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| author | Jason Evans <jasone@canonware.com> | 2014-01-21 22:59:40 (GMT) |
|---|---|---|
| committer | Jason Evans <jasone@canonware.com> | 2014-01-21 22:59:40 (GMT) |
| commit | 898960247a8b2e6534738b7a3a244855f379faf9 (patch) | |
| tree | 015c344cb5cabbf7362707f5600d37563425c2ed | |
| parent | e2206edebcce662e3979c68ba182d0bcf38141ba (diff) | |
| download | jemalloc-898960247a8b2e6534738b7a3a244855f379faf9.zip jemalloc-898960247a8b2e6534738b7a3a244855f379faf9.tar.gz jemalloc-898960247a8b2e6534738b7a3a244855f379faf9.tar.bz2 | |
Subvert tail call optimization in backtrace test.
Re-structure alloc_[01](), which are mutually tail-recursive functions,
to do (unnecessary) work post-recursion so that the compiler cannot
perform tail call optimization, thus preserving intentionally unique
call paths in captured backtraces.
| -rw-r--r-- | test/unit/prof_accum.c | 28 |
1 files changed, 17 insertions, 11 deletions
diff --git a/test/unit/prof_accum.c b/test/unit/prof_accum.c index b5f1c8d..cf3f287 100644 --- a/test/unit/prof_accum.c +++ b/test/unit/prof_accum.c @@ -28,18 +28,24 @@ static void *alloc_##n(unsigned bits); static void * \ alloc_##n(unsigned bits) \ { \ + void *p; \ \ - if (bits == 0) { \ - void *p = mallocx(1, 0); \ - assert_ptr_not_null(p, "Unexpected mallocx() failure"); \ - return (p); \ - } \ - \ - switch (bits & 0x1U) { \ - case 0: return (alloc_0(bits >> 1)); \ - case 1: return (alloc_1(bits >> 1)); \ - default: not_reached(); \ + if (bits == 0) \ + p = mallocx(1, 0); \ + else { \ + switch (bits & 0x1U) { \ + case 0: \ + p = alloc_0(bits >> 1); \ + break; \ + case 1: \ + p = alloc_1(bits >> 1); \ + break; \ + default: not_reached(); \ + } \ } \ + /* Intentionally sabotage tail call optimization. */ \ + assert_ptr_not_null(p, "Unexpected mallocx() failure"); \ + return (p); \ } alloc_n_proto(0) alloc_n_proto(1) @@ -74,7 +80,7 @@ thd_start(void *varg) i+1 == NALLOCS_PER_THREAD) { bt_count = prof_bt_count(); assert_zu_le(bt_count_prev+(i-i_prev), bt_count, - "Expected larger bactrace count increase"); + "Expected larger backtrace count increase"); i_prev = i; bt_count_prev = bt_count; } |