Fix CPU features detection and stack alignment assert on iOS

runtime/vm/cpu_arm.cc

Index: runtime/vm/cpu_arm.cc
diff --git a/runtime/vm/cpu_arm.cc b/runtime/vm/cpu_arm.cc
index 91d0364b3d2b76ad0456d414fd70c32ef4d93508..491468afa34ff60482430abaa6916af71099d109 100644
--- a/runtime/vm/cpu_arm.cc
+++ b/runtime/vm/cpu_arm.cc
@@ -128,6 +128,25 @@ bool HostCPUFeatures::initialized_ = false;
 
 
 #if !defined(USING_SIMULATOR)
+#if TARGET_OS_IOS
+void HostCPUFeatures::InitOnce() {
+  // TODO(24743): Actually check the CPU features and fail if we're missing
+  // something assumed in a precompiled snapshot.

[zra, 2015/10/27 20:58:41]

How do you know what is assumed by a precompiled snapshot?

+  hardware_ = "";
+  // When the VM is targetted to ARMv7, pretend that the CPU is ARMv7 even if
+  // the CPU is actually AArch64.
+  arm_version_ = ARMv7;
+  // Always assume we have floating point unit since we dont support ARMv6 in
+  // this path.
+  vfp_supported_ = FLAG_use_vfp;
+  integer_division_supported_ = FLAG_use_integer_division;
+  neon_supported_ = FLAG_use_neon;
+  hardfp_supported_ = true;
+#if defined(DEBUG)
+  initialized_ = true;
+#endif
+}
+#else  // TARGET_OS_IOS
 void HostCPUFeatures::InitOnce() {
   bool is_arm64 = false;
   CpuInfo::InitOnce();
@@ -202,7 +221,7 @@ void HostCPUFeatures::InitOnce() {
   initialized_ = true;
 #endif
 }
-
+#endif  // TARGET_OS_IOS
 
 void HostCPUFeatures::Cleanup() {
   DEBUG_ASSERT(initialized_);