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| author | Richard Biener <rguenther@suse.de> | 2022-07-29 10:40:34 +0200 |
|---|---|---|
| committer | Richard Biener <rguenther@suse.de> | 2022-07-29 12:05:35 +0200 |
| commit | 49ba4fdeb648c149fa7d964ba812084262c3d06f (patch) | |
| tree | 02b07dbb3ef6160801c567afab03ff7c8514f5c3 | |
| parent | b5f5d1b36edbcd7d923f2e2653e54e52637c715b (diff) | |
| download | gcc-49ba4fdeb648c149fa7d964ba812084262c3d06f.zip gcc-49ba4fdeb648c149fa7d964ba812084262c3d06f.tar.gz gcc-49ba4fdeb648c149fa7d964ba812084262c3d06f.tar.bz2 | |
tree-optimization/105679 - disable backward threading of unlikely entry
The following makes the backward threader reject threads whose entry
edge is probably never executed according to the profile. That in
particular, for the testcase, avoids threading the irq == 1 check
on the path where irq > 31, thereby avoiding spurious -Warray-bounds
diagnostics
if (irq_1(D) > 31)
goto <bb 3>; [0.00%]
else
goto <bb 4>; [100.00%]
;; basic block 3, loop depth 0, count 0 (precise), probably never executed
_2 = (unsigned long) irq_1(D);
__builtin___ubsan_handle_shift_out_of_bounds (&*.Lubsan_data0, 1, _2);
_3 = 1 << irq_1(D);
mask_4 = (u32) _3;
entry = instance_5(D)->array[irq_1(D)];
capture (mask_4);
if (level_6(D) != 0)
goto <bb 7>; [34.00%]
else
goto <bb 5>; [66.00%]
;; basic block 5, loop depth 0, count 708669600 (estimated locally), maybe hot if (irq_1(D) == 1)
goto <bb 7>; [20.97%]
else
goto <bb 6>; [79.03%]
PR tree-optimization/105679
* tree-ssa-threadbackward.cc
(back_threader_profitability::profitable_path_p): Avoid threading
when the entry edge is probably never executed.
| -rw-r--r-- | gcc/tree-ssa-threadbackward.cc | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/gcc/tree-ssa-threadbackward.cc b/gcc/tree-ssa-threadbackward.cc index 3519aca..90f5331 100644 --- a/gcc/tree-ssa-threadbackward.cc +++ b/gcc/tree-ssa-threadbackward.cc @@ -777,6 +777,15 @@ back_threader_profitability::profitable_path_p (const vec<basic_block> &m_path, "exceeds PARAM_MAX_FSM_THREAD_PATH_INSNS.\n"); return false; } + edge entry = find_edge (m_path[m_path.length () - 1], + m_path[m_path.length () - 2]); + if (probably_never_executed_edge_p (cfun, entry)) + { + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, " FAIL: Jump-thread path not considered: " + "path entry is probably never executed.\n"); + return false; + } } else if (!m_speed_p && n_insns > 1) { |