/* Dead code elimination pass for the GNU compiler.
- Copyright (C) 2002, 2003, 2004, 2005, 2006, 2007, 2008
- Free Software Foundation, Inc.
+ Copyright (C) 2002-2015 Free Software Foundation, Inc.
Contributed by Ben Elliston <bje@redhat.com>
and Andrew MacLeod <amacleod@redhat.com>
Adapted to use control dependence by Steven Bosscher, SUSE Labs.
-
+
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
<http://www.gnu.org/licenses/>. */
#include "system.h"
#include "coretypes.h"
#include "tm.h"
-#include "ggc.h"
-
-/* These RTL headers are needed for basic-block.h. */
-#include "rtl.h"
-#include "tm_p.h"
+#include "alias.h"
+#include "symtab.h"
+#include "tree.h"
+#include "fold-const.h"
+#include "calls.h"
+#include "gimple-pretty-print.h"
+#include "predict.h"
#include "hard-reg-set.h"
-#include "obstack.h"
+#include "function.h"
+#include "dominance.h"
+#include "cfg.h"
+#include "cfganal.h"
#include "basic-block.h"
-
-#include "tree.h"
-#include "diagnostic.h"
-#include "tree-flow.h"
+#include "tree-ssa-alias.h"
+#include "internal-fn.h"
+#include "tree-eh.h"
+#include "gimple-expr.h"
#include "gimple.h"
-#include "tree-dump.h"
-#include "tree-pass.h"
-#include "timevar.h"
+#include "gimplify.h"
+#include "gimple-iterator.h"
+#include "gimple-ssa.h"
+#include "tree-cfg.h"
+#include "tree-phinodes.h"
+#include "ssa-iterators.h"
+#include "stringpool.h"
+#include "tree-ssanames.h"
+#include "tree-ssa-loop-niter.h"
+#include "tree-into-ssa.h"
+#include "rtl.h"
#include "flags.h"
+#include "insn-config.h"
+#include "expmed.h"
+#include "dojump.h"
+#include "explow.h"
+#include "emit-rtl.h"
+#include "varasm.h"
+#include "stmt.h"
+#include "expr.h"
+#include "tree-dfa.h"
+#include "tree-pass.h"
#include "cfgloop.h"
#include "tree-scalar-evolution.h"
+#include "tree-chkp.h"
+#include "tree-ssa-propagate.h"
+#include "gimple-fold.h"
static struct stmt_stats
{
#define STMT_NECESSARY GF_PLF_1
-static VEC(gimple,heap) *worklist;
+static vec<gimple> worklist;
/* Vector indicating an SSA name has already been processed and marked
as necessary. */
static sbitmap processed;
-/* Vector indicating that last_stmt if a basic block has already been
- marked as necessary. */
+/* Vector indicating that the last statement of a basic block has already
+ been marked as necessary. */
static sbitmap last_stmt_necessary;
/* Vector indicating that BB contains statements that are live. */
use a bitmap for each block recording its edges. An array holds the
bitmap. The Ith bit in the bitmap is set if that block is dependent
on the Ith edge. */
-static bitmap *control_dependence_map;
+static control_dependences *cd;
/* Vector indicating that a basic block has already had all the edges
processed that it is control dependent on. */
to be recomputed. */
static bool cfg_altered;
-/* Execute code that follows the macro for each edge (given number
- EDGE_NUMBER within the CODE) for which the block with index N is
- control dependent. */
-#define EXECUTE_IF_CONTROL_DEPENDENT(BI, N, EDGE_NUMBER) \
- EXECUTE_IF_SET_IN_BITMAP (control_dependence_map[(N)], 0, \
- (EDGE_NUMBER), (BI))
-
-
-/* Indicate block BB is control dependent on an edge with index EDGE_INDEX. */
-static inline void
-set_control_dependence_map_bit (basic_block bb, int edge_index)
-{
- if (bb == ENTRY_BLOCK_PTR)
- return;
- gcc_assert (bb != EXIT_BLOCK_PTR);
- bitmap_set_bit (control_dependence_map[bb->index], edge_index);
-}
-
-/* Clear all control dependences for block BB. */
-static inline void
-clear_control_dependence_bitmap (basic_block bb)
-{
- bitmap_clear (control_dependence_map[bb->index]);
-}
-
-
-/* Find the immediate postdominator PDOM of the specified basic block BLOCK.
- This function is necessary because some blocks have negative numbers. */
-
-static inline basic_block
-find_pdom (basic_block block)
-{
- gcc_assert (block != ENTRY_BLOCK_PTR);
-
- if (block == EXIT_BLOCK_PTR)
- return EXIT_BLOCK_PTR;
- else
- {
- basic_block bb = get_immediate_dominator (CDI_POST_DOMINATORS, block);
- if (! bb)
- return EXIT_BLOCK_PTR;
- return bb;
- }
-}
-
-
-/* Determine all blocks' control dependences on the given edge with edge_list
- EL index EDGE_INDEX, ala Morgan, Section 3.6. */
-
-static void
-find_control_dependence (struct edge_list *el, int edge_index)
-{
- basic_block current_block;
- basic_block ending_block;
-
- gcc_assert (INDEX_EDGE_PRED_BB (el, edge_index) != EXIT_BLOCK_PTR);
-
- if (INDEX_EDGE_PRED_BB (el, edge_index) == ENTRY_BLOCK_PTR)
- ending_block = single_succ (ENTRY_BLOCK_PTR);
- else
- ending_block = find_pdom (INDEX_EDGE_PRED_BB (el, edge_index));
-
- for (current_block = INDEX_EDGE_SUCC_BB (el, edge_index);
- current_block != ending_block && current_block != EXIT_BLOCK_PTR;
- current_block = find_pdom (current_block))
- {
- edge e = INDEX_EDGE (el, edge_index);
-
- /* For abnormal edges, we don't make current_block control
- dependent because instructions that throw are always necessary
- anyway. */
- if (e->flags & EDGE_ABNORMAL)
- continue;
-
- set_control_dependence_map_bit (current_block, edge_index);
- }
-}
-
-
-/* Record all blocks' control dependences on all edges in the edge
- list EL, ala Morgan, Section 3.6. */
-
-static void
-find_all_control_dependences (struct edge_list *el)
-{
- int i;
-
- for (i = 0; i < NUM_EDGES (el); ++i)
- find_control_dependence (el, i);
-}
/* If STMT is not already marked necessary, mark it, and add it to the
worklist if ADD_TO_WORKLIST is true. */
+
static inline void
mark_stmt_necessary (gimple stmt, bool add_to_worklist)
{
gimple_set_plf (stmt, STMT_NECESSARY, true);
if (add_to_worklist)
- VEC_safe_push (gimple, heap, worklist, stmt);
- if (bb_contains_live_stmts)
- SET_BIT (bb_contains_live_stmts, gimple_bb (stmt)->index);
+ worklist.safe_push (stmt);
+ if (bb_contains_live_stmts && !is_gimple_debug (stmt))
+ bitmap_set_bit (bb_contains_live_stmts, gimple_bb (stmt)->index);
}
gcc_assert (op);
ver = SSA_NAME_VERSION (op);
- if (TEST_BIT (processed, ver))
+ if (bitmap_bit_p (processed, ver))
{
stmt = SSA_NAME_DEF_STMT (op);
gcc_assert (gimple_nop_p (stmt)
|| gimple_plf (stmt, STMT_NECESSARY));
return;
}
- SET_BIT (processed, ver);
+ bitmap_set_bit (processed, ver);
stmt = SSA_NAME_DEF_STMT (op);
gcc_assert (stmt);
gimple_set_plf (stmt, STMT_NECESSARY, true);
if (bb_contains_live_stmts)
- SET_BIT (bb_contains_live_stmts, gimple_bb (stmt)->index);
- VEC_safe_push (gimple, heap, worklist, stmt);
+ bitmap_set_bit (bb_contains_live_stmts, gimple_bb (stmt)->index);
+ worklist.safe_push (stmt);
}
static void
mark_stmt_if_obviously_necessary (gimple stmt, bool aggressive)
{
- tree lhs = NULL_TREE;
/* With non-call exceptions, we have to assume that all statements could
- throw. If a statement may throw, it is inherently necessary. */
- if (flag_non_call_exceptions
+ throw. If a statement could throw, it can be deemed necessary. */
+ if (cfun->can_throw_non_call_exceptions
+ && !cfun->can_delete_dead_exceptions
&& stmt_could_throw_p (stmt))
{
mark_stmt_necessary (stmt, true);
return;
case GIMPLE_CALL:
- /* Most, but not all function calls are required. Function calls that
- produce no result and have no side effects (i.e. const pure
- functions) are unnecessary. */
