From 554fd8c5195424bdbcabf5de30fdc183aba391bd Mon Sep 17 00:00:00 2001 From: upstream source tree Date: Sun, 15 Mar 2015 20:14:05 -0400 Subject: obtained gcc-4.6.4.tar.bz2 from upstream website; verified gcc-4.6.4.tar.bz2.sig; imported gcc-4.6.4 source tree from verified upstream tarball. downloading a git-generated archive based on the 'upstream' tag should provide you with a source tree that is binary identical to the one extracted from the above tarball. if you have obtained the source via the command 'git clone', however, do note that line-endings of files in your working directory might differ from line-endings of the respective files in the upstream repository. --- gcc/tree-ssa-copyrename.c | 395 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 395 insertions(+) create mode 100644 gcc/tree-ssa-copyrename.c (limited to 'gcc/tree-ssa-copyrename.c') diff --git a/gcc/tree-ssa-copyrename.c b/gcc/tree-ssa-copyrename.c new file mode 100644 index 000000000..dfc0b4edb --- /dev/null +++ b/gcc/tree-ssa-copyrename.c @@ -0,0 +1,395 @@ +/* Rename SSA copies. + Copyright (C) 2004, 2006, 2007, 2008, 2009, 2010, 2011 + Free Software Foundation, Inc. + Contributed by Andrew MacLeod + +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 3, or (at your option) +any later version. + +GCC is distributed in the hope that it will be useful, +but WITHOUT ANY WARRANTY; without even the implied warranty of +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +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 COPYING3. If not see +. */ + +#include "config.h" +#include "system.h" +#include "coretypes.h" +#include "tm.h" +#include "tree.h" +#include "gimple.h" +#include "flags.h" +#include "basic-block.h" +#include "function.h" +#include "tree-pretty-print.h" +#include "bitmap.h" +#include "tree-flow.h" +#include "gimple.h" +#include "tree-inline.h" +#include "timevar.h" +#include "hashtab.h" +#include "tree-dump.h" +#include "tree-ssa-live.h" +#include "tree-pass.h" +#include "langhooks.h" + +/* The following routines implement the SSA copy renaming phase. + + This optimization looks for copies between 2 SSA_NAMES, either through a + direct copy, or an implicit one via a PHI node result and its arguments. + + Each copy is examined to determine if it is possible to rename the base + variable of one of the operands to the same variable as the other operand. + i.e. + T.3_5 = + a_1 = T.3_5 + + If this copy couldn't be copy propagated, it could possibly remain in the + program throughout the optimization phases. After SSA->normal, it would + become: + + T.3 = + a = T.3 + + Since T.3_5 is distinct from all other SSA versions of T.3, there is no + fundamental reason why the base variable needs to be T.3, subject to + certain restrictions. This optimization attempts to determine if we can + change the base variable on copies like this, and result in code such as: + + a_5 = + a_1 = a_5 + + This gives the SSA->normal pass a shot at coalescing a_1 and a_5. If it is + possible, the copy goes away completely. If it isn't possible, a new temp + will be created for a_5, and you will end up with the exact same code: + + a.8 = + a = a.8 + + The other benefit of performing this optimization relates to what variables + are chosen in copies. Gimplification of the program uses temporaries for + a lot of things. expressions like + + a_1 = + = a_1 + + get turned into + + T.3_5 = + a_1 = T.3_5 + = a_1 + + Copy propagation is done in a forward direction, and if we can propagate + through the copy, we end up with: + + T.3_5 = + = T.3_5 + + The copy is gone, but so is all reference to the user variable 'a'. By + performing this optimization, we would see the sequence: + + a_5 = + a_1 = a_5 + = a_1 + + which copy propagation would then turn into: + + a_5 = + = a_5 + + and so we still retain the user variable whenever possible. */ + + +/* Coalesce the partitions in MAP representing VAR1 and VAR2 if it is valid. + Choose a representative for the partition, and send debug info to DEBUG. */ + +static bool +copy_rename_partition_coalesce (var_map map, tree var1, tree var2, FILE *debug) +{ + int p1, p2, p3; + tree root1, root2; + tree rep1, rep2; + bool ign1, ign2, abnorm; + + gcc_assert (TREE_CODE (var1) == SSA_NAME); + gcc_assert (TREE_CODE (var2) == SSA_NAME); + + register_ssa_partition (map, var1); + register_ssa_partition (map, var2); + + p1 = partition_find (map->var_partition, SSA_NAME_VERSION (var1)); + p2 = partition_find (map->var_partition, SSA_NAME_VERSION (var2)); + + if (debug) + { + fprintf (debug, "Try : "); + print_generic_expr (debug, var1, TDF_SLIM); + fprintf (debug, "(P%d) & ", p1); + print_generic_expr (debug, var2, TDF_SLIM); + fprintf (debug, "(P%d)", p2); + } + + gcc_assert (p1 != NO_PARTITION); + gcc_assert (p2 != NO_PARTITION); + + rep1 = partition_to_var (map, p1); + rep2 = partition_to_var (map, p2); + root1 = SSA_NAME_VAR (rep1); + root2 = SSA_NAME_VAR (rep2); + + if (p1 == p2) + { + if (debug) + fprintf (debug, " : Already coalesced.\n"); + return false; + } + + /* Don't coalesce if one of the variables occurs in an abnormal PHI. */ + abnorm = (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (rep1) + || SSA_NAME_OCCURS_IN_ABNORMAL_PHI (rep2)); + if (abnorm) + { + if (debug) + fprintf (debug, " : Abnormal PHI barrier. No coalesce.\n"); + return false; + } + + /* Partitions already have the same root, simply merge them. */ + if (root1 == root2) + { + p1 = partition_union (map->var_partition, p1, p2); + if (debug) + fprintf (debug, " : Same root, coalesced --> P%d.\n", p1); + return false; + } + + /* Never attempt to coalesce 2 different parameters. */ + if (TREE_CODE (root1) == PARM_DECL && TREE_CODE (root2) == PARM_DECL) + { + if (debug) + fprintf (debug, " : 2 different PARM_DECLS. No coalesce.\n"); + return false; + } + + if ((TREE_CODE (root1) == RESULT_DECL) != (TREE_CODE (root2) == RESULT_DECL)) + { + if (debug) + fprintf (debug, " : One root a RESULT_DECL. No coalesce.\n"); + return false; + } + + ign1 = TREE_CODE (root1) == VAR_DECL && DECL_IGNORED_P (root1); + ign2 = TREE_CODE (root2) == VAR_DECL && DECL_IGNORED_P (root2); + + /* Never attempt to coalesce 2 user variables unless one is an inline + variable. */ + if (!ign1 && !ign2) + { + if (DECL_FROM_INLINE (root2)) + ign2 = true; + else if (DECL_FROM_INLINE (root1)) + ign1 = true; + else + { + if (debug) + fprintf (debug, " : 2 different USER vars. No coalesce.\n"); + return false; + } + } + + /* If both values have default defs, we can't coalesce. If only one has a + tag, make sure that variable is the new root partition. */ + if (gimple_default_def (cfun, root1)) + { + if (gimple_default_def (cfun, root2)) + { + if (debug) + fprintf (debug, " : 2 default defs. No coalesce.\n"); + return false; + } + else + { + ign2 = true; + ign1 = false; + } + } + else if (gimple_default_def (cfun, root2)) + { + ign1 = true; + ign2 = false; + } + + /* Don't coalesce if the new chosen root variable would be read-only. + If both ign1 && ign2, then the root var of the larger partition + wins, so reject in that case if any of the root vars is TREE_READONLY. + Otherwise reject only if the root var, on which replace_ssa_name_symbol + will be called below, is readonly. */ + if ((TREE_READONLY (root1) && ign2) || (TREE_READONLY (root2) && ign1)) + { + if (debug) + fprintf (debug, " : Readonly variable. No coalesce.