Fix issues with Arm's use of embedded constant pools

src/arm/frames-arm.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_ARM_FRAMES_ARM_H_
 #define V8_ARM_FRAMES_ARM_H_
 
 namespace v8 {
 namespace internal {
 
@@ skipping 48 matching lines @@
 
 // Double registers d8 to d15 are callee-saved.
 const int kNumDoubleCalleeSaved = 8;
 
 
 // Number of registers for which space is reserved in safepoints. Must be a
 // multiple of 8.
 // TODO(regis): Only 8 registers may actually be sufficient. Revisit.
 const int kNumSafepointRegisters = 16;
 
+// The embedded constant pool pointer (r8/pp) is not included in the safepoint
+// since it is not tagged.  This register is preserved in the stack frame where
+// its value will be updated if GC code movement occurs.  Including it in the
+// safepoint (where it will not be relocated) would cause a stale value to be
+// restored.
+const RegList kConstantPointerRegMask =
+    FLAG_enable_embedded_constant_pool ? (1 << 8) : 0;
+const int kNumConstantPoolPointerReg =
+    FLAG_enable_embedded_constant_pool ? 1 : 0;
+
 // Define the list of registers actually saved at safepoints.
 // Note that the number of saved registers may be smaller than the reserved
 // space, i.e. kNumSafepointSavedRegisters <= kNumSafepointRegisters.
-const RegList kSafepointSavedRegisters = kJSCallerSaved | kCalleeSaved;
-const int kNumSafepointSavedRegisters = kNumJSCallerSaved + kNumCalleeSaved;
+const RegList kSafepointSavedRegisters =
+    kJSCallerSaved | (kCalleeSaved & ~kConstantPointerRegMask);
+const int kNumSafepointSavedRegisters =
+    kNumJSCallerSaved + kNumCalleeSaved - kNumConstantPoolPointerReg;
 
 // ----------------------------------------------------
 
 
 class EntryFrameConstants : public AllStatic {
  public:
   static const int kCallerFPOffset =
       -(StandardFrameConstants::kFixedFrameSizeFromFp + kPointerSize);
 };
 
@@ skipping 64 matching lines @@
 
 inline Object* JavaScriptFrame::function_slot_object() const {
   const int offset = JavaScriptFrameConstants::kFunctionOffset;
   return Memory::Object_at(fp() + offset);
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_ARM_FRAMES_ARM_H_