[libc] Start to refactor riscv platform abstraction to support both 32 and 64 bits versions

[mikhail.ramalho]

Summary

This patch is the first in a series of patches to refactor the riscv
abstraction in libc to support both riscv32 and riscv64. This patch
enables the compilation of libc with LLVM_LIBC_FULL_BUILD=OFF and libm
disabled. This patch also fixes the strtol test cases so the tests
enabled by this libc configuration are now passing in riscv32 as well.

We updated the cmake file to match the new riscv32 arch and force
LIBC_TARGET_ARCHITECTURE to be "riscv" whenever we find "riscv32" or
"riscv64". This is required as LIBC_TARGET_ARCHITECTURE is used in the
path for several platform specific implementations.

A int get_except() is also added until to allow the compilation in
riscv32, until we implement the platform specific implementation for
this arch.

[mikhail.ramalho]

Renamed dirs riscv64 to riscv

[mikhail.ramalho]

ping

[michaelrj]

Overall LGTM, though are we sure that having the riscv 64 bit and 32 bit targets is the correct path? On other platforms so far we've separated the 32 bit and 64 bit targets.

[sivachandra]

This is fine. But, can you share the status of what works and what does not on riscv32 and also your riscv32 environment?

[mikhail.ramalho]

In D148797#4292915, @michaelrj wrote:

Overall LGTM, though are we sure that having the riscv 64 bit and 32 bit targets is the correct path? On other platforms so far we've separated the 32 bit and 64 bit targets.

My guess is that the code will just work... I believe the only change between the two targets is setjmp/longjmp, where the 64 bits version uses fld, ld, sd, fsd, and the 32 bits will need flw, lw, sw, fsw.

In D148797#4292916, @sivachandra wrote:

This is fine. But, can you share the status of what works and what does not on riscv32 and also your riscv32 environment?

Sure, in the commit message, you mean?

Right now, basic libc should compile, i.e., fullbuild=off and no libm.

For testing, I'm using:

root@qemuriscv32:~# uname -a
Linux qemuriscv32 6.1.20-yocto-standard #1 SMP PREEMPT Sat Mar 18 02:48:04 UTC 2023 riscv32 GNU/Linux

root@qemuriscv32:~# clang -v
clang version 16.0.1 (https://github.com/llvm/llvm-project cd89023f797900e4492da58b7bed36f702120011)
Target: riscv32-poky-linux
Thread model: posix
InstalledDir: /usr/bin
Found candidate GCC installation: /usr/bin/../lib/gcc/riscv32-poky-linux/12.2.0
Found candidate GCC installation: /usr/bin/../lib/riscv32-poky-linux/12.2.0
Selected GCC installation: /usr/bin/../lib/riscv32-poky-linux/12.2.0

For development, I'm using ToT clang.

[sivachandra]

In D148797#4293642, @mikhail.ramalho wrote:

My guess is that the code will just work... I believe the only change between the two targets is setjmp/longjmp, where the 64 bits version uses fld, ld, sd, fsd, and the 32 bits will need flw, lw, sw, fsw.

Are you able to validate your guess with testing?

In D148797#4292916, @sivachandra wrote:

This is fine. But, can you share the status of what works and what does not on riscv32 and also your riscv32 environment?

Sure, in the commit message, you mean?

Yes, in the commit message at the least.

For testing, I'm using:

root@qemuriscv32:~# uname -a
Linux qemuriscv32 6.1.20-yocto-standard #1 SMP PREEMPT Sat Mar 18 02:48:04 UTC 2023 riscv32 GNU/Linux

Can you start a discourse thread with detailed instructions on how to setup the riscv32 emulator? Or, feel free to send a riscv focused doc patch - we will figure out where and how exactly to land it during the review.

[mikhail.ramalho]

Are you able to validate your guess with testing?

For the current code, yes. I'm currently changing the floating-point code to properly handle UInt<128> and so far it's working properly. I'm not sure about the code when libc_full=ON is enabled but I'm only foreseeing the setjmp/longjmp issue I've mentioned.

