ARM: Improve register allocation and constraints (try 2)....

src/arm/assembler-arm.h

 // Copyright (c) 1994-2006 Sun Microsystems Inc.
 // All Rights Reserved.
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions
 // are met:
 //
 // - Redistributions of source code must retain the above copyright notice,
 // this list of conditions and the following disclaimer.
 //
@@ skipping 149 matching lines @@
     *m = code_ & 0x1;
     *vm = code_ >> 1;
   }
 
   int code_;
 };
 
 
 // Double word VFP register.
 struct DwVfpRegister {
-  // d0 has been excluded from allocation. This is following ia32
-  // where xmm0 is excluded. This should be revisited.
-  // Currently d0 is used as a scratch register.
-  // d1 has also been excluded from allocation to be used as a scratch
-  // register as well.
   static const int kNumRegisters = 16;
-  static const int kNumAllocatableRegisters = 15;
+  // A few double registers are reserved: one as a scratch register and one to
+  // hold 0.0, that does not fit in the immediate field of vmov instructions.
+  //  d14: 0.0
+  //  d15: scratch register.
+  static const int kNumReservedRegisters = 2;
+  static const int kNumAllocatableRegisters = kNumRegisters -
+      kNumReservedRegisters;
 
   static int ToAllocationIndex(DwVfpRegister reg) {
     ASSERT(reg.code() != 0);
     return reg.code() - 1;
   }
 
   static DwVfpRegister FromAllocationIndex(int index) {
     ASSERT(index >= 0 && index < kNumAllocatableRegisters);
     return from_code(index + 1);
   }
 
   static const char* AllocationIndexToString(int index) {
     ASSERT(index >= 0 && index < kNumAllocatableRegisters);
     const char* const names[] = {
+      "d0",
       "d1",
       "d2",
       "d3",
       "d4",
       "d5",
       "d6",
       "d7",
       "d8",
       "d9",
       "d10",
       "d11",
       "d12",
-      "d13",
-      "d14",
-      "d15"
+      "d13"
     };
     return names[index];
   }
 
   static DwVfpRegister from_code(int code) {
     DwVfpRegister r = { code };
     return r;
   }
 
   // Supporting d0 to d15, can be later extended to d31.
@@ skipping 83 matching lines @@
 const DwVfpRegister d10 = { 10 };
 const DwVfpRegister d11 = { 11 };
 const DwVfpRegister d12 = { 12 };
 const DwVfpRegister d13 = { 13 };
 const DwVfpRegister d14 = { 14 };
 const DwVfpRegister d15 = { 15 };
 
 // Aliases for double registers.
 const DwVfpRegister kFirstCalleeSavedDoubleReg = d8;
 const DwVfpRegister kLastCalleeSavedDoubleReg = d15;
+const DwVfpRegister kDoubleRegZero = d14;
 
 
 // Coprocessor register
 struct CRegister {
   bool is_valid() const { return 0 <= code_ && code_ < 16; }
   bool is(CRegister creg) const { return code_ == creg.code_; }
   int code() const {
     ASSERT(is_valid());
     return code_;
   }
@@ skipping 1078 matching lines @@
  public:
   explicit EnsureSpace(Assembler* assembler) {
     assembler->CheckBuffer();
   }
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_ARM_ASSEMBLER_ARM_H_