Use the iOS ABI when running SIMARM on Mac or targeting iOS.

runtime/vm/globals.h

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef VM_GLOBALS_H_
 #define VM_GLOBALS_H_
 
 // This file contains global definitions for the VM library only. Anything that
 // is more globally useful should be added to 'vm/globals.h'.
 
@@ skipping 91 matching lines @@
 #endif
 
 #else  // !defined(TARGET_OS_WINDOWS))
 
 // Assume GCC-like inline syntax is valid.
 #if defined(HOST_ARCH_IA32)
 #define COPY_FP_REGISTER(fp) asm volatile ("movl %%ebp, %0" : "=r" (fp) );
 #elif defined(HOST_ARCH_X64)
 #define COPY_FP_REGISTER(fp) asm volatile ("movq %%rbp, %0" : "=r" (fp) );
 #elif defined(HOST_ARCH_ARM)
+#  if defined(TARGET_OS_MAC)
+#define COPY_FP_REGISTER(fp) asm volatile ("mov %0, r7" : "=r" (fp) );
+#  else
 #define COPY_FP_REGISTER(fp) asm volatile ("mov %0, r11" : "=r" (fp) );
+#  endif
 #elif defined(HOST_ARCH_ARM64)
 #define COPY_FP_REGISTER(fp) asm volatile ("mov %0, x29" : "=r" (fp) );
 #elif defined(HOST_ARCH_MIPS)
 #define COPY_FP_REGISTER(fp) asm volatile ("move %0, $fp" : "=r" (fp) );
 #else
 #error Unknown host architecture.
 #endif
 
 
 #endif  // !defined(TARGET_OS_WINDOWS))
 
 }  // namespace dart
 
 #endif  // VM_GLOBALS_H_