\n"); + return false; + } + + /* Don't coalesce if the two variables aren't type compatible . */ + if (!types_compatible_p (TREE_TYPE (root1), TREE_TYPE (root2)) + /* There is a disconnect between the middle-end type-system and + VRP, avoid coalescing enum types with different bounds. */ + || ((TREE_CODE (TREE_TYPE (root1)) == ENUMERAL_TYPE + || TREE_CODE (TREE_TYPE (root2)) == ENUMERAL_TYPE) + && TREE_TYPE (root1) != TREE_TYPE (root2))) + { + if (debug) + fprintf (debug, " : Incompatible types. No coalesce.\n"); + return false; + } + + /* Merge the two partitions. */ + p3 = partition_union (map->var_partition, p1, p2); + + /* Set the root variable of the partition to the better choice, if there is + one. */ + if (!ign2) + replace_ssa_name_symbol (partition_to_var (map, p3), root2); + else if (!ign1) + replace_ssa_name_symbol (partition_to_var (map, p3), root1); + + if (debug) + { + fprintf (debug, " --> P%d ", p3); + print_generic_expr (debug, SSA_NAME_VAR (partition_to_var (map, p3)), + TDF_SLIM); + fprintf (debug, "\n"); + } + return true; +} + + +/* This function will make a pass through the IL, and attempt to coalesce any + SSA versions which occur in PHI's or copies. Coalescing is accomplished by + changing the underlying root variable of all coalesced version. This will + then cause the SSA->normal pass to attempt to coalesce them all to the same + variable. */ + +static unsigned int +rename_ssa_copies (void) +{ + var_map map; + basic_block bb; + gimple_stmt_iterator gsi; + tree var, part_var; + gimple stmt, phi; + unsigned x; + FILE *debug; + bool updated = false; + + if (dump_file && (dump_flags & TDF_DETAILS)) + debug = dump_file; + else + debug = NULL; + + map = init_var_map (num_ssa_names); + + FOR_EACH_BB (bb) + { + /* Scan for real copies. */ + for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi)) + { + stmt = gsi_stmt (gsi); + if (gimple_assign_ssa_name_copy_p (stmt)) + { + tree lhs = gimple_assign_lhs (stmt); + tree rhs = gimple_assign_rhs1 (stmt); + + updated |= copy_rename_partition_coalesce (map, lhs, rhs, debug); + } + } + } + + FOR_EACH_BB (bb) + { + /* Treat PHI nodes as copies between the result and each argument. */ + for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi)) + { + size_t i; + tree res; + + phi = gsi_stmt (gsi); + res = gimple_phi_result (phi); + + /* Do not process virtual SSA_NAMES. */ + if (!is_gimple_reg (SSA_NAME_VAR (res))) + continue; + + for (i = 0; i < gimple_phi_num_args (phi); i++) + { + tree arg = gimple_phi_arg (phi, i)->def; + if (TREE_CODE (arg) == SSA_NAME) + updated |= copy_rename_partition_coalesce (map, res, arg, debug); + } + } + } + + if (debug) + dump_var_map (debug, map); + + /* Now one more pass to make all elements of a partition share the same + root variable. */ + + for (x = 1; x < num_ssa_names; x++) + { + part_var = partition_to_var (map, x); + if (!part_var) + continue; + var = ssa_name (x); + if (debug) + { + if (SSA_NAME_VAR (var) != SSA_NAME_VAR (part_var)) + { + fprintf (debug, "Coalesced "); + print_generic_expr (debug, var, TDF_SLIM); + fprintf (debug, " to "); + print_generic_expr (debug, part_var, TDF_SLIM); + fprintf (debug, "\n"); + } + } + replace_ssa_name_symbol (var, SSA_NAME_VAR (part_var)); + } + + delete_var_map (map); + return updated ? TODO_remove_unused_locals : 0; +} + +/* Return true if copy rename is to be performed. */ + +static bool +gate_copyrename (void) +{ + return flag_tree_copyrename != 0; +} + +struct gimple_opt_pass pass_rename_ssa_copies = +{ + { + GIMPLE_PASS, + "copyrename", /* name */ + gate_copyrename, /* gate */ + rename_ssa_copies, /* execute */ + NULL, /* sub */ + NULL, /* next */ + 0, /* static_pass_number */ + TV_TREE_COPY_RENAME, /* tv_id */ + PROP_cfg | PROP_ssa, /* properties_required */ + 0, /* properties_provided */ + 0, /* properties_destroyed */ + 0, /* todo_flags_start */ + TODO_dump_func | TODO_verify_ssa /* todo_flags_finish */ + } +}; -- cgit v1.2.3