- 11 9月, 2012 7 次提交
-
-
由 Rich Felker 提交于
by using the "ir" constraint (immediate or register) and the carefully constructed instruction addu $2,$0,%2 which can take either an immediate or a register for %2, the new inline asm admits maximal optimization with no register spillage to the stack when the compiler successfully performs constant propagration, but still works by allocating a register when the syscall number cannot be recognized as a constant. in the case of syscalls with 0-3 arguments it barely matters, but for 4-argument syscalls, using an immediate for the syscall number avoids creating a stack frame for the syscall wrapper function.
-
由 Rich Felker 提交于
all past and current kernel versions have done so, but there seems to be no reason it's necessary and the sentiment from everyone I've asked has been that we should not rely on it. instead, use r7 (an argument register) which will necessarily be preserved upon syscall restart. however this only works for 0-3 argument syscalls, and we have to resort to the function call for 4-argument syscalls.
-
由 Rich Felker 提交于
for the sake of simplicity, I've only used rep movsb rather than breaking up the copy for using rep movsd/q. on all modern cpus, this seems to be fine, but if there are performance problems, there might be a need to go back and add support for rep movsd/q.
-
由 Rich Felker 提交于
-
由 Rich Felker 提交于
before restrict was added, memove called memcpy for forward copies and used a byte-at-a-time loop for reverse copies. this was changed to avoid invoking UB now that memcpy has an undefined copying order, making memmove considerably slower. performance is still rather bad, so I'll be adding asm soon.
-
由 Rich Felker 提交于
-
由 Rich Felker 提交于
this should both fix the issue with ARM needing -lgcc_eh (although that's really a bug in the libgcc build process that's causing considerable bloat, which should be fixed) and make it easier to build musl using clang/llvm in place of gcc. unfortunately I don't know a good way to detect and support pcc's -lpcc since it's not in pcc's default library search path...
-
- 10 9月, 2012 8 次提交
-
-
由 Rich Felker 提交于
-
由 Rich Felker 提交于
-
由 Rich Felker 提交于
-
由 Rich Felker 提交于
-
由 Rich Felker 提交于
-
由 Rich Felker 提交于
-
由 Rich Felker 提交于
-
由 Rich Felker 提交于
no syscalls actually use that many arguments; the issue is that some syscalls with 64-bit arguments have them ordered badly so that breaking them into aligned 32-bit half-arguments wastes slots with padding, and a 7th slot is needed for the last argument.
-
- 09 9月, 2012 12 次提交
-
-
由 Rich Felker 提交于
most pure-syscall-wrapper functions compile to the smallest/simplest code possible (save r7 ; load syscall # ; svc 0 ; restore r7 ; tail call to __syscall_ret).
-
由 Rich Felker 提交于
this drastically reduces the size of some functions which are purely syscall wrappers. disabled for clang due to known bugs satisfying register constraints.
-
由 Rich Felker 提交于
-
由 Rich Felker 提交于
this code was using $10 to save the syscall number, but $10 is not necessarily preserved by the kernel across syscalls. only mattered for syscalls that got interrupted by a signal and restarted. as far as i can tell, $25 is preserved by the kernel across syscalls.
-
由 Rich Felker 提交于
something is wrong with the logic for the argument layout, resulting in compile errors on mips due to too many args to syscall... further information on how it's supposed to work will be needed before it can be reactivated.
-
由 Rich Felker 提交于
now public syscall.h only exposes __NR_* and SYS_* constants and the variadic syscall function. no macros or inline functions, no __syscall_ret or other internal details, no 16-/32-bit legacy syscall renaming, etc. this logic has all been moved to src/internal/syscall.h with the arch-specific parts in arch/$(ARCH)/syscall_arch.h, and the amount of arch-specific stuff has been reduced to a minimum. changes still need to be reviewed/double-checked. minimal testing on i386 and mips has already been performed.
-
由 Rich Felker 提交于
-
由 Rich Felker 提交于
based on patch by Justin Cormack
-
由 Rich Felker 提交于
-
由 Rich Felker 提交于
-
由 Rich Felker 提交于
not sure why this was missed in the earlier commit.
-
由 Rich Felker 提交于
-
- 08 9月, 2012 13 次提交
-
-
由 Rich Felker 提交于
-
由 Rich Felker 提交于
-
由 Rich Felker 提交于
-
由 Rich Felker 提交于
-
由 Rich Felker 提交于
-
由 Rich Felker 提交于
this is equivalent to posix_fallocate except that it has an extra mode/flags argument to control its behavior, and stores the error in errno rather than returning an error code.
-
由 Rich Felker 提交于
the syscall takes an extra flag argument which should be zero to meet the POSIX requirements.
-
由 Rich Felker 提交于
-
由 Rich Felker 提交于
features.h contains the fallback logic for pre-C11 compilers
-
由 Rich Felker 提交于
-
由 Rich Felker 提交于
-
由 Rich Felker 提交于
the old behavior of exposing nothing except plain ISO C can be obtained by defining __STRICT_ANSI__ or using a compiler option (such as -std=c99) that predefines it. the new default featureset is POSIX with XSI plus _BSD_SOURCE. any explicit feature test macros will inhibit the default. installation docs have also been updated to reflect this change.
-
由 Rich Felker 提交于
clang does not presently support the "v" constraint we want to use to get the result from $3, and trying to use register...__asm__("$3") to do the same invokes serious compiler bugs. so for now, i'm working around the issue with an extra temp register and putting $3 in the clobber list instead of using it as output. when the bugs in clang are fixed, this issue should be revisited to generate smaller/faster code like what gcc gets.
-