[profiler, linux/android] Check whether a sample is ARM or Thumb code to decide which FP register t…

runtime/vm/signal_handler_linux.cc

 // Copyright (c) 2013, 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"
 #include "vm/instructions.h"
 #include "vm/simulator.h"
 #include "vm/signal_handler.h"
 #if defined(HOST_OS_LINUX)
 
@@ skipping 18 matching lines @@
 
 
 uintptr_t SignalHandler::GetFramePointer(const mcontext_t& mcontext) {
   uintptr_t fp = 0;
 
 #if defined(HOST_ARCH_IA32)
   fp = static_cast<uintptr_t>(mcontext.gregs[REG_EBP]);
 #elif defined(HOST_ARCH_X64)
   fp = static_cast<uintptr_t>(mcontext.gregs[REG_RBP]);
 #elif defined(HOST_ARCH_ARM)
-  fp = static_cast<uintptr_t>(mcontext.arm_fp);
+  // B1.3.3 Program Status Registers (PSRs)
+  if ((mcontext.arm_cpsr & (1 << 5)) != 0) {
+    // Thumb mode.
+    fp = static_cast<uintptr_t>(mcontext.arm_r7);
+  } else {
+    // ARM mode.
+    fp = static_cast<uintptr_t>(mcontext.arm_fp);
+  }
 #elif defined(HOST_ARCH_ARM64)
   fp = static_cast<uintptr_t>(mcontext.regs[29]);
 #else
 #error Unsupported architecture.
 #endif  // HOST_ARCH_...
 
   return fp;
 }
 
 
@@ skipping 61 matching lines @@
   sigemptyset(&act.sa_mask);
   act.sa_flags = 0;
   int r = sigaction(SIGPROF, &act, NULL);
   ASSERT(r == 0);
 }
 
 
 }  // namespace dart
 
 #endif  // defined(HOST_OS_LINUX)