Increase sanity of integer division handling on ARM

- In the INT32 BinaryOpStub, fix type feedback collection for DIV,
  bringing it in line with other platforms.
- In Lithium codegen, emit proper inlined code, don't call the stub.
- Drive-by fix: assert appropriate CpuFeaturesScope for SDIV.

R=ulan@chromium.org

Review URL: https://codereview.chromium.org/16082008

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@15057 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/arm/assembler-arm.cc

@@ -1368,6 +1368,7 @@ void Assembler::mls(Register dst, Register src1, Register src2, Register srcA,
 void Assembler::sdiv(Register dst, Register src1, Register src2,
                      Condition cond) {
   ASSERT(!dst.is(pc) && !src1.is(pc) && !src2.is(pc));
+  ASSERT(IsEnabled(SUDIV));
   emit(cond | B26 | B25| B24 | B20 | dst.code()*B16 | 0xf * B12 |
        src2.code()*B8 | B4 | src1.code());
 }

src/arm/code-stubs-arm.cc

@@ -1707,6 +1707,7 @@ void BinaryOpStub_GenerateSmiSmiOperation(MacroAssembler* masm,
       __ Ret();
 
       if (CpuFeatures::IsSupported(SUDIV)) {
+        CpuFeatureScope scope(masm, SUDIV);
         Label result_not_zero;
 
         __ bind(&div_with_sdiv);
@@ -1763,6 +1764,7 @@ void BinaryOpStub_GenerateSmiSmiOperation(MacroAssembler* masm,
       __ Ret();
 
       if (CpuFeatures::IsSupported(SUDIV)) {
+        CpuFeatureScope scope(masm, SUDIV);
         __ bind(&modulo_with_sdiv);
         __ mov(scratch2, right);
         // Perform modulus with sdiv and mls.
@@ -2208,42 +2210,25 @@ void BinaryOpStub::GenerateInt32Stub(MacroAssembler* masm) {
             UNREACHABLE();
         }
 
-        if (op_ != Token::DIV) {
-          // These operations produce an integer result.
-          // Try to return a smi if we can.
-          // Otherwise return a heap number if allowed, or jump to type
-          // transition.
-
-          if (result_type_ <= BinaryOpIC::INT32) {
-            __ TryDoubleToInt32Exact(scratch1, d5, d8);
-            // If the ne condition is set, result does
-            // not fit in a 32-bit integer.
-            __ b(ne, &transition);
-          } else {
-            __ vcvt_s32_f64(s8, d5);
-            __ vmov(scratch1, s8);
-          }
-
-          // Check if the result fits in a smi.
-          __ add(scratch2, scratch1, Operand(0x40000000), SetCC);
-          // If not try to return a heap number.
-          __ b(mi, &return_heap_number);
-          // Check for minus zero. Return heap number for minus zero if
-          // double results are allowed; otherwise transition.
+        if (result_type_ <= BinaryOpIC::INT32) {
+          __ TryDoubleToInt32Exact(scratch1, d5, d8);
+          // If the ne condition is set, result does
+          // not fit in a 32-bit integer.
+          __ b(ne, &transition);
+          // Try to tag the result as a Smi, return heap number on overflow.
+          __ SmiTag(scratch1, SetCC);
+          __ b(vs, &return_heap_number);
+          // Check for minus zero, transition in that case (because we need
+          // to return a heap number).
           Label not_zero;
-          __ cmp(scratch1, Operand::Zero());
+          ASSERT(kSmiTag == 0);
           __ b(ne, &not_zero);
           __ vmov(scratch2, d5.high());
           __ tst(scratch2, Operand(HeapNumber::kSignMask));
-          __ b(ne, result_type_ <= BinaryOpIC::INT32 ? &transition
-                                                     : &return_heap_number);
+          __ b(ne, &transition);
           __ bind(&not_zero);
-
-          // Tag the result and return.
-          __ SmiTag(r0, scratch1);
+          __ mov(r0, scratch1);
           __ Ret();
-        } else {
-          // DIV just falls through to allocating a heap number.
         }
 
