new_rhs = maybe_fold_stmt_addition (gimple_expr_type (use_stmt),
+ array_ref, rhs2);
+ if (new_rhs)
{
- tree op0 = TREE_OPERAND (def_rhs, 0);
- tree op1 = TREE_OPERAND (def_rhs, 1);
- enum tree_code new_code;
- tree t;
-
- /* If the variable was defined via X + C, then we must
- subtract C from the constant in the conditional.
- Otherwise we add C to the constant in the
- conditional. The result must fold into a valid
- gimple operand to be optimizable. */
- new_code = (TREE_CODE (def_rhs) == PLUS_EXPR
- ? MINUS_EXPR : PLUS_EXPR);
- t = int_const_binop (new_code, TREE_OPERAND (cond, 1), op1, 0);
- if (!is_gimple_val (t))
- return NULL_TREE;
-
- new_cond = build (cond_code, boolean_type_node, op0, t);
+ gimple_assign_set_rhs_from_tree (use_stmt_gsi, new_rhs);
+ use_stmt = gsi_stmt (*use_stmt_gsi);
+ update_stmt (use_stmt);
+ tidy_after_forward_propagate_addr (use_stmt);
+ return true;
}
}
- /* These cases require comparisons of a naked SSA_NAME or
- comparison of an SSA_NAME against zero or one. */
- else if (TREE_CODE (cond) == SSA_NAME
- || integer_zerop (TREE_OPERAND (cond, 1))
- || integer_onep (TREE_OPERAND (cond, 1)))
+ /* Try to optimize &x[0] p+ OFFSET where OFFSET is defined by
+ converting a multiplication of an index by the size of the
+ array elements, then the result is converted into the proper
+ type for the arithmetic. */
+ if (TREE_CODE (rhs2) == SSA_NAME
+ && useless_type_conversion_p (TREE_TYPE (name), TREE_TYPE (def_rhs))
+ /* Avoid problems with IVopts creating PLUS_EXPRs with a
+ different type than their operands. */
+ && useless_type_conversion_p (TREE_TYPE (lhs), TREE_TYPE (def_rhs)))
+ return forward_propagate_addr_into_variable_array_index (rhs2, def_rhs,
+ use_stmt_gsi);
+ return false;
+}
+
+/* STMT is a statement of the form SSA_NAME = ADDR_EXPR <whatever>.
+
+ Try to forward propagate the ADDR_EXPR into all uses of the SSA_NAME.
+ Often this will allow for removal of an ADDR_EXPR and INDIRECT_REF
+ node or for recovery of array indexing from pointer arithmetic.
+ Returns true, if all uses have been propagated into. */
+
+static bool
+forward_propagate_addr_expr (tree name, tree rhs)
+{
+ int stmt_loop_depth = gimple_bb (SSA_NAME_DEF_STMT (name))->loop_depth;
+ imm_use_iterator iter;
+ gimple use_stmt;
+ bool all = true;
+ bool single_use_p = has_single_use (name);
+
+ FOR_EACH_IMM_USE_STMT (use_stmt, iter, name)
{
- /* If TEST_VAR is set from a relational operation
- between two SSA_NAMEs or a combination of an SSA_NAME
- and a constant, then it is interesting. */
- if (COMPARISON_CLASS_P (def_rhs))
+ bool result;
+ tree use_rhs;
+
+ /* If the use is not in a simple assignment statement, then
+ there is nothing we can do. */
+ if (gimple_code (use_stmt) != GIMPLE_ASSIGN)
{
- tree op0 = TREE_OPERAND (def_rhs, 0);
- tree op1 = TREE_OPERAND (def_rhs, 1);
-
- /* Both operands of DEF_RHS must be SSA_NAMEs or
- constants. */
