ARM: Improve register allocation and constraints.

Gives ~20% boost for Crypto benchmark on A9.

BUG=none
TEST=none

Review URL: http://codereview.chromium.org//7148018
Patch from Martyn Capewell <m.m.capewell@googlemail.com>.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@8381 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/arm/assembler-arm.h

@@ -167,13 +167,14 @@ struct SwVfpRegister {
 
 // 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);
@@ -188,6 +189,7 @@ struct DwVfpRegister {
   static const char* AllocationIndexToString(int index) {
     ASSERT(index >= 0 && index < kNumAllocatableRegisters);
     const char* const names[] = {
+      "d0",
       "d1",
       "d2",
       "d3",
@@ -200,9 +202,7 @@ struct DwVfpRegister {
       "d10",
       "d11",
       "d12",
-      "d13",
-      "d14",
-      "d15"
+      "d13"
     };
     return names[index];
   }
@@ -306,6 +306,7 @@ const DwVfpRegister d15 = { 15 };
 // Aliases for double registers.
 const DwVfpRegister kFirstCalleeSavedDoubleReg = d8;
 const DwVfpRegister kLastCalleeSavedDoubleReg = d15;
+const DwVfpRegister kDoubleRegZero = d14;
 
 
 // Coprocessor register

src/arm/code-stubs-arm.cc

@@ -3541,6 +3541,8 @@ void JSEntryStub::GenerateBody(MacroAssembler* masm, bool is_construct) {
     CpuFeatures::Scope scope(VFP3);
     // Save callee-saved vfp registers.
     __ vstm(db_w, sp, kFirstCalleeSavedDoubleReg, kLastCalleeSavedDoubleReg);
+    // Set up the reserved register for 0.0.
+    __ vmov(kDoubleRegZero, 0.0);
   }
 
   // Get address of argv, see stm above.

src/arm/lithium-arm.cc

@@ -823,7 +823,7 @@ LInstruction* LChunkBuilder::DoBit(Token::Value op,
 
     LOperand* left = UseRegisterAtStart(instr->LeastConstantOperand());
     LOperand* right = UseOrConstantAtStart(instr->MostConstantOperand());
-    return DefineSameAsFirst(new LBitI(op, left, right));
+    return DefineAsRegister(new LBitI(op, left, right));
   } else {
     ASSERT(instr->representation().IsTagged());
     ASSERT(instr->left()->representation().IsTagged());
@@ -862,7 +862,7 @@ LInstruction* LChunkBuilder::DoShift(Token::Value op,
     right = chunk_->DefineConstantOperand(constant);
     constant_value = constant->Integer32Value() & 0x1f;
   } else {
-    right = UseRegister(right_value);
+    right = UseRegisterAtStart(right_value);
   }
 
   // Shift operations can only deoptimize if we do a logical shift
@@ -879,7 +879,7 @@ LInstruction* LChunkBuilder::DoShift(Token::Value op,
   }
 
   LInstruction* result =
-      DefineSameAsFirst(new LShiftI(op, left, right, does_deopt));
+      DefineAsRegister(new LShiftI(op, left, right, does_deopt));
   return does_deopt ? AssignEnvironment(result) : result;
 }
 
@@ -893,7 +893,7 @@ LInstruction* LChunkBuilder::DoArithmeticD(Token::Value op,
   LOperand* left = UseRegisterAtStart(instr->left());
   LOperand* right = UseRegisterAtStart(instr->right());
   LArithmeticD* result = new LArithmeticD(op, left, right);
-  return DefineSameAsFirst(result);
+  return DefineAsRegister(result);
 }
 
 
@@ -1237,15 +1237,15 @@ LInstruction* LChunkBuilder::DoUnaryMathOperation(HUnaryMathOperation* instr) {
     LUnaryMathOperation* result = new LUnaryMathOperation(input, temp);
     switch (op) {
       case kMathAbs:
-        return AssignEnvironment(AssignPointerMap(DefineSameAsFirst(result)));
+        return AssignEnvironment(AssignPointerMap(DefineAsRegister(result)));
       case kMathFloor:
         return AssignEnvironment(AssignPointerMap(DefineAsRegister(result)));
       case kMathSqrt:
-        return DefineSameAsFirst(result);
+        return DefineAsRegister(result);
       case kMathRound:
         return AssignEnvironment(DefineAsRegister(result));
       case kMathPowHalf:
-        return DefineSameAsFirst(result);
+        return DefineAsRegister(result);
       default:
         UNREACHABLE();
         return NULL;
@@ -1323,7 +1323,7 @@ LInstruction* LChunkBuilder::DoBitAnd(HBitAnd* instr) {
 LInstruction* LChunkBuilder::DoBitNot(HBitNot* instr) {
   ASSERT(instr->value()->representation().IsInteger32());
   ASSERT(instr->representation().IsInteger32());
-  return DefineSameAsFirst(new LBitNotI(UseRegisterAtStart(instr->value())));
+  return DefineAsRegister(new LBitNotI(UseRegisterAtStart(instr->value())));
 }
 
