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 62dd94c07850e617e7f8afe141c9fa030e85eb04..b4b7a37554fb7178098b898711b4df99c1b24cf7 100644
--- a/src/arm/assembler-arm.h
+++ b/src/arm/assembler-arm.h
@@ -117,7 +117,8 @@ 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();
@@ -200,6 +201,7 @@ 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 };