Support Int32 representation for selected binary operations.

runtime/vm/intermediate_language_ia32.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/globals.h"  // Needed here to get TARGET_ARCH_IA32.
 #if defined(TARGET_ARCH_IA32)
 
 #include "vm/intermediate_language.h"
 
 #include "vm/dart_entry.h"
@@ skipping 157 matching lines @@
   if (kNumTemps == 1) {
     locs->set_temp(0, Location::RequiresRegister());
   }
   return locs;
 }
 
 
 void UnboxedConstantInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
   // The register allocator drops constant definitions that have no uses.
   if (!locs()->out(0).IsInvalid()) {
-     XmmRegister result = locs()->out(0).fpu_reg();
-    if (constant_address() == 0) {
-      Register boxed = locs()->temp(0).reg();
-      __ LoadObjectSafely(boxed, value());
-      __ movsd(result, FieldAddress(boxed, Double::value_offset()));
-    } else if (Utils::DoublesBitEqual(Double::Cast(value()).value(), 0.0)) {
-      __ xorps(result, result);
-    } else {
-      __ movsd(result, Address::Absolute(constant_address()));
+    switch (representation()) {
+      case kUnboxedDouble: {
+        XmmRegister result = locs()->out(0).fpu_reg();
+        if (constant_address() == 0) {
+          Register boxed = locs()->temp(0).reg();
+          __ LoadObjectSafely(boxed, value());
+          __ movsd(result, FieldAddress(boxed, Double::value_offset()));
+        } else if (Utils::DoublesBitEqual(Double::Cast(value()).value(), 0.0)) {
+          __ xorps(result, result);
+        } else {
+          __ movsd(result, Address::Absolute(constant_address()));
+        }
+        break;
+      }
+      case kUnboxedInt32:
+        __ movl(locs()->out(0).reg(), Immediate(Smi::Cast(value()).Value()));
+        break;
+      default:
+        UNREACHABLE();
     }
   }
 }
 
 
 LocationSummary* AssertAssignableInstr::MakeLocationSummary(Isolate* isolate,
                                                             bool opt) const {
   const intptr_t kNumInputs = 3;
   const intptr_t kNumTemps = 0;
   LocationSummary* summary = new(isolate) LocationSummary(
@@ skipping 838 matching lines @@
 
 LocationSummary* LoadIndexedInstr::MakeLocationSummary(Isolate* isolate,
                                                        bool opt) const {
   const intptr_t kNumInputs = 2;
   const intptr_t kNumTemps = 0;
   LocationSummary* locs = new(isolate) LocationSummary(
       isolate, kNumInputs, kNumTemps, LocationSummary::kNoCall);
   locs->set_in(0, Location::RequiresRegister());
   if (CanBeImmediateIndex(index(), class_id())) {
     // CanBeImmediateIndex must return false for unsafe smis.
-    locs->set_in(1, Location::Constant(index()->BoundConstant()));
+    locs->set_in(1, Location::Constant(index()->definition()->AsConstant()));
   } else {
     // The index is either untagged (element size == 1) or a smi (for all
     // element sizes > 1).
     locs->set_in(1, (index_scale() == 1)
                         ? Location::WritableRegister()
                         : Location::RequiresRegister());
   }
   if ((representation() == kUnboxedDouble) ||
       (representation() == kUnboxedFloat32x4) ||
       (representation() == kUnboxedInt32x4) ||
@@ skipping 175 matching lines @@
 
