Re: [PATCH 14/21] PR jit/63854: Fix leak of paths within jump threading

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

On Wed, Nov 19, 2014 at 11:46 AM, David Malcolm <dmalcolm@redhat.com> wrote:
> Paths are allocated as:
>    vec<jump_thread_edge *> *path = new vec<jump_thread_edge *> ();
> i.e. the vec itself is on the heap, so a mere:
>       path->release ();
> is merely releasing the buffer the vec holds, not the vec itself.

Ok.

Thanks,
RIchard.

> This patch updates the two sites that release paths to also delete them,
> fixing leaks like this seen by valgrind:
> 160 bytes in 20 blocks are definitely lost in loss record 165 of 241
>    at 0x4A06965: operator new(unsigned long) (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
>    by 0x556E5AF: thread_across_edge(gimple_statement_base*, edge_def*, bool, vec<tree_node*, va_heap, vl_ptr>*, tree_node
> * (*)(gimple_statement_base*, gimple_statement_base*)) (tree-ssa-threadedge.c:1124)
>    by 0x547B73B: dom_opt_dom_walker::thread_across_edge(edge_def*) (tree-ssa-dom.c:1184)
>    by 0x5480183: dom_opt_dom_walker::after_dom_children(basic_block_def*) (tree-ssa-dom.c:2015)
>    by 0x5C1C5F7: dom_walker::walk(basic_block_def*) (domwalk.c:218)
>    by 0x547AE83: (anonymous namespace)::pass_dominator::execute(function*) (tree-ssa-dom.c:919)
>    by 0x52235BD: execute_one_pass(opt_pass*) (passes.c:2306)
>    by 0x5223834: execute_pass_list_1(opt_pass*) (passes.c:2358)
>    by 0x5223865: execute_pass_list_1(opt_pass*) (passes.c:2359)
>    by 0x52238A2: execute_pass_list(function*, opt_pass*) (passes.c:2369)
>    by 0x4E4888F: cgraph_node::expand() (cgraphunit.c:1773)
>    by 0x4E48F29: expand_all_functions() (cgraphunit.c:1909)
>
> [Space-wise, a vec <T, A, vl_ptr> is just a pointer, hence the 8 bytes
> per block seen in the valgrind report]
>
> gcc/ChangeLog:
>         PR jit/63854
>         * tree-ssa-threadedge.c (thread_across_edge): Don't just release
>         "path", delete it.
>         * tree-ssa-threadupdate.c (delete_jump_thread_path): Likewise.
> ---
>  gcc/tree-ssa-threadedge.c   | 1 +
>  gcc/tree-ssa-threadupdate.c | 1 +
>  2 files changed, 2 insertions(+)
>
> diff --git a/gcc/tree-ssa-threadedge.c b/gcc/tree-ssa-threadedge.c
> index d5b9696..9ee1cae 100644
> --- a/gcc/tree-ssa-threadedge.c
> +++ b/gcc/tree-ssa-threadedge.c
> @@ -1149,6 +1149,7 @@ thread_across_edge (gimple dummy_cond,
>          through the vector entries.  */
>        gcc_assert (path->length () == 0);
>        path->release ();
> +      delete path;
>
>        /* A negative status indicates the target block was deemed too big to
>          duplicate.  Just quit now rather than trying to use the block as
> diff --git a/gcc/tree-ssa-threadupdate.c b/gcc/tree-ssa-threadupdate.c
> index 151ed83..5cb9f86 100644
> --- a/gcc/tree-ssa-threadupdate.c
> +++ b/gcc/tree-ssa-threadupdate.c
> @@ -2481,6 +2481,7 @@ delete_jump_thread_path (vec<jump_thread_edge *> *path)
>    for (unsigned int i = 0; i < path->length (); i++)
>      delete (*path)[i];
>    path->release();
> +  delete path;
>  }
>
>  /* Register a jump threading opportunity.  We queue up all the jump
> --
> 1.8.5.3
>