aarch64, Darwin, libgcc: Add support for aarch64 darwin.

1. libgcc, aarch64, Darwin: Initial libgcc boiler-plate changes.

Initial changes to build libgcc for aarch64 Darwin (declare the port,
handle Mach-O assembler syntax and arrange for building the main extra
pieces).

2. libgcc, aarch64, Darwin: Do not build legacy EH shim.

Darwin aarch64 does not exist for macOS 10.6, so there is no need to
build a shim to target it.

Signed-off-by: Iain Sandoe <iain@sandoe.co.uk>

libgcc/

	* config.host: Omit the Darwin10 unwinder shim for aarch64 Darwin.

3. libgcc, aarch64, Darwin: Darwin should use an OS call to clear caches.

The sys_icache_invalidate() function is the right one to use.

The fixes issue #17

4. libgcc, aarch64, Darwin: Enable heap trampolines.

gcc/config/aarch64/aarch64.cc

@@ -28575,7 +28575,7 @@ aarch64_libgcc_floating_mode_supported_p
 
 /* The architecture reserves bits 0 and 1 so use bit 2 for descriptors.  */
 #undef TARGET_CUSTOM_FUNCTION_DESCRIPTORS
-#define TARGET_CUSTOM_FUNCTION_DESCRIPTORS 4
+#define TARGET_CUSTOM_FUNCTION_DESCRIPTORS AARCH64_CUSTOM_FUNCTION_TEST
 
 #undef TARGET_HARD_REGNO_NREGS
 #define TARGET_HARD_REGNO_NREGS aarch64_hard_regno_nregs

gcc/config/aarch64/aarch64.h

@@ -146,6 +146,12 @@
 /* Heap alignment (same as BIGGEST_ALIGNMENT and STACK_BOUNDARY).  */
 #define MALLOC_ABI_ALIGNMENT  128
 
+/* We will and with this value to test if a custom function descriptor needs
+   a static chain.  The function boundary must the adjusted so that the bit
+   this represents is no longer part of the address.  0 Disables the custom
+   function descriptors.  */
+#define AARCH64_CUSTOM_FUNCTION_TEST 4
+
 /* Defined by the ABI */
 #define WCHAR_TYPE "unsigned int"
 #define WCHAR_TYPE_SIZE			32

gcc/config/aarch64/darwin.h

@@ -54,6 +54,10 @@ along with GCC; see the file COPYING3.  If not see
 #undef LONG_DOUBLE_TYPE_SIZE
 #define LONG_DOUBLE_TYPE_SIZE	64
 
+/* Disable custom function descriptors on Darwin, it breaks ABI.  */
+#undef AARCH64_CUSTOM_FUNCTION_TEST
+#define AARCH64_CUSTOM_FUNCTION_TEST 0
+
 /* Non-PIE executables are forbidden by the aarch64-darwin security model;
    remove the option from link-lines since they just produce a warning from
    ld64 and are then ignored anyway.  */
@@ -268,3 +272,8 @@ along with GCC; see the file COPYING3.  If not see
 #define SYMBOL_FLAG_SUBT_DEP (SYMBOL_FLAG_MACH_DEP)
 
 #undef ASM_OUTPUT_DEF_FROM_DECLS
+
+#undef CLEAR_INSN_CACHE
+#define CLEAR_INSN_CACHE(beg, end)				\
+  extern void sys_icache_invalidate(void *start, size_t len);	\
+  sys_icache_invalidate ((beg), (size_t)((end)-(beg)))