         __ bind(&return_heap_number);

src/arm/lithium-arm.cc

@@ -1345,18 +1345,14 @@ LInstruction* LChunkBuilder::DoDiv(HDiv* instr) {
       ASSERT(!instr->CheckFlag(HValue::kCanBeDivByZero));
       LOperand* value = UseRegisterAtStart(instr->left());
       LDivI* div =
-          new(zone()) LDivI(value, UseOrConstant(instr->right()));
+          new(zone()) LDivI(value, UseOrConstant(instr->right()), NULL);
       return AssignEnvironment(DefineSameAsFirst(div));
     }
-    // TODO(1042) The fixed register allocation
-    // is needed because we call TypeRecordingBinaryOpStub from
-    // the generated code, which requires registers r0
-    // and r1 to be used. We should remove that
-    // when we provide a native implementation.
-    LOperand* dividend = UseFixed(instr->left(), r0);
-    LOperand* divisor = UseFixed(instr->right(), r1);
-    return AssignEnvironment(AssignPointerMap(
-             DefineFixed(new(zone()) LDivI(dividend, divisor), r0)));
+    LOperand* dividend = UseRegister(instr->left());
+    LOperand* divisor = UseRegister(instr->right());
+    LOperand* temp = CpuFeatures::IsSupported(SUDIV) ? NULL : FixedTemp(d4);
+    LDivI* div = new(zone()) LDivI(dividend, divisor, temp);
+    return AssignEnvironment(DefineAsRegister(div));
   } else {
     return DoArithmeticT(Token::DIV, instr);
   }

src/arm/lithium-arm.h

@@ -597,15 +597,17 @@ class LModI: public LTemplateInstruction<1, 2, 2> {
 };
 
 
-class LDivI: public LTemplateInstruction<1, 2, 0> {
+class LDivI: public LTemplateInstruction<1, 2, 1> {
  public:
-  LDivI(LOperand* left, LOperand* right) {
+  LDivI(LOperand* left, LOperand* right, LOperand* temp) {
     inputs_[0] = left;
     inputs_[1] = right;
+    temps_[0] = temp;
   }
 
   LOperand* left() { return inputs_[0]; }
   LOperand* right() { return inputs_[1]; }
+  LOperand* temp() { return temps_[0]; }
 
   DECLARE_CONCRETE_INSTRUCTION(DivI, "div-i")
   DECLARE_HYDROGEN_ACCESSOR(Div)

src/arm/lithium-codegen-arm.cc

@@ -1417,21 +1417,6 @@ void LCodeGen::EmitSignedIntegerDivisionByConstant(
 
 
 void LCodeGen::DoDivI(LDivI* instr) {
-  class DeferredDivI: public LDeferredCode {
-   public:
-    DeferredDivI(LCodeGen* codegen, LDivI* instr)
-        : LDeferredCode(codegen), instr_(instr) { }
-    virtual void Generate() {
-      codegen()->DoDeferredBinaryOpStub(instr_->pointer_map(),
-                                        instr_->left(),
-                                        instr_->right(),
-                                        Token::DIV);
-    }
-    virtual LInstruction* instr() { return instr_; }
-   private:
-    LDivI* instr_;
-  };
-
   if (instr->hydrogen()->HasPowerOf2Divisor()) {
     Register dividend = ToRegister(instr->left());
     int32_t divisor =
@@ -1498,40 +1483,32 @@ void LCodeGen::DoDivI(LDivI* instr) {
     __ bind(&left_not_min_int);
   }
 
-  Label done, deoptimize;
-  // Test for a few common cases first.
-  __ cmp(right, Operand(1));
-  __ mov(result, left, LeaveCC, eq);
-  __ b(eq, &done);
-
-  __ cmp(right, Operand(2));
-  __ tst(left, Operand(1), eq);
-  __ mov(result, Operand(left, ASR, 1), LeaveCC, eq);
-  __ b(eq, &done);
-
-  __ cmp(right, Operand(4));
-  __ tst(left, Operand(3), eq);
-  __ mov(result, Operand(left, ASR, 2), LeaveCC, eq);
-  __ b(eq, &done);
-
-  // Call the stub. The numbers in r0 and r1 have
-  // to be tagged to Smis. If that is not possible, deoptimize.
-  DeferredDivI* deferred = new(zone()) DeferredDivI(this, instr);
-
-  __ TrySmiTag(left, &deoptimize);
-  __ TrySmiTag(right, &deoptimize);
-
-  __ b(al, deferred->entry());
-  __ bind(deferred->exit());
-
-  // If the result in r0 is a Smi, untag it, else deoptimize.
-  __ JumpIfNotSmi(result, &deoptimize);
-  __ SmiUntag(result);
-  __ b(&done);
+  if (CpuFeatures::IsSupported(SUDIV)) {
+    CpuFeatureScope scope(masm(), SUDIV);
+    __ sdiv(result, left, right);
 
