[libc] Add Convenience syscall Template Function

[abrachet]

Summary

This patch adds a convenience template function so we don't need to cast all types to long manually when calling __llvm_libc::syscall.

[gchatelet]

Yeah that would be nice to separate the formatting [NFC] from the template addition. It's hard spot what changed in the file :)

[sivachandra]

Yes, can you please separate the formatting from the actual change?

libc/config/linux/x86_64/syscall.h.inc

 #include "src/__support/common.h"
 
 #define SYSCALL_CLOBBER_LIST "rcx", "r11", "memory"
 
 namespace __llvm_libc {
 
 __attribute__((always_inline)) inline long syscall(long __number) {
   long retcode;
-  LIBC_INLINE_ASM("syscall" :
-             "=a"(retcode) :
-             "a"(__number) :
-             SYSCALL_CLOBBER_LIST);
+  LIBC_INLINE_ASM("syscall"
+                  : "=a"(retcode)
+                  : "a"(__number)
+                  : SYSCALL_CLOBBER_LIST);
   return retcode;
 }
 
 __attribute__((always_inline)) inline long syscall(long __number, long __arg1) {
   long retcode;
-  LIBC_INLINE_ASM("syscall" :
-             "=a"(retcode) :
-             "a"(__number), "D"(__arg1) :
-             SYSCALL_CLOBBER_LIST);
+  LIBC_INLINE_ASM("syscall"
+                  : "=a"(retcode)
+                  : "a"(__number), "D"(__arg1)
+                  : SYSCALL_CLOBBER_LIST);
   return retcode;
 }
 
-__attribute__((always_inline)) inline long syscall(
-    long __number, long __arg1, long __arg2) {
+__attribute__((always_inline)) inline long syscall(long __number, long __arg1,
+                                                   long __arg2) {
   long retcode;
-  LIBC_INLINE_ASM("syscall" :
-             "=a"(retcode) :
-             "a"(__number), "D"(__arg1), "S"(__arg2) :
-             SYSCALL_CLOBBER_LIST);
+  LIBC_INLINE_ASM("syscall"
+                  : "=a"(retcode)
+                  : "a"(__number), "D"(__arg1), "S"(__arg2)
+                  : SYSCALL_CLOBBER_LIST);
   return retcode;
 }
 
-__attribute__((always_inline)) inline long syscall(
-    long __number, long __arg1, long __arg2, long __arg3) {
+__attribute__((always_inline)) inline long syscall(long __number, long __arg1,
+                                                   long __arg2, long __arg3) {
   long retcode;
-  LIBC_INLINE_ASM("syscall" :
-             "=a"(retcode) :
-             "a"(__number), "D"(__arg1), "S"(__arg2), "d"(__arg3) :
-             SYSCALL_CLOBBER_LIST);
+  LIBC_INLINE_ASM("syscall"
+                  : "=a"(retcode)
+                  : "a"(__number), "D"(__arg1), "S"(__arg2), "d"(__arg3)
+                  : SYSCALL_CLOBBER_LIST);
   return retcode;
 }
 
-__attribute__((always_inline)) inline long syscall(
-    long __number, long __arg1, long __arg2, long __arg3, long __arg4) {
+__attribute__((always_inline)) inline long
+syscall(long __number, long __arg1, long __arg2, long __arg3, long __arg4) {
   long retcode;
   register long r10 __asm__("r10") = __arg4;
-  LIBC_INLINE_ASM("syscall" :
-             "=a"(retcode) :
-             "a"(__number), "D"(__arg1), "S"(__arg2), "d"(__arg3), "r"(r10) :
-             SYSCALL_CLOBBER_LIST);
+  LIBC_INLINE_ASM("syscall"
+                  : "=a"(retcode)
+                  : "a"(__number), "D"(__arg1), "S"(__arg2), "d"(__arg3),
+                    "r"(r10)
+                  : SYSCALL_CLOBBER_LIST);
   return retcode;
 }
 
-__attribute__((always_inline)) inline long syscall(
-    long __number, long __arg1, long __arg2, long __arg3, long __arg4,
-    long __arg5) {
+__attribute__((always_inline)) inline long syscall(long __number, long __arg1,
+                                                   long __arg2, long __arg3,
+                                                   long __arg4, long __arg5) {
   long retcode;
   register long r10 __asm__("r10") = __arg4;
   register long r8 __asm__("r8") = __arg5;
-  LIBC_INLINE_ASM(
-      "syscall" :
-      "=a"(retcode) :
-      "a"(__number), "D"(__arg1), "S"(__arg2), "d"(__arg3), "r"(r10), "r"(r8) :
-      SYSCALL_CLOBBER_LIST);
+  LIBC_INLINE_ASM("syscall"
+                  : "=a"(retcode)
+                  : "a"(__number), "D"(__arg1), "S"(__arg2), "d"(__arg3),
+                    "r"(r10), "r"(r8)
+                  : SYSCALL_CLOBBER_LIST);
   return retcode;
 }
 
-__attribute__((always_inline)) inline long syscall(
-    long __number, long __arg1, long __arg2, long __arg3, long __arg4,
-    long __arg5, long __arg6) {
+__attribute__((always_inline)) inline long syscall(long __number, long __arg1,
+                                                   long __arg2, long __arg3,
+                                                   long __arg4, long __arg5,
+                                                   long __arg6) {
   long retcode;
   register long r10 __asm__("r10") = __arg4;
   register long r8 __asm__("r8") = __arg5;
   register long r9 __asm__("r9") = __arg6;
-  LIBC_INLINE_ASM(
-      "syscall" :
-      "=a"(retcode) :
-      "a"(__number), "D"(__arg1), "S"(__arg2), "d"(__arg3), "r"(r10), "r"(r8), "r"(r9) :
-      SYSCALL_CLOBBER_LIST);
+  LIBC_INLINE_ASM("syscall"
+                  : "=a"(retcode)
+                  : "a"(__number), "D"(__arg1), "S"(__arg2), "d"(__arg3),
+                    "r"(r10), "r"(r8), "r"(r9)
+                  : SYSCALL_CLOBBER_LIST);
   return retcode;
 }
 
+template <typename... Ts>
+__attribute__((always_inline)) inline long syscall(long __number, Ts... ts) {
+  static_assert(sizeof...(Ts) <= 6, "Too many arguments for syscall");
+  return syscall(__number, (long)ts...);
+}
+
 #undef SYSCALL_CLOBBER_LIST
 
 } // namespace __llvm_libc