- if (gimple_has_side_effects (stmt))
- {
- mark_stmt_necessary (stmt, true);
- return;
- }
- if (!gimple_call_lhs (stmt))
- return;
- lhs = gimple_call_lhs (stmt);
- /* Fall through */
-
- case GIMPLE_ASSIGN:
- if (!lhs)
- lhs = gimple_assign_lhs (stmt);
- /* These values are mildly magic bits of the EH runtime. We can't
- see the entire lifetime of these values until landing pads are
- generated. */
- if (TREE_CODE (lhs) == EXC_PTR_EXPR
- || TREE_CODE (lhs) == FILTER_EXPR)
- {
- mark_stmt_necessary (stmt, true);
+ {
+ tree callee = gimple_call_fndecl (stmt);
+ if (callee != NULL_TREE
+ && DECL_BUILT_IN_CLASS (callee) == BUILT_IN_NORMAL)
+ switch (DECL_FUNCTION_CODE (callee))
+ {
+ case BUILT_IN_MALLOC:
+ case BUILT_IN_ALIGNED_ALLOC:
+ case BUILT_IN_CALLOC:
+ case BUILT_IN_ALLOCA:
+ case BUILT_IN_ALLOCA_WITH_ALIGN:
+ return;
+
+ default:;
+ }
+ /* Most, but not all function calls are required. Function calls that
+ produce no result and have no side effects (i.e. const pure
+ functions) are unnecessary. */
+ if (gimple_has_side_effects (stmt))
+ {
+ mark_stmt_necessary (stmt, true);
+ return;
+ }
+ if (!gimple_call_lhs (stmt))
return;
- }
- break;
+ break;
+ }
+
+ case GIMPLE_DEBUG:
+ /* Debug temps without a value are not useful. ??? If we could
+ easily locate the debug temp bind stmt for a use thereof,
+ would could refrain from marking all debug temps here, and
+ mark them only if they're used. */
+ if (!gimple_debug_bind_p (stmt)
+ || gimple_debug_bind_has_value_p (stmt)
+ || TREE_CODE (gimple_debug_bind_get_var (stmt)) != DEBUG_EXPR_DECL)
+ mark_stmt_necessary (stmt, false);
+ return;
case GIMPLE_GOTO:
gcc_assert (!simple_goto_p (stmt));
mark_stmt_necessary (stmt, true);
break;
+ case GIMPLE_ASSIGN:
+ if (gimple_clobber_p (stmt))
+ return;
+ break;
+
default:
break;
}
return;
}
- if (is_hidden_global_store (stmt))
+ if (stmt_may_clobber_global_p (stmt))
{
mark_stmt_necessary (stmt, true);
return;
}
-/* Make corresponding control dependent edges necessary. We only
- have to do this once for each basic block, so we clear the bitmap
- after we're done. */
+/* Mark the last statement of BB as necessary. */
+
static void
-mark_control_dependent_edges_necessary (basic_block bb, struct edge_list *el)
+mark_last_stmt_necessary (basic_block bb)
+{
+ gimple stmt = last_stmt (bb);
+
+ bitmap_set_bit (last_stmt_necessary, bb->index);
+ bitmap_set_bit (bb_contains_live_stmts, bb->index);
+
+ /* We actually mark the statement only if it is a control statement. */
+ if (stmt && is_ctrl_stmt (stmt))
+ mark_stmt_necessary (stmt, true);
+}
+
+
+/* Mark control dependent edges of BB as necessary. We have to do this only
+ once for each basic block so we set the appropriate bit after we're done.
+
+ When IGNORE_SELF is true, ignore BB in the list of control dependences. */
+
+static void
+mark_control_dependent_edges_necessary (basic_block bb, bool ignore_self)
{
bitmap_iterator bi;
unsigned edge_number;
+ bool skipped = false;
- gcc_assert (bb != EXIT_BLOCK_PTR);
+ gcc_assert (bb != EXIT_BLOCK_PTR_FOR_FN (cfun));
- if (bb == ENTRY_BLOCK_PTR)
+ if (bb == ENTRY_BLOCK_PTR_FOR_FN (cfun))
return;
- EXECUTE_IF_CONTROL_DEPENDENT (bi, bb->index, edge_number)
+ EXECUTE_IF_SET_IN_BITMAP (cd->get_edges_dependent_on (bb->index),
+ 0, edge_number, bi)
{
- gimple stmt;
- basic_block cd_bb = INDEX_EDGE_PRED_BB (el, edge_number);
+ basic_block cd_bb = cd->get_edge (edge_number)->src;
- if (TEST_BIT (last_stmt_necessary, cd_bb->index))
- continue;
- SET_BIT (last_stmt_necessary, cd_bb->index);
- SET_BIT (bb_contains_live_stmts, cd_bb->index);
+ if (ignore_self && cd_bb == bb)
+ {
+ skipped = true;
+ continue;
+ }
- stmt = last_stmt (cd_bb);
- if (stmt && is_ctrl_stmt (stmt))
- mark_stmt_necessary (stmt, true);
+ if (!bitmap_bit_p (last_stmt_necessary, cd_bb->index))
+ mark_last_stmt_necessary (cd_bb);
}
+
+ if (!skipped)
+ bitmap_set_bit (visited_control_parents, bb->index);
}
dependence analysis. */
static void
-find_obviously_necessary_stmts (struct edge_list *el)
+find_obviously_necessary_stmts (bool aggressive)
{
basic_block bb;
gimple_stmt_iterator gsi;
edge e;
gimple phi, stmt;
+ int flags;
- FOR_EACH_BB (bb)
+ FOR_EACH_BB_FN (bb, cfun)
{
/* PHI nodes are never inherently necessary. */
for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi))
{
stmt = gsi_stmt (gsi);
gimple_set_plf (stmt, STMT_NECESSARY, false);
- mark_stmt_if_obviously_necessary (stmt, el != NULL);
+ mark_stmt_if_obviously_necessary (stmt, aggressive);
}
}
/* Pure and const functions are finite and thus have no infinite loops in
them. */
- if ((TREE_READONLY (current_function_decl)
- || DECL_PURE_P (current_function_decl))
- && !DECL_LOOPING_CONST_OR_PURE_P (current_function_decl))
+ flags = flags_from_decl_or_type (current_function_decl);
+ if ((flags & (ECF_CONST|ECF_PURE)) && !(flags & ECF_LOOPING_CONST_OR_PURE))
return;
/* Prevent the empty possibly infinite loops from being removed. */
- if (el)
+ if (aggressive)
{
- loop_iterator li;
struct loop *loop;
scev_initialize ();
if (mark_irreducible_loops ())
- FOR_EACH_BB (bb)
+ FOR_EACH_BB_FN (bb, cfun)
{
edge_iterator ei;
FOR_EACH_EDGE (e, ei, bb->succs)
if (dump_file)
fprintf (dump_file, "Marking back edge of irreducible loop %i->%i\n",
e->src->index, e->dest->index);
- mark_control_dependent_edges_necessary (e->dest, el);
+ mark_control_dependent_edges_necessary (e->dest, false);
}
}
- FOR_EACH_LOOP (li, loop, 0)
+ FOR_EACH_LOOP (loop, 0)
if (!finite_loop_p (loop))
{
if (dump_file)
fprintf (dump_file, "can not prove finiteness of loop %i\n", loop->num);
- mark_control_dependent_edges_necessary (loop->latch, el);
+ mark_control_dependent_edges_necessary (loop->latch, false);
}
scev_finalize ();
}
static bool
ref_may_be_aliased (tree ref)
{
+ gcc_assert (TREE_CODE (ref) != WITH_SIZE_EXPR);
while (handled_component_p (ref))
ref = TREE_OPERAND (ref, 0);
+ if (TREE_CODE (ref) == MEM_REF
+ && TREE_CODE (TREE_OPERAND (ref, 0)) == ADDR_EXPR)
+ ref = TREE_OPERAND (TREE_OPERAND (ref, 0), 0);
return !(DECL_P (ref)
&& !may_be_aliased (ref));
}
static bitmap visited = NULL;
static unsigned int longest_chain = 0;
static unsigned int total_chain = 0;
+static unsigned int nr_walks = 0;
static bool chain_ovfl = false;
/* Worker for the walker that marks reaching definitions of REF,
which is based on a non-aliased decl, necessary. It returns
true whenever the defining statement of the current VDEF is
a kill for REF, as no dominating may-defs are necessary for REF
- anymore. DATA points to cached get_ref_base_and_extent data for REF. */
+ anymore. DATA points to the basic-block that contains the
+ stmt that refers to REF. */
static bool
-mark_aliased_reaching_defs_necessary_1 (ao_ref *ref, tree vdef,
- void *data ATTRIBUTE_UNUSED)
+mark_aliased_reaching_defs_necessary_1 (ao_ref *ref, tree vdef, void *data)
{
gimple def_stmt = SSA_NAME_DEF_STMT (vdef);
/* If the stmt lhs kills ref, then we can stop walking. */
if (gimple_has_lhs (def_stmt)
- && TREE_CODE (gimple_get_lhs (def_stmt)) != SSA_NAME)
+ && TREE_CODE (gimple_get_lhs (def_stmt)) != SSA_NAME
+ /* The assignment is not necessarily carried out if it can throw
+ and we can catch it in the current function where we could inspect
+ the previous value.