 LocationSummary* StoreIndexedInstr::MakeLocationSummary(Isolate* isolate,
                                                         bool opt) const {
   const intptr_t kNumInputs = 3;
   const intptr_t kNumTemps = 0;
   LocationSummary* locs = new(isolate) LocationSummary(
       isolate, kNumInputs, kNumTemps, LocationSummary::kNoCall);
   locs->set_in(0, Location::RequiresRegister());
   if (CanBeImmediateIndex(index(), class_id())) {
     // CanBeImmediateIndex must return false for unsafe smis.
-    locs->set_in(1, Location::Constant(index()->BoundConstant()));
+    locs->set_in(1, Location::Constant(index()->definition()->AsConstant()));
   } else {
     // The index is either untagged (element size == 1) or a smi (for all
     // element sizes > 1).
     locs->set_in(1, (index_scale() == 1)
                         ? Location::WritableRegister()
                         : Location::RequiresRegister());
   }
   switch (class_id()) {
     case kArrayCid:
       locs->set_in(2, ShouldEmitStoreBarrier()
@@ skipping 1516 matching lines @@
                                                        bool opt) const {
   const intptr_t kNumInputs = 2;
   if (op_kind() == Token::kTRUNCDIV) {
     const intptr_t kNumTemps = 1;
     LocationSummary* summary = new(isolate) LocationSummary(
         isolate, kNumInputs, kNumTemps, LocationSummary::kNoCall);
     if (RightIsPowerOfTwoConstant()) {
       summary->set_in(0, Location::RequiresRegister());
       ConstantInstr* right_constant = right()->definition()->AsConstant();
       // The programmer only controls one bit, so the constant is safe.
-      summary->set_in(1, Location::Constant(right_constant->value()));
+      summary->set_in(1, Location::Constant(right_constant));
       summary->set_temp(0, Location::RequiresRegister());
       summary->set_out(0, Location::SameAsFirstInput());
     } else {
       // Both inputs must be writable because they will be untagged.
       summary->set_in(0, Location::RegisterLocation(EAX));
       summary->set_in(1, Location::WritableRegister());
       summary->set_out(0, Location::SameAsFirstInput());
       // Will be used for sign extension and division.
       summary->set_temp(0, Location::RegisterLocation(EDX));
     }
@@ skipping 343 matching lines @@
       UNREACHABLE();
       break;
     }
     default:
       UNREACHABLE();
       break;
   }
 }
 
 
+LocationSummary* BinaryInt32OpInstr::MakeLocationSummary(Isolate* isolate,
+                                                         bool opt) const {
+  const intptr_t kNumInputs = 2;
+  if (op_kind() == Token::kTRUNCDIV) {
+    UNREACHABLE();
+    return NULL;
+  } else if (op_kind() == Token::kMOD) {
+     UNREACHABLE();
+    return NULL;
+  } else if (op_kind() == Token::kSHR) {
+    const intptr_t kNumTemps = 0;
+    LocationSummary* summary = new(isolate) LocationSummary(
+        isolate, kNumInputs, kNumTemps, LocationSummary::kNoCall);
+    summary->set_in(0, Location::RequiresRegister());
+    summary->set_in(1, Location::FixedRegisterOrSmiConstant(right(), ECX));
+    summary->set_out(0, Location::SameAsFirstInput());
+    return summary;
+  } else if (op_kind() == Token::kSHL) {
+    const intptr_t kNumTemps = !IsTruncating() ? 1 : 0;
+    LocationSummary* summary = new(isolate) LocationSummary(
+        isolate, kNumInputs, kNumTemps, LocationSummary::kNoCall);
+    summary->set_in(0, Location::RequiresRegister());
+    summary->set_in(1, Location::FixedRegisterOrSmiConstant(right(), ECX));
+    if (!IsTruncating()) {
+      summary->set_temp(0, Location::RequiresRegister());
+    }
+    summary->set_out(0, Location::SameAsFirstInput());
+    return summary;
+  } else {
+    const intptr_t kNumTemps = 0;
+    LocationSummary* summary = new(isolate) LocationSummary(
+        isolate, kNumInputs, kNumTemps, LocationSummary::kNoCall);
+    summary->set_in(0, Location::RequiresRegister());
+    ConstantInstr* constant = right()->definition()->AsConstant();
+    if (constant == NULL) {
+      if (right()->definition()->IsUnboxedConstant()) {
+        asm("int $3");

[Florian Schneider, 2014/08/27 09:36:51]

Remove debugging left-over?

[Vyacheslav Egorov (Google), 2014/08/27 11:45:37]

Done.

