Compilers have a bad habit of removing "superfluous" memset calls that
are trying to zero memory. For example, when memset()ing a buffer and
then free()ing it, the compiler might decide that the memset is
unobservable and thus can be removed.
Previously we tried to stop this by a) implementing memset in assembly
on x86 and b) putting the function in its own file for other platforms.
This change removes those tricks in favour of using asm directives to
scare the compiler away. As best as our compiler folks can tell, this is
sufficient and will continue to be so.
Change-Id: I40e0a62c3043038bafd8c63a91814a75a3c59269
Reviewed-on: https://boringssl-review.googlesource.com/1339
Reviewed-by: David Benjamin <davidben@chromium.org>
Reviewed-by: Adam Langley <agl@google.com>
Apart from the obvious little issues, this also works around a
(seeming) libtool/linker:
a.c defines a symbol:
int kFoo;
b.c uses it:
extern int kFoo;
int f() {
return kFoo;
}
compile them:
$ gcc -c a.c
$ gcc -c b.c
and create a dummy main in order to run it, main.c:
int f();
int main() {
return f();
}
this works as expected:
$ gcc main.c a.o b.o
but, if we make an archive:
$ ar q lib.a a.o b.o
and use that:
$ gcc main.c lib.a
Undefined symbols for architecture x86_64
"_kFoo", referenced from:
_f in lib.a(b.o)
(It doesn't matter what order the .o files are put into the .a)
Linux and Windows don't seem to have this problem.
nm on a.o shows that the symbol is of type "C", which is a "common symbol"[1].
Basically the linker will merge multiple common symbol definitions together.
If ones makes a.c read:
int kFoo = 0;
Then one gets a type "D" symbol - a "data section symbol" and everything works
just fine.
This might actually be a libtool bug instead of an ld bug: Looking at `xxd
lib.a | less`, the __.SYMDEF SORTED index at the beginning of the archive
doesn't contain an entry for kFoo unless initialised.
Change-Id: I4cdad9ba46e9919221c3cbd79637508959359427
Now that the consuming code in ssl/ is removed, there is no need for this.
Leave SSL_COMP and STACK_OF(SSL_COMP) for now so as not to break any code which
manipulates the output of SSL_COMP_get_compression_methods to disable
compression.
Change-Id: Idf0a5debd96589ef6e7e56acf5d9259412b7d7a1
Initial fork from f2d678e6e89b6508147086610e985d4e8416e867 (1.0.2 beta).
(This change contains substantial changes from the original and
effectively starts a new history.)