I can send a bigger patch when both riscv32/64 are enabled if you fell that's a better approach.

Can you start a discourse thread with detailed instructions on how to setup the riscv32 emulator? Or, feel free to send a riscv focused doc patch - we will figure out where and how exactly to land it during the review.

Sure, I was planning to write a blog post about it too soon.

[mikhail.ramalho]

• Added details about the current status of the riscv32 port in the commit message
• Added LIBC_TARGET_ARCH_IS_ANY_RISCV and fix a syscall infinite recursion

[sivachandra]

This change LGTM in general. But, I would like to have instructions on how to test this before I accept it. Couple of reasons:

1. We want to have an estimate for the public CI.
2. Since this patch is unifying riscv64 and riscv32, I want to see how much of riscv32 actually works. Things like, if a riscv64 change does not work for riscv32, would we require that the contributor/patch author block on riscv32 changes?

[mikhail.ramalho]

Fixed strtol tests to pass in riscv32

[mikhail.ramalho]

• Fixed wrong define
• Rebased

[mikhail.ramalho]

Changed some defines to LIBC_TARGET_ARCH_IS_ANY_RISCV

[sivachandra]

In D148797#4299288, @sivachandra wrote:

This change LGTM in general. But, I would like to have instructions on how to test this before I accept it. Couple of reasons:

1. We want to have an estimate for the public CI.
2. Since this patch is unifying riscv64 and riscv32, I want to see how much of riscv32 actually works. Things like, if a riscv64 change does not work for riscv32, would we require that the contributor/patch author block on riscv32 changes?

I would like to see answers to the above questions before we can take this patch forward.

[mikhail.ramalho]

In D148797#4299288, @sivachandra wrote:

This change LGTM in general. But, I would like to have instructions on how to test this before I accept it. Couple of reasons:

1. We want to have an estimate for the public CI.

Sorry, I didn't understand the question. What do you mean by that?

2. Since this patch is unifying riscv64 and riscv32, I want to see how much of riscv32 actually works. Things like, if a riscv64 change does not work for riscv32, would we require that the contributor/patch author block on riscv32 changes?

So far most of the changes needed to port the code to rv32 are related to either UInt<128> not playing nice with the rest of the code or the need to use alternative syscalls (usually with the suffix 64). Once the current patches land, all the test cases with LIBC_FULL=OFF will pass.

Except for the assembly in longjmp/setjmp, the rest of the code should just work in rv32.

[michaelrj]

Every platform we support gets broken occasionally by patches that forget to take it into account. Without buildbots telling us when the platform is broken, then we can't fix it. An example for this would be the arm32 failing to update for several months and our strtol tests breaking on it, leading to this patch: https://reviews.llvm.org/D151935.
For this reason we require anyone adding a new platform to demonstrate their plan for supporting that platform through CI. You can look at the "CI Builders" section on this page for more details: https://libc.llvm.org/porting.html

[mikhail.ramalho]

Rebased

[mikhail.ramalho]

@sivachandra @michaelrj I'm working with @asb to bring a rv32 buildbot up this week.

I created a script that will copy all the test cases + test data to an rv32 image running on qemu, and then use CMake's -DCROSSCOMPILING flag to run the tests.

On my machine, it takes around 20 min to run ninja check-libc, but since the bots only do ninja libc-integration-tests, ninja libc-api-test, and ninja libc-unit-tests, each run should be faster than that.

May I ask if this addresses your comments? We'll need this patch + D158033 + D150211 to get rv32 compilation working.

[michaelrj]

If you have a plan for your buildbot then I think we can add RISC-V 32 as a supported platform. I've added some comments on this patch, but since I will be OOO soon I won't be able to give final approval.

libc/src/__support/OSUtil/linux/syscall.h

23 ↗

(On Diff #548235)

are syscalls exactly the same for RISC-V 32 and 64? If not, is it worthwhile to keep these separate?

libc/test/src/math/exhaustive/CMakeLists.txt

24 ↗

(On Diff #548235)

why do these all need atomic?