+      }
+    }
+    if (constant != NULL) {
+      summary->set_in(1, Location::RegisterOrSmiConstant(right()));
+    } else {
+      summary->set_in(1, Location::PrefersRegister());
+    }
+    summary->set_out(0, Location::SameAsFirstInput());
+    return summary;
+  }
+}
+
+
+static void EmitInt32ShiftLeft(FlowGraphCompiler* compiler,
+                               BinaryInt32OpInstr* shift_left) {
+  const bool is_truncating = shift_left->IsTruncating();
+  const LocationSummary& locs = *shift_left->locs();
+  Register left = locs.in(0).reg();
+  Register result = locs.out(0).reg();
+  ASSERT(left == result);
+  Label* deopt = shift_left->CanDeoptimize() ?
+      compiler->AddDeoptStub(shift_left->deopt_id(), ICData::kDeoptBinarySmiOp)
+      : NULL;
+  ASSERT(locs.in(1).IsConstant());
+
+  const Object& constant = locs.in(1).constant();
+  ASSERT(constant.IsSmi());
+  // shll operation masks the count to 5 bits.
+  const intptr_t kCountLimit = 0x1F;
+  const intptr_t value = Smi::Cast(constant).Value();
+  if (value == 0) {
+    // No code needed.
+  } else if ((value < 0) || (value >= kCountLimit)) {
+    // This condition may not be known earlier in some cases because
+    // of constant propagation, inlining, etc.
+    if ((value >= kCountLimit) && is_truncating) {
+      __ xorl(result, result);
+    } else {
+      // Result is Mint or exception.
+      __ jmp(deopt);
+    }
+  } else {
+    if (!is_truncating) {
+      // Check for overflow.
+      Register temp = locs.temp(0).reg();
+      __ movl(temp, left);
+      __ shll(left, Immediate(value));
+      __ sarl(left, Immediate(value));
+      __ cmpl(left, temp);
+      __ j(NOT_EQUAL, deopt);  // Overflow.
+    }
+    // Shift for result now we know there is no overflow.
+    __ shll(left, Immediate(value));
+  }
+}
+
+
+void BinaryInt32OpInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
+  if (op_kind() == Token::kSHL) {
+    EmitInt32ShiftLeft(compiler, this);
+    return;
+  }
+
+  Register left = locs()->in(0).reg();
+  Register result = locs()->out(0).reg();
+  ASSERT(left == result);
+  Label* deopt = NULL;
+  if (CanDeoptimize()) {
+    deopt  = compiler->AddDeoptStub(deopt_id(), ICData::kDeoptBinarySmiOp);
+  }
+
+  if (locs()->in(1).IsConstant()) {
+    const Object& constant = locs()->in(1).constant();
+    ASSERT(constant.IsSmi());
+    const intptr_t value = Smi::Cast(constant).Value();
+    switch (op_kind()) {
+    case Token::kADD:
+        if (value != 0) {
+          // Checking overflow without emitting an instruction would be wrong.
+          __ addl(left, Immediate(value));
+          if (deopt != NULL) __ j(OVERFLOW, deopt);
+        }
+        break;
+      case Token::kSUB: {
+        if (value != 0) {
+          // Checking overflow without emitting an instruction would be wrong.
+          __ subl(left, Immediate(value));
+          if (deopt != NULL) __ j(OVERFLOW, deopt);
+        }
+        break;
+      }
+      case Token::kMUL: {
+        if (value == 2) {
+          __ shll(left, Immediate(1));
+        } else {
+          __ imull(left, Immediate(value));
+        }
+        if (deopt != NULL) __ j(OVERFLOW, deopt);
+        break;
+      }
+      case Token::kTRUNCDIV: {
+        UNREACHABLE();

[Florian Schneider, 2014/08/27 09:36:51]

UNIMPLEMENTED?

[Vyacheslav Egorov (Google), 2014/08/27 11:45:37]

UNREACHABLE() is more meaningful because supported operations are filtered
outside by IsSupported.

