From a3ff15afb4c697117aa8916c47b358045dbf0fe9 Mon Sep 17 00:00:00 2001 From: Aldy Hernandez Date: Fri, 3 Sep 2021 10:09:41 +0200 Subject: [PATCH] Dump reason why threads are being cancelled and abstract code. We are inconsistent on dumping out reasons why a thread was canceled. This makes debugging jump threading problems harder because paths can be canceled with no reason given. This patch abstracts out the thread canceling code and adds a reason for every cancellation. Tested on x86-64 Linux. gcc/ChangeLog: * tree-ssa-threadupdate.c (cancel_thread): New. (jump_thread_path_registry::thread_block_1): Use cancel_thread. (jump_thread_path_registry::mark_threaded_blocks): Same. (jump_thread_path_registry::register_jump_thread): Same. --- gcc/tree-ssa-threadupdate.c | 56 +++++++++++++++++++++++---------------------- 1 file changed, 29 insertions(+), 27 deletions(-) diff --git a/gcc/tree-ssa-threadupdate.c b/gcc/tree-ssa-threadupdate.c index 1d32a02..18f16ef 100644 --- a/gcc/tree-ssa-threadupdate.c +++ b/gcc/tree-ssa-threadupdate.c @@ -245,6 +245,23 @@ debug (const vec *path) debug (*path); } +/* Release the memory associated with PATH, and if dumping is enabled, + dump out the reason why the thread was canceled. */ + +static void +cancel_thread (vec *path, const char *reason = NULL) +{ + if (dump_file && (dump_flags & TDF_DETAILS)) + { + if (reason) + fprintf (dump_file, "%s:\n", reason); + + dump_jump_thread_path (dump_file, *path, false); + fprintf (dump_file, "\n"); + } + path->release (); +} + /* Simple hashing function. For any given incoming edge E, we're going to be most concerned with the final destination of its jump thread path. So hash on the block index of the final edge in the path. */ @@ -1449,7 +1466,7 @@ jump_thread_path_registry::thread_block_1 (basic_block bb, /* Since this case is not handled by our special code to thread through a loop header, we must explicitly cancel the threading request here. */ - path->release (); + cancel_thread (path, "Threading through unhandled loop header"); e->aux = NULL; continue; } @@ -1488,7 +1505,7 @@ jump_thread_path_registry::thread_block_1 (basic_block bb, if (i != path->length ()) { - path->release (); + cancel_thread (path, "Threading through loop exit"); e->aux = NULL; continue; } @@ -1847,7 +1864,7 @@ fail: if (path) { - path->release (); + cancel_thread (path, "Failure in thread_through_loop_header"); e->aux = NULL; } } @@ -1975,9 +1992,7 @@ jump_thread_path_registry::mark_threaded_blocks (bitmap threaded_blocks) else { m_paths.unordered_remove (i); - if (dump_file && (dump_flags & TDF_DETAILS)) - dump_jump_thread_path (dump_file, *path, false); - path->release (); + cancel_thread (path); } } else @@ -2012,9 +2027,7 @@ jump_thread_path_registry::mark_threaded_blocks (bitmap threaded_blocks) { e->aux = NULL; m_paths.unordered_remove (i); - if (dump_file && (dump_flags & TDF_DETAILS)) - dump_jump_thread_path (dump_file, *path, false); - path->release (); + cancel_thread (path); } } else @@ -2060,9 +2073,7 @@ jump_thread_path_registry::mark_threaded_blocks (bitmap threaded_blocks) if (j != path->length ()) { - if (dump_file && (dump_flags & TDF_DETAILS)) - dump_jump_thread_path (dump_file, *path, false); - path->release (); + cancel_thread (path); e->aux = NULL; } else @@ -2109,7 +2120,7 @@ jump_thread_path_registry::mark_threaded_blocks (bitmap threaded_blocks) if (e2 && !phi_args_equal_on_edges (e2, final_edge)) { - path->release (); + cancel_thread (path); e->aux = NULL; } } @@ -2332,9 +2343,7 @@ jump_thread_path_registry::adjust_paths_after_duplication if (j == cand_path->length ()) { remove_candidate_from_list: - if (dump_file && (dump_flags & TDF_DETAILS)) - fprintf (dump_file, "adjusted candidate: [EMPTY]\n"); - cand_path->release (); + cancel_thread (cand_path, "Adjusted candidate is EMPTY"); m_paths.unordered_remove (cand_path_num); continue; } @@ -2595,7 +2604,7 @@ jump_thread_path_registry::thread_through_all_blocks if (j != path->length ()) { - path->release (); + cancel_thread (path, "Thread references removed edge"); m_paths.unordered_remove (i); continue; } @@ -2629,7 +2638,7 @@ jump_thread_path_registry::thread_through_all_blocks || !valid_jump_thread_path (path)) { /* Remove invalid FSM jump-thread paths. */ - path->release (); + cancel_thread (path, "Invalid FSM jump-thread path"); m_paths.unordered_remove (i); continue; } @@ -2665,7 +2674,7 @@ jump_thread_path_registry::thread_through_all_blocks /* Do not jump-thread twice from the same block. */ if (visited_starting_edges.contains (entry)) { - path->release (); + cancel_thread (path, "Avoiding threading twice from same BB"); m_paths.unordered_remove (i); } else @@ -2766,14 +2775,7 @@ jump_thread_path_registry::register_jump_thread (vec *path) { if ((*path)[i]->e == NULL) { - if (dump_file && (dump_flags & TDF_DETAILS)) - { - fprintf (dump_file, - "Found NULL edge in jump threading path. Cancelling jump thread:\n"); - dump_jump_thread_path (dump_file, *path, false); - } - - path->release (); + cancel_thread (path, "Found NULL edge in jump threading path"); return false; } -- 2.7.4