- if ((TREE_CODE (op0) != SSA_NAME
- && !is_gimple_min_invariant (op0))
- || (TREE_CODE (op1) != SSA_NAME
- && !is_gimple_min_invariant (op1)))
- return NULL_TREE;
-
- /* Don't propagate if the first operand occurs in
- an abnormal PHI. */
- if (TREE_CODE (op0) == SSA_NAME
- && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op0))
- return NULL_TREE;
-
- /* Don't propagate if the second operand occurs in
- an abnormal PHI. */
- if (TREE_CODE (op1) == SSA_NAME
- && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op1))
- return NULL_TREE;
-
- if (has_single_use (test_var))
- {
- /* TEST_VAR was set from a relational operator. */
- tree op0 = TREE_OPERAND (def_rhs, 0);
- tree op1 = TREE_OPERAND (def_rhs, 1);
-
- new_cond = build (TREE_CODE (def_rhs),
- boolean_type_node, op0, op1);
-
- /* Invert the conditional if necessary. */
- if ((cond_code == EQ_EXPR
- && integer_zerop (TREE_OPERAND (cond, 1)))
- || (cond_code == NE_EXPR
- && integer_onep (TREE_OPERAND (cond, 1))))
- {
- new_cond = invert_truthvalue (new_cond);
-
- /* If we did not get a simple relational
- expression or bare SSA_NAME, then we can
- not optimize this case. */
- if (!COMPARISON_CLASS_P (new_cond)
- && TREE_CODE (new_cond) != SSA_NAME)
- new_cond = NULL_TREE;
- }
- }
+ all = false;
+ continue;
}
- /* If TEST_VAR is set from a TRUTH_NOT_EXPR, then it
- is interesting. */
- else if (TREE_CODE (def_rhs) == TRUTH_NOT_EXPR)
+ /* If the use is in a deeper loop nest, then we do not want
+ to propagate the ADDR_EXPR into the loop as that is likely
+ adding expression evaluations into the loop. */
+ if (gimple_bb (use_stmt)->loop_depth > stmt_loop_depth)
{
- enum tree_code new_code;
-
- def_rhs = TREE_OPERAND (def_rhs, 0);
-
- /* DEF_RHS must be an SSA_NAME or constant. */
- if (TREE_CODE (def_rhs) != SSA_NAME
- && !is_gimple_min_invariant (def_rhs))
- return NULL_TREE;
-
- /* Don't propagate if the operand occurs in
- an abnormal PHI. */
- if (TREE_CODE (def_rhs) == SSA_NAME
- && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (def_rhs))
- return NULL_TREE;
-
- if (cond_code == SSA_NAME
- || (cond_code == NE_EXPR
- && integer_zerop (TREE_OPERAND (cond, 1)))
- || (cond_code == EQ_EXPR
- && integer_onep (TREE_OPERAND (cond, 1))))
- new_code = EQ_EXPR;
- else
- new_code = NE_EXPR;
+ all = false;
+ continue;
+ }
- new_cond = build2 (new_code, boolean_type_node, def_rhs,
- fold_convert (TREE_TYPE (def_rhs),
- integer_zero_node));
+ push_stmt_changes (&use_stmt);
+
+ {
+ gimple_stmt_iterator gsi = gsi_for_stmt (use_stmt);
+ result = forward_propagate_addr_expr_1 (name, rhs, &gsi,
+ single_use_p);
+ use_stmt = gsi_stmt (gsi);
+ }
+ all &= result;
+
+ pop_stmt_changes (&use_stmt);
+
+ /* Remove intermediate now unused copy and conversion chains. */
+ use_rhs = gimple_assign_rhs1 (use_stmt);
+ if (result
+ && TREE_CODE (gimple_assign_lhs (use_stmt)) == SSA_NAME
+ && (TREE_CODE (use_rhs) == SSA_NAME
