Fix CPU features detection and stack alignment assert on iOS

runtime/vm/cpu_arm.cc

 // 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.
 
 #include "vm/globals.h"
 #if defined(TARGET_ARCH_ARM)
 
 #include "vm/assembler.h"
 #include "vm/cpu.h"
 #include "vm/cpuinfo.h"
@@ skipping 110 matching lines @@
 bool HostCPUFeatures::hardfp_supported_ = false;
 const char* HostCPUFeatures::hardware_ = NULL;
 ARMVersion HostCPUFeatures::arm_version_ = ARMvUnknown;
 intptr_t HostCPUFeatures::store_pc_read_offset_ = 8;
 #if defined(DEBUG)
 bool HostCPUFeatures::initialized_ = false;
 #endif
 
 
 #if !defined(USING_SIMULATOR)
+#if TARGET_OS_IOS
+void HostCPUFeatures::InitOnce() {

[rmacnak, 2015/10/27 20:44:22]

TODO(24743): Actually check the CPU features and fail if we're missing something
assumed in a precompiled snapshot.

[Chinmay, 2015/10/27 20:49:47]

ack

+  hardware_ = "";
+  // When the VM is targetted to ARMv7, pretend that the CPU is ARMv7 even if
+  // the CPU is actuall 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();
   hardware_ = CpuInfo::GetCpuModel();
 
   // Check for ARMv5TE, ARMv6, ARMv7, or aarch64.
   // It can be in either the Processor or Model information fields.
   if (CpuInfo::FieldContains(kCpuInfoProcessor, "aarch64") ||
       CpuInfo::FieldContains(kCpuInfoModel, "aarch64")) {
     // pretend that this arm64 cpu is really an ARMv7
@@ skipping 54 matching lines @@
 #if defined(__ARM_PCS_VFP)
   hardfp_supported_ = true;
 #else
   hardfp_supported_ = false;
 #endif
 
 #if defined(DEBUG)
   initialized_ = true;
 #endif
 }
-
+#endif  // TARGET_OS_IOS
 
 void HostCPUFeatures::Cleanup() {
   DEBUG_ASSERT(initialized_);
 #if defined(DEBUG)
   initialized_ = false;
 #endif
   ASSERT(hardware_ != NULL);
   free(const_cast<char*>(hardware_));
   hardware_ = NULL;
   CpuInfo::Cleanup();
@@ skipping 29 matching lines @@
   ASSERT(hardware_ != NULL);
   free(const_cast<char*>(hardware_));
   hardware_ = NULL;
   CpuInfo::Cleanup();
 }
 #endif  // !defined(USING_SIMULATOR)
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_ARM