[PATCH] Avoid variable length arrays and remove declarations within code
Mike Hommey
mh+jemalloc at glandium.org
Tue Apr 24 14:22:02 PDT 2012
From: Mike Hommey <mh at glandium.org>
MSVC doesn't support C99, and building as C++ to be able to use them is
dangerous, as C++ and C99 are incompatible.
Introduce a VARIABLE_ARRAY macro that either uses VLA when supported,
or alloca() otherwise. Note that using alloca() inside loops doesn't
quite work like VLAs, thus the use of VARIABLE_ARRAY there is discouraged.
It might be worth investigating ways to check whether VARIABLE_ARRAY is
used in such context at runtime in debug builds and bail out if that
happens.
---
include/jemalloc/internal/jemalloc_internal.h.in | 14 ++++++++++++++
include/jemalloc/internal/prof.h | 3 ++-
src/arena.c | 18 ++++++++++--------
src/ctl.c | 4 ++--
src/stats.c | 4 ++--
src/tsd.c | 2 +-
test/bitmap.c | 16 ++++++++++++----
7 files changed, 43 insertions(+), 18 deletions(-)
diff --git a/include/jemalloc/internal/jemalloc_internal.h.in b/include/jemalloc/internal/jemalloc_internal.h.in
index 691f50a..dcc17c8 100644
--- a/include/jemalloc/internal/jemalloc_internal.h.in
+++ b/include/jemalloc/internal/jemalloc_internal.h.in
@@ -319,6 +319,20 @@ static const bool config_ivsalloc =
#define ALIGNMENT_CEILING(s, alignment) \
(((s) + (alignment - 1)) & (-(alignment)))
+/* Declare a variable length array */
+#if __STDC_VERSION__ < 199901L
+#ifdef _MSC_VER
+#include <malloc.h>
+#define alloca _alloca
+#else
+#include <alloca.h>
+#endif
+#define VARIABLE_ARRAY(name, type, size) \
+ type *name = alloca(sizeof(type) * size)
+#else
+#define VARIABLE_ARRAY(name, type, size) type name[size]
+#endif
+
#ifdef JEMALLOC_VALGRIND
/*
* The JEMALLOC_VALGRIND_*() macros must be macros rather than functions
diff --git a/include/jemalloc/internal/prof.h b/include/jemalloc/internal/prof.h
index 093ac93..e091478 100644
--- a/include/jemalloc/internal/prof.h
+++ b/include/jemalloc/internal/prof.h
@@ -526,8 +526,9 @@ prof_free(const void *ptr, size_t size)
cassert(config_prof);
if ((uintptr_t)ctx > (uintptr_t)1) {
+ prof_thr_cnt_t *tcnt;
assert(size == isalloc(ptr, true));
- prof_thr_cnt_t *tcnt = prof_lookup(ctx->bt);
+ tcnt = prof_lookup(ctx->bt);
if (tcnt != NULL) {
tcnt->epoch++;
diff --git a/src/arena.c b/src/arena.c
index f13b5e1..7fac361 100644
--- a/src/arena.c
+++ b/src/arena.c
@@ -640,14 +640,14 @@ arena_chunk_purge(arena_t *arena, arena_chunk_t *chunk)
if (mapelm->bits & CHUNK_MAP_LARGE)
pageind += mapelm->bits >> LG_PAGE;
else {
+ size_t binind;
+ arena_bin_info_t *bin_info;
arena_run_t *run = (arena_run_t *)((uintptr_t)
chunk + (uintptr_t)(pageind << LG_PAGE));
assert((mapelm->bits >> LG_PAGE) == 0);
- size_t binind = arena_bin_index(arena,
- run->bin);
- arena_bin_info_t *bin_info =
- &arena_bin_info[binind];
+ binind = arena_bin_index(arena, run->bin);
+ bin_info = &arena_bin_info[binind];
pageind += bin_info->run_size >> LG_PAGE;
}
}
@@ -1056,11 +1056,12 @@ arena_bin_runs_first(arena_bin_t *bin)
if (mapelm != NULL) {
arena_chunk_t *chunk;
size_t pageind;
+ arena_run_t *run;
chunk = (arena_chunk_t *)CHUNK_ADDR2BASE(mapelm);
pageind = ((((uintptr_t)mapelm - (uintptr_t)chunk->map) /
sizeof(arena_chunk_map_t))) + map_bias;
- arena_run_t *run = (arena_run_t *)((uintptr_t)chunk +
+ run = (arena_run_t *)((uintptr_t)chunk +
(uintptr_t)((pageind - (mapelm->bits >> LG_PAGE)) <<
LG_PAGE));
return (run);
@@ -1596,14 +1597,15 @@ arena_dalloc_bin(arena_t *arena, arena_chunk_t *chunk, void *ptr,
size_t pageind;
arena_run_t *run;
arena_bin_t *bin;
- size_t size;
+ arena_bin_info_t *bin_info;
+ size_t size, binind;
