aarch64: Add support for Go closures

src/aarch64/ffi.c

@@ -539,13 +539,14 @@ ffi_status ffi_prep_cif_machdep_var(ffi_cif *cif,
 #endif /* __APPLE__ */
 
 extern void ffi_call_SYSV (struct call_context *context, void *frame,
-			   void (*fn)(void), void *rvalue, int flags)
-	FFI_HIDDEN;
+			   void (*fn)(void), void *rvalue, int flags,
+			   void *closure) FFI_HIDDEN;
 
 /* Call a function with the provided arguments and capture the return
    value.  */
-void
-ffi_call (ffi_cif *cif, void (*fn)(void), void *orig_rvalue, void **avalue)
+static void
+ffi_call_int (ffi_cif *cif, void (*fn)(void), void *orig_rvalue,
+	      void **avalue, void *closure)
 {
   struct call_context *context;
   void *stack, *frame, *rvalue;
@@ -698,12 +699,27 @@ ffi_call (ffi_cif *cif, void (*fn)(void), void *orig_rvalue, void **avalue)
 #endif
     }
 
-  ffi_call_SYSV (context, frame, fn, rvalue, flags);
+  ffi_call_SYSV (context, frame, fn, rvalue, flags, closure);
 
   if (flags & AARCH64_RET_NEED_COPY)
     memcpy (orig_rvalue, rvalue, rtype_size);
 }
 
+void
+ffi_call (ffi_cif *cif, void (*fn) (void), void *rvalue, void **avalue)
+{
+  ffi_call_int (cif, fn, rvalue, avalue, NULL);
+}
+
+#ifdef FFI_GO_CLOSURES
+void
+ffi_call_go (ffi_cif *cif, void (*fn) (void), void *rvalue,
+	     void **avalue, void *closure)
+{
+  ffi_call_int (cif, fn, rvalue, avalue, closure);
+}
+#endif /* FFI_GO_CLOSURES */
+
 /* Build a trampoline.  */
 
 extern void ffi_closure_SYSV (void) FFI_HIDDEN;
@@ -744,6 +760,32 @@ ffi_prep_closure_loc (ffi_closure *closure,
   return FFI_OK;
 }
 
+#ifdef FFI_GO_CLOSURES
+extern void ffi_go_closure_SYSV (void) FFI_HIDDEN;
+extern void ffi_go_closure_SYSV_V (void) FFI_HIDDEN;
+
+ffi_status
+ffi_prep_go_closure (ffi_go_closure *closure, ffi_cif* cif,
+                     void (*fun)(ffi_cif*,void*,void**,void*))
+{
+  void (*start)(void);
+
+  if (cif->abi != FFI_SYSV)
+    return FFI_BAD_ABI;
+
+  if (cif->flags & AARCH64_FLAG_ARG_V)
+    start = ffi_go_closure_SYSV_V;
+  else
+    start = ffi_go_closure_SYSV;
+
+  closure->tramp = start;
+  closure->cif = cif;
+  closure->fun = fun;
+
+  return FFI_OK;
+}
+#endif /* FFI_GO_CLOSURES */
+
 /* Primary handler to setup and invoke a function within a closure.
 
    A closure when invoked enters via the assembler wrapper

src/aarch64/ffitarget.h

@@ -50,6 +50,10 @@ typedef enum ffi_abi
 #if defined (__APPLE__)
 #define FFI_TARGET_SPECIFIC_VARIADIC
 #define FFI_EXTRA_CIF_FIELDS unsigned aarch64_nfixedargs
+#else
+/* iOS reserves x18 for the system.  Disable Go closures until
+   a new static chain is chosen.  */
+#define FFI_GO_CLOSURES 1
 #endif
 
 #define FFI_TARGET_HAS_COMPLEX_TYPE

src/aarch64/sysv.S

@@ -50,7 +50,8 @@ SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.  */
 
 /* ffi_call_SYSV
    extern void ffi_call_SYSV (void *stack, void *frame,
-			      void (*fn)(void), void *rvalue, int flags);
+			      void (*fn)(void), void *rvalue,
+			      int flags, void *closure);
 
    Therefore on entry we have:
 