+ ??? We only need to care about the RHS throwing. For aggregate
+ assignments or similar calls and non-call exceptions the LHS
+ might throw as well. */
+ && !stmt_can_throw_internal (def_stmt))
{
tree base, lhs = gimple_get_lhs (def_stmt);
HOST_WIDE_INT size, offset, max_size;
}
/* Or they need to be exactly the same. */
else if (ref->ref
+ /* Make sure there is no induction variable involved
+ in the references (gcc.c-torture/execute/pr42142.c).
+ The simplest way is to check if the kill dominates
+ the use. */
+ /* But when both are in the same block we cannot
+ easily tell whether we came from a backedge
+ unless we decide to compute stmt UIDs
+ (see PR58246). */
+ && (basic_block) data != gimple_bb (def_stmt)
+ && dominated_by_p (CDI_DOMINATORS, (basic_block) data,
+ gimple_bb (def_stmt))
&& operand_equal_p (ref->ref, lhs, 0))
return true;
}
ao_ref_init (&refd, ref);
chain = walk_aliased_vdefs (&refd, gimple_vuse (stmt),
mark_aliased_reaching_defs_necessary_1,
- NULL, NULL);
+ gimple_bb (stmt), NULL);
if (chain > longest_chain)
longest_chain = chain;
total_chain += chain;
+ nr_walks++;
}
/* Worker for the walker that marks reaching definitions of REF, which
/* We have to skip already visited (and thus necessary) statements
to make the chaining work after we dropped back to simple mode. */
if (chain_ovfl
- && TEST_BIT (processed, SSA_NAME_VERSION (vdef)))
+ && bitmap_bit_p (processed, SSA_NAME_VERSION (vdef)))
{
gcc_assert (gimple_nop_p (def_stmt)
|| gimple_plf (def_stmt, STMT_NECESSARY));
return false;
}
+ /* We want to skip statments that do not constitute stores but have
+ a virtual definition. */
+ if (is_gimple_call (def_stmt))
+ {
+ tree callee = gimple_call_fndecl (def_stmt);
+ if (callee != NULL_TREE
+ && DECL_BUILT_IN_CLASS (callee) == BUILT_IN_NORMAL)
+ switch (DECL_FUNCTION_CODE (callee))
+ {
+ case BUILT_IN_MALLOC:
+ case BUILT_IN_ALIGNED_ALLOC:
+ case BUILT_IN_CALLOC:
+ case BUILT_IN_ALLOCA:
+ case BUILT_IN_ALLOCA_WITH_ALIGN:
+ case BUILT_IN_FREE:
+ return false;
+
+ default:;
+ }
+ }
+
mark_operand_necessary (vdef);
return false;
/* Propagate necessity using the operands of necessary statements.
Process the uses on each statement in the worklist, and add all
feeding statements which contribute to the calculation of this
- value to the worklist.
+ value to the worklist.
In conservative mode, EL is NULL. */
static void
-propagate_necessity (struct edge_list *el)
+propagate_necessity (bool aggressive)
{
gimple stmt;
- bool aggressive = (el ? true : false);
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file, "\nProcessing worklist:\n");
- while (VEC_length (gimple, worklist) > 0)
+ while (worklist.length () > 0)
{
/* Take STMT from worklist. */
- stmt = VEC_pop (gimple, worklist);
+ stmt = worklist.pop ();
if (dump_file && (dump_flags & TDF_DETAILS))
{
if (aggressive)
{
- /* Mark the last statements of the basic blocks that the block
- containing STMT is control dependent on, but only if we haven't
+ /* Mark the last statement of the basic blocks on which the block
+ containing STMT is control dependent, but only if we haven't
already done so. */
basic_block bb = gimple_bb (stmt);
- if (bb != ENTRY_BLOCK_PTR
- && ! TEST_BIT (visited_control_parents, bb->index))
- {
- SET_BIT (visited_control_parents, bb->index);
- mark_control_dependent_edges_necessary (bb, el);
- }
+ if (bb != ENTRY_BLOCK_PTR_FOR_FN (cfun)
+ && !bitmap_bit_p (visited_control_parents, bb->index))
+ mark_control_dependent_edges_necessary (bb, false);
}
if (gimple_code (stmt) == GIMPLE_PHI
/* We do not process virtual PHI nodes nor do we track their
necessity. */
- && is_gimple_reg (gimple_phi_result (stmt)))
+ && !virtual_operand_p (gimple_phi_result (stmt)))
{
/* PHI nodes are somewhat special in that each PHI alternative has
data and control dependencies. All the statements feeding the
we also consider the control dependent edges leading to the
predecessor block associated with each PHI alternative as
necessary. */
+ gphi *phi = as_a <gphi *> (stmt);
size_t k;
for (k = 0; k < gimple_phi_num_args (stmt); k++)
mark_operand_necessary (arg);
}
+ /* For PHI operands it matters from where the control flow arrives
+ to the BB. Consider the following example:
+
+ a=exp1;
+ b=exp2;
+ if (test)
+ ;
+ else
+ ;
+ c=PHI(a,b)
+
+ We need to mark control dependence of the empty basic blocks, since they
+ contains computation of PHI operands.
+
+ Doing so is too restrictive in the case the predecestor block is in
+ the loop. Consider:
+
+ if (b)
+ {
+ int i;
+ for (i = 0; i<1000; ++i)
+ ;
+ j = 0;
+ }
+ return j;
+
+ There is PHI for J in the BB containing return statement.
+ In this case the control dependence of predecestor block (that is
+ within the empty loop) also contains the block determining number
+ of iterations of the block that would prevent removing of empty
+ loop in this case.
+
+ This scenario can be avoided by splitting critical edges.
+ To save the critical edge splitting pass we identify how the control
+ dependence would look like if the edge was split.
+
+ Consider the modified CFG created from current CFG by splitting
+ edge B->C. In the postdominance tree of modified CFG, C' is
+ always child of C. There are two cases how chlids of C' can look
+ like:
+
+ 1) C' is leaf
+
+ In this case the only basic block C' is control dependent on is B.
+
+ 2) C' has single child that is B
+
+ In this case control dependence of C' is same as control
+ dependence of B in original CFG except for block B itself.