 
@@ -1372,11 +1372,14 @@ LInstruction* LChunkBuilder::DoMod(HMod* instr) {
       mod = new LModI(dividend,
                       divisor,
                       TempRegister(),
-                      FixedTemp(d1),
-                      FixedTemp(d2));
+                      FixedTemp(d10),
+                      FixedTemp(d11));
     }
 
-    return AssignEnvironment(DefineSameAsFirst(mod));
+    bool needs_env = (instr->CheckFlag(HValue::kBailoutOnMinusZero) ||
+                      instr->CheckFlag(HValue::kCanBeDivByZero));
+    return needs_env ? AssignEnvironment(DefineAsRegister(mod))
+                     : DefineAsRegister(mod);
   } else if (instr->representation().IsTagged()) {
     return DoArithmeticT(Token::MOD, instr);
   } else {
@@ -1396,15 +1399,18 @@ LInstruction* LChunkBuilder::DoMul(HMul* instr) {
   if (instr->representation().IsInteger32()) {
     ASSERT(instr->left()->representation().IsInteger32());
     ASSERT(instr->right()->representation().IsInteger32());
-    LOperand* left = UseRegisterAtStart(instr->LeastConstantOperand());
+    LOperand* left;
     LOperand* right = UseOrConstant(instr->MostConstantOperand());
     LOperand* temp = NULL;
     if (instr->CheckFlag(HValue::kBailoutOnMinusZero) &&
         (instr->CheckFlag(HValue::kCanOverflow) ||
         !right->IsConstantOperand())) {
+      left = UseRegister(instr->LeastConstantOperand());
       temp = TempRegister();
+    } else {
+      left = UseRegisterAtStart(instr->LeastConstantOperand());
     }
-    return AssignEnvironment(DefineSameAsFirst(new LMulI(left, right, temp)));
+    return AssignEnvironment(DefineAsRegister(new LMulI(left, right, temp)));
 
   } else if (instr->representation().IsDouble()) {
     return DoArithmeticD(Token::MUL, instr);
@@ -1422,7 +1428,7 @@ LInstruction* LChunkBuilder::DoSub(HSub* instr) {
     LOperand* left = UseRegisterAtStart(instr->left());
     LOperand* right = UseOrConstantAtStart(instr->right());
     LSubI* sub = new LSubI(left, right);
-    LInstruction* result = DefineSameAsFirst(sub);
+    LInstruction* result = DefineAsRegister(sub);
     if (instr->CheckFlag(HValue::kCanOverflow)) {
       result = AssignEnvironment(result);
     }
@@ -1442,7 +1448,7 @@ LInstruction* LChunkBuilder::DoAdd(HAdd* instr) {
     LOperand* left = UseRegisterAtStart(instr->LeastConstantOperand());
     LOperand* right = UseOrConstantAtStart(instr->MostConstantOperand());
     LAddI* add = new LAddI(left, right);
-    LInstruction* result = DefineSameAsFirst(add);
+    LInstruction* result = DefineAsRegister(add);
     if (instr->CheckFlag(HValue::kCanOverflow)) {
       result = AssignEnvironment(result);
     }
@@ -1608,7 +1614,7 @@ LInstruction* LChunkBuilder::DoElementsKind(HElementsKind* instr) {
 LInstruction* LChunkBuilder::DoValueOf(HValueOf* instr) {
   LOperand* object = UseRegister(instr->value());
   LValueOf* result = new LValueOf(object, TempRegister());
-  return AssignEnvironment(DefineSameAsFirst(result));
+  return AssignEnvironment(DefineAsRegister(result));
 }
 
 
@@ -1663,7 +1669,7 @@ LInstruction* LChunkBuilder::DoChange(HChange* instr) {
         LOperand* temp1 = TempRegister();
         LOperand* temp2 = instr->CanTruncateToInt32() ? TempRegister()
                                                       : NULL;
-        LOperand* temp3 = instr->CanTruncateToInt32() ? FixedTemp(d3)
+        LOperand* temp3 = instr->CanTruncateToInt32() ? FixedTemp(d11)
                                                       : NULL;
         res = DefineSameAsFirst(new LTaggedToI(value, temp1, temp2, temp3));
         res = AssignEnvironment(res);
@@ -1757,14 +1763,14 @@ LInstruction* LChunkBuilder::DoClampToUint8(HClampToUint8* instr) {
   Representation input_rep = value->representation();
   LOperand* reg = UseRegister(value);
   if (input_rep.IsDouble()) {
-    return DefineAsRegister(new LClampDToUint8(reg, FixedTemp(d1)));
+    return DefineAsRegister(new LClampDToUint8(reg, FixedTemp(d11)));
   } else if (input_rep.IsInteger32()) {
     return DefineAsRegister(new LClampIToUint8(reg));
   } else {
     ASSERT(input_rep.IsTagged());
     // Register allocator doesn't (yet) support allocation of double
     // temps. Reserve d1 explicitly.
-    LClampTToUint8* result = new LClampTToUint8(reg, FixedTemp(d1));
+    LClampTToUint8* result = new LClampTToUint8(reg, FixedTemp(d11));
     return AssignEnvironment(DefineAsRegister(result));
   }
 }
@@ -1788,7 +1794,7 @@ LInstruction* LChunkBuilder::DoToInt32(HToInt32* instr) {
     ASSERT(input_rep.IsTagged());
     LOperand* temp1 = TempRegister();
     LOperand* temp2 = TempRegister();
-    LOperand* temp3 = FixedTemp(d3);
+    LOperand* temp3 = FixedTemp(d11);
     LTaggedToI* res = new LTaggedToI(reg, temp1, temp2, temp3);
     return AssignEnvironment(DefineSameAsFirst(res));
   }
@@ -1926,7 +1932,7 @@ LInstruction* LChunkBuilder::DoLoadKeyedFastElement(
   LOperand* obj = UseRegisterAtStart(instr->object());
   LOperand* key = UseRegisterAtStart(instr->key());
   LLoadKeyedFastElement* result = new LLoadKeyedFastElement(obj, key);
-  return AssignEnvironment(DefineSameAsFirst(result));
+  return AssignEnvironment(DefineAsRegister(result));
 }
 
