VM: Don't do free("") in shutdown when we can't find the cpu model field in /proc/cpuinfo.

runtime/vm/cpuinfo_linux.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_OS_LINUX)
 
 #include "vm/cpuinfo.h"
 #include "vm/cpuid.h"
 #include "vm/proccpuinfo.h"
@@ skipping 10 matching lines @@
 const char* CpuInfo::fields_[kCpuInfoMax] = {0};
 
 void CpuInfo::InitOnce() {
 #if defined(HOST_ARCH_IA32) || defined(HOST_ARCH_X64)
   fields_[kCpuInfoProcessor] = "vendor_id";
   fields_[kCpuInfoModel] = "model name";
   fields_[kCpuInfoHardware] = "model name";
   fields_[kCpuInfoFeatures] = "flags";
   method_ = kCpuInfoCpuId;
   CpuId::InitOnce();
-#elif defined(HOST_ARCH_ARM) || defined(HOST_ARCH_ARM64)
-  // TODO(zra): Verify that these field names are correct for arm64.
+#elif defined(HOST_ARCH_ARM)
   fields_[kCpuInfoProcessor] = "Processor";
   fields_[kCpuInfoModel] = "model name";
   fields_[kCpuInfoHardware] = "Hardware";
   fields_[kCpuInfoFeatures] = "Features";
   method_ = kCpuInfoSystem;
   ProcCpuInfo::InitOnce();
+#elif defined(HOST_ARCH_ARM64)
+  fields_[kCpuInfoProcessor] = "Processor";
+  fields_[kCpuInfoModel] = "CPU implementer";
+  fields_[kCpuInfoHardware] = "CPU implementer";
+  fields_[kCpuInfoFeatures] = "Features";
+  method_ = kCpuInfoSystem;
+  ProcCpuInfo::InitOnce();
 #elif defined(HOST_ARCH_MIPS)
   fields_[kCpuInfoProcessor] = "system type";
   fields_[kCpuInfoModel] = "cpu model";
   fields_[kCpuInfoHardware] = "cpu model";
   fields_[kCpuInfoFeatures] = "ASEs implemented";
   method_ = kCpuInfoSystem;
   ProcCpuInfo::InitOnce();
 #else
 #error Unrecognized target architecture
 #endif
@@ skipping 71 matching lines @@
            (strcmp(field, fields_[kCpuInfoFeatures]) == 0);
   } else {
     ASSERT(method_ == kCpuInfoSystem);
     return ProcCpuInfo::HasField(field);
   }
 }
 
 }  // namespace dart
 
 #endif  // defined(TARGET_OS_LINUX)