ARM: Make use of d16-d31 when available.

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 3b9bb804fd331c144563d6522239c6967933a817..1e2082ec36d4c6d0e0db639d645271825cd2eba4 100644
--- a/src/arm/assembler-arm.h
+++ b/src/arm/assembler-arm.h
@@ -190,24 +190,45 @@ struct SwVfpRegister {
 
 // Double word VFP register.
 struct DwVfpRegister {
-  static const int kNumRegisters = 16;
+  static const int kNumRegisters = 32; // XXX
   // 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 NumAvailableRegisters() {
+    return 32; // XXX: 16 or 32, detected at runtime.
+  }
+  static int NumAllocatableRegisters() {
+    return NumAvailableRegisters() - kNumReservedRegisters;
+  }
+  static DwVfpRegister FirstCalleeSavedReg() { return from_code(8); }
+  static DwVfpRegister LastCalleeSavedReg() {
+    return from_code(15);
+  }
+  static DwVfpRegister ZeroReg() {
+    return from_code(14);
+  }
+  static DwVfpRegister ScratchReg() {
+    return from_code(15);
+  }
+  static int NumCalleeSaved() {
+    return LastCalleeSavedReg().code() - FirstCalleeSavedReg().code() + 1;
+  }
 
   inline static int ToAllocationIndex(DwVfpRegister reg);
 
   static DwVfpRegister FromAllocationIndex(int index) {
-    ASSERT(index >= 0 && index < kNumAllocatableRegisters);
-    return from_code(index);
+    ASSERT(index >= 0 && index < NumAllocatableRegisters());
+    if (index < ZeroReg().code())
+      return from_code(index);
+    return from_code(index + kNumReservedRegisters);
   }
 
   static const char* AllocationIndexToString(int index) {
-    ASSERT(index >= 0 && index < kNumAllocatableRegisters);
+    ASSERT(index >= 0 && index < NumAllocatableRegisters());
+    if (index >= ZeroReg().code())
+      index += kNumReservedRegisters;
     const char* const names[] = {
       "d0",
       "d1",
@@ -222,7 +243,25 @@ struct DwVfpRegister {
       "d10",
       "d11",
       "d12",
-      "d13"
+      "d13",
+      "d14",
+      "d15",
+      "d16",
+      "d17",
+      "d18",
+      "d19",
+      "d20",
+      "d21",
+      "d22",
+      "d23",
+      "d24",
+      "d25",
+      "d26",
+      "d27",
+      "d28",
+      "d29",
+      "d30",
+      "d31"
     };
     return names[index];
   }
@@ -232,10 +271,12 @@ struct DwVfpRegister {
     return r;
   }
 
-  // Supporting d0 to d15, can be later extended to d31.
-  bool is_valid() const { return 0 <= code_ && code_ < 16; }
+  bool is_valid() const {
+    return 0 <= code_ && code_ < NumAvailableRegisters();
+  }
   bool is(DwVfpRegister reg) const { return code_ == reg.code_; }
   SwVfpRegister low() const {
+    ASSERT(code_ < 16);
     SwVfpRegister reg;
     reg.code_ = code_ * 2;
 
@@ -243,6 +284,7 @@ struct DwVfpRegister {
     return reg;
   }
   SwVfpRegister high() const {
+    ASSERT(code_ < 16);
     SwVfpRegister reg;
     reg.code_ = (code_ * 2) + 1;
 
@@ -322,14 +364,22 @@ const DwVfpRegister d12 = { 12 };
 const DwVfpRegister d13 = { 13 };
 const DwVfpRegister d14 = { 14 };
 const DwVfpRegister d15 = { 15 };
-
-// Aliases for double registers.  Defined using #define instead of
-// "static const DwVfpRegister&" because Clang complains otherwise when a
-// compilation unit that includes this header doesn't use the variables.
-#define kFirstCalleeSavedDoubleReg d8
-#define kLastCalleeSavedDoubleReg d15
-#define kDoubleRegZero d14
-#define kScratchDoubleReg d15
+const DwVfpRegister d16 = { 16 };
+const DwVfpRegister d17 = { 17 };
+const DwVfpRegister d18 = { 18 };
+const DwVfpRegister d19 = { 19 };
+const DwVfpRegister d20 = { 20 };
+const DwVfpRegister d21 = { 21 };
+const DwVfpRegister d22 = { 22 };
+const DwVfpRegister d23 = { 23 };
+const DwVfpRegister d24 = { 24 };
+const DwVfpRegister d25 = { 25 };
+const DwVfpRegister d26 = { 26 };
+const DwVfpRegister d27 = { 27 };
+const DwVfpRegister d28 = { 28 };
+const DwVfpRegister d29 = { 29 };
+const DwVfpRegister d30 = { 30 };
+const DwVfpRegister d31 = { 31 };
 
 
 // Coprocessor register
@@ -994,10 +1044,7 @@ class Assembler : public AssemblerBase {
             LFlag l = Short);  // v5 and above
 
   // Support for VFP.
-  // All these APIs support S0 to S31 and D0 to D15.
-  // Currently these APIs do not support extended D registers, i.e, D16 to D31.
-  // However, some simple modifications can allow
-  // these APIs to support D16 to D31.
+  // All these APIs support S0 to S31 and D0 to D31.
 
   void vldr(const DwVfpRegister dst,
             const Register base,