Use frame pointer to walk ARM stack on iOS.

Review URL: http://breakpad.appspot.com/314001

git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@869 4c0a9323-5329-0410-9bdc-e9ce6186880e

src/processor/stackwalker_arm.h

@@ -40,7 +40,6 @@
 #ifndef PROCESSOR_STACKWALKER_ARM_H__
 #define PROCESSOR_STACKWALKER_ARM_H__
 
-
 #include "google_breakpad/common/breakpad_types.h"
 #include "google_breakpad/common/minidump_format.h"
 #include "google_breakpad/processor/stackwalker.h"
@@ -57,6 +56,7 @@ class StackwalkerARM : public Stackwalker {
   // to the base Stackwalker constructor.
   StackwalkerARM(const SystemInfo *system_info,
                  const MDRawContextARM *context,
+                 int fp_register,
                  MemoryRegion *memory,
                  const CodeModules *modules,
                  SymbolSupplier *supplier,
@@ -78,8 +78,12 @@ class StackwalkerARM : public Stackwalker {
   StackFrameARM *GetCallerByCFIFrameInfo(const vector<StackFrame *> &frames,
                                          CFIFrameInfo *cfi_frame_info);
 
+  // Use the frame pointer. The caller takes ownership of the returned frame.
+  // Return NULL on failure.
+  StackFrameARM *GetCallerByFramePointer(const vector<StackFrame *> &frames);
+
   // Scan the stack for plausible return addresses. The caller takes ownership
-  // of the returned frame. Return NULL on failure. 
+  // of the returned frame. Return NULL on failure.
   StackFrameARM *GetCallerByStackScan(const vector<StackFrame *> &frames);
 
   // Stores the CPU context corresponding to the youngest stack frame, to
@@ -90,6 +94,10 @@ class StackwalkerARM : public Stackwalker {
   // CONTEXT_VALID_ALL in real use; it is only changeable for the sake of
   // unit tests.
   int context_frame_validity_;
+
+  // The register to use a as frame pointer. The value is -1 if frame pointer
+  // cannot be used.
+  int fp_register_;
 };