+        break;
+      }
+      case Token::kBIT_AND: {
+        // No overflow check.
+        __ andl(left, Immediate(value));
+        break;
+      }
+      case Token::kBIT_OR: {
+        // No overflow check.
+        __ orl(left, Immediate(value));
+        break;
+      }
+      case Token::kBIT_XOR: {
+        // No overflow check.
+        __ xorl(left, Immediate(value));
+        break;
+      }
+      case Token::kSHR: {
+        // sarl operation masks the count to 5 bits.
+        const intptr_t kCountLimit = 0x1F;
+        if (value == 0) {
+          // TODO(vegorov): should be handled outside.
+          break;
+        } else if (value < 0) {
+          // TODO(vegorov): should be handled outside.
+          __ jmp(deopt);
+          break;
+        }
+
+        if (value >= kCountLimit) {
+          __ sarl(left, Immediate(kCountLimit));
+        } else {
+          __ sarl(left, Immediate(value));
+        }
+
+        break;
+      }
+
+      default:
+        UNREACHABLE();
+        break;
+    }
+    return;
+  }  // if locs()->in(1).IsConstant()
+
+  if (locs()->in(1).IsStackSlot()) {
+    const Address& right = locs()->in(1).ToStackSlotAddress();
+    switch (op_kind()) {
+      case Token::kADD: {
+        __ addl(left, right);
+        if (deopt != NULL) __ j(OVERFLOW, deopt);
+        break;
+      }
+      case Token::kSUB: {
+        __ subl(left, right);
+        if (deopt != NULL) __ j(OVERFLOW, deopt);
+        break;
+      }
+      case Token::kMUL: {
+        __ imull(left, right);
+        if (deopt != NULL) __ j(OVERFLOW, deopt);
+        break;
+      }
+      case Token::kBIT_AND: {
+        // No overflow check.
+        __ andl(left, right);
+        break;
+      }
+      case Token::kBIT_OR: {
+        // No overflow check.
+        __ orl(left, right);
+        break;
+      }
+      case Token::kBIT_XOR: {
+        // No overflow check.
+        __ xorl(left, right);
+        break;
+      }
+      default:
+        UNREACHABLE();
+    }
+    return;
+  }  // if locs()->in(1).IsStackSlot.
+
+  // if locs()->in(1).IsRegister.
+  Register right = locs()->in(1).reg();
+  switch (op_kind()) {
+    case Token::kADD: {
+      __ addl(left, right);
+      if (deopt != NULL) __ j(OVERFLOW, deopt);
+      break;
+    }
+    case Token::kSUB: {
+      __ subl(left, right);
+      if (deopt != NULL) __ j(OVERFLOW, deopt);
+      break;
+    }
+    case Token::kMUL: {
+      __ imull(left, right);
+      if (deopt != NULL) __ j(OVERFLOW, deopt);
+      break;
+    }
+    case Token::kBIT_AND: {
+      // No overflow check.
+      __ andl(left, right);
+      break;
+    }
+    case Token::kBIT_OR: {
+      // No overflow check.
+      __ orl(left, right);
+      break;
+    }
+    case Token::kBIT_XOR: {
+      // No overflow check.
+      __ xorl(left, right);
+      break;
+    }
+    case Token::kTRUNCDIV: {
+      UNREACHABLE();

[Florian Schneider, 2014/08/27 09:36:51]

UNIMPLEMENTED?

[Vyacheslav Egorov (Google), 2014/08/27 11:45:37]

Ditto.

+      break;
+    }
+    case Token::kMOD: {
+      UNREACHABLE();

[Florian Schneider, 2014/08/27 09:36:51]

UNIMPLEMENTED?

[Vyacheslav Egorov (Google), 2014/08/27 11:45:37]

Ditto

+      break;
+    }
+    case Token::kSHR: {
+      UNREACHABLE();

[Florian Schneider, 2014/08/27 09:36:51]

UNIMPLEMENTED?

[Vyacheslav Egorov (Google), 2014/08/27 11:45:37]

Ditto.

+      break;
+    }
+    case Token::kDIV: {
+      // Dispatches to 'Double./'.
+      // TODO(srdjan): Implement as conversion to double and double division.
+      UNREACHABLE();
+      break;
+    }
+    case Token::kOR:
+    case Token::kAND: {
+      // Flow graph builder has dissected this operation to guarantee correct
+      // behavior (short-circuit evaluation).
+      UNREACHABLE();
+      break;
+    }
+    default:
+      UNREACHABLE();
+      break;
+  }
+}
+
+
 LocationSummary* CheckEitherNonSmiInstr::MakeLocationSummary(Isolate* isolate,
                                                              bool opt) const {
   intptr_t left_cid = left()->Type()->ToCid();
   intptr_t right_cid = right()->Type()->ToCid();
   ASSERT((left_cid != kDoubleCid) && (right_cid != kDoubleCid));
   const intptr_t kNumInputs = 2;
   const bool need_temp = (left()->definition() != right()->definition())
                       && (left_cid != kSmiCid)
                       && (right_cid != kSmiCid);
   const intptr_t kNumTemps = need_temp ? 1 : 0;
@@ skipping 1514 matching lines @@
 }
 
