On 11/25/14 18:39, David Malcolm wrote:
Running various JIT testcases under valgrid showed this one-time leak:
8,464 (336 direct, 8,128 indirect) bytes in 1 blocks are definitely lost in
loss record 144 of 147
at 0x4A081D4: calloc (in
/usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
by 0x5DF4EA0: xcalloc (xmalloc.c:162)
by 0x5DB0D9C: pretty_printer::pretty_printer(char const*, int)
(pretty-print.c:777)
by 0x54DA67D: __static_initialization_and_destruction_0(int, int)
(tree-pretty-print.c:66)
by 0x54DA6AF: _GLOBAL__sub_I_tree_pretty_print.c (tree-pretty-print.c:3542)
by 0x309540F2D9: call_init.part.0 (dl-init.c:82)
by 0x309540F3C2: _dl_init (dl-init.c:34)
by 0x3095401229: ??? (in /usr/lib64/ld-2.18.so)
by 0x1: ???
by 0xFFEFFFFBE: ???
by 0xFFEFFFFDA: ???
tree-pretty-print.c:66 is:
static pretty_printer buffer;
pretty-print.c:777 is:
pretty_printer::pretty_printer (const char *p, int l)
: buffer (new (XCNEW (output_buffer)) output_buffer ()),
This is the ctor of "buffer" (the pretty_printer) running at startup
by the dynamic linker, allocating its "buffer" output_buffer field
and the pair of obstacks it contains.
[Arguably "buffer" is a poor name for a pretty_printer, and these
should be named "pp" or somesuch, though that seems like it should
be a separate patch, which I'll do as a followup].
However, this ctor gets rerun the first time that
maybe_init_pretty_print is called, reallocating the output_buffer and
its obstacks, leaking the old ones:
static void
maybe_init_pretty_print (FILE *file)
{
if (!initialized)
{
new (&buffer) pretty_printer ();
/* etc */
}
/* etc */
}
This is a one-time leak, so it's worth fixing mostly for the sake of
keeping the valgrind output clean.
Having objects with non-empty ctors/dtors in a statically-allocated
section feels like too much C++ to me: we can't rely on the order in
which they run, and in the past I've been bitten by runtimes that
didn't support them fully (where the compiler worked, but the
linker/startup code didn't).
Hence this patch fixes the leak by rewriting the global "buffer" to
be a pointer, allocating the pp on the heap, eliminating the
before-main static ctor/dtor pair.
gcc/ChangeLog:
PR jit/63854
* tree-pretty-print.c: Eliminate include of <new>.
(buffer): Convert this variable from a pretty_printer to a
pretty_printer *.
(initialized): Eliminate this variable in favor of the NULL-ness
of "buffer".
(print_generic_decl): Update for "buffer" becoming a pointer.
(print_generic_stmt): Likewise.
(print_generic_stmt_indented): Likewise.
(print_generic_expr): Likewise.
(maybe_init_pretty_print): Likewise, allocating "buffer" on the
heap and using its non-NULL-ness to ensure idempotency.
OK.
Jeff