pageind = ((uintptr_t)ptr - (uintptr_t)chunk) >> LG_PAGE;
run = (arena_run_t *)((uintptr_t)chunk + (uintptr_t)((pageind -
(mapelm->bits >> LG_PAGE)) << LG_PAGE));
bin = run->bin;
- size_t binind = arena_bin_index(arena, bin);
- arena_bin_info_t *bin_info = &arena_bin_info[binind];
+ binind = arena_bin_index(arena, bin);
+ bin_info = &arena_bin_info[binind];
if (config_fill || config_stats)
size = bin_info->reg_size;
diff --git a/src/ctl.c b/src/ctl.c
index 4dbbefc..122e84e 100644
--- a/src/ctl.c
+++ b/src/ctl.c
@@ -520,7 +520,7 @@ static void
ctl_refresh(void)
{
unsigned i;
- arena_t *tarenas[narenas];
+ VARIABLE_ARRAY(tarenas, arena_t *, narenas);
if (config_stats) {
malloc_mutex_lock(&chunks_mtx);
@@ -1233,7 +1233,7 @@ arenas_purge_ctl(const size_t *mib, size_t miblen, void *oldp, size_t *oldlenp,
ret = EFAULT;
goto label_return;
} else {
- arena_t *tarenas[narenas];
+ VARIABLE_ARRAY(tarenas, arena_t *, narenas);
malloc_mutex_lock(&arenas_lock);
memcpy(tarenas, arenas, sizeof(arena_t *) * narenas);
diff --git a/src/stats.c b/src/stats.c
index 08f7098..3b5df44 100644
--- a/src/stats.c
+++ b/src/stats.c
@@ -498,7 +498,7 @@ stats_print(void (*write_cb)(void *, const char *), void *cbopaque,
CTL_GET("arenas.narenas", &narenas, unsigned);
{
- bool initialized[narenas];
+ VARIABLE_ARRAY(initialized, bool, narenas);
size_t isz;
unsigned i, ninitialized;
@@ -527,7 +527,7 @@ stats_print(void (*write_cb)(void *, const char *), void *cbopaque,
CTL_GET("arenas.narenas", &narenas, unsigned);
{
- bool initialized[narenas];
+ VARIABLE_ARRAY(initialized, bool, narenas);
size_t isz;
unsigned i;
diff --git a/src/tsd.c b/src/tsd.c
index 09f06e8..d7714b0 100644
--- a/src/tsd.c
+++ b/src/tsd.c
@@ -36,7 +36,7 @@ JEMALLOC_ATTR(visibility("default"))
void
_malloc_thread_cleanup(void)
{
- bool pending[ncleanups], again;
+ bool pending[MALLOC_TSD_CLEANUPS_MAX], again;
unsigned i;
for (i = 0; i < ncleanups; i++)
diff --git a/test/bitmap.c b/test/bitmap.c
index ff50ecb..b2cb630 100644
--- a/test/bitmap.c
+++ b/test/bitmap.c
@@ -30,11 +30,13 @@ test_bitmap_init(void)
bitmap_info_init(&binfo, i);
{
size_t j;
- bitmap_t bitmap[bitmap_info_ngroups(&binfo)];
+ bitmap_t *bitmap = malloc(sizeof(bitmap_t) *
+ bitmap_info_ngroups(&binfo));
bitmap_init(bitmap, &binfo);
for (j = 0; j < i; j++)
assert(bitmap_get(bitmap, &binfo, j) == false);
+ free(bitmap);
}
}
@@ -50,12 +52,14 @@ test_bitmap_set(void)
bitmap_info_init(&binfo, i);
{
size_t j;
- bitmap_t bitmap[bitmap_info_ngroups(&binfo)];
+ bitmap_t *bitmap = malloc(sizeof(bitmap_t) *
+ bitmap_info_ngroups(&binfo));
bitmap_init(bitmap, &binfo);
for (j = 0; j < i; j++)
bitmap_set(bitmap, &binfo, j);
assert(bitmap_full(bitmap, &binfo));
+ free(bitmap);
}
}
}
@@ -70,7 +74,8 @@ test_bitmap_unset(void)
bitmap_info_init(&binfo, i);
{
size_t j;
- bitmap_t bitmap[bitmap_info_ngroups(&binfo)];
+ bitmap_t *bitmap = malloc(sizeof(bitmap_t) *
+ bitmap_info_ngroups(&binfo));
bitmap_init(bitmap, &binfo);
for (j = 0; j < i; j++)
@@ -81,6 +86,7 @@ test_bitmap_unset(void)
for (j = 0; j < i; j++)
bitmap_set(bitmap, &binfo, j);
assert(bitmap_full(bitmap, &binfo));
+ free(bitmap);
}
}
}
@@ -95,7 +101,8 @@ test_bitmap_sfu(void)
bitmap_info_init(&binfo, i);
{
ssize_t j;
- bitmap_t bitmap[bitmap_info_ngroups(&binfo)];
+ bitmap_t *bitmap = malloc(sizeof(bitmap_t) *
+ bitmap_info_ngroups(&binfo));
bitmap_init(bitmap, &binfo);
/* Iteratively set bits starting at the beginning. */
@@ -125,6 +132,7 @@ test_bitmap_sfu(void)
}
assert(bitmap_sfu(bitmap, &binfo) == i - 1);
assert(bitmap_full(bitmap, &binfo));
+ free(bitmap);
}
}
}
--
1.7.10
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