+ (since C' postdominate B in modified CFG)
+
+ Now how to decide what case happens? There are two basic options:
+
+ a) C postdominate B. Then C immediately postdominate B and
+ case 2 happens iff there is no other way from B to C except
+ the edge B->C.
+
+ There is other way from B to C iff there is succesor of B that
+ is not postdominated by B. Testing this condition is somewhat
+ expensive, because we need to iterate all succesors of B.
+ We are safe to assume that this does not happen: we will mark B
+ as needed when processing the other path from B to C that is
+ conrol dependent on B and marking control dependencies of B
+ itself is harmless because they will be processed anyway after
+ processing control statement in B.
+
+ b) C does not postdominate B. Always case 1 happens since there is
+ path from C to exit that does not go through B and thus also C'. */
+
if (aggressive && !degenerate_phi_p (stmt))
{
for (k = 0; k < gimple_phi_num_args (stmt); k++)
{
- basic_block arg_bb = gimple_phi_arg_edge (stmt, k)->src;
- if (arg_bb != ENTRY_BLOCK_PTR
- && ! TEST_BIT (visited_control_parents, arg_bb->index))
+ basic_block arg_bb = gimple_phi_arg_edge (phi, k)->src;
+
+ if (gimple_bb (stmt)
+ != get_immediate_dominator (CDI_POST_DOMINATORS, arg_bb))
{
- SET_BIT (visited_control_parents, arg_bb->index);
- mark_control_dependent_edges_necessary (arg_bb, el);
+ if (!bitmap_bit_p (last_stmt_necessary, arg_bb->index))
+ mark_last_stmt_necessary (arg_bb);
}
+ else if (arg_bb != ENTRY_BLOCK_PTR_FOR_FN (cfun)
+ && !bitmap_bit_p (visited_control_parents,
+ arg_bb->index))
+ mark_control_dependent_edges_necessary (arg_bb, true);
}
}
}
else
{
/* Propagate through the operands. Examine all the USE, VUSE and
- VDEF operands in this statement. Mark all the statements
+ VDEF operands in this statement. Mark all the statements
which feed this statement's uses as necessary. */
ssa_op_iter iter;
tree use;
+ /* If this is a call to free which is directly fed by an
+ allocation function do not mark that necessary through
+ processing the argument. */
+ if (gimple_call_builtin_p (stmt, BUILT_IN_FREE))
+ {
+ tree ptr = gimple_call_arg (stmt, 0);
+ gimple def_stmt;
+ tree def_callee;
+ /* If the pointer we free is defined by an allocation
+ function do not add the call to the worklist. */
+ if (TREE_CODE (ptr) == SSA_NAME
+ && is_gimple_call (def_stmt = SSA_NAME_DEF_STMT (ptr))
+ && (def_callee = gimple_call_fndecl (def_stmt))
+ && DECL_BUILT_IN_CLASS (def_callee) == BUILT_IN_NORMAL
+ && (DECL_FUNCTION_CODE (def_callee) == BUILT_IN_ALIGNED_ALLOC
+ || DECL_FUNCTION_CODE (def_callee) == BUILT_IN_MALLOC
+ || DECL_FUNCTION_CODE (def_callee) == BUILT_IN_CALLOC))
+ {
+ gimple bounds_def_stmt;
+ tree bounds;
+
+ /* For instrumented calls we should also check used
+ bounds are returned by the same allocation call. */
+ if (!gimple_call_with_bounds_p (stmt)
+ || ((bounds = gimple_call_arg (stmt, 1))
+ && TREE_CODE (bounds) == SSA_NAME
+ && (bounds_def_stmt = SSA_NAME_DEF_STMT (bounds))
+ && chkp_gimple_call_builtin_p (bounds_def_stmt,
+ BUILT_IN_CHKP_BNDRET)
+ && gimple_call_arg (bounds_def_stmt, 0) == ptr))
+ continue;
+ }
+ }
+
FOR_EACH_SSA_TREE_OPERAND (use, stmt, iter, SSA_OP_USE)
mark_operand_necessary (use);
if (callee != NULL_TREE
&& DECL_BUILT_IN_CLASS (callee) == BUILT_IN_NORMAL
&& (DECL_FUNCTION_CODE (callee) == BUILT_IN_MEMSET
+ || DECL_FUNCTION_CODE (callee) == BUILT_IN_MEMSET_CHK
|| DECL_FUNCTION_CODE (callee) == BUILT_IN_MALLOC
- || DECL_FUNCTION_CODE (callee) == BUILT_IN_FREE))
+ || DECL_FUNCTION_CODE (callee) == BUILT_IN_ALIGNED_ALLOC
+ || DECL_FUNCTION_CODE (callee) == BUILT_IN_CALLOC
+ || DECL_FUNCTION_CODE (callee) == BUILT_IN_FREE
+ || DECL_FUNCTION_CODE (callee) == BUILT_IN_VA_END
+ || DECL_FUNCTION_CODE (callee) == BUILT_IN_ALLOCA
+ || (DECL_FUNCTION_CODE (callee)
+ == BUILT_IN_ALLOCA_WITH_ALIGN)
+ || DECL_FUNCTION_CODE (callee) == BUILT_IN_STACK_SAVE
+ || DECL_FUNCTION_CODE (callee) == BUILT_IN_STACK_RESTORE
+ || DECL_FUNCTION_CODE (callee) == BUILT_IN_ASSUME_ALIGNED))
continue;
/* Calls implicitly load from memory, their arguments
if (TREE_CODE (arg) == SSA_NAME
|| is_gimple_min_invariant (arg))
continue;
+ if (TREE_CODE (arg) == WITH_SIZE_EXPR)
+ arg = TREE_OPERAND (arg, 0);
if (!ref_may_be_aliased (arg))
mark_aliased_reaching_defs_necessary (stmt, arg);
}
else if (gimple_assign_single_p (stmt))
{
tree rhs;
- bool rhs_aliased = false;
/* If this is a load mark things necessary. */
rhs = gimple_assign_rhs1 (stmt);
if (TREE_CODE (rhs) != SSA_NAME
- && !is_gimple_min_invariant (rhs))
+ && !is_gimple_min_invariant (rhs)
+ && TREE_CODE (rhs) != CONSTRUCTOR)
{
if (!ref_may_be_aliased (rhs))
mark_aliased_reaching_defs_necessary (stmt, rhs);
else
- rhs_aliased = true;
+ mark_all_reaching_defs_necessary (stmt);
}
- if (rhs_aliased)
- mark_all_reaching_defs_necessary (stmt);
}
- else if (gimple_code (stmt) == GIMPLE_RETURN)
+ else if (greturn *return_stmt = dyn_cast <greturn *> (stmt))
{
- tree rhs = gimple_return_retval (stmt);
+ tree rhs = gimple_return_retval (return_stmt);
/* A return statement may perform a load. */
- if (TREE_CODE (rhs) != SSA_NAME
- && !is_gimple_min_invariant (rhs))
+ if (rhs
+ && TREE_CODE (rhs) != SSA_NAME
+ && !is_gimple_min_invariant (rhs)
+ && TREE_CODE (rhs) != CONSTRUCTOR)
{
if (!ref_may_be_aliased (rhs))
mark_aliased_reaching_defs_necessary (stmt, rhs);
mark_all_reaching_defs_necessary (stmt);
}
}
- else if (gimple_code (stmt) == GIMPLE_ASM)
+ else if (gasm *asm_stmt = dyn_cast <gasm *> (stmt))
{
unsigned i;
mark_all_reaching_defs_necessary (stmt);
/* Inputs may perform loads. */
- for (i = 0; i < gimple_asm_ninputs (stmt); ++i)
+ for (i = 0; i < gimple_asm_ninputs (asm_stmt); ++i)
{