 
 void UnaryDoubleOpInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
   XmmRegister value = locs()->in(0).fpu_reg();
   ASSERT(locs()->out(0).fpu_reg() == value);
   __ DoubleNegate(value);
 }
 
 
+LocationSummary* Int32ToDoubleInstr::MakeLocationSummary(Isolate* isolate,
+                                                       bool opt) const {
+  const intptr_t kNumInputs = 1;
+  const intptr_t kNumTemps = 0;
+  LocationSummary* result = new(isolate) LocationSummary(
+      isolate, kNumInputs, kNumTemps, LocationSummary::kNoCall);
+  result->set_in(0, Location::WritableRegister());
+  result->set_out(0, Location::RequiresFpuRegister());
+  return result;
+}
+
+
+void Int32ToDoubleInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
+  Register value = locs()->in(0).reg();
+  FpuRegister result = locs()->out(0).fpu_reg();
+  __ cvtsi2sd(result, value);
+}
+
+
 LocationSummary* SmiToDoubleInstr::MakeLocationSummary(Isolate* isolate,
                                                        bool opt) const {
   const intptr_t kNumInputs = 1;
   const intptr_t kNumTemps = 0;
   LocationSummary* result = new(isolate) LocationSummary(
       isolate, kNumInputs, kNumTemps, LocationSummary::kNoCall);
   result->set_in(0, Location::WritableRegister());
   result->set_out(0, Location::RequiresFpuRegister());
   return result;
 }
@@ skipping 1217 matching lines @@
 CompileType ShiftUint32OpInstr::ComputeType() const {
   return CompileType::Int();
 }
 
 
 CompileType UnaryUint32OpInstr::ComputeType() const {
   return CompileType::Int();
 }
 
 
-CompileType BoxUint32Instr::ComputeType() const {
-  return CompileType::Int();
-}
-
-
-CompileType UnboxUint32Instr::ComputeType() const {
-  return CompileType::Int();
-}
-
-
 LocationSummary* BinaryUint32OpInstr::MakeLocationSummary(Isolate* isolate,
                                                           bool opt) const {
   const intptr_t kNumInputs = 2;
   const intptr_t kNumTemps = (op_kind() == Token::kMUL) ? 1 : 0;
   LocationSummary* summary = new(isolate) LocationSummary(
       isolate, kNumInputs, kNumTemps, LocationSummary::kNoCall);
   if (op_kind() == Token::kMUL) {
     summary->set_in(0, Location::RegisterLocation(EAX));
     summary->set_temp(0, Location::RegisterLocation(EDX));
   } else {
@@ skipping 152 matching lines @@
 
   __ notl(out);
 }
 
 
 LocationSummary* BoxUint32Instr::MakeLocationSummary(Isolate* isolate,
                                                      bool opt) const {
   const intptr_t kNumInputs = 1;
   const intptr_t kNumTemps = 0;
   LocationSummary* summary = new(isolate) LocationSummary(
-      isolate, kNumInputs, kNumTemps, LocationSummary::kCallOnSlowPath);
+      isolate,
+      kNumInputs,
+      kNumTemps,
+      ValueFitsSmi() ? LocationSummary::kNoCall
+                     : LocationSummary::kCallOnSlowPath);
   summary->set_in(0, Location::RequiresRegister());
-  summary->set_out(0, Location::RequiresRegister());
+  summary->set_out(0, ValueFitsSmi() ? Location::SameAsFirstInput()
+                                     : Location::RequiresRegister());
   return summary;
 }
 
 
 void BoxUint32Instr::EmitNativeCode(FlowGraphCompiler* compiler) {
   Register value = locs()->in(0).reg();
   Register out = locs()->out(0).reg();
-  ASSERT(value != out);
 