+ || (CONVERT_EXPR_P (use_rhs)
+ && TREE_CODE (TREE_OPERAND (use_rhs, 0)) == SSA_NAME)))
+ {
+ gimple_stmt_iterator gsi = gsi_for_stmt (use_stmt);
+ release_defs (use_stmt);
+ gsi_remove (&gsi, true);
}
+ }
+
+ return all;
+}
+
+/* Forward propagate the comparison defined in STMT like
+ cond_1 = x CMP y to uses of the form
+ a_1 = (T')cond_1
+ a_1 = !cond_1
+ a_1 = cond_1 != 0
+ Returns true if stmt is now unused. */
+
+static bool
+forward_propagate_comparison (gimple stmt)
+{
+ tree name = gimple_assign_lhs (stmt);
+ gimple use_stmt;
+ tree tmp = NULL_TREE;
+
+ /* Don't propagate ssa names that occur in abnormal phis. */
+ if ((TREE_CODE (gimple_assign_rhs1 (stmt)) == SSA_NAME
+ && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (gimple_assign_rhs1 (stmt)))
+ || (TREE_CODE (gimple_assign_rhs2 (stmt)) == SSA_NAME
+ && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (gimple_assign_rhs2 (stmt))))
+ return false;
+
+ /* Do not un-cse comparisons. But propagate through copies. */
+ use_stmt = get_prop_dest_stmt (name, &name);
+ if (!use_stmt)
+ return false;
+
+ /* Conversion of the condition result to another integral type. */
+ if (is_gimple_assign (use_stmt)
+ && (CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (use_stmt))
+ || TREE_CODE_CLASS (gimple_assign_rhs_code (use_stmt))
+ == tcc_comparison
+ || gimple_assign_rhs_code (use_stmt) == TRUTH_NOT_EXPR)
+ && INTEGRAL_TYPE_P (TREE_TYPE (gimple_assign_lhs (use_stmt))))
+ {
+ tree lhs = gimple_assign_lhs (use_stmt);
- /* If TEST_VAR was set from a cast of an integer type
- to a boolean type or a cast of a boolean to an
- integral, then it is interesting. */
- else if (TREE_CODE (def_rhs) == NOP_EXPR
- || TREE_CODE (def_rhs) == CONVERT_EXPR)
+ /* We can propagate the condition into a conversion. */
+ if (CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (use_stmt)))
{
- tree outer_type;
- tree inner_type;
-
- outer_type = TREE_TYPE (def_rhs);
- inner_type = TREE_TYPE (TREE_OPERAND (def_rhs, 0));
-
- if ((TREE_CODE (outer_type) == BOOLEAN_TYPE
- && INTEGRAL_TYPE_P (inner_type))
- || (TREE_CODE (inner_type) == BOOLEAN_TYPE
- && INTEGRAL_TYPE_P (outer_type)))
- ;
- else if (INTEGRAL_TYPE_P (outer_type)
- && INTEGRAL_TYPE_P (inner_type)
- && TREE_CODE (TREE_OPERAND (def_rhs, 0)) == SSA_NAME
- && ssa_name_defined_by_comparison_p (TREE_OPERAND (def_rhs,
- 0)))
- ;
- else
- return NULL_TREE;
+ /* Avoid using fold here as that may create a COND_EXPR with
+ non-boolean condition as canonical form. */
+ tmp = build2 (gimple_assign_rhs_code (stmt), TREE_TYPE (lhs),
+ gimple_assign_rhs1 (stmt), gimple_assign_rhs2 (stmt));
+ }
+ /* We can propagate the condition into X op CST where op
+ is EQ_EXPR or NE_EXPR and CST is either one or zero. */
+ else if (TREE_CODE_CLASS (gimple_assign_rhs_code (use_stmt))
+ == tcc_comparison
+ && TREE_CODE (gimple_assign_rhs1 (use_stmt)) == SSA_NAME
+ && TREE_CODE (gimple_assign_rhs2 (use_stmt)) == INTEGER_CST)
