Re: [PATCH 01/08] PR jit/63854: Fix leak in tree-ssa-math-opts.c

[Richard Biener <richard dot guenther at gmail dot com>]

On Wed, Nov 26, 2014 at 2:39 AM, David Malcolm <dmalcolm@redhat.com> wrote:
> Running testsuite/jit.dg/test-functions.c under valgrind showed this
> leak (amongst others):
>
> 400 bytes in 10 blocks are definitely lost in loss record 142 of 181
>    at 0x4A0645D: malloc (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
>    by 0x5DCDF2F: xrealloc (xmalloc.c:177)
>    by 0x53726CE: void va_heap::reserve<gimple_statement_base*>(vec<gimple_statement_base*, va_heap, vl_embed>*&, unsigned int, bool) (vec.h:310)
>    by 0x5371BB1: vec<gimple_statement_base*, va_heap, vl_ptr>::reserve(unsigned int, bool) (vec.h:1428)
>    by 0x5370F5D: vec<gimple_statement_base*, va_heap, vl_ptr>::safe_push(gimple_statement_base* const&) (vec.h:1537)
>    by 0x5523E71: maybe_record_sincos(vec<gimple_statement_base*, va_heap, vl_ptr>*, basic_block_def**, gimple_statement_base*) (tree-ssa-math-opts.c:718)
>    by 0x552403E: execute_cse_sincos_1(tree_node*) (tree-ssa-math-opts.c:760)
>    by 0x5526224: (anonymous namespace)::pass_cse_sincos::execute(function*) (tree-ssa-math-opts.c:1497)
>    by 0x5250095: execute_one_pass(opt_pass*) (passes.c:2311)
>    by 0x525030C: execute_pass_list_1(opt_pass*) (passes.c:2363)
>    by 0x525033D: execute_pass_list_1(opt_pass*) (passes.c:2364)
>    by 0x525037A: execute_pass_list(function*, opt_pass*) (passes.c:2374)
>
> For some reason (which I've filed for myself as PR jit/64020), this
> code was bailing out:
>
>   fndecl = mathfn_built_in (type, BUILT_IN_CEXPI);
>   if (!fndecl)
>     return false;
>
> That exit path is missing a:
>   stmts.release ();
> and thus is leaking the buffer of stmts on the way out.
>
> Fix it by converting stmts from vec<> to auto_vec<>, to avoid the need to
> have handwritten release calls on every exit path.

Ok.

Thanks,
Richard.

> gcc/ChangeLog:
>         PR jit/63854
>         * tree-ssa-math-opts.c (execute_cse_sincos_1): Fix a missing
>         release of stmts by converting it to an auto_vec.
> ---
>  gcc/tree-ssa-math-opts.c | 9 ++-------
>  1 file changed, 2 insertions(+), 7 deletions(-)
>
> diff --git a/gcc/tree-ssa-math-opts.c b/gcc/tree-ssa-math-opts.c
> index f9c30bf..5e08c7ee 100644
> --- a/gcc/tree-ssa-math-opts.c
> +++ b/gcc/tree-ssa-math-opts.c
> @@ -740,7 +740,7 @@ execute_cse_sincos_1 (tree name)
>    tree fndecl, res, type;
>    gimple def_stmt, use_stmt, stmt;
>    int seen_cos = 0, seen_sin = 0, seen_cexpi = 0;
> -  vec<gimple> stmts = vNULL;
> +  auto_vec<gimple> stmts;
>    basic_block top_bb = NULL;
>    int i;
>    bool cfg_changed = false;
> @@ -773,10 +773,7 @@ execute_cse_sincos_1 (tree name)
>      }
>
>    if (seen_cos + seen_sin + seen_cexpi <= 1)
> -    {
> -      stmts.release ();
> -      return false;
> -    }
> +    return false;
>
>    /* Simply insert cexpi at the beginning of top_bb but not earlier than
>       the name def statement.  */
> @@ -835,8 +832,6 @@ execute_cse_sincos_1 (tree name)
>           cfg_changed = true;
>      }
>
> -  stmts.release ();
> -
>    return cfg_changed;
>  }
>
> --
> 1.8.5.3
>