[PATCH 7/N] Fix newly introduced memory leak in tree-ssa-loop-ivopts.c

Martin Liška mliska@suse.cz
Fri Nov 27 08:31:00 GMT 2015

On 11/27/2015 04:54 AM, Bin.Cheng wrote:
> On Fri, Nov 27, 2015 at 5:08 AM, Martin Liška <mliska@suse.cz> wrote:
>> Hi.
>> There's one more patch that fixes really of lot memory leaks related to loop
>> ivopts.
>> The regression was introduced by r230647.
>> Patch was tested in the series with the rest and the compiler bootstraps
>> successfully.
>> Ready for trunk?
> Hi Martin,
> Thanks for fixing my issue.  The IVO part of patch is OK.
> Just for me to understand, iv_common_cand is freed via free_ptr_hash,
> and thus typed_free_remove.  So what leaks is the iv_use * vector in
> struct iv_common_cand, right?  I did forget to free that.


You are right, the suggested patch uses delete operator for deallocation of iv_common_cand
structure. That eventually calls dtor of auto_vec.

> BTW, how do you monitor memory use in GCC, maybe I can run same test
> for my future patches.

I've been working on removal of memory leaks using valgrind, just configure the compiler with
'--enable-valgrind-annotations' and run for instance:

valgrind --leak-check=yes --trace-children=yes ./gcc/xgcc -Bgcc ../gcc/testsuite/gcc.dg/tree-ssa/loop-32.c -c -O2

==13919== 216 bytes in 3 blocks are definitely lost in loss record 679 of 795
==13919==    at 0x4C2A00F: malloc (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
==13919==    by 0x107CEDF: xrealloc (xmalloc.c:178)
==13919==    by 0xAC46AA: reserve<iv_use*> (vec.h:288)
==13919==    by 0xAC46AA: reserve (vec.h:1406)
==13919==    by 0xAC46AA: reserve_exact (vec.h:1426)
==13919==    by 0xAC46AA: create (vec.h:1441)
==13919==    by 0xAC46AA: record_common_cand(ivopts_data*, tree_node*, tree_node*, iv_use*) (tree-ssa-loop-ivopts.c:3133)
==13919==    by 0xAC49C5: add_iv_candidate_for_use(ivopts_data*, iv_use*) (tree-ssa-loop-ivopts.c:3220)
==13919==    by 0xAC4EA2: add_iv_candidate_for_uses (tree-ssa-loop-ivopts.c:3294)
==13919==    by 0xAC4EA2: find_iv_candidates(ivopts_data*) (tree-ssa-loop-ivopts.c:5705)
==13919==    by 0xAC839D: tree_ssa_iv_optimize_loop (tree-ssa-loop-ivopts.c:7708)
==13919==    by 0xAC839D: tree_ssa_iv_optimize() (tree-ssa-loop-ivopts.c:7758)
==13919==    by 0xADE4D0: (anonymous namespace)::pass_iv_optimize::execute(function*) (tree-ssa-loop.c:520)
==13919==    by 0x920033: execute_one_pass(opt_pass*) (passes.c:2335)
==13919==    by 0x920547: execute_pass_list_1(opt_pass*) [clone .constprop.84] (passes.c:2408)
==13919==    by 0x920559: execute_pass_list_1(opt_pass*) [clone .constprop.84] (passes.c:2409)
==13919==    by 0x920559: execute_pass_list_1(opt_pass*) [clone .constprop.84] (passes.c:2409)
==13919==    by 0x9205A4: execute_pass_list(function*, opt_pass*) (passes.c:2419)


> Thanks,
> bin

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