+ {
+ enum tree_code code = gimple_assign_rhs_code (use_stmt);
+ tree cst = gimple_assign_rhs2 (use_stmt);
+ tree cond;
+
+ cond = build2 (gimple_assign_rhs_code (stmt),
+ TREE_TYPE (cst),
+ gimple_assign_rhs1 (stmt),
+ gimple_assign_rhs2 (stmt));
+
+ tmp = combine_cond_expr_cond (code, TREE_TYPE (lhs), cond, cst, false);
+ if (tmp == NULL_TREE)
+ return false;
+ }
+ /* We can propagate the condition into a statement that
+ computes the logical negation of the comparison result. */
+ else if (gimple_assign_rhs_code (use_stmt) == TRUTH_NOT_EXPR)
+ {
+ tree type = TREE_TYPE (gimple_assign_rhs1 (stmt));
+ bool nans = HONOR_NANS (TYPE_MODE (type));
+ enum tree_code code;
+ code = invert_tree_comparison (gimple_assign_rhs_code (stmt), nans);
+ if (code == ERROR_MARK)
+ return false;
+
+ tmp = build2 (code, TREE_TYPE (lhs), gimple_assign_rhs1 (stmt),
+ gimple_assign_rhs2 (stmt));
+ }
+ else
+ return false;
- /* Don't propagate if the operand occurs in
- an abnormal PHI. */
- if (TREE_CODE (TREE_OPERAND (def_rhs, 0)) == SSA_NAME
- && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (TREE_OPERAND
- (def_rhs, 0)))
- return NULL_TREE;
+ {
+ gimple_stmt_iterator gsi = gsi_for_stmt (use_stmt);
+ gimple_assign_set_rhs_from_tree (&gsi, unshare_expr (tmp));
+ use_stmt = gsi_stmt (gsi);
+ update_stmt (use_stmt);
+ }
- if (has_single_use (test_var))
- {
- enum tree_code new_code;
- tree new_arg;
-
- if (cond_code == SSA_NAME
- || (cond_code == NE_EXPR
- && integer_zerop (TREE_OPERAND (cond, 1)))
- || (cond_code == EQ_EXPR
- && integer_onep (TREE_OPERAND (cond, 1))))
- new_code = NE_EXPR;
- else
- new_code = EQ_EXPR;
+ /* Remove defining statements. */
+ remove_prop_source_from_use (name, stmt);
- new_arg = TREE_OPERAND (def_rhs, 0);
- new_cond = build2 (new_code, boolean_type_node, new_arg,
- fold_convert (TREE_TYPE (new_arg),
- integer_zero_node));
- }
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ {
+ tree old_rhs = rhs_to_tree (TREE_TYPE (gimple_assign_lhs (stmt)),
+ stmt);
+ fprintf (dump_file, " Replaced '");
+ print_generic_expr (dump_file, old_rhs, dump_flags);
+ fprintf (dump_file, "' with '");
+ print_generic_expr (dump_file, tmp, dump_flags);
+ fprintf (dump_file, "'\n");
}
+
+ return true;
}
- *test_var_p = test_var;
- return new_cond;
+ return false;
}
-/* Forward propagate a single-use variable into COND_EXPR as many
- times as possible. */
+/* If we have lhs = ~x (STMT), look and see if earlier we had x = ~y.
+ If so, we can change STMT into lhs = y which can later be copy
+ propagated. Similarly for negation.
+
+ This could trivially be formulated as a forward propagation
+ to immediate uses. However, we already had an implementation
+ from DOM which used backward propagation via the use-def links.
+
+ It turns out that backward propagation is actually faster as
+ there's less work to do for each NOT/NEG expression we find.