- tree op = TREE_VALUE (gimple_asm_input_op (stmt, i));
+ tree op = TREE_VALUE (gimple_asm_input_op (asm_stmt, i));
if (TREE_CODE (op) != SSA_NAME
&& !is_gimple_min_invariant (op)
+ && TREE_CODE (op) != CONSTRUCTOR
&& !ref_may_be_aliased (op))
mark_aliased_reaching_defs_necessary (stmt, op);
}
}
+ else if (gimple_code (stmt) == GIMPLE_TRANSACTION)
+ {
+ /* The beginning of a transaction is a memory barrier. */
+ /* ??? If we were really cool, we'd only be a barrier
+ for the memories touched within the transaction. */
+ mark_all_reaching_defs_necessary (stmt);
+ }
else
gcc_unreachable ();
/* If we over-used our alias oracle budget drop to simple
- mode. The cost metric allows quadratic behavior up to
- a constant maximal chain and after that falls back to
+ mode. The cost metric allows quadratic behavior
+ (number of uses times number of may-defs queries) up to
+ a constant maximal number of queries and after that falls back to
super-linear complexity. */
- if (longest_chain > 256
- && total_chain > 256 * longest_chain)
+ if (/* Constant but quadratic for small functions. */
+ total_chain > 128 * 128
+ /* Linear in the number of may-defs. */
+ && total_chain > 32 * longest_chain
+ /* Linear in the number of uses. */
+ && total_chain > nr_walks * 32)
{
chain_ovfl = true;
if (visited)
}
}
-/* Replace all uses of result of PHI by underlying variable and mark it
- for renaming. */
-
-static void
-mark_virtual_phi_result_for_renaming (gimple phi)
-{
- bool used = false;
- imm_use_iterator iter;
- use_operand_p use_p;
- gimple stmt;
- if (dump_file && (dump_flags & TDF_DETAILS))
- {
- fprintf (dump_file, "Marking result for renaming : ");
- print_gimple_stmt (dump_file, phi, 0, TDF_SLIM);
- fprintf (dump_file, "\n");
- }
- FOR_EACH_IMM_USE_STMT (stmt, iter, gimple_phi_result (phi))
- {
- FOR_EACH_IMM_USE_ON_STMT (use_p, iter)
- SET_USE (use_p, SSA_NAME_VAR (gimple_phi_result (phi)));
- update_stmt (stmt);
- used = true;
- }
- if (used)
- mark_sym_for_renaming (SSA_NAME_VAR (PHI_RESULT (phi)));
-}
-
/* Remove dead PHI nodes from block BB. */
static bool
remove_dead_phis (basic_block bb)
{
bool something_changed = false;
- gimple_seq phis;
- gimple phi;
- gimple_stmt_iterator gsi;
- phis = phi_nodes (bb);
+ gphi *phi;
+ gphi_iterator gsi;
- for (gsi = gsi_start (phis); !gsi_end_p (gsi);)
+ for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi);)
{
stats.total_phis++;
- phi = gsi_stmt (gsi);
+ phi = gsi.phi ();
/* We do not track necessity of virtual PHI nodes. Instead do
very simple dead PHI removal here. */
- if (!is_gimple_reg (gimple_phi_result (phi)))
+ if (virtual_operand_p (gimple_phi_result (phi)))
{
/* Virtual PHI nodes with one or identical arguments
can be removed. */
return something_changed;
}
-/* Find first live post dominator of BB. */
-
-static basic_block
-get_live_post_dom (basic_block bb)
-{
- basic_block post_dom_bb;
-
-
- /* The post dominance info has to be up-to-date. */
- gcc_assert (dom_info_state (CDI_POST_DOMINATORS) == DOM_OK);
-
- /* Get the immediate post dominator of bb. */
- post_dom_bb = get_immediate_dominator (CDI_POST_DOMINATORS, bb);
- /* And look for first live one. */
- while (post_dom_bb != EXIT_BLOCK_PTR
- && !TEST_BIT (bb_contains_live_stmts, post_dom_bb->index))
- post_dom_bb = get_immediate_dominator (CDI_POST_DOMINATORS, post_dom_bb);
-
- return post_dom_bb;
-}
-
/* Forward edge E to respective POST_DOM_BB and update PHIs. */
static edge
forward_edge_to_pdom (edge e, basic_block post_dom_bb)
{
- gimple_stmt_iterator gsi;
+ gphi_iterator gsi;
edge e2 = NULL;
edge_iterator ei;
e2 = redirect_edge_and_branch (e, post_dom_bb);
cfg_altered = true;
- /* If edge was already around, no updating is neccesary. */
+ /* If edge was already around, no updating is necessary. */
if (e2 != e)
return e2;
- if (phi_nodes (post_dom_bb))
+ if (!gimple_seq_empty_p (phi_nodes (post_dom_bb)))
{
/* We are sure that for every live PHI we are seeing control dependent BB.
- This means that we can look up the end of control dependent path leading
- to the PHI itself. */
+ This means that we can pick any edge to duplicate PHI args from. */
FOR_EACH_EDGE (e2, ei, post_dom_bb->preds)
- if (e2 != e && dominated_by_p (CDI_POST_DOMINATORS, e->src, e2->src))
+ if (e2 != e)
break;
for (gsi = gsi_start_phis (post_dom_bb); !gsi_end_p (gsi);)
{
- gimple phi = gsi_stmt (gsi);
+ gphi *phi = gsi.phi ();
tree op;
source_location locus;
- /* Dead PHI do not imply control dependency. */
- if (!gimple_plf (phi, STMT_NECESSARY)
- && is_gimple_reg (gimple_phi_result (phi)))
+ /* PHIs for virtuals have no control dependency relation on them.
+ We are lost here and must force renaming of the symbol. */
+ if (virtual_operand_p (gimple_phi_result (phi)))
{
- gsi_next (&gsi);
+ mark_virtual_phi_result_for_renaming (phi);
+ remove_phi_node (&gsi, true);
continue;
}
- if (gimple_phi_arg_def (phi, e->dest_idx))
+
+ /* Dead PHI do not imply control dependency. */
+ if (!gimple_plf (phi, STMT_NECESSARY))
{
gsi_next (&gsi);
continue;
}
- /* We didn't find edge to update. This can happen for PHIs on virtuals
- since there is no control dependency relation on them. We are lost
- here and must force renaming of the symbol. */
- if (!is_gimple_reg (gimple_phi_result (phi)))
- {
- mark_virtual_phi_result_for_renaming (phi);
- remove_phi_node (&gsi, true);
- continue;
- }
- if (!e2)
- {
- op = gimple_phi_arg_def (phi, e->dest_idx == 0 ? 1 : 0);
- locus = gimple_phi_arg_location (phi, e->dest_idx == 0 ? 1 : 0);
- }
- else
- {
- op = gimple_phi_arg_def (phi, e2->dest_idx);
- locus = gimple_phi_arg_location (phi, e2->dest_idx);
- }
+ op = gimple_phi_arg_def (phi, e2->dest_idx);
+ locus = gimple_phi_arg_location (phi, e2->dest_idx);
add_phi_arg (phi, op, e, locus);
