diff options
Diffstat (limited to 'gcc/tree-ssa-threadbackward.c')
| -rw-r--r-- | gcc/tree-ssa-threadbackward.c | 36 |
1 files changed, 33 insertions, 3 deletions
diff --git a/gcc/tree-ssa-threadbackward.c b/gcc/tree-ssa-threadbackward.c index ff6481c..5be6ee4 100644 --- a/gcc/tree-ssa-threadbackward.c +++ b/gcc/tree-ssa-threadbackward.c @@ -36,6 +36,22 @@ along with GCC; see the file COPYING3. If not see static int max_threaded_paths; +/* Simple helper to get the last statement from BB, which is assumed + to be a control statement. */ +static gimple * +get_gimple_control_stmt (basic_block bb) +{ + gimple_stmt_iterator gsi = gsi_last_bb (bb); + + if (gsi_end_p (gsi)) + return NULL; + + gimple *stmt = gsi_stmt (gsi); + enum gimple_code code = gimple_code (stmt); + gcc_assert (code == GIMPLE_COND || code == GIMPLE_SWITCH || code == GIMPLE_GOTO); + return stmt; +} + /* Return true if the CFG contains at least one path from START_BB to END_BB. When a path is found, record in PATH the blocks from END_BB to START_BB. VISITED_BBS is used to make sure we don't fall into an infinite loop. Bound @@ -70,17 +86,17 @@ fsm_find_thread_path (basic_block start_bb, basic_block end_bb, return false; } -/* We trace the value of the SSA_NAME EXPR back through any phi nodes looking +/* We trace the value of the SSA_NAME NAME back through any phi nodes looking for places where it gets a constant value and save the path. Stop after having recorded MAX_PATHS jump threading paths. */ static void -fsm_find_control_statement_thread_paths (tree expr, +fsm_find_control_statement_thread_paths (tree name, hash_set<basic_block> *visited_bbs, vec<basic_block, va_gc> *&path, bool seen_loop_phi) { - gimple *def_stmt = SSA_NAME_DEF_STMT (expr); + gimple *def_stmt = SSA_NAME_DEF_STMT (name); basic_block var_bb = gimple_bb (def_stmt); if (var_bb == NULL) @@ -284,6 +300,20 @@ fsm_find_control_statement_thread_paths (tree expr, jump_thread_path->safe_push (x); } + gimple *stmt = get_gimple_control_stmt ((*path)[0]); + gcc_assert (stmt); + /* We have found a constant value for ARG. For GIMPLE_SWITCH + and GIMPLE_GOTO, we use it as-is. However, for a GIMPLE_COND + we need to substitute, fold and simplify. */ + if (gimple_code (stmt) == GIMPLE_COND) + { + enum tree_code cond_code = gimple_cond_code (stmt); + + /* We know the underyling format of the condition. */ + arg = fold_binary (cond_code, boolean_type_node, + arg, gimple_cond_rhs (stmt)); + } + /* Add the edge taken when the control variable has value ARG. */ edge taken_edge = find_taken_edge ((*path)[0], arg); jump_thread_edge *x |