+ Backwards propagation needs to look at the statement in a single
+ backlink. Forward propagation needs to look at potentially more
+ than one forward link. */
static void
-forward_propagate_into_cond (tree cond_expr)
+simplify_not_neg_expr (gimple_stmt_iterator *gsi_p)
{
- gcc_assert (TREE_CODE (cond_expr) == COND_EXPR);
+ gimple stmt = gsi_stmt (*gsi_p);
+ tree rhs = gimple_assign_rhs1 (stmt);
+ gimple rhs_def_stmt = SSA_NAME_DEF_STMT (rhs);
- while (1)
+ /* See if the RHS_DEF_STMT has the same form as our statement. */
+ if (is_gimple_assign (rhs_def_stmt)
+ && gimple_assign_rhs_code (rhs_def_stmt) == gimple_assign_rhs_code (stmt))
{
- tree test_var = NULL_TREE;
- tree cond = COND_EXPR_COND (cond_expr);
- tree new_cond = forward_propagate_into_cond_1 (cond, &test_var);
-
- /* Return if unsuccessful. */
- if (new_cond == NULL_TREE)
- break;
+ tree rhs_def_operand = gimple_assign_rhs1 (rhs_def_stmt);
- /* Dump details. */
- if (dump_file && (dump_flags & TDF_DETAILS))
+ /* Verify that RHS_DEF_OPERAND is a suitable SSA_NAME. */
+ if (TREE_CODE (rhs_def_operand) == SSA_NAME
+ && ! SSA_NAME_OCCURS_IN_ABNORMAL_PHI (rhs_def_operand))
{
- fprintf (dump_file, " Replaced '");
- print_generic_expr (dump_file, cond, dump_flags);
- fprintf (dump_file, "' with '");
- print_generic_expr (dump_file, new_cond, dump_flags);
- fprintf (dump_file, "'\n");
+ gimple_assign_set_rhs_from_tree (gsi_p, rhs_def_operand);
+ stmt = gsi_stmt (*gsi_p);
+ update_stmt (stmt);
}
+ }
+}
- COND_EXPR_COND (cond_expr) = new_cond;
- update_stmt (cond_expr);
+/* STMT is a SWITCH_EXPR for which we attempt to find equivalent forms of
+ the condition which we may be able to optimize better. */
- if (has_zero_uses (test_var))
+static void
+simplify_gimple_switch (gimple stmt)
+{
+ tree cond = gimple_switch_index (stmt);
+ tree def, to, ti;
+ gimple def_stmt;
+
+ /* The optimization that we really care about is removing unnecessary
+ casts. That will let us do much better in propagating the inferred
+ constant at the switch target. */
+ if (TREE_CODE (cond) == SSA_NAME)
+ {
+ def_stmt = SSA_NAME_DEF_STMT (cond);
+ if (is_gimple_assign (def_stmt))
{
- tree def = SSA_NAME_DEF_STMT (test_var);
- block_stmt_iterator bsi = bsi_for_stmt (def);
- bsi_remove (&bsi);
+ if (gimple_assign_rhs_code (def_stmt) == NOP_EXPR)
+ {
+ int need_precision;
+ bool fail;
+
+ def = gimple_assign_rhs1 (def_stmt);
+
+#ifdef ENABLE_CHECKING
+ /* ??? Why was Jeff testing this? We are gimple... */
+ gcc_assert (is_gimple_val (def));
+#endif
+
+ to = TREE_TYPE (cond);
+ ti = TREE_TYPE (def);
+
+ /* If we have an extension that preserves value, then we
+ can copy the source value into the switch. */
+
+ need_precision = TYPE_PRECISION (ti);
+ fail = false;
+ if (! INTEGRAL_TYPE_P (ti))
+ fail = true;
+ else if (TYPE_UNSIGNED (to) && !TYPE_UNSIGNED (ti))
+ fail = true;
+ else if (!TYPE_UNSIGNED (to) && TYPE_UNSIGNED (ti))
+ need_precision += 1;
+ if (TYPE_PRECISION (to) < need_precision)
+ fail = true;
+
+ if (!fail)
+ {
+ gimple_switch_set_index (stmt, def);
+ update_stmt (stmt);
+ }
+ }
}
}
}
/* Main entry point for the forward propagation optimizer. */
-static void
+static unsigned int
tree_ssa_forward_propagate_single_use_vars (void)
{
basic_block bb;
+ unsigned int todoflags = 0;
+
+ cfg_changed = false;
FOR_EACH_BB (bb)
{
- tree last = last_stmt (bb);