[mikhail.ramalho]

In D148797#4596926, @michaelrj wrote:

If you have a plan for your buildbot then I think we can add RISC-V 32 as a supported platform. I've added some comments on this patch, but since I will be OOO soon I won't be able to give final approval.

We should probably have it running by next week, I already submitted the required changes to llvm-zorg. It will be on staging for now, until we are sure that it's working properly.

libc/src/__support/OSUtil/linux/syscall.h

23 ↗

(On Diff #548235)

Do you mean the syscall numbers? The ones defined in syscall_numbers.h.inc?

If so, they are all guarded by the corresponding #ifdef __NR_*... This riscv/syscall.h file only defines the macros to call the syscalls.

libc/test/src/math/exhaustive/CMakeLists.txt

24 ↗

(On Diff #548235)

They were failing with a missing atomic dependency when using stdout, I'll re-run the tests without it now that we have a new interface for it.

[mikhail.ramalho]

• Make unit test static
• Fix some comments
• Rebased

[mikhail.ramalho]

• rebased

[mikhail.ramalho]

@sivachandra @michaelrj the rv32 buildbot is up on staging now: https://lab.llvm.org/staging/#/console

I believe this addresses the last of your comments for this PR.

[mikhail.ramalho]

Rebased

[mikhail.ramalho]

ping

[michaelrj]

LGTM, thank you for finishing this!

libc/cmake/modules/LLVMLibCArchitectures.cmake

function(get_arch_and_system_from_triple triple arch_var sys_var)
   elseif(target_arch MATCHES "^aarch64")
     set(target_arch "aarch64")
   elseif(target_arch MATCHES "(x86_64)|(AMD64|amd64)|(^i.86$)")
     set(target_arch "x86_64")
   elseif(target_arch MATCHES "^(powerpc|ppc)")
     set(target_arch "power")
   elseif(target_arch MATCHES "^riscv64")
     set(target_arch "riscv64")
+  elseif(target_arch MATCHES "^riscv32")
+    set(target_arch "riscv32")
   else()
     return()
   endif()
 
   set(${arch_var} ${target_arch} PARENT_SCOPE)
   list(GET triple_comps ${system_index} target_sys)
 
   # Correcting OS name for Apple's systems.

 if(LIBC_TARGET_ARCHITECTURE STREQUAL "arm")
   set(LIBC_TARGET_ARCHITECTURE_IS_ARM TRUE)
 elseif(LIBC_TARGET_ARCHITECTURE STREQUAL "aarch64")
   set(LIBC_TARGET_ARCHITECTURE_IS_AARCH64 TRUE)
 elseif(LIBC_TARGET_ARCHITECTURE STREQUAL "x86_64")
   set(LIBC_TARGET_ARCHITECTURE_IS_X86 TRUE)
 elseif(LIBC_TARGET_ARCHITECTURE STREQUAL "riscv64")
   set(LIBC_TARGET_ARCHITECTURE_IS_RISCV64 TRUE)
+  set(LIBC_TARGET_ARCHITECTURE "riscv")
+elseif(LIBC_TARGET_ARCHITECTURE STREQUAL "riscv32")
+  set(LIBC_TARGET_ARCHITECTURE_IS_RISCV32 TRUE)
+  set(LIBC_TARGET_ARCHITECTURE "riscv")
 else()
   message(FATAL_ERROR
           "Unsupported libc target architecture ${LIBC_TARGET_ARCHITECTURE}")
 endif()
 
 if(LIBC_TARGET_OS STREQUAL "baremetal")
   set(LIBC_TARGET_OS_IS_BAREMETAL TRUE)
 elseif(LIBC_TARGET_OS STREQUAL "linux")

