De-pessimize SigSetConverter usage.
While looking at the disassembly for the epoll stuff I noticed that this
expands to quite a lot of code that the compiler can't optimize out for
LP64 (because it doesn't know that the "copy the argument into a local
and then use the local" bit isn't important).
There are two obvious options here. Something like this:
```
int signalfd64(int fd, const sigset64_t* mask, int flags) {
return __signalfd4(fd, mask, sizeof(*mask), flags);
}
int signalfd(int fd, const sigset_t* mask, int flags) {
#if defined(__LP64__)
return signalfd64(fd, mask, flags);
#else
SigSetConverter set = {.sigset = *mask};
return signalfd64(fd, &set.sigset64, flags);
#endif
}
```
Or something like this:
```
int signalfd64(int fd, const sigset64_t* mask, int flags) {
return __signalfd4(fd, mask, sizeof(*mask), flags);
}
#if defined(__LP64__)
__strong_alias(signalfd, signalfd64);
#else
int signalfd(int fd, const sigset_t* mask, int flags) {
SigSetConverter set = {};
set.sigset = *mask;
return signalfd64(fd, &set.sigset64, flags);
}
#endif
```
The former is slightly more verbose, but seems a bit more obvious, so I
initially went with that. (The former is more verbose in the generated
code too, given that the latter expands to _no_ code, just another symbol
pointing to the same code address.)
Having done that, I realized that slight changes to the interface would
let clang optimize away most/all of the overhead for LP64 with the only
preprocessor hackery being in SigSetConverter itself.
I also pulled out the legacy bsd `int` conversions since they're only
used in two (secret!) functions, so it's clearer to just have a separate
union for them. While doing so, I suppressed those functions for
riscv64, since there's no reason to keep carrying that mistake forward.
posix_spawn() is another simple case that doesn't actually benefit from
SigSetConverter, so I've given that its own anonymous union too.
Test: treehugger
Change-Id: Iaf67486da40d40fc53ec69717c3492ab7ab81ad6
diff --git a/libc/bionic/spawn.cpp b/libc/bionic/spawn.cpp
index 5d76f77..38f99ad 100644
--- a/libc/bionic/spawn.cpp
+++ b/libc/bionic/spawn.cpp
@@ -41,7 +41,6 @@
#include <android/fdsan.h>
#include "private/ScopedSignalBlocker.h"
-#include "private/SigSetConverter.h"
static int set_cloexec(int i) {
int v = fcntl(i, F_GETFD);
@@ -131,8 +130,10 @@
pid_t pgroup;
sched_param schedparam;
int schedpolicy;
- SigSetConverter sigmask;
- SigSetConverter sigdefault;
+ union {
+ sigset_t sigset;
+ sigset64_t sigset64;
+ } sigmask, sigdefault;
};
static void ApplyAttrs(short flags, const posix_spawnattr_t* attr) {