https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114698
Peter Bergner <bergner at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Component|target |ipa
CC| |hubicka at gcc dot gnu.org
--- Comment #2 from Peter Bergner <bergner at gcc dot gnu.org> ---
I've confirmed that the function being miscompiled is
src/sha2.c:SHA256_Transform() on line 440. I can add configure dcfldd with a
normal -O2 and add a __attribute__((optimize (3))) to this function and I see
bad output. I can also configure dcfldd with -O3 and add a
__attribute__((optimize (2))) to this function and I see good output.
Doing a git bisect, it identified the following GCC commit as causing the bug:
64f3e71c302b4a13e61656ee509e7050b9bce978 is the first bad commit
commit 64f3e71c302b4a13e61656ee509e7050b9bce978
Author: Jan Hubicka <j...@suse.cz>
Date: Sun Nov 14 18:49:15 2021 +0100
Extend modref to track kills
This patch adds kill tracking to ipa-modref. This is representd by array
of accesses to memory locations that are known to be overwritten by the
function.
gcc/ChangeLog:
2021-11-14 Jan Hubicka <hubi...@ucw.cz>
* ipa-modref-tree.c (modref_access_node::update_for_kills): New
member function.
(modref_access_node::merge_for_kills): Likewise.
(modref_access_node::insert_kill): Likewise.
* ipa-modref-tree.h (modref_access_node::update_for_kills,
modref_access_node::merge_for_kills,
modref_access_node::insert_kill):
Declare.
(modref_access_node::useful_for_kill): New member function.
* ipa-modref.c (modref_summary::useful_p): Release useless kills.
(lto_modref_summary): Add kills.
(modref_summary::dump): Dump kills.
(record_access): Add mdoref_access_node parameter.
(record_access_lto): Likewise.
(merge_call_side_effects): Merge kills.
(analyze_call): Add ALWAYS_EXECUTED param and pass it around.
(struct summary_ptrs): Add always_executed filed.
(analyze_load): Update.
(analyze_store): Update; record kills.
(analyze_stmt): Add always_executed; record kills in clobbers.
(analyze_function): Track always_executed.
(modref_summaries::duplicate): Duplicate kills.
(update_signature): Release kills.
* ipa-modref.h (struct modref_summary): Add kills.
* tree-ssa-alias.c (alias_stats): Add kill stats.
(dump_alias_stats): Dump kill stats.
(store_kills_ref_p): Break out from ...
(stmt_kills_ref_p): Use it; handle modref info based kills.
gcc/testsuite/ChangeLog:
2021-11-14 Jan Hubicka <hubi...@ucw.cz>
* gcc.dg/tree-ssa/modref-dse-3.c: New test.
gcc/ipa-modref-tree.c | 179 +++++++++++++++++++++++
gcc/ipa-modref-tree.h | 15 ++
gcc/ipa-modref.c | 126 +++++++++++++---
gcc/ipa-modref.h | 1 +
gcc/testsuite/gcc.dg/tree-ssa/modref-dse-3.c | 22 +++
gcc/tree-ssa-alias.c | 207 +++++++++++++++++++--------
6 files changed, 471 insertions(+), 79 deletions(-)