libc/config/linux/riscv/entrypoints.txt

 set(TARGET_LIBC_ENTRYPOINTS
     # ctype.h entrypoints
     libc.src.ctype.isalnum
     libc.src.ctype.isalpha
     libc.src.ctype.isascii
     libc.src.ctype.isblank
     libc.src.ctype.iscntrl
     libc.src.ctype.isdigit
     libc.src.ctype.isgraph
     libc.src.ctype.islower
     libc.src.ctype.isprint
     libc.src.ctype.ispunct
     libc.src.ctype.isspace
     libc.src.ctype.isupper
     libc.src.ctype.isxdigit
     libc.src.ctype.toascii
     libc.src.ctype.tolower
     libc.src.ctype.toupper
 
     # errno.h entrypoints
     libc.src.errno.errno
 
     # fcntl.h entrypoints
     libc.src.fcntl.creat
     libc.src.fcntl.open
     libc.src.fcntl.openat
 
     # sched.h entrypoints
     libc.src.sched.sched_getaffinity
     libc.src.sched.sched_setaffinity
     libc.src.sched.sched_yield
 
     # string.h entrypoints
     libc.src.string.bcmp
     libc.src.string.bcopy
     libc.src.string.bzero
     libc.src.string.index
     libc.src.string.memccpy
     libc.src.string.memchr
     libc.src.string.memcmp
     libc.src.string.memcpy
     libc.src.string.memmem
     libc.src.string.memmove
     libc.src.string.mempcpy
     libc.src.string.memrchr
     libc.src.string.memset
     libc.src.string.rindex
     libc.src.string.stpcpy
     libc.src.string.stpncpy
     libc.src.string.strcasecmp
     libc.src.string.strcasestr
     libc.src.string.strcat
     libc.src.string.strchr
     libc.src.string.strchrnul
     libc.src.string.strcmp
     libc.src.string.strcoll
     libc.src.string.strcpy
     libc.src.string.strcspn
     libc.src.string.strdup
     libc.src.string.strerror
     libc.src.string.strerror_r
     libc.src.string.strlcat
     libc.src.string.strlcpy
     libc.src.string.strlen
     libc.src.string.strncasecmp
     libc.src.string.strncat
     libc.src.string.strncmp
     libc.src.string.strncpy
     libc.src.string.strndup
     libc.src.string.strnlen
     libc.src.string.strpbrk
     libc.src.string.strrchr
     libc.src.string.strsep
     libc.src.string.strsignal
     libc.src.string.strspn
     libc.src.string.strstr
     libc.src.string.strtok
     libc.src.string.strtok_r
     libc.src.string.strxfrm
 
     # inttypes.h entrypoints
     libc.src.inttypes.imaxabs
     libc.src.inttypes.imaxdiv
     libc.src.inttypes.strtoimax
     libc.src.inttypes.strtoumax
 
     # stdlib.h entrypoints
     libc.src.stdlib.abs
     libc.src.stdlib.atoi
     libc.src.stdlib.atof
     libc.src.stdlib.atol
     libc.src.stdlib.atoll
     libc.src.stdlib.bsearch
     libc.src.stdlib.div
     libc.src.stdlib.labs
     libc.src.stdlib.ldiv
     libc.src.stdlib.llabs
     libc.src.stdlib.lldiv
     libc.src.stdlib.qsort
     libc.src.stdlib.rand
     libc.src.stdlib.srand
     libc.src.stdlib.strtod
     libc.src.stdlib.strtof
     libc.src.stdlib.strtol
     libc.src.stdlib.strtold
     libc.src.stdlib.strtoll
     libc.src.stdlib.strtoul
     libc.src.stdlib.strtoull
 
     # stdlib.h external entrypoints
     libc.src.stdlib.malloc
     libc.src.stdlib.calloc
     libc.src.stdlib.realloc
     libc.src.stdlib.aligned_alloc
     libc.src.stdlib.free
 
