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authorAndi Kleen <ak@linux.intel.com>2011-09-29 13:14:51 +0000
committerAndi Kleen <ak@gcc.gnu.org>2011-09-29 13:14:51 +0000
commitdde8b3609b40a5e9073a7638d492b8c29af2e24c (patch)
tree572521c2983256f9fae580c8be83c1898f33a849 /gcc/cp/repo.c
parent4056cc1ba5e5590529b257a12f80270d552019b9 (diff)
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Change random seeds to 64bit and drop re-crcing
I had some trouble with random build failures in a large LTO project and it turned out to be random seed collisions in a highly parallel build (thanks to Honza for suggesting that) There were multiple problems: - The way to generate the random seed is not very random (milliseconds time plus pid) and prone to collisions on highly parallel builds - It's only 32bit - Several users take the existing ascii seed and re-CRC32 it again, which doesn't exactly improve it. This patch changes that to: - Always use 64bit seeds as numbers (no re-crcing) - Change all users to use HOST_WIDE_INT - When the user specifies a random seed it's still crc32ed, but only in this case. Passes bootstrap + testsuite on x86_64-linux. gcc/cp: 2011-09-26 Andi Kleen <ak@linux.intel.com> * repo.c (finish_repo): Use HOST_WIDE_INT_PRINT_HEX_PURE. gcc/: 2011-09-26 Andi Kleen <ak@linux.intel.com> * hwint.h (HOST_WIDE_INT_PRINT_HEX_PURE): Add. * lto-streamer.c (lto_get_section_name): Remove crc32_string. Handle numerical random seed. * lto-streamer.h (lto_file_decl_data): Change id to unsigned HOST_WIDE_INT. * toplev.c (random_seed): Add. (init_random_seed): Change for numerical random seed. (get_random_seed): Return as HOST_WIDE_INT. (set_random_seed): Crc32 existing string. * toplev.h (get_random_seed): Change to numercal return. * tree.c (get_file_function_name): Remove CRC. Handle numerical random seed. gcc/lto/: 2011-09-26 Andi Kleen <ak@linux.intel.com> * lto.c (lto_resolution_read): Remove id dumping. (lto_section_with_id): Turn id HOST_WIDE_ID. (create_subid_section_table): Dito. From-SVN: r179347
Diffstat (limited to 'gcc/cp/repo.c')
-rw-r--r--gcc/cp/repo.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/gcc/cp/repo.c b/gcc/cp/repo.c
index 16a192e..ca971b6 100644
--- a/gcc/cp/repo.c
+++ b/gcc/cp/repo.c
@@ -263,7 +263,8 @@ finish_repo (void)
anonymous namespaces will get the same mangling when this
file is recompiled. */
if (!strstr (args, "'-frandom-seed="))
- fprintf (repo_file, " '-frandom-seed=%s'", get_random_seed (false));
+ fprintf (repo_file, " '-frandom-seed=" HOST_WIDE_INT_PRINT_HEX_PURE "'",
+ get_random_seed (false));
fprintf (repo_file, "\n");
}