libgcc/config.host

@@ -82,7 +82,7 @@ m32c*-*-*)
         cpu_type=m32c
 	tmake_file=t-fdpbit
         ;;
-aarch64*-*-*)
+aarch64*-*-* | arm64*-*-*)
 	cpu_type=aarch64
 	;;
 alpha*-*-*)
@@ -272,7 +272,7 @@ case ${host} in
       echo "Warning: libgcc configured to support macOS 10.5" 1>&2
       ;;
   esac
-  extra_parts="crt3.o libd10-uwfef.a crttms.o crttme.o libemutls_w.a"
+  extra_parts="crt3.o crttms.o crttme.o libemutls_w.a"
   ;;
 *-*-dragonfly*)
   tmake_file="$tmake_file t-crtstuff-pic t-libgcc-pic t-eh-dw2-dip"
@@ -416,6 +416,16 @@ aarch64*-*-elf | aarch64*-*-rtems*)
 	tmake_file="${tmake_file} t-dfprules"
 	md_unwind_header=aarch64/aarch64-unwind.h
 	;;
+aarch64*-*-darwin*)
+	extra_parts="$extra_parts crtfastmath.o"
+	tmake_file="${tmake_file} ${cpu_type}/t-lse "
+	tmake_file="${tmake_file} t-crtfm"
+	# No soft float for now because our long double is DF not TF.
+	md_unwind_header=aarch64/aarch64-unwind.h
+	if test x$off_stack_trampolines = xyes; then
+	    tmake_file="${tmake_file} ${cpu_type}/t-heap-trampoline"
+	fi
+	;;
 aarch64*-*-freebsd*)
 	extra_parts="$extra_parts crtfastmath.o"
 	tmake_file="${tmake_file} ${cpu_type}/t-aarch64"
@@ -715,11 +725,13 @@ hppa*-*-netbsd*)
 i[34567]86-*-darwin*)
 	tmake_file="$tmake_file i386/t-crtpc t-crtfm i386/t-msabi"
 	tm_file="$tm_file i386/darwin-lib.h"
+	extra_parts="$extra_parts libd10-uwfef.a "
 	extra_parts="$extra_parts crtprec32.o crtprec64.o crtprec80.o crtfastmath.o"
 	;;
 x86_64-*-darwin*)
 	tmake_file="$tmake_file i386/t-crtpc t-crtfm i386/t-msabi"
 	tm_file="$tm_file i386/darwin-lib.h"
+	extra_parts="$extra_parts libd10-uwfef.a "
 	extra_parts="$extra_parts crtprec32.o crtprec64.o crtprec80.o crtfastmath.o"
 	if test x$off_stack_trampolines = xyes; then
 	    tmake_file="${tmake_file} i386/t-heap-trampoline"
@@ -1195,12 +1207,14 @@ powerpc-*-darwin*)
 	# We build the darwin10 EH shim for Rosetta (running on x86 machines).
 	tm_file="$tm_file i386/darwin-lib.h"
 	tmake_file="$tmake_file rs6000/t-ppc64-fp rs6000/t-ibm-ldouble"
+	extra_parts="$extra_parts libd10-uwfef.a "
 	extra_parts="$extra_parts crt2.o crt3_2.o libef_ppc.a dw_ppc.o"
 	;;
 powerpc64-*-darwin*)
 	# We build the darwin10 EH shim for Rosetta (running on x86 machines).
 	tm_file="$tm_file i386/darwin-lib.h"
 	tmake_file="$tmake_file rs6000/t-darwin64 rs6000/t-ibm-ldouble"
+	extra_parts="$extra_parts libd10-uwfef.a "
 	extra_parts="$extra_parts crt2.o crt3_2.o libef_ppc.a dw_ppc.o"
 	;;
 powerpc*-*-freebsd*)

libgcc/config/aarch64/lse.S

@@ -58,7 +58,11 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 #endif
 
 /* Declare the symbol gating the LSE implementations.  */
+#if __ELF__
 	.hidden	__aarch64_have_lse_atomics
+#else
+	.private_extern	__aarch64_have_lse_atomics
+#endif
 
 /* Turn size and memory model defines into mnemonic fragments.  */
 #if SIZE == 1
@@ -164,6 +168,7 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 #define BTI_C	hint	34
 
 /* Start and end a function.  */
+#if __ELF__
 .macro	STARTFN name
 	.text
 	.balign	16
@@ -187,6 +192,29 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 	cbz	w(tmp0), \label
 .endm
 
+#else
+.macro	STARTFN name
+	.text
+	.balign	16
+	.private_extern	_\name
+	.cfi_startproc
+_\name:
+	BTI_C
+.endm
+
+.macro	ENDFN name
+	.cfi_endproc
+.endm
+
+/* Branch to LABEL if LSE is disabled.  */
+.macro	JUMP_IF_NOT_LSE label
+	adrp	x(tmp0), ___aarch64_have_lse_atomics@PAGE
+	ldrb	w(tmp0), [x(tmp0), ___aarch64_have_lse_atomics@PAGEOFF]
+	cbz	w(tmp0), \label
+.endm
+
+#endif
+
 #ifdef L_cas
 
 STARTFN	NAME(cas)

libgcc/config/aarch64/t-darwin

@@ -0,0 +1,7 @@
+# FIXME: decide what we need here, or delete this file.
+
+HOST_LIBGCC2_CFLAGS += -mmacosx-version-min=11.0
+
+LIB2_SIDITI_CONV_FUNCS = yes
+
+BUILD_LIBGCCS1 =