     # stdio.h entrypoints
     libc.src.stdio.remove
     libc.src.stdio.sprintf
     libc.src.stdio.snprintf
     libc.src.stdio.fprintf
     libc.src.stdio.printf
 
     # sys/mman.h entrypoints
     libc.src.sys.mman.madvise
     libc.src.sys.mman.mmap
     libc.src.sys.mman.mprotect
     libc.src.sys.mman.munmap
     libc.src.sys.mman.posix_madvise
 
     # sys/random.h entrypoints
     libc.src.sys.random.getrandom
 
     # sys/resource.h entrypoints
     libc.src.sys.resource.getrlimit
     libc.src.sys.resource.setrlimit
 
     # sys/sendfile entrypoints
     libc.src.sys.sendfile.sendfile
 
     # sys/stat.h entrypoints
     libc.src.sys.stat.chmod
     libc.src.sys.stat.fchmod
     libc.src.sys.stat.fchmodat
     libc.src.sys.stat.fstat
     libc.src.sys.stat.lstat
     libc.src.sys.stat.mkdir
     libc.src.sys.stat.mkdirat
     libc.src.sys.stat.stat
 
     # sys/utsname.h entrypoints
     libc.src.sys.utsname.uname
 
     # sys/wait.h entrypoints
     libc.src.sys.wait.wait
     libc.src.sys.wait.wait4
     libc.src.sys.wait.waitpid
 
     # termios.h entrypoints
     libc.src.termios.cfgetispeed
     libc.src.termios.cfgetospeed
     libc.src.termios.cfsetispeed
     libc.src.termios.cfsetospeed
     libc.src.termios.tcgetattr
     libc.src.termios.tcgetsid
     libc.src.termios.tcdrain
     libc.src.termios.tcflow
     libc.src.termios.tcflush
     libc.src.termios.tcsendbreak
     libc.src.termios.tcsetattr
 
     # unistd.h entrypoints
     libc.src.unistd.access
     libc.src.unistd.chdir
     libc.src.unistd.close
     libc.src.unistd.dup
     libc.src.unistd.dup2
     libc.src.unistd.dup3
     libc.src.unistd.execve
     libc.src.unistd.fchdir
     libc.src.unistd.fsync
     libc.src.unistd.ftruncate
     libc.src.unistd.getcwd
     libc.src.unistd.geteuid
     libc.src.unistd.getpid
     libc.src.unistd.getppid
     libc.src.unistd.getuid
     libc.src.unistd.isatty
     libc.src.unistd.link
     libc.src.unistd.linkat
     libc.src.unistd.lseek
     libc.src.unistd.pread
     libc.src.unistd.pwrite
     libc.src.unistd.read
     libc.src.unistd.readlink
     libc.src.unistd.readlinkat
     libc.src.unistd.rmdir
     libc.src.unistd.symlink
     libc.src.unistd.symlinkat
     libc.src.unistd.sysconf
     libc.src.unistd.truncate
     libc.src.unistd.unlink
     libc.src.unistd.unlinkat
     libc.src.unistd.write
 
     # wchar.h entrypoints
     libc.src.wchar.wctob
 )
 
 set(TARGET_LIBM_ENTRYPOINTS
     # fenv.h entrypoints
     libc.src.fenv.feclearexcept
     libc.src.fenv.fedisableexcept
     libc.src.fenv.feenableexcept
     libc.src.fenv.fegetenv
     libc.src.fenv.fegetexcept
     libc.src.fenv.fegetexceptflag
     libc.src.fenv.fegetround
     libc.src.fenv.feholdexcept
     libc.src.fenv.fesetenv
     libc.src.fenv.fesetexceptflag
     libc.src.fenv.fesetround
     libc.src.fenv.feraiseexcept
     libc.src.fenv.fetestexcept
     libc.src.fenv.feupdateenv
 