- gcc_assert (e2 || degenerate_phi_p (phi));
+ /* The resulting PHI if not dead can only be degenerate. */
+ gcc_assert (degenerate_phi_p (phi));
gsi_next (&gsi);
}
}
edge e, e2;
edge_iterator ei;
- post_dom_bb = get_live_post_dom (bb);
+ post_dom_bb = get_immediate_dominator (CDI_POST_DOMINATORS, bb);
e = find_edge (bb, post_dom_bb);
fake edges in the dominator tree. */
if (e)
;
- else if (! post_dom_bb || post_dom_bb == EXIT_BLOCK_PTR)
+ else if (! post_dom_bb || post_dom_bb == EXIT_BLOCK_PTR_FOR_FN (cfun))
e = EDGE_SUCC (bb, 0);
else
e = forward_edge_to_pdom (EDGE_SUCC (bb, 0), post_dom_bb);
if (e != e2)
{
cfg_altered = true;
- remove_edge (e2);
+ /* If we made a BB unconditionally exit a loop then this
+ transform alters the set of BBs in the loop. Schedule
+ a fixup. */
+ if (loop_exit_edge_p (bb->loop_father, e))
+ loops_state_set (LOOPS_NEED_FIXUP);
+ remove_edge (e2);
}
else
ei_next (&ei);
}
+ /* If this is a store into a variable that is being optimized away,
+ add a debug bind stmt if possible. */
+ if (MAY_HAVE_DEBUG_STMTS
+ && gimple_assign_single_p (stmt)
+ && is_gimple_val (gimple_assign_rhs1 (stmt)))
+ {
+ tree lhs = gimple_assign_lhs (stmt);
+ if ((TREE_CODE (lhs) == VAR_DECL || TREE_CODE (lhs) == PARM_DECL)
+ && !DECL_IGNORED_P (lhs)
+ && is_gimple_reg_type (TREE_TYPE (lhs))
+ && !is_global_var (lhs)
+ && !DECL_HAS_VALUE_EXPR_P (lhs))
+ {
+ tree rhs = gimple_assign_rhs1 (stmt);
+ gdebug *note
+ = gimple_build_debug_bind (lhs, unshare_expr (rhs), stmt);
+ gsi_insert_after (i, note, GSI_SAME_STMT);
+ }
+ }
+
unlink_stmt_vdef (stmt);
- gsi_remove (i, true);
- release_defs (stmt);
+ gsi_remove (i, true);
+ release_defs (stmt);
}
+/* Helper for maybe_optimize_arith_overflow. Find in *TP if there are any
+ uses of data (SSA_NAME) other than REALPART_EXPR referencing it. */
+
+static tree
+find_non_realpart_uses (tree *tp, int *walk_subtrees, void *data)
+{
+ if (TYPE_P (*tp) || TREE_CODE (*tp) == REALPART_EXPR)
+ *walk_subtrees = 0;
+ if (*tp == (tree) data)
+ return *tp;
+ return NULL_TREE;
+}
+
+/* If the IMAGPART_EXPR of the {ADD,SUB,MUL}_OVERFLOW result is never used,
+ but REALPART_EXPR is, optimize the {ADD,SUB,MUL}_OVERFLOW internal calls
+ into plain unsigned {PLUS,MINUS,MULT}_EXPR, and if needed reset debug
+ uses. */
+
+static void
+maybe_optimize_arith_overflow (gimple_stmt_iterator *gsi,
+ enum tree_code subcode)
+{
+ gimple stmt = gsi_stmt (*gsi);
+ tree lhs = gimple_call_lhs (stmt);
+
+ if (lhs == NULL || TREE_CODE (lhs) != SSA_NAME)
+ return;
+
+ imm_use_iterator imm_iter;
+ use_operand_p use_p;
+ bool has_debug_uses = false;
+ bool has_realpart_uses = false;
+ bool has_other_uses = false;
+ FOR_EACH_IMM_USE_FAST (use_p, imm_iter, lhs)
+ {
+ gimple use_stmt = USE_STMT (use_p);
+ if (is_gimple_debug (use_stmt))
+ has_debug_uses = true;
+ else if (is_gimple_assign (use_stmt)
+ && gimple_assign_rhs_code (use_stmt) == REALPART_EXPR
+ && TREE_OPERAND (gimple_assign_rhs1 (use_stmt), 0) == lhs)
+ has_realpart_uses = true;
+ else
+ {
+ has_other_uses = true;
+ break;
+ }
+ }
+
+ if (!has_realpart_uses || has_other_uses)
+ return;
+
+ tree arg0 = gimple_call_arg (stmt, 0);
+ tree arg1 = gimple_call_arg (stmt, 1);
+ location_t loc = gimple_location (stmt);
+ tree type = TREE_TYPE (TREE_TYPE (lhs));
+ tree utype = type;
+ if (!TYPE_UNSIGNED (type))
+ utype = build_nonstandard_integer_type (TYPE_PRECISION (type), 1);
+ tree result = fold_build2_loc (loc, subcode, utype,
+ fold_convert_loc (loc, utype, arg0),
+ fold_convert_loc (loc, utype, arg1));
+ result = fold_convert_loc (loc, type, result);
+
+ if (has_debug_uses)
+ {
+ gimple use_stmt;
+ FOR_EACH_IMM_USE_STMT (use_stmt, imm_iter, lhs)
+ {
+ if (!gimple_debug_bind_p (use_stmt))
+ continue;
+ tree v = gimple_debug_bind_get_value (use_stmt);
+ if (walk_tree (&v, find_non_realpart_uses, lhs, NULL))
+ {
+ gimple_debug_bind_reset_value (use_stmt);
+ update_stmt (use_stmt);
+ }
+ }
+ }
+
+ if (TREE_CODE (result) == INTEGER_CST && TREE_OVERFLOW (result))
+ result = drop_tree_overflow (result);
+ tree overflow = build_zero_cst (type);
+ tree ctype = build_complex_type (type);
+ if (TREE_CODE (result) == INTEGER_CST)
+ result = build_complex (ctype, result, overflow);
+ else
+ result = build2_loc (gimple_location (stmt), COMPLEX_EXPR,
+ ctype, result, overflow);
+
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ {
+ fprintf (dump_file, "Transforming call: ");
+ print_gimple_stmt (dump_file, stmt, 0, TDF_SLIM);
+ fprintf (dump_file, "because the overflow result is never used into: ");
+ print_generic_stmt (dump_file, result, TDF_SLIM);
+ fprintf (dump_file, "\n");
+ }
+
+ if (!update_call_from_tree (gsi, result))
+ gimplify_and_update_call_from_tree (gsi, result);
+}
/* Eliminate unnecessary statements. Any instruction not marked as necessary
contributes nothing to the program, and can be deleted. */
{
bool something_changed = false;
basic_block bb;
- gimple_stmt_iterator gsi;
+ gimple_stmt_iterator gsi, psi;
gimple stmt;
tree call;
+ vec<basic_block> h;
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file, "\nEliminating unnecessary statements:\n");
clear_special_calls ();
- FOR_EACH_BB (bb)
+ /* Walking basic blocks and statements in reverse order avoids
+ releasing SSA names before any other DEFs that refer to them are
+ released. This helps avoid loss of debug information, as we get
+ a chance to propagate all RHSs of removed SSAs into debug uses,
+ rather than only the latest ones. E.g., consider:
+
+ x_3 = y_1 + z_2;
+ a_5 = x_3 - b_4;
+ # DEBUG a => a_5
+
+ If we were to release x_3 before a_5, when we reached a_5 and
+ tried to substitute it into the debug stmt, we'd see x_3 there,
+ but x_3's DEF, type, etc would have already been disconnected.
