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

runtime/vm/intermediate_language_x64.cc

Index: runtime/vm/intermediate_language_x64.cc
===================================================================
--- runtime/vm/intermediate_language_x64.cc	(revision 17135)
+++ runtime/vm/intermediate_language_x64.cc	(working copy)
@@ -936,6 +936,9 @@
   LocationSummary* locs =
       new LocationSummary(kNumInputs, kNumTemps, LocationSummary::kNoCall);
   locs->set_in(0, Location::RequiresRegister());
+  // The smi index is either untagged and tagged again at the end of the
+  // operation (element size == 1), or it is left smi tagged (for all element
+  // sizes > 1).
   locs->set_in(1, CanBeImmediateIndex(index(), class_id())
                     ? Location::RegisterOrSmiConstant(index())
                     : Location::RequiresRegister());
@@ -1005,6 +1008,9 @@
   LocationSummary* locs =
       new LocationSummary(kNumInputs, kNumTemps, LocationSummary::kNoCall);
   locs->set_in(0, Location::RequiresRegister());
+  // The smi index is either untagged and tagged again at the end of the
+  // operation (element size == 1), or it is left smi tagged (for all element
+  // sizes > 1).
   locs->set_in(1, CanBeImmediateIndex(index(), class_id())
                     ? Location::RegisterOrSmiConstant(index())
                     : Location::RequiresRegister());
@@ -1024,8 +1030,10 @@
   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());
     }
@@ -1062,29 +1070,47 @@
   }
 
   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));
+      __ movq(result, element_address);
+      break;
   }
-
-  ASSERT((class_id() == kArrayCid) || (class_id() == kImmutableArrayCid));
-  __ movq(result, element_address);
 }
 
 
 LocationSummary* StoreIndexedInstr::MakeLocationSummary() const {
   const intptr_t kNumInputs = 3;
-  const intptr_