Add atomic and bswap functions to libcompiler_rt

There have been several mentions on our mailing lists about missing
atomic functions in our system libraries (e.g. __atomic_load_8 and
friends), and recently I saw __bswapdi2 and __bswapsi2 mentioned too.

To address this, add implementations for the functions from compiler-rt
to the system compiler support libraries, e.g. libcompiler_rt.a and and
libgcc_s.so.

This also needs a small fixup in compiler-rt's atomic.c, to ensure that
32-bit mips can build correctly.

Bump __FreeBSD_version to make it easier for port maintainers to detect
when these functions were added.

MFC after:	2 weeks
Differential Revision: https://reviews.freebsd.org/D26159

contrib/llvm-project/compiler-rt/lib/builtins/atomic.c

@@ -125,8 +125,8 @@ static __inline Lock *lock_for_pointer(void *ptr) {
 #define IS_LOCK_FREE_2 __c11_atomic_is_lock_free(2)
 #define IS_LOCK_FREE_4 __c11_atomic_is_lock_free(4)
 
-/// 32 bit PowerPC doesn't support 8-byte lock_free atomics
-#if !defined(__powerpc64__) && defined(__powerpc__)
+/// 32 bit MIPS and PowerPC don't support 8-byte lock_free atomics
+#if defined(__mips__) || (!defined(__powerpc64__) && defined(__powerpc__))
 #define IS_LOCK_FREE_8 0
 #else
 #define IS_LOCK_FREE_8 __c11_atomic_is_lock_free(8)

lib/libcompiler_rt/Makefile.inc

@@ -1,5 +1,7 @@
 # $FreeBSD$
 
+.include <bsd.compiler.mk>
+
 CRTARCH=	${MACHINE_CPUARCH:C/amd64/x86_64/}
 
 CRTSRC=		${SRCTOP}/contrib/llvm-project/compiler-rt/lib/builtins
@@ -18,6 +20,9 @@ SRCF+=		ashldi3
 SRCF+=		ashlti3
 SRCF+=		ashrdi3
 SRCF+=		ashrti3
+SRCF+=		atomic
+SRCF+=		bswapdi2
+SRCF+=		bswapsi2
 SRCF+=		clear_cache
 SRCF+=		clzdi2
 SRCF+=		clzsi2
@@ -120,6 +125,10 @@ SRCF+=		umoddi3
 SRCF+=		umodsi3
 SRCF+=		umodti3
 
+.if "${COMPILER_TYPE}" == "clang"
+CFLAGS.atomic.c+=      -Wno-atomic-alignment
+.endif
+
 # Avoid using SSE2 instructions on i386, if unsupported.
 .if ${MACHINE_CPUARCH} == "i386" && empty(MACHINE_CPU:Msse2)
 SRCS+=		floatdidf.c
@@ -212,12 +221,6 @@ CFLAGS+=	-DEMIT_SYNC_ATOMICS
 SRCF+=		stdatomic
 .endif
 
-.if "${COMPILER_TYPE}" == "clang" && \
-    (${MACHINE_ARCH} == "powerpc" || ${MACHINE_ARCH} == "powerpcspe")
-SRCS+=          atomic.c
-CFLAGS.atomic.c+=      -Wno-atomic-alignment
-.endif
-
 .for file in ${SRCF}
 .if ${MACHINE_ARCH:Marmv[67]*} && (!defined(CPUTYPE) || ${CPUTYPE:M*soft*} == "") \
     && exists(${CRTSRC}/${CRTARCH}/${file}vfp.S)
@@ -239,8 +242,6 @@ SRCS+=		aeabi_memmove.S
 SRCS+=		aeabi_memset.S
 SRCS+=		aeabi_uidivmod.S
 SRCS+=		aeabi_uldivmod.S
-SRCS+=		bswapdi2.S
-SRCS+=		bswapsi2.S
 SRCS+=		switch16.S
 SRCS+=		switch32.S
 SRCS+=		switch8.S
@@ -248,12 +249,6 @@ SRCS+=		switchu8.S
 SRCS+=		sync_synchronize.S
 .endif
 
-# On some archs GCC-6.3 requires bswap32 built-in.
-.if ${MACHINE_CPUARCH} == "mips" || ${MACHINE_CPUARCH} == "riscv"
-SRCS+=		bswapdi2.c
-SRCS+=		bswapsi2.c
-.endif
-
 .if ${MACHINE_ARCH:Mriscv*sf}
 CFLAGS+=	-D__SOFT_FP__
 .endif

sys/sys/param.h

@@ -60,7 +60,7 @@
  *		in the range 5 to 9.
  */
 #undef __FreeBSD_version
-#define __FreeBSD_version 1300112	/* Master, propagated to newvers */
+#define __FreeBSD_version 1300113	/* Master, propagated to newvers */
 
 /*
  * __FreeBSD_kernel__ indicates that this system uses the kernel of FreeBSD,