   Label not_smi, done;
 
-  // TODO(johnmccutchan): Use range information to fast path smi / mint boxing.
-  // Test if this value is <= kSmiMax.
-  __ cmpl(value, Immediate(kSmiMax));
-  __ j(ABOVE, &not_smi);
-  // Smi.
-  __ movl(out, value);
-  __ SmiTag(out);
-  __ jmp(&done);
-  __ Bind(&not_smi);
-  // Allocate a mint.
-  BoxAllocationSlowPath::Allocate(
-      compiler, this, compiler->mint_class(), out, kNoRegister);
-  // Copy low word into mint.
-  __ movl(FieldAddress(out, Mint::value_offset()), value);
-  // Zero high word.
-  __ movl(FieldAddress(out, Mint::value_offset() + kWordSize), Immediate(0));
-  __ Bind(&done);
+  if (ValueFitsSmi()) {
+    ASSERT(value == out);
+    __ SmiTag(value);
+  } else {
+    ASSERT(value != out);
+    __ cmpl(value, Immediate(kSmiMax));
+    __ j(ABOVE, &not_smi);
+    // Smi.
+    __ movl(out, value);
+    __ SmiTag(out);
+    __ jmp(&done);
+    __ Bind(&not_smi);
+    // Allocate a mint.
+    BoxAllocationSlowPath::Allocate(
+        compiler, this, compiler->mint_class(), out, kNoRegister);
+    // Copy low word into mint.
+    __ movl(FieldAddress(out, Mint::value_offset()), value);
+    // Zero high word.
+    __ movl(FieldAddress(out, Mint::value_offset() + kWordSize), Immediate(0));
+    __ Bind(&done);
+  }
 }
 
 
+LocationSummary* BoxInt32Instr::MakeLocationSummary(Isolate* isolate,
+                                                    bool opt) const {
+  const intptr_t kNumInputs = 1;
+  const intptr_t kNumTemps = 0;
+  LocationSummary* summary = new(isolate) LocationSummary(
+      isolate, kNumInputs, kNumTemps,
+      ValueFitsSmi() ? LocationSummary::kNoCall
+                     : LocationSummary::kCallOnSlowPath);
+  summary->set_in(0, ValueFitsSmi() ? Location::RequiresRegister()
+                                    : Location::WritableRegister());
+  summary->set_out(0, ValueFitsSmi() ? Location::SameAsFirstInput()
+                                     : Location::RequiresRegister());
+  return summary;
+}
+
+
+void BoxInt32Instr::EmitNativeCode(FlowGraphCompiler* compiler) {
+  Register value = locs()->in(0).reg();
+  Register out = locs()->out(0).reg();
+
+  if (out != value) {
+    __ movl(out, value);
+  }
+  __ shll(out, Immediate(1));
+  if (!ValueFitsSmi()) {
+    Label done;
+    __ j(NO_OVERFLOW, &done);
+    // Allocate a mint.
+    BoxAllocationSlowPath::Allocate(
+        compiler, this, compiler->mint_class(), out, kNoRegister);
+    __ movl(FieldAddress(out, Mint::value_offset()), value);
+    __ sarl(value, Immediate(31));  // Sign extend.
+    __ movl(FieldAddress(out, Mint::value_offset() + kWordSize), value);
+    __ Bind(&done);
+  }
+}
+
+
 LocationSummary* UnboxUint32Instr::MakeLocationSummary(Isolate* isolate,
                                                        bool opt) const {
   const intptr_t value_cid = value()->Type()->ToCid();
   const intptr_t kNumInputs = 1;
   const intptr_t kNumTemps =
       ((value_cid == kMintCid) || (value_cid == kSmiCid)) ? 0 : 1;
   LocationSummary* summary = new(isolate) LocationSummary(
       isolate, kNumInputs, kNumTemps, LocationSummary::kNoCall);
   summary->set_in(0, Location::RequiresRegister());
   if (kNumTemps > 0) {
@@ skipping 25 matching lines @@
     __ j(NOT_EQUAL, deopt);
     __ movl(value, FieldAddress(value, Mint::value_offset()));
     __ jmp(&done);
     __ Bind(&is_smi);
     __ SmiUntag(value);
     __ Bind(&done);
   }
 }
 
