Optimized loads/stores for scalar list: Uint8Clamped, Int8, Int16, Uint16.

runtime/vm/intermediate_language_ia32.cc

 // Copyright (c) 2012, 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 "lib/error.h"
@@ skipping 1142 matching lines @@
 }
 
 
 void LoadIndexedInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
   Register array = locs()->in(0).reg();
   Location index = locs()->in(1);
 
   if (class_id() == kExternalUint8ArrayCid) {
     Register result = locs()->out().reg();
     Address element_address = index.IsRegister()
-        ? Address(result, index.reg(), TIMES_1, 0)
-        : Address(result, Smi::Cast(index.constant()).Value());
+        ? FlowGraphCompiler::ExternalElementAddressForRegIndex(
+            class_id(), result, index.reg())
+        : FlowGraphCompiler::ExternalElementAddressForIntIndex(
+            class_id(), result, Smi::Cast(index.constant()).Value());
     if (index.IsRegister()) {
       __ SmiUntag(index.reg());
     }
     __ movl(result,
             FieldAddress(array, ExternalUint8Array::external_data_offset()));
     __ movl(result,
             Address(result, ExternalByteArrayData<uint8_t>::data_offset()));
     __ movzxb(result, element_address);
     __ SmiTag(result);
     if (index.IsRegister()) {
       __ SmiTag(index.reg());  // Re-tag.
     }
     return;
   }
 
-  FieldAddress element_address = index.IsRegister() ?
-      FlowGraphCompiler::ElementAddressForRegIndex(
-          class_id(), array, index.reg()) :
-      FlowGraphCompiler::ElementAddressForIntIndex(
+  FieldAddress element_address = index.IsRegister()
+      ? FlowGraphCompiler::ElementAddressForRegIndex(
+          class_id(), array, index.reg())
+      : FlowGraphCompiler::ElementAddressForIntIndex(
           class_id(), array, Smi::Cast(index.constant()).Value());
 
   if (representation() == kUnboxedDouble) {
     XmmRegister result = locs()->out().xmm_reg();
     if (class_id() == kFloat32ArrayCid) {
       // Load single precision float.
       __ movss(result, element_address);
       // Promote to double.
       __ cvtss2sd(result, locs()->out().xmm_reg());
     } else {
       ASSERT(class_id() == kFloat64ArrayCid);
       __ movsd(result, element_address);
     }
     return;
   }
 
   Register result = locs()->out().reg();
-  if ((class_id() == kUint8ArrayCid) ||
-      (class_id() == kUint8ClampedArrayCid)) {
-    if (index.IsRegister()) {
-      __ SmiUntag(index.reg());
-    }
-    __ movzxb(result, element_address);
-    __ SmiTag(result);
-    if (index.IsRegister()) {
-      __ SmiTag(index.reg());  // Re-tag.
-    }
-    return;
+  switch (class_id()) {
+    case kInt8ArrayCid:
+    case kUint8ArrayCid:
+    case kUint8ClampedArrayCid:
+      if (index.IsRegister()) {
+        __ SmiUntag(index.reg());
+      }
+      if (class_id() == kInt8ArrayCid) {
+        __ movsxb(result, element_address);
+      } else {
+        __ movzxb(result, element_address);
+      }
+      __ SmiTag(result);
+      if (index.IsRegister()) {
+        __ SmiTag(index.reg());  // Re-tag.
+      }
+      break;
+    case kInt16ArrayCid:
+      __ movsxw(result, element_address);
+      __ SmiTag(result);
+      break;
+    case kUint16ArrayCid:
+      __ movzxw(result, element_address);
+      __ SmiTag(result);
+      break;
+    default:
+      ASSERT((class_id() == kArrayCid) || (class_id() == kImmutableArrayCid));
+      __ movl(result, element_address);
+      break;
   }
-
-  ASSERT((class_id() == kArrayCid) || (class_id() == kImmutableArrayCid));
-  __ movl(result, element_address);
 }
 
 
 LocationSummary* StoreIndexedInstr::MakeLocationSummary() const {
   const intptr_t kNumInputs = 3;
   const intptr_t kNumTemps = 0;
   LocationSummary* locs =
       new LocationSummary(kNumInputs, kNumTemps, LocationSummary::kNoCall);
   locs->set_in(0, Location::RequiresRegister());
   locs->set_in(1, CanBeImmediateIndex(index(), class_id())
                     ? Location::RegisterOrSmiConstant(index())
                     : Location::RequiresRegister());

[srdjan, 2013/01/16 17:47:33]

SInce index gets untagged, do you need writable register?

[Florian Schneider, 2013/01/17 10:27:14]

The smi index either gets retagged at the end (element size == 1) or it is left
smi tagged (for all element sizes > 1). I'll add a comment.

I'm thinking about changing this though: If we add a constraint
WritableRegisterOrConstant, we can avoid the tagging the index again completely.

   switch (class_id()) {
     case kArrayCid:
       locs->set_in(2, ShouldEmitStoreBarrier()
                         ? Location::WritableRegister()
                         : Location::RegisterOrConstant(value()));
       break;
+    case kInt8ArrayCid:
     case kUint8ArrayCid:
+    case kUint8ClampedArrayCid:
       // TODO(fschneider): Add location constraint for byte registers (EAX,
       // EBX, ECX, EDX) instead of using a fixed register.
       locs->set_in(2, Location::FixedRegisterOrSmiConstant(value(), EAX));
       break;
+    case kInt16ArrayCid:
+    case kUint16ArrayCid:

[srdjan, 2013/01/16 17:47:33]

Add a comment why a writable register.