- if (last && TREE_CODE (last) == COND_EXPR)
- forward_propagate_into_cond (last);
+ gimple_stmt_iterator gsi;
+
+ /* Note we update GSI within the loop as necessary. */
+ for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); )
+ {
+ gimple stmt = gsi_stmt (gsi);
+
+ /* If this statement sets an SSA_NAME to an address,
+ try to propagate the address into the uses of the SSA_NAME. */
+ if (is_gimple_assign (stmt))
+ {
+ tree lhs = gimple_assign_lhs (stmt);
+ tree rhs = gimple_assign_rhs1 (stmt);
+
+ if (TREE_CODE (lhs) != SSA_NAME)
+ {
+ gsi_next (&gsi);
+ continue;
+ }
+
+ if (gimple_assign_rhs_code (stmt) == ADDR_EXPR
+ /* Handle pointer conversions on invariant addresses
+ as well, as this is valid gimple. */
+ || (CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (stmt))
+ && TREE_CODE (rhs) == ADDR_EXPR
+ && POINTER_TYPE_P (TREE_TYPE (lhs))))
+ {
+ STRIP_NOPS (rhs);
+ if (!stmt_references_abnormal_ssa_name (stmt)
+ && forward_propagate_addr_expr (lhs, rhs))
+ {
+ release_defs (stmt);
+ todoflags |= TODO_remove_unused_locals;
+ gsi_remove (&gsi, true);
+ }
+ else
+ gsi_next (&gsi);
+ }
+ else if ((gimple_assign_rhs_code (stmt) == BIT_NOT_EXPR
+ || gimple_assign_rhs_code (stmt) == NEGATE_EXPR)
+ && TREE_CODE (rhs) == SSA_NAME)
+ {
+ simplify_not_neg_expr (&gsi);
+ gsi_next (&gsi);
+ }
+ else if (gimple_assign_rhs_code (stmt) == COND_EXPR)
+ {
+ /* In this case the entire COND_EXPR is in rhs1. */
+ int did_something;
+ fold_defer_overflow_warnings ();
+ did_something = forward_propagate_into_cond (&gsi);
+ stmt = gsi_stmt (gsi);
+ if (did_something == 2)
+ cfg_changed = true;
+ fold_undefer_overflow_warnings (!TREE_NO_WARNING (rhs)
+ && did_something, stmt, WARN_STRICT_OVERFLOW_CONDITIONAL);
+ gsi_next (&gsi);
+ }
+ else if (TREE_CODE_CLASS (gimple_assign_rhs_code (stmt))
+ == tcc_comparison)
+ {
+ if (forward_propagate_comparison (stmt))
+ {
+ release_defs (stmt);
+ todoflags |= TODO_remove_unused_locals;
+ gsi_remove (&gsi, true);
+ }
+ else
+ gsi_next (&gsi);
+ }
+ else
+ gsi_next (&gsi);
+ }
+ else if (gimple_code (stmt) == GIMPLE_SWITCH)
+ {
+ simplify_gimple_switch (stmt);
+ gsi_next (&gsi);
+ }
+ else if (gimple_code (stmt) == GIMPLE_COND)
+ {
+ int did_something;
+ fold_defer_overflow_warnings ();
+ did_something = forward_propagate_into_gimple_cond (stmt);
+ if (did_something == 2)
+ cfg_changed = true;
+ fold_undefer_overflow_warnings (did_something, stmt,
+ WARN_STRICT_OVERFLOW_CONDITIONAL);
+ gsi_next (&gsi);
+ }
+ else
+ gsi_next (&gsi);
+ }
}
+
+ if (cfg_changed)
+ todoflags |= TODO_cleanup_cfg;
+ return todoflags;
}
return 1;
}
-struct tree_opt_pass pass_forwprop = {
+struct gimple_opt_pass pass_forwprop =
+{
+ {
+ GIMPLE_PASS,
"forwprop", /* name */
gate_forwprop, /* gate */
tree_ssa_forward_propagate_single_use_vars, /* execute */
NULL, /* next */
0, /* static_pass_number */
TV_TREE_FORWPROP, /* tv_id */
- PROP_cfg | PROP_ssa
- | PROP_alias, /* properties_required */
+ PROP_cfg | PROP_ssa, /* properties_required */
0, /* properties_provided */
0, /* properties_destroyed */
0, /* todo_flags_start */
- TODO_dump_func | TODO_ggc_collect /* todo_flags_finish */
- | TODO_verify_ssa,
- 0 /* letter */
+ TODO_dump_func
+ | TODO_ggc_collect
+ | TODO_update_ssa
+ | TODO_verify_ssa /* todo_flags_finish */
+ }
};
+
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