 
+LocationSummary* UnboxInt32Instr::MakeLocationSummary(Isolate* isolate,
+                                                       bool opt) const {
+  const intptr_t value_cid = value()->Type()->ToCid();
+  const intptr_t kNumInputs = 1;
+  const intptr_t kNumTemps = CanDeoptimize() ? 1 : 0;
+  LocationSummary* summary = new(isolate) LocationSummary(
+      isolate, kNumInputs, kNumTemps, LocationSummary::kNoCall);
+  summary->set_in(0, Location::RequiresRegister());
+  if (kNumTemps > 0) {
+    summary->set_temp(0, Location::RequiresRegister());
+  }
+  summary->set_out(0, (value_cid == kSmiCid) ? Location::SameAsFirstInput()
+                                             : Location::RequiresRegister());
+  return summary;
+}
+
+
+static void LoadInt32FromMint(FlowGraphCompiler* compiler,
+                              Register mint,
+                              Register result,
+                              Register temp,
+                              Label* deopt) {
+  __ movl(result, FieldAddress(mint, Mint::value_offset()));
+  if (deopt != NULL) {
+    __ movl(temp, result);
+    __ sarl(temp, Immediate(31));
+    __ cmpl(temp, FieldAddress(mint, Mint::value_offset() + kWordSize));
+    __ j(NOT_EQUAL, deopt);
+  }
+}
+
+
+void UnboxInt32Instr::EmitNativeCode(FlowGraphCompiler* compiler) {
+  const intptr_t value_cid = value()->Type()->ToCid();
+  const Register value = locs()->in(0).reg();
+  const Register result = locs()->out(0).reg();
+
+  // TODO(johnmccutchan): Emit better code for constant inputs.
+  if (value_cid == kMintCid) {
+    Register temp = CanDeoptimize() ? locs()->temp(0).reg() : kNoRegister;
+    Label* deopt = CanDeoptimize() ?
+        compiler->AddDeoptStub(deopt_id_, ICData::kDeoptUnboxInteger) : NULL;
+    LoadInt32FromMint(compiler,
+                      value,
+                      result,
+                      temp,
+                      deopt);
+  } else if (value_cid == kSmiCid) {
+    ASSERT(value == result);
+    __ SmiUntag(value);
+  } else {
+    Register temp = locs()->temp(0).reg();
+    Label* deopt = compiler->AddDeoptStub(deopt_id_,
+                                          ICData::kDeoptUnboxInteger);
+    Label is_smi, done;
+    __ testl(value, Immediate(kSmiTagMask));
+    __ j(ZERO, &is_smi);
+    __ CompareClassId(value, kMintCid, temp);
+    __ j(NOT_EQUAL, deopt);
+    LoadInt32FromMint(compiler,
+                      value,
+                      result,
+                      temp,
+                      deopt);
+    __ movl(value, FieldAddress(value, Mint::value_offset()));
+    __ jmp(&done);
+    __ Bind(&is_smi);
+    __ SmiUntag(value);
+    __ Bind(&done);
+  }
+}
+
+
 LocationSummary* UnboxedIntConverterInstr::MakeLocationSummary(Isolate* isolate,
                                                                bool opt) const {
   const intptr_t kNumInputs = 1;
   const intptr_t kNumTemps = 0;
   LocationSummary* summary = new(isolate) LocationSummary(
       isolate, kNumInputs, kNumTemps, LocationSummary::kNoCall);
-  if (from() == kUnboxedMint) {
-    summary->set_in(0, Location::Pair(Location::RequiresRegister(),
-                                      Location::RequiresRegister()));
+  if ((from() == kUnboxedInt32 || from() == kUnboxedUint32) &&
+      (to() == kUnboxedInt32 || to() == kUnboxedUint32)) {
+    summary->set_in(0, Location::RequiresRegister());
+    summary->set_out(0, Location::SameAsFirstInput());
+  } else if (from() == kUnboxedMint) {
+    summary->set_in(0, Location::Pair(
+        CanDeoptimize() ? Location::WritableRegister()
+                        : Location::RequiresRegister(),
+        Location::RequiresRegister()));
     summary->set_out(0, Location::RequiresRegister());
-  } else {
-    ASSERT(from() == kUnboxedUint32);
+  } else if (from() == kUnboxedUint32) {
     summary->set_in(0, Location::RequiresRegister());
     summary->set_out(0, Location::Pair(Location::RequiresRegister(),
                                        Location::RequiresRegister()));
+  } else if (from() == kUnboxedInt32) {
+    summary->set_in(0, Location::RegisterLocation(EAX));
+    summary->set_out(0, Location::Pair(Location::RegisterLocation(EAX),
+                                       Location::RegisterLocation(EDX)));
   }
   return summary;
 }
 