 

src/arm/lithium-codegen-arm.h

@@ -148,7 +148,7 @@ class LCodeGen BASE_EMBEDDED {
   HGraph* graph() const { return chunk_->graph(); }
 
   Register scratch0() { return r9; }
-  DwVfpRegister double_scratch0() { return d0; }
+  DwVfpRegister double_scratch0() { return d15; }
 
   int GetNextEmittedBlock(int block);
   LInstruction* GetNextInstruction();

src/arm/macro-assembler-arm.cc

@@ -309,9 +309,9 @@ void MacroAssembler::Move(Register dst, Handle<Object> value) {
 }
 
 
-void MacroAssembler::Move(Register dst, Register src) {
+void MacroAssembler::Move(Register dst, Register src, Condition cond) {
   if (!dst.is(src)) {
-    mov(dst, src);
+    mov(dst, src, LeaveCC, cond);
   }
 }
 
@@ -755,6 +755,23 @@ void MacroAssembler::VFPCompareAndLoadFlags(const DwVfpRegister src1,
   vmrs(fpscr_flags, cond);
 }
 
+void MacroAssembler::Vmov(const DwVfpRegister dst,
+                          const double imm,
+                          const Condition cond) {
+  ASSERT(CpuFeatures::IsEnabled(VFP3));
+  static const DoubleRepresentation minus_zero(-0.0);
+  static const DoubleRepresentation zero(0.0);
+  DoubleRepresentation value(imm);
+  // Handle special values first.
+  if (value.bits == zero.bits) {
+    vmov(dst, kDoubleRegZero, cond);
+  } else if (value.bits == minus_zero.bits) {
+    vneg(dst, kDoubleRegZero, cond);
+  } else {
+    vmov(dst, imm, cond);
+  }
+}
+
 
 void MacroAssembler::EnterFrame(StackFrame::Type type) {
   // r0-r3: preserved
@@ -3112,7 +3129,7 @@ void MacroAssembler::ClampDoubleToUint8(Register result_reg,
   Label done;
   Label in_bounds;
 
-  vmov(temp_double_reg, 0.0);
+  Vmov(temp_double_reg, 0.0);
   VFPCompareAndSetFlags(input_reg, temp_double_reg);
   b(gt, &above_zero);
 
@@ -3122,7 +3139,7 @@ void MacroAssembler::ClampDoubleToUint8(Register result_reg,
 
   // Double value is >= 255, return 255.
   bind(&above_zero);
-  vmov(temp_double_reg, 255.0);
+  Vmov(temp_double_reg, 255.0);
   VFPCompareAndSetFlags(input_reg, temp_double_reg);
   b(le, &in_bounds);
   mov(result_reg, Operand(255));
@@ -3130,7 +3147,7 @@ void MacroAssembler::ClampDoubleToUint8(Register result_reg,
 
   // In 0-255 range, round and truncate.
   bind(&in_bounds);
-  vmov(temp_double_reg, 0.5);
+  Vmov(temp_double_reg, 0.5);
   vadd(temp_double_reg, input_reg, temp_double_reg);
   vcvt_u32_f64(s0, temp_double_reg);
   vmov(result_reg, s0);

src/arm/macro-assembler-arm.h

@@ -143,7 +143,7 @@ class MacroAssembler: public Assembler {
 
   // Register move. May do nothing if the registers are identical.
   void Move(Register dst, Handle<Object> value);
-  void Move(Register dst, Register src);
+  void Move(Register dst, Register src, Condition cond = al);
   void Move(DoubleRegister dst, DoubleRegister src);
 
   // Load an object from the root table.
@@ -312,6 +312,10 @@ class MacroAssembler: public Assembler {
                               const Register fpscr_flags,
                               const Condition cond = al);
 
+  void Vmov(const DwVfpRegister dst,
+            const double imm,
+            const Condition cond = al);
+
 
   // ---------------------------------------------------------------------------
   // Activation frames