From a6adb2bcd8145353943377d6119c1d7a4242bae1 Mon Sep 17 00:00:00 2001 From: Rich Felker Date: Wed, 16 Jul 2014 21:32:06 -0400 Subject: work around constant folding bug 61144 in gcc 4.9.0 and 4.9.1 previously we detected this bug in configure and issued advice for a workaround, but this turned out not to work. since then gcc 4.9.0 has appeared in several distributions, and now 4.9.1 has been released without a fix despite this being a wrong code generation bug which is supposed to be a release-blocker, per gcc policy. since the scope of the bug seems to affect only data objects (rather than functions) whose definitions are overridable, and there are only a very small number of these in musl, I am just changing them from const to volatile for the time being. simply removing the const would be sufficient to make gcc 4.9.1 work (the non-const case was inadvertently fixed as part of another change in gcc), and this would also be sufficient with 4.9.0 if we forced -O0 on the affected files or on the whole build. however it's cleaner to just remove all the broken compiler detection and use volatile, which will ensure that they are never constant-folded. the quality of a non-broken compiler's output should not be affected except for the fact that these objects are no longer const and thus possibly add a few bytes to data/bss. this change can be reconsidered and possibly reverted at some point in the future when the broken gcc versions are no longer relevant. --- src/thread/pthread_create.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'src/thread/pthread_create.c') diff --git a/src/thread/pthread_create.c b/src/thread/pthread_create.c index 64151254..e77e54a5 100644 --- a/src/thread/pthread_create.c +++ b/src/thread/pthread_create.c @@ -116,12 +116,12 @@ static int start(void *p) #define ROUND(x) (((x)+PAGE_SIZE-1)&-PAGE_SIZE) /* pthread_key_create.c overrides this */ -static const size_t dummy = 0; +static volatile size_t dummy = 0; weak_alias(dummy, __pthread_tsd_size); -static void *const dummy_tsd[1] = { 0 }; +static void *dummy_tsd[1] = { 0 }; weak_alias(dummy_tsd, __pthread_tsd_main); -static FILE *const dummy_file = 0; +static FILE *volatile dummy_file = 0; weak_alias(dummy_file, __stdin_used); weak_alias(dummy_file, __stdout_used); weak_alias(dummy_file, __stderr_used); -- cgit v1.2.1