 
 void UnboxedIntConverterInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
-  if (from() == kUnboxedMint) {
+  if (from() == kUnboxedInt32 && to() == kUnboxedUint32) {
+    // Representations are bitwise equivalent.
+    ASSERT(locs()->out(0).reg() == locs()->in(0).reg());
+  } else if (from() == kUnboxedUint32 && to() == kUnboxedInt32) {
+    // Representations are bitwise equivalent.
+    ASSERT(locs()->out(0).reg() == locs()->in(0).reg());
+    if (CanDeoptimize()) {
+      Label* deopt =
+          compiler->AddDeoptStub(deopt_id(), ICData::kDeoptUnboxInteger);
+      __ testl(locs()->out(0).reg(), locs()->out(0).reg());
+      __ j(NEGATIVE, deopt);
+    }
+  } else if (from() == kUnboxedMint) {
+    // TODO(vegorov) kUnboxedMint -> kInt32 conversion is currently usually
+    // dominated by a CheckSmi(BoxInteger(val)) which is an artifact of ordering
+    // of optimization passes and the way we check smi-ness of values.
+    // Optimize it away.
+    ASSERT(to() == kUnboxedInt32 || to() == kUnboxedUint32);
     PairLocation* in_pair = locs()->in(0).AsPairLocation();
     Register in_lo = in_pair->At(0).reg();
+    Register in_hi = in_pair->At(1).reg();
     Register out = locs()->out(0).reg();
     // Copy low word.
     __ movl(out, in_lo);
-  } else {
-    ASSERT(from() == kUnboxedUint32);
+    if (CanDeoptimize()) {
+      Label* deopt =
+          compiler->AddDeoptStub(deopt_id(), ICData::kDeoptUnboxInteger);
+      __ sarl(in_lo, Immediate(31));
+      __ cmpl(in_lo, in_hi);
+      __ j(NOT_EQUAL, deopt);
+    }
+  } else if (from() == kUnboxedUint32) {
+    ASSERT(to() == kUnboxedMint);
     Register in = locs()->in(0).reg();
     PairLocation* out_pair = locs()->out(0).AsPairLocation();
     Register out_lo = out_pair->At(0).reg();
     Register out_hi = out_pair->At(1).reg();
     // Copy low word.
     __ movl(out_lo, in);
     // Zero upper word.
     __ xorl(out_hi, out_hi);
+  } else if (from() == kUnboxedInt32) {
+    ASSERT(to() == kUnboxedMint);
+    PairLocation* out_pair = locs()->out(0).AsPairLocation();
+    Register out_lo = out_pair->At(0).reg();
+    Register out_hi = out_pair->At(1).reg();
+    ASSERT(locs()->in(0).reg() == EAX);
+    ASSERT(out_lo == EAX && out_hi == EDX);
+    __ cdq();
+  } else {
+    UNREACHABLE();
   }
 }
 
 
 LocationSummary* ThrowInstr::MakeLocationSummary(Isolate* isolate,
                                                  bool opt) const {
   return new(isolate) LocationSummary(isolate, 0, 0, LocationSummary::kCall);
 }
 
 
@@ skipping 343 matching lines @@
   __ movl(EDX, Immediate(kInvalidObjectPointer));
   __ movl(EDX, Immediate(kInvalidObjectPointer));
 #endif
 }
 
 }  // namespace dart
 
 #undef __
 
 #endif  // defined TARGET_ARCH_IA32