     # math.h entrypoints
     libc.src.math.acosf
     libc.src.math.acoshf
     libc.src.math.asin
     libc.src.math.asinf
     libc.src.math.asinhf
     libc.src.math.atanf
     libc.src.math.atanhf
     libc.src.math.copysign
     libc.src.math.copysignf
     libc.src.math.copysignl
     libc.src.math.ceil
     libc.src.math.ceilf
     libc.src.math.ceill
     libc.src.math.coshf
     libc.src.math.cosf
     libc.src.math.expf
     libc.src.math.exp10f
     libc.src.math.exp2f
     libc.src.math.expm1f
     libc.src.math.fabs
     libc.src.math.fabsf
     libc.src.math.fabsl
     libc.src.math.fdim
     libc.src.math.fdimf
     libc.src.math.fdiml
     libc.src.math.floor
     libc.src.math.floorf
     libc.src.math.floorl
     libc.src.math.fma
     libc.src.math.fmaf
     libc.src.math.fmin
     libc.src.math.fminf
     libc.src.math.fminl
     libc.src.math.fmax
     libc.src.math.fmaxf
     libc.src.math.fmaxl
     libc.src.math.fmod
     libc.src.math.fmodf
     libc.src.math.frexp
     libc.src.math.frexpf
     libc.src.math.frexpl
     libc.src.math.hypot
     libc.src.math.hypotf
     libc.src.math.ilogb
     libc.src.math.ilogbf
     libc.src.math.ilogbl
     libc.src.math.ldexp
     libc.src.math.ldexpf
     libc.src.math.ldexpl
     libc.src.math.llrint
     libc.src.math.llrintf
     libc.src.math.llrintl
     libc.src.math.llround
     libc.src.math.llroundf
     libc.src.math.llroundl
     libc.src.math.log10f
     libc.src.math.log1pf
     libc.src.math.log2f
     libc.src.math.logf
     libc.src.math.logb
     libc.src.math.logbf
     libc.src.math.logbl
     libc.src.math.lrint
     libc.src.math.lrintf
     libc.src.math.lrintl
     libc.src.math.lround
     libc.src.math.lroundf
     libc.src.math.lroundl
     libc.src.math.modf
     libc.src.math.modff
     libc.src.math.modfl
     libc.src.math.nearbyint
     libc.src.math.nearbyintf
     libc.src.math.nearbyintl
     libc.src.math.nextafter
     libc.src.math.nextafterf
     libc.src.math.nextafterl
     libc.src.math.pow
     libc.src.math.remainderf
     libc.src.math.remainder
     libc.src.math.remainderl
     libc.src.math.remquof
     libc.src.math.remquo
     libc.src.math.remquol
     libc.src.math.rint
     libc.src.math.rintf
     libc.src.math.rintl
     libc.src.math.round
     libc.src.math.roundf
     libc.src.math.roundl
     libc.src.math.scalbn
     libc.src.math.scalbnf
     libc.src.math.scalbnl
     libc.src.math.sincosf
     libc.src.math.sinhf
     libc.src.math.sinf
     libc.src.math.sqrt
     libc.src.math.sqrtf
     libc.src.math.sqrtl
     libc.src.math.tanf
     libc.src.math.tanhf
     libc.src.math.trunc
     libc.src.math.truncf
     libc.src.math.truncl
 )
 
 if(LLVM_LIBC_FULL_BUILD)
   list(APPEND TARGET_LIBC_ENTRYPOINTS
     # assert.h entrypoints
     libc.src.assert.__assert_fail
 
     # network.h entrypoints
     libc.src.network.htonl
     libc.src.network.htons
     libc.src.network.ntohl
     libc.src.network.ntohs
 
