diff options
| author | Jeff Law <law@redhat.com> | 2016-03-01 16:12:10 -0700 |
|---|---|---|
| committer | Jeff Law <law@gcc.gnu.org> | 2016-03-01 16:12:10 -0700 |
| commit | eab2541b860c48203115ac6dca3284e982015d2c (patch) | |
| tree | 48b5cf44ccfa93c5f48324a74c4d329401120df3 /gcc/tree-ssa-threadbackward.c | |
| parent | 0bca04b822bc5ee0f5bbb2ba5df6669a433d0bf5 (diff) | |
| download | gcc-eab2541b860c48203115ac6dca3284e982015d2c.zip gcc-eab2541b860c48203115ac6dca3284e982015d2c.tar.gz gcc-eab2541b860c48203115ac6dca3284e982015d2c.tar.bz2 | |
re PR tree-optimization/69196 (code size regression with jump threading at -O2)
PR tree-optimization/69196
* tree-ssa-threadbackward.c (fsm_find_control_statement_thread_paths):
Appropriately clamp the number of statements to copy when the
thread path does not traverse a loop backedge.
PR tree-optimization/69196
* gcc.dg/tree-ssa/pr69196.c: New test.
From-SVN: r233870
Diffstat (limited to 'gcc/tree-ssa-threadbackward.c')
| -rw-r--r-- | gcc/tree-ssa-threadbackward.c | 20 |
1 files changed, 20 insertions, 0 deletions
diff --git a/gcc/tree-ssa-threadbackward.c b/gcc/tree-ssa-threadbackward.c index 3028504..747296b 100644 --- a/gcc/tree-ssa-threadbackward.c +++ b/gcc/tree-ssa-threadbackward.c @@ -429,6 +429,26 @@ fsm_find_control_statement_thread_paths (tree name, continue; } + + /* If this path does not thread through the loop latch, then we are + using the FSM threader to find old style jump threads. This + is good, except the FSM threader does not re-use an existing + threading path to reduce code duplication. + + So for that case, drastically reduce the number of statements + we are allowed to copy. */ + if (!threaded_through_latch + && (n_insns * PARAM_VALUE (PARAM_FSM_SCALE_PATH_STMTS) + >= PARAM_VALUE (PARAM_MAX_JUMP_THREAD_DUPLICATION_STMTS))) + { + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, + "FSM did not thread around loop and would copy too " + "many statements.\n"); + path->pop (); + continue; + } + /* When there is a multi-way branch on the path, then threading can explode the CFG due to duplicating the edges for that multi-way branch. So like above, only allow a multi-way branch on the path |