+ By going backwards, the debug stmt first changes to:
+
+ # DEBUG a => x_3 - b_4
+
+ and then to:
+
+ # DEBUG a => y_1 + z_2 - b_4
+
+ as desired. */
+ gcc_assert (dom_info_available_p (CDI_DOMINATORS));
+ h = get_all_dominated_blocks (CDI_DOMINATORS,
+ single_succ (ENTRY_BLOCK_PTR_FOR_FN (cfun)));
+
+ while (h.length ())
{
+ bb = h.pop ();
+
/* Remove dead statements. */
- for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi);)
+ for (gsi = gsi_last_bb (bb); !gsi_end_p (gsi); gsi = psi)
{
stmt = gsi_stmt (gsi);
+ psi = gsi;
+ gsi_prev (&psi);
+
stats.total++;
- /* If GSI is not necessary then remove it. */
- if (!gimple_plf (stmt, STMT_NECESSARY))
+ /* We can mark a call to free as not necessary if the
+ defining statement of its argument is not necessary
+ (and thus is getting removed). */
+ if (gimple_plf (stmt, STMT_NECESSARY)
+ && gimple_call_builtin_p (stmt, BUILT_IN_FREE))
{
- remove_dead_stmt (&gsi, bb);
- something_changed = true;
+ tree ptr = gimple_call_arg (stmt, 0);
+ if (TREE_CODE (ptr) == SSA_NAME)
+ {
+ gimple def_stmt = SSA_NAME_DEF_STMT (ptr);
+ if (!gimple_nop_p (def_stmt)
+ && !gimple_plf (def_stmt, STMT_NECESSARY))
+ gimple_set_plf (stmt, STMT_NECESSARY, false);
+ }
+ /* We did not propagate necessity for free calls fed
+ by allocation function to allow unnecessary
+ alloc-free sequence elimination. For instrumented
+ calls it also means we did not mark bounds producer
+ as necessary and it is time to do it in case free
+ call is not removed. */
+ if (gimple_call_with_bounds_p (stmt))
+ {
+ gimple bounds_def_stmt;
+ tree bounds = gimple_call_arg (stmt, 1);
+ gcc_assert (TREE_CODE (bounds) == SSA_NAME);
+ bounds_def_stmt = SSA_NAME_DEF_STMT (bounds);
+ if (bounds_def_stmt
+ && !gimple_plf (bounds_def_stmt, STMT_NECESSARY))
+ gimple_set_plf (bounds_def_stmt, STMT_NECESSARY,
+ gimple_plf (stmt, STMT_NECESSARY));
+ }
}
- else if (is_gimple_call (stmt))
+
+ /* If GSI is not necessary then remove it. */
+ if (!gimple_plf (stmt, STMT_NECESSARY))
{
- call = gimple_call_fndecl (stmt);
- if (call)
+ /* Keep clobbers that we can keep live live. */
+ if (gimple_clobber_p (stmt))
{
- tree name;
-
- /* When LHS of var = call (); is dead, simplify it into
- call (); saving one operand. */
- name = gimple_call_lhs (stmt);
- if (name && TREE_CODE (name) == SSA_NAME
- && !TEST_BIT (processed, SSA_NAME_VERSION (name)))
+ ssa_op_iter iter;
+ use_operand_p use_p;
+ bool dead = false;
+ FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, SSA_OP_USE)
{
- something_changed = true;
- if (dump_file && (dump_flags & TDF_DETAILS))
+ tree name = USE_FROM_PTR (use_p);
+ if (!SSA_NAME_IS_DEFAULT_DEF (name)
+ && !bitmap_bit_p (processed, SSA_NAME_VERSION (name)))
{
- fprintf (dump_file, "Deleting LHS of call: ");
- print_gimple_stmt (dump_file, stmt, 0, TDF_SLIM);
- fprintf (dump_file, "\n");
+ dead = true;
+ break;
}
-
- gimple_call_set_lhs (stmt, NULL_TREE);
- maybe_clean_or_replace_eh_stmt (stmt, stmt);
- update_stmt (stmt);
- release_ssa_name (name);
}
- notice_special_calls (stmt);
+ if (!dead)
+ continue;
}
- gsi_next (&gsi);
+ if (!is_gimple_debug (stmt))
+ something_changed = true;
+ remove_dead_stmt (&gsi, bb);
}
- else
+ else if (is_gimple_call (stmt))
{
- gsi_next (&gsi);
+ tree name = gimple_call_lhs (stmt);
+
+ notice_special_calls (as_a <gcall *> (stmt));
+
+ /* When LHS of var = call (); is dead, simplify it into
+ call (); saving one operand. */
+ if (name
+ && TREE_CODE (name) == SSA_NAME
+ && !bitmap_bit_p (processed, SSA_NAME_VERSION (name))
+ /* Avoid doing so for allocation calls which we
+ did not mark as necessary, it will confuse the
+ special logic we apply to malloc/free pair removal. */
+ && (!(call = gimple_call_fndecl (stmt))
+ || DECL_BUILT_IN_CLASS (call) != BUILT_IN_NORMAL
+ || (DECL_FUNCTION_CODE (call) != BUILT_IN_ALIGNED_ALLOC
+ && DECL_FUNCTION_CODE (call) != BUILT_IN_MALLOC
+ && DECL_FUNCTION_CODE (call) != BUILT_IN_CALLOC
+ && DECL_FUNCTION_CODE (call) != BUILT_IN_ALLOCA
+ && (DECL_FUNCTION_CODE (call)
+ != BUILT_IN_ALLOCA_WITH_ALIGN)))
+ /* Avoid doing so for bndret calls for the same reason. */
+ && !chkp_gimple_call_builtin_p (stmt, BUILT_IN_CHKP_BNDRET))
+ {
+ something_changed = true;
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ {
+ fprintf (dump_file, "Deleting LHS of call: ");
+ print_gimple_stmt (dump_file, stmt, 0, TDF_SLIM);
+ fprintf (dump_file, "\n");
+ }
+
+ gimple_call_set_lhs (stmt, NULL_TREE);
+ maybe_clean_or_replace_eh_stmt (stmt, stmt);
+ update_stmt (stmt);
+ release_ssa_name (name);
+
+ /* GOMP_SIMD_LANE without lhs is not needed. */
+ if (gimple_call_internal_p (stmt)
+ && gimple_call_internal_fn (stmt) == IFN_GOMP_SIMD_LANE)
+ remove_dead_stmt (&gsi, bb);
+ }
+ else if (gimple_call_internal_p (stmt))
+ switch (gimple_call_internal_fn (stmt))
+ {
+ case IFN_ADD_OVERFLOW:
+ maybe_optimize_arith_overflow (&gsi, PLUS_EXPR);
+ break;
+ case IFN_SUB_OVERFLOW:
+ maybe_optimize_arith_overflow (&gsi, MINUS_EXPR);
+ break;
+ case IFN_MUL_OVERFLOW:
+ maybe_optimize_arith_overflow (&gsi, MULT_EXPR);
+ break;
+ default:
+ break;
+ }
}
}
}
+
+ h.release ();
+
/* Since we don't track liveness of virtual PHI nodes, it is possible that we
rendered some PHI nodes unreachable while they are still in use.
Mark them for renaming. */
if (cfg_altered)
{
- basic_block next_bb;
+ basic_block prev_bb;
+
find_unreachable_blocks ();
- for (bb = ENTRY_BLOCK_PTR->next_bb; bb != EXIT_BLOCK_PTR; bb = next_bb)
+
+ /* Delete all unreachable basic blocks in reverse dominator order. */
+ for (bb = EXIT_BLOCK_PTR_FOR_FN (cfun)->prev_bb;
+ bb != ENTRY_BLOCK_PTR_FOR_FN (cfun); bb = prev_bb)
{
- next_bb = bb->next_bb;
- if (!TEST_BIT (bb_contains_live_stmts, bb->index)
+ prev_bb = bb->prev_bb;
+
+ if (!bitmap_bit_p (bb_contains_live_stmts, bb->index)
|| !(bb->flags & BB_REACHABLE))
{
- for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi))
- if (!is_gimple_reg (gimple_phi_result (gsi_stmt (gsi))))
+ for (gphi_iterator gsi = gsi_start_phis (bb); !gsi_end_p (gsi);
+ gsi_next (&gsi))
+ if (virtual_operand_p (gimple_phi_result (gsi.phi ())))
{
bool found = false;
imm_use_iterator iter;
- FOR_EACH_IMM_USE_STMT (stmt, iter, gimple_phi_result (gsi_stmt (gsi)))
+ FOR_EACH_IMM_USE_STMT (stmt, iter,
+ gimple_phi_result (gsi.phi ()))
{
if (!(gimple_bb (stmt)->flags & BB_REACHABLE))
continue;
}
}
if (found)
- mark_virtual_phi_result_for_renaming (gsi_stmt (gsi));
+ mark_virtual_phi_result_for_renaming (gsi.phi ());
}
+
if (!(bb->flags & BB_REACHABLE))
- delete_basic_block (bb);
+ {
+ /* Speed up the removal of blocks that don't
+ dominate others. Walking backwards, this should
+ be the common case. ??? Do we need to recompute
+ dominators because of cfg_altered? */
+ if (!MAY_HAVE_DEBUG_STMTS
+ || !first_dom_son (CDI_DOMINATORS, bb))
+ delete_basic_block (bb);
+ else
+ {
+ h = get_all_dominated_blocks (CDI_DOMINATORS, bb);
+
+ while (h.length ())
+ {
+ bb = h.pop ();
+ prev_bb = bb->prev_bb;
+ /* Rearrangements to the CFG may have failed
+ to update the dominators tree, so that
+ formerly-dominated blocks are now
+ otherwise reachable. */
+ if (!!(bb->flags & BB_REACHABLE))
+ continue;
+ delete_basic_block (bb);
+ }
+
+ h.release ();
+ }
+ }
}
}
}
- FOR_EACH_BB (bb)
+ FOR_EACH_BB_FN (bb, cfun)
{
/* Remove dead PHI nodes. */
something_changed |= remove_dead_phis (bb);
if (aggressive)
{
- int i;
-
- control_dependence_map = XNEWVEC (bitmap, last_basic_block);
- for (i = 0; i < last_basic_block; ++i)
- control_dependence_map[i] = BITMAP_ALLOC (NULL);
-
- last_stmt_necessary = sbitmap_alloc (last_basic_block);
- sbitmap_zero (last_stmt_necessary);
- bb_contains_live_stmts = sbitmap_alloc (last_basic_block);
- sbitmap_zero (bb_contains_live_stmts);
+ last_stmt_necessary = sbitmap_alloc (last_basic_block_for_fn (cfun));
+ bitmap_clear (last_stmt_necessary);
+ bb_contains_live_stmts = sbitmap_alloc (last_basic_block_for_fn (cfun));
+ bitmap_clear (bb_contains_live_stmts);
}
processed = sbitmap_alloc (num_ssa_names + 1);
- sbitmap_zero (processed);
+ bitmap_clear (processed);
- worklist = VEC_alloc (gimple, heap, 64);
+ worklist.create (64);
cfg_altered = false;
}
{
if (aggressive)
{
- int i;
-
- for (i = 0; i < last_basic_block; ++i)
- BITMAP_FREE (control_dependence_map[i]);
- free (control_dependence_map);
-
+ delete cd;
sbitmap_free (visited_control_parents);
sbitmap_free (last_stmt_necessary);
sbitmap_free (bb_contains_live_stmts);
sbitmap_free (processed);
- VEC_free (gimple, heap, worklist);
+ worklist.release ();
}
/* Main routine to eliminate dead code.