[Florian Schneider, 2013/01/17 10:27:14]

Done.

+      locs->set_in(2, Location::WritableRegister());
+      break;
     case kFloat32ArrayCid:
       // Need temp register for float-to-double conversion.
       locs->AddTemp(Location::RequiresXmmRegister());
       // Fall through.
     case kFloat64ArrayCid:
       // TODO(srdjan): Support Float64 constants.
       locs->set_in(2, Location::RequiresXmmRegister());
       break;
     default:
       UNREACHABLE();
@@ skipping 19 matching lines @@
         Register value = locs()->in(2).reg();
         __ StoreIntoObject(array, element_address, value);
       } else if (locs()->in(2).IsConstant()) {
         const Object& constant = locs()->in(2).constant();
         __ StoreIntoObjectNoBarrier(array, element_address, constant);
       } else {
         Register value = locs()->in(2).reg();
         __ StoreIntoObjectNoBarrier(array, element_address, value);
       }
       break;
+    case kInt8ArrayCid:
     case kUint8ArrayCid:
       if (index.IsRegister()) {
         __ SmiUntag(index.reg());
       }
       if (locs()->in(2).IsConstant()) {
         const Smi& constant = Smi::Cast(locs()->in(2).constant());
         __ movb(element_address,
                 Immediate(static_cast<int8_t>(constant.Value())));
       } else {
         ASSERT(locs()->in(2).reg() == EAX);
         __ SmiUntag(EAX);
         __ movb(element_address, AL);
       }
       if (index.IsRegister()) {
         __ SmiTag(index.reg());  // Re-tag.
       }
       break;
+    case kUint8ClampedArrayCid: {
+      if (index.IsRegister()) {
+        __ SmiUntag(index.reg());
+      }
+      if (locs()->in(2).IsConstant()) {
+        const Smi& constant = Smi::Cast(locs()->in(2).constant());
+        intptr_t value = constant.Value();
+        // Clamp to 0x0 or 0xFF respectively.
+        if (value > 0xFF) {
+          value = 0xFF;
+        } else if (value < 0) {
+          value = 0;
+        }
+        __ movb(element_address,
+                Immediate(static_cast<int8_t>(value)));
+      } else {
+        ASSERT(locs()->in(2).reg() == EAX);
+        Label store_value, store_0xff;
+        __ SmiUntag(EAX);
+        __ cmpl(EAX, Immediate(0xFF));
+        __ j(BELOW_EQUAL, &store_value, Assembler::kNearJump);
+        // Clamp to 0x0 or 0xFF respectively.
+        __ j(GREATER, &store_0xff);
+        __ xorl(EAX, EAX);
+        __ jmp(&store_value, Assembler::kNearJump);
+        __ Bind(&store_0xff);
+        __ movl(EAX, Immediate(0xFF));
+        __ Bind(&store_value);
+        __ movb(element_address, AL);
+      }
+      if (index.IsRegister()) {
+        __ SmiTag(index.reg());  // Re-tag.
+      }
+      break;
+    }
+    case kInt16ArrayCid:
+    case kUint16ArrayCid: {
+        Register value = locs()->in(2).reg();
+        __ SmiUntag(value);
+        __ movw(element_address, value);
+        break;
+      }
     case kFloat32ArrayCid:
       // Convert to single precision.
       __ cvtsd2ss(locs()->temp(0).xmm_reg(), locs()->in(2).xmm_reg());
       // Store.
       __ movss(element_address, locs()->temp(0).xmm_reg());
       break;
     case kFloat64ArrayCid:
       __ movsd(element_address, locs()->in(2).xmm_reg());
       break;
     default:
@@ skipping 106 matching lines @@
       new LocationSummary(kNumInputs, kNumTemps, LocationSummary::kCall);
   locs->set_in(0, Location::RegisterLocation(ECX));
   locs->set_out(Location::RegisterLocation(EAX));
   return locs;
 }
 
 
 void CreateArrayInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
   // Allocate the array.  EDX = length, ECX = element type.
   ASSERT(locs()->in(0).reg() == ECX);
-  __ movl(EDX,  Immediate(Smi::RawValue(ArgumentCount())));
+  __ movl(EDX, Immediate(Smi::RawValue(ArgumentCount())));
   compiler->GenerateCall(token_pos(),
                          &StubCode::AllocateArrayLabel(),
                          PcDescriptors::kOther,
                          locs());
   ASSERT(locs()->out().reg() == EAX);
 
   // Pop the element values from the stack into the array.
   __ leal(EDX, FieldAddress(EAX, Array::data_offset()));
   for (int i = ArgumentCount() - 1; i >= 0; --i) {
     __ popl(Address(EDX, i * kWordSize));
@@ skipping 1428 matching lines @@
   __ pcmpeqq(XMM0, XMM0);  // Generate all 1's.
   __ pxor(value, XMM0);
 }
 
 
 }  // namespace dart
 
 #undef __
 
 #endif  // defined TARGET_ARCH_X64