Some places in the startup code use char * values that can sometimes be
string literals, and can sometimes be dynamically built using xstrdup or
concat.
This isn't a problem for cc1 etc since this is only called once, but
for libgccjit they are small per-invocation leaks.
There's no clean way to release them: retrofitting logic to decide if
we're dealing with a string literal vs a dynamically-allocated buffer
(and if something else is pointing to said buffer) is messy and
error-prone; they are also unconnected to the GC.
Hence the cleanest way to fix the leak is to add a new long-term
allocator, to gcc::context. This gives back buffers that will persist
until the gcc::context is cleaned away.
Using this fixes these leaks seen via valgrind:
28 bytes in 4 blocks are definitely lost in loss record 13 of 209
at 0x4A0645D: malloc (in
/usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
by 0x5D76417: xmalloc (xmalloc.c:147)
by 0x5D76509: xstrdup (xstrdup.c:34)
by 0x532CC38: process_options() (toplev.c:1316)
by 0x532DFF4: do_compile() (toplev.c:1976)
by 0x532E3B0: toplev::main(int, char**) (toplev.c:2117)
by 0x4DE7983: gcc::jit::playback::context::compile() (jit-playback.c:1646)
by 0x4DD791A: gcc::jit::recording::context::compile() (jit-recording.c:861)
by 0x4DD5E12: gcc_jit_context_compile (libgccjit.c:2014)
by 0x401CA4: test_jit (harness.h:190)
by 0x401D88: main (harness.h:232)
108 bytes in 12 blocks are definitely lost in loss record 135 of 241
at 0x4A0645D: malloc (in
/usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
by 0x5D75E07: xmalloc (xmalloc.c:147)
by 0x5D7098B: concat (concat.c:147)
by 0x563A342: build_common_builtin_nodes() (tree.c:10145)
by 0x4DC91FC: jit_langhook_init() (dummy-frontend.c:128)
by 0x532D3F4: lang_dependent_init(char const*) (toplev.c:1790)
by 0x532D9C8: do_compile() (toplev.c:2007)
by 0x532DCAC: toplev::main(int, char**) (toplev.c:2118)
by 0x4DE76AF: gcc::jit::playback::context::compile() (jit-playback.c:1615)
by 0x4DD76DA: gcc::jit::recording::context::compile() (jit-recording.c:861)
by 0x4DD5BD2: gcc_jit_context_compile (libgccjit.c:2014)
by 0x401DC4: test_jit (harness.h:190)
108 bytes in 12 blocks are definitely lost in loss record 136 of 241
at 0x4A0645D: malloc (in
/usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
by 0x5D75E07: xmalloc (xmalloc.c:147)
by 0x5D7098B: concat (concat.c:147)
by 0x563A3B6: build_common_builtin_nodes() (tree.c:10151)
by 0x4DC91FC: jit_langhook_init() (dummy-frontend.c:128)
by 0x532D3F4: lang_dependent_init(char const*) (toplev.c:1790)
by 0x532D9C8: do_compile() (toplev.c:2007)
by 0x532DCAC: toplev::main(int, char**) (toplev.c:2118)
by 0x4DE76AF: gcc::jit::playback::context::compile() (jit-playback.c:1615)
by 0x4DD76DA: gcc::jit::recording::context::compile() (jit-recording.c:861)
by 0x4DD5BD2: gcc_jit_context_compile (libgccjit.c:2014)
by 0x401DC4: test_jit (harness.h:190)
136 bytes in 4 blocks are definitely lost in loss record 129 of 209
at 0x4A0645D: malloc (in
/usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
by 0x5D76417: xmalloc (xmalloc.c:147)
by 0x532BE28: init_asm_output(char const*) (toplev.c:936)
by 0x532DB34: lang_dependent_init(char const*) (toplev.c:1795)
by 0x532E0CC: do_compile() (toplev.c:2006)
by 0x532E3B0: toplev::main(int, char**) (toplev.c:2117)
by 0x4DE7983: gcc::jit::playback::context::compile() (jit-playback.c:1646)
by 0x4DD791A: gcc::jit::recording::context::compile() (jit-recording.c:861)
by 0x4DD5E12: gcc_jit_context_compile (libgccjit.c:2014)
by 0x401CA4: test_jit (harness.h:190)
by 0x401D88: main (harness.h:232)
gcc/ChangeLog:
PR jit/63854
* context.c (gcc::context::context): Initialize m_longterm_obstack.
(gcc::context::~context): Free m_longterm_obstack.
(gcc::context::longterm_xalloc): New method.
(gcc::context::longterm_xstrdup): New method.
* context.h: Include obstack.h
(gcc::context::longterm_xalloc): New method.
(gcc::context::longterm_xallocvecT): New method
(gcc::context::longterm_xstrdup): New method.
(gcc::context::m_longterm_obstack): New field.
* toplev.c (init_asm_output): Use g-longterm_xallocvec char
rather than XNEWVEC when allocating dumpname to avoid a leak.
(process_options): Likewise, use g-longterm_xstrdup rather than
xstrdup when allocating name (and hence aux_base_name).
* tree.c: Include context.h.
(build_common_builtin_nodes): When writing dynamically-allocated
entries into built_in_names, use g-longterm_xstrdup to take a
copy of the buffer acquired by concat to avoid a leak.
---
gcc/context.c | 18 ++
gcc/context.h | 46 ++
gcc/toplev.c | 4 ++--
gcc/tree.c| 17 +++--
4 files changed, 77 insertions(+), 8