-  __ bind(&deoptimize);
-  DeoptimizeIf(al, instr->environment());
-  __ bind(&done);
+    // Compute remainder and deopt if it's not zero.
+    const Register remainder = scratch0();
+    __ mls(remainder, result, right, left);
+    __ cmp(remainder, Operand::Zero());
+    DeoptimizeIf(ne, instr->environment());
+  } else {
+    const DoubleRegister vleft = ToDoubleRegister(instr->temp());
+    const DoubleRegister vright = double_scratch0();
+    __ vmov(vleft.low(), left);
+    __ vmov(vright.low(), right);
+    __ vcvt_f64_s32(vleft, vleft.low());
+    __ vcvt_f64_s32(vright, vright.low());
+    __ vdiv(vleft, vleft, vright);  // vleft now contains the result.
+
+    // Convert back to integer32; deopt if exact conversion is not possible.
+    // Use vright as scratch register.
+    __ vcvt_s32_f64(vright.low(), vleft);
+    __ vmov(result, vright.low());
+    __ vcvt_f64_s32(vright, vright.low());
+    __ VFPCompareAndSetFlags(vleft, vright);
+    DeoptimizeIf(ne, instr->environment());
+  }
 }
 
 
@@ -1630,38 +1607,6 @@ void LCodeGen::DoMathFloorOfDiv(LMathFloorOfDiv* instr) {
 }
 
 
-void LCodeGen::DoDeferredBinaryOpStub(LPointerMap* pointer_map,
-                                      LOperand* left_argument,
-                                      LOperand* right_argument,
-                                      Token::Value op) {
-  Register left = ToRegister(left_argument);
-  Register right = ToRegister(right_argument);
-
-  PushSafepointRegistersScope scope(this, Safepoint::kWithRegistersAndDoubles);
-  // Move left to r1 and right to r0 for the stub call.
-  if (left.is(r1)) {
-    __ Move(r0, right);
-  } else if (left.is(r0) && right.is(r1)) {
-    __ Swap(r0, r1, r2);
-  } else if (left.is(r0)) {
-    ASSERT(!right.is(r1));
-    __ mov(r1, r0);
-    __ mov(r0, right);
-  } else {
-    ASSERT(!left.is(r0) && !right.is(r0));
-    __ mov(r0, right);
-    __ mov(r1, left);
-  }
-  BinaryOpStub stub(op, OVERWRITE_LEFT);
-  __ CallStub(&stub);
-  RecordSafepointWithRegistersAndDoubles(pointer_map,
-                                         0,
-                                         Safepoint::kNoLazyDeopt);
-  // Overwrite the stored value of r0 with the result of the stub.
-  __ StoreToSafepointRegistersAndDoublesSlot(r0, r0);
-}
-
-
 void LCodeGen::DoMulI(LMulI* instr) {
   Register scratch = scratch0();
   Register result = ToRegister(instr->result());

src/arm/lithium-codegen-arm.h

@@ -138,10 +138,6 @@ class LCodeGen BASE_EMBEDDED {
   void FinishCode(Handle<Code> code);
 
   // Deferred code support.
-  void DoDeferredBinaryOpStub(LPointerMap* pointer_map,
-                              LOperand* left_argument,
-                              LOperand* right_argument,
-                              Token::Value op);
   void DoDeferredNumberTagD(LNumberTagD* instr);
 
   enum IntegerSignedness { SIGNED_INT32, UNSIGNED_INT32 };

src/hydrogen-instructions.cc

@@ -1513,6 +1513,11 @@ HValue* HUnaryMathOperation::Canonicalize() {
     // If the input is integer32 then we replace the floor instruction
     // with its input. This happens before the representation changes are
     // introduced.
+
+    // TODO(2205): The above comment is lying. All of this happens
+    // *after* representation changes are introduced. We should check
+    // for value->IsChange() and react accordingly if yes.
+
     if (value()->representation().IsInteger32()) return value();
 
 #if defined(V8_TARGET_ARCH_ARM) || defined(V8_TARGET_ARCH_IA32) || \

src/ia32/assembler-ia32.cc

@@ -2351,7 +2351,7 @@ void Assembler::movd(const Operand& dst, XMMRegister src) {
 
 
 void Assembler::extractps(Register dst, XMMRegister src, byte imm8) {
-  ASSERT(CpuFeatures::IsSupported(SSE4_1));
+  ASSERT(IsEnabled(SSE4_1));
   ASSERT(is_uint8(imm8));
   EnsureSpace ensure_space(this);
   EMIT(0x66);