@@ -59,6 +60,7 @@ SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.  */
    x2 fn
    x3 rvalue
    x4 flags
+   x5 closure
 */
 
 	cfi_startproc
@@ -74,6 +76,9 @@ CNAME(ffi_call_SYSV):
 
 	mov	x9, x2			/* save fn */
 	mov	x8, x3			/* install structure return */
+#ifdef FFI_GO_CLOSURES
+	mov	x18, x5			/* install static chain */
+#endif
 	stp	x3, x4, [x29, #16]	/* save rvalue and flags */
 
 	/* Load the vector argument passing registers, if necessary.  */
@@ -245,6 +250,7 @@ CNAME(ffi_closure_SYSV):
 	/* Load ffi_closure_inner arguments.  */
 	ldp	x0, x1, [x17, #FFI_TRAMPOLINE_SIZE]	/* load cif, fn */
 	ldr	x2, [x17, #FFI_TRAMPOLINE_SIZE+16]	/* load user_data */
+.Ldo_closure:
 	add	x3, sp, #16				/* load context */
 	add	x4, sp, #ffi_closure_SYSV_FS		/* load stack */
 	add	x5, sp, #16+CALL_CONTEXT_SIZE		/* load rvalue */
@@ -336,3 +342,57 @@ CNAME(ffi_closure_SYSV):
 	.hidden	CNAME(ffi_closure_SYSV)
 	.size	CNAME(ffi_closure_SYSV), . - CNAME(ffi_closure_SYSV)
 #endif
+
+#ifdef FFI_GO_CLOSURES
+	.align 4
+CNAME(ffi_go_closure_SYSV_V):
+	cfi_startproc
+	stp     x29, x30, [sp, #-ffi_closure_SYSV_FS]!
+	cfi_adjust_cfa_offset (ffi_closure_SYSV_FS)
+	cfi_rel_offset (x29, 0)
+	cfi_rel_offset (x30, 8)
+
+	/* Save the argument passing vector registers.  */
+	stp     q0, q1, [sp, #16 + 0]
+	stp     q2, q3, [sp, #16 + 32]
+	stp     q4, q5, [sp, #16 + 64]
+	stp     q6, q7, [sp, #16 + 96]
+	b	0f
+	cfi_endproc
+
+	.globl	CNAME(ffi_go_closure_SYSV_V)
+#ifdef __ELF__
+	.type	CNAME(ffi_go_closure_SYSV_V), #function
+	.hidden	CNAME(ffi_go_closure_SYSV_V)
+	.size	CNAME(ffi_go_closure_SYSV_V), . - CNAME(ffi_go_closure_SYSV_V)
+#endif
+
+	.align	4
+	cfi_startproc
+CNAME(ffi_go_closure_SYSV):
+	stp     x29, x30, [sp, #-ffi_closure_SYSV_FS]!
+	cfi_adjust_cfa_offset (ffi_closure_SYSV_FS)
+	cfi_rel_offset (x29, 0)
+	cfi_rel_offset (x30, 8)
+0:
+	mov     x29, sp
+
+	/* Save the argument passing core registers.  */
+	stp     x0, x1, [sp, #16 + 16*N_V_ARG_REG + 0]
+	stp     x2, x3, [sp, #16 + 16*N_V_ARG_REG + 16]
+	stp     x4, x5, [sp, #16 + 16*N_V_ARG_REG + 32]
+	stp     x6, x7, [sp, #16 + 16*N_V_ARG_REG + 48]
+
+	/* Load ffi_closure_inner arguments.  */
+	ldp	x0, x1, [x18, #8]			/* load cif, fn */
+	mov	x2, x18					/* load user_data */
+	b	.Ldo_closure
+	cfi_endproc
+
+	.globl	CNAME(ffi_go_closure_SYSV)
+#ifdef __ELF__
+	.type	CNAME(ffi_go_closure_SYSV), #function
+	.hidden	CNAME(ffi_go_closure_SYSV)
+	.size	CNAME(ffi_go_closure_SYSV), . - CNAME(ffi_go_closure_SYSV)
+#endif
+#endif /* FFI_GO_CLOSURES */