static unsigned int
perform_tree_ssa_dce (bool aggressive)
{
- struct edge_list *el = NULL;
bool something_changed = 0;
+ calculate_dominance_info (CDI_DOMINATORS);
+
/* Preheaders are needed for SCEV to work.
Simple lateches and recorded exits improve chances that loop will
proved to be finite in testcases such as in loop-15.c and loop-24.c */
if (aggressive)
{
/* Compute control dependence. */
- timevar_push (TV_CONTROL_DEPENDENCES);
calculate_dominance_info (CDI_POST_DOMINATORS);
- el = create_edge_list ();
- find_all_control_dependences (el);
- timevar_pop (TV_CONTROL_DEPENDENCES);
+ cd = new control_dependences (create_edge_list ());
- visited_control_parents = sbitmap_alloc (last_basic_block);
- sbitmap_zero (visited_control_parents);
+ visited_control_parents =
+ sbitmap_alloc (last_basic_block_for_fn (cfun));
+ bitmap_clear (visited_control_parents);
mark_dfs_back_edges ();
}
- find_obviously_necessary_stmts (el);
+ find_obviously_necessary_stmts (aggressive);
if (aggressive)
loop_optimizer_finalize ();
longest_chain = 0;
total_chain = 0;
+ nr_walks = 0;
chain_ovfl = false;
- propagate_necessity (el);
+ visited = BITMAP_ALLOC (NULL);
+ propagate_necessity (aggressive);
BITMAP_FREE (visited);
something_changed |= eliminate_unnecessary_stmts ();
tree_dce_done (aggressive);
- free_edge_list (el);
-
if (something_changed)
- return (TODO_update_ssa | TODO_cleanup_cfg | TODO_ggc_collect
- | TODO_remove_unused_locals);
- else
- return 0;
+ {
+ free_numbers_of_iterations_estimates ();
+ if (scev_initialized_p ())
+ scev_reset ();
+ return TODO_update_ssa | TODO_cleanup_cfg;
+ }
+ return 0;
}
/* Pass entry points. */
return perform_tree_ssa_dce (/*aggressive=*/false);
}
-static unsigned int
-tree_ssa_dce_loop (void)
-{
- unsigned int todo;
- todo = perform_tree_ssa_dce (/*aggressive=*/false);
- if (todo)
- {
- free_numbers_of_iterations_estimates ();
- scev_reset ();
- }
- return todo;
-}
-
static unsigned int
tree_ssa_cd_dce (void)
{
return perform_tree_ssa_dce (/*aggressive=*/optimize >= 2);
}
-static bool
-gate_dce (void)
+namespace {
+
+const pass_data pass_data_dce =
+{
+ GIMPLE_PASS, /* type */
+ "dce", /* name */
+ OPTGROUP_NONE, /* optinfo_flags */
+ TV_TREE_DCE, /* tv_id */
+ ( PROP_cfg | PROP_ssa ), /* properties_required */
+ 0, /* properties_provided */
+ 0, /* properties_destroyed */
+ 0, /* todo_flags_start */
+ 0, /* todo_flags_finish */
+};
+
+class pass_dce : public gimple_opt_pass
+{
+public:
+ pass_dce (gcc::context *ctxt)
+ : gimple_opt_pass (pass_data_dce, ctxt)
+ {}
+
+ /* opt_pass methods: */
+ opt_pass * clone () { return new pass_dce (m_ctxt); }
+ virtual bool gate (function *) { return flag_tree_dce != 0; }
+ virtual unsigned int execute (function *) { return tree_ssa_dce (); }
+
+}; // class pass_dce
+
+} // anon namespace
+
+gimple_opt_pass *
+make_pass_dce (gcc::context *ctxt)
{
- return flag_tree_dce != 0;
+ return new pass_dce (ctxt);
}
-struct gimple_opt_pass pass_dce =
+namespace {
+
+const pass_data pass_data_cd_dce =
{
- {
- GIMPLE_PASS,
- "dce", /* name */
- gate_dce, /* gate */
- tree_ssa_dce, /* execute */
- NULL, /* sub */
- NULL, /* next */
- 0, /* static_pass_number */
- TV_TREE_DCE, /* 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 */
- }
+ GIMPLE_PASS, /* type */
+ "cddce", /* name */
+ OPTGROUP_NONE, /* optinfo_flags */
+ TV_TREE_CD_DCE, /* tv_id */
+ ( PROP_cfg | PROP_ssa ), /* properties_required */
+ 0, /* properties_provided */
+ 0, /* properties_destroyed */
+ 0, /* todo_flags_start */
+ 0, /* todo_flags_finish */
};
-struct gimple_opt_pass pass_dce_loop =
+class pass_cd_dce : public gimple_opt_pass
{
- {
- GIMPLE_PASS,
- "dceloop", /* name */
- gate_dce, /* gate */
- tree_ssa_dce_loop, /* execute */
- NULL, /* sub */
- NULL, /* next */
- 0, /* static_pass_number */
- TV_TREE_DCE, /* 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 */
- }
-};
+public:
+ pass_cd_dce (gcc::context *ctxt)
+ : gimple_opt_pass (pass_data_cd_dce, ctxt)
+ {}
+
+ /* opt_pass methods: */
+ opt_pass * clone () { return new pass_cd_dce (m_ctxt); }
+ virtual bool gate (function *) { return flag_tree_dce != 0; }
+ virtual unsigned int execute (function *) { return tree_ssa_cd_dce (); }
-struct gimple_opt_pass pass_cd_dce =
+}; // class pass_cd_dce
+
+} // anon namespace
+
+gimple_opt_pass *
+make_pass_cd_dce (gcc::context *ctxt)
{
- {
- GIMPLE_PASS,
- "cddce", /* name */
- gate_dce, /* gate */
- tree_ssa_cd_dce, /* execute */
- NULL, /* sub */
- NULL, /* next */
- 0, /* static_pass_number */
- TV_TREE_CD_DCE, /* 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_verify_flow /* todo_flags_finish */
- }
-};
+ return new pass_cd_dce (ctxt);
+}