Out-of-line constant pool on Arm: Stage 1 - Free up r7 for use as constant pool pointer register

src/arm/assembler-arm.h

Index: src/arm/assembler-arm.h
diff --git a/src/arm/assembler-arm.h b/src/arm/assembler-arm.h
index 13990219dd9437fc77c044eb672a90c8a925b516..d7b8f02504cd082ebbfcdcc23fb67c4c5e6f1299 100644
--- a/src/arm/assembler-arm.h
+++ b/src/arm/assembler-arm.h
@@ -118,7 +118,8 @@ class CpuFeatures : public AllStatic {
 // Core register
 struct Register {
   static const int kNumRegisters = 16;
-  static const int kMaxNumAllocatableRegisters = 8;
+  static const int kMaxNumAllocatableRegisters =
+      FLAG_enable_ool_constant_pool ? 7 : 8;
   static const int kSizeInBytes = 4;
 
   inline static int NumAllocatableRegisters();
@@ -201,6 +202,7 @@ const Register r3  = { kRegister_r3_Code };
 const Register r4  = { kRegister_r4_Code };
 const Register r5  = { kRegister_r5_Code };
 const Register r6  = { kRegister_r6_Code };
+// Used as constant pool pointer register if FLAGS_enable_ool_constant_pool.
 const Register r7  = { kRegister_r7_Code };
 // Used as context register.
 const Register r8  = { kRegister_r8_Code };