     # pthread.h entrypoints
     libc.src.pthread.pthread_atfork
     libc.src.pthread.pthread_attr_destroy
     libc.src.pthread.pthread_attr_init
     libc.src.pthread.pthread_attr_getdetachstate
     libc.src.pthread.pthread_attr_getguardsize
     libc.src.pthread.pthread_attr_getstack
     libc.src.pthread.pthread_attr_getstacksize
     libc.src.pthread.pthread_attr_setdetachstate
     libc.src.pthread.pthread_attr_setguardsize
     libc.src.pthread.pthread_attr_setstack
     libc.src.pthread.pthread_attr_setstacksize
     libc.src.pthread.pthread_create
     libc.src.pthread.pthread_detach
     libc.src.pthread.pthread_equal
     libc.src.pthread.pthread_exit
     libc.src.pthread.pthread_getname_np
     libc.src.pthread.pthread_getspecific
     libc.src.pthread.pthread_join
     libc.src.pthread.pthread_key_create
     libc.src.pthread.pthread_key_delete
     libc.src.pthread.pthread_self
     libc.src.pthread.pthread_setname_np
     libc.src.pthread.pthread_mutex_destroy
     libc.src.pthread.pthread_mutex_init
     libc.src.pthread.pthread_mutex_lock
     libc.src.pthread.pthread_mutex_unlock
     libc.src.pthread.pthread_mutexattr_destroy
     libc.src.pthread.pthread_mutexattr_init
     libc.src.pthread.pthread_mutexattr_getpshared
     libc.src.pthread.pthread_mutexattr_getrobust
     libc.src.pthread.pthread_mutexattr_gettype
     libc.src.pthread.pthread_mutexattr_setpshared
     libc.src.pthread.pthread_mutexattr_setrobust
     libc.src.pthread.pthread_mutexattr_settype
     libc.src.pthread.pthread_once
     libc.src.pthread.pthread_setspecific
 
     # sched.h entrypoints
     libc.src.sched.__sched_getcpucount
 
     # setjmp.h entrypoints
     libc.src.setjmp.longjmp
     libc.src.setjmp.setjmp
 
     # stdio.h entrypoints
     libc.src.stdio.clearerr
     libc.src.stdio.clearerr_unlocked
     libc.src.stdio.fclose
     libc.src.stdio.flockfile
     libc.src.stdio.feof
     libc.src.stdio.feof_unlocked
     libc.src.stdio.ferror
     libc.src.stdio.ferror_unlocked
     libc.src.stdio.fgetc
     libc.src.stdio.fgetc_unlocked
     libc.src.stdio.fgets
     libc.src.stdio.fflush
     libc.src.stdio.fopen
     libc.src.stdio.fputc
     libc.src.stdio.fputs
     libc.src.stdio.fopencookie
     libc.src.stdio.fread
     libc.src.stdio.fread_unlocked
     libc.src.stdio.fseek
     libc.src.stdio.ftell
     libc.src.stdio.funlockfile
     libc.src.stdio.fwrite
     libc.src.stdio.fwrite_unlocked
     libc.src.stdio.getc
     libc.src.stdio.getc_unlocked
     libc.src.stdio.getchar
     libc.src.stdio.getchar_unlocked
     libc.src.stdio.printf
     libc.src.stdio.sscanf
     libc.src.stdio.scanf
     libc.src.stdio.fscanf
     libc.src.stdio.putc
     libc.src.stdio.putchar
     libc.src.stdio.puts
     libc.src.stdio.setbuf
     libc.src.stdio.setvbuf
     libc.src.stdio.stderr
     libc.src.stdio.stdin
     libc.src.stdio.stdout
     libc.src.stdio.ungetc
 
     # stdlib.h entrypoints
     libc.src.stdlib._Exit
     libc.src.stdlib.abort
     libc.src.stdlib.atexit
     libc.src.stdlib.exit
     libc.src.stdlib.getenv
 
     # signal.h entrypoints
     libc.src.signal.raise
     libc.src.signal.kill
     libc.src.signal.sigaction
     libc.src.signal.sigaltstack
     libc.src.signal.sigdelset
     libc.src.signal.sigaddset
     libc.src.signal.sigemptyset
     libc.src.signal.sigprocmask
     libc.src.signal.sigfillset
     libc.src.signal.signal
 
     # spawn.h entrypoints
     libc.src.spawn.posix_spawn
     libc.src.spawn.posix_spawn_file_actions_addclose
     libc.src.spawn.posix_spawn_file_actions_adddup2
     libc.src.spawn.posix_spawn_file_actions_addopen
     libc.src.spawn.posix_spawn_file_actions_destroy
     libc.src.spawn.posix_spawn_file_actions_init
 
     # threads.h entrypoints
     libc.src.threads.call_once
     libc.src.threads.cnd_broadcast
     libc.src.threads.cnd_destroy
     libc.src.threads.cnd_init
     libc.src.threads.cnd_signal
     libc.src.threads.cnd_wait
     libc.src.threads.mtx_destroy
     libc.src.threads.mtx_init
     libc.src.threads.mtx_lock
     libc.src.threads.mtx_unlock
     libc.src.threads.thrd_create
     libc.src.threads.thrd_current
     libc.src.threads.thrd_detach
     libc.src.threads.thrd_equal
     libc.src.threads.thrd_exit
     libc.src.threads.thrd_join
     libc.src.threads.tss_create
     libc.src.threads.tss_delete
     libc.src.threads.tss_get
     libc.src.threads.tss_set
 
     # time.h entrypoints
     libc.src.time.asctime
     libc.src.time.asctime_r
     libc.src.time.clock_gettime
     libc.src.time.clock
     libc.src.time.difftime
     libc.src.time.gettimeofday
     libc.src.time.gmtime
     libc.src.time.gmtime_r
     libc.src.time.mktime
     libc.src.time.nanosleep
     libc.src.time.time
 
     # unistd.h entrypoints
     libc.src.unistd.environ
     libc.src.unistd.execv
     libc.src.unistd.fork
     libc.src.unistd.__llvm_libc_syscall
     libc.src.unistd.getopt
     libc.src.unistd.optarg
     libc.src.unistd.optind
     libc.src.unistd.optopt
     libc.src.unistd.opterr
     libc.src.unistd.swab
 
     # sys/select.h entrypoints
     libc.src.sys.select.select
   )
 endif()
 
 set(TARGET_LLVMLIBC_ENTRYPOINTS
   ${TARGET_LIBC_ENTRYPOINTS}
   ${TARGET_LIBM_ENTRYPOINTS}
 )

libc/config/linux/riscv/headers.txt

 set(TARGET_PUBLIC_HEADERS
     libc.include.assert
     libc.include.ctype
     libc.include.errno
     libc.include.fcntl
     libc.include.fenv
     libc.include.inttypes
     libc.include.math
     libc.include.pthread
     libc.include.sched
     libc.include.signal
     libc.include.spawn
     libc.include.setjmp
     libc.include.stdio
     libc.include.stdlib
     libc.include.string
     libc.include.strings
     libc.include.termios
     libc.include.threads
     libc.include.time
     libc.include.unistd
     libc.include.wchar
 
     libc.include.arpa_inet
 
     libc.include.sys_auxv
     libc.include.sys_ioctl
     libc.include.sys_mman
     libc.include.sys_prctl
     libc.include.sys_random
     libc.include.sys_resource
     libc.include.sys_select
     libc.include.sys_socket
     libc.include.sys_stat
     libc.include.sys_syscall
     libc.include.sys_time
     libc.include.sys_types
     libc.include.sys_utsname
     libc.include.sys_wait
 )

libc/src/__support/FPUtil/FEnvImpl.h

 namespace __llvm_libc::fputil {
 
 // All dummy functions silently succeed.
 
 LIBC_INLINE int clear_except(int) { return 0; }
 
 LIBC_INLINE int test_except(int) { return 0; }
 
+LIBC_INLINE int get_except() { return 0; }
+
 LIBC_INLINE int set_except(int) { return 0; }
 
 LIBC_INLINE int raise_except(int) { return 0; }
 
 LIBC_INLINE int enable_except(int) { return 0; }
 
 LIBC_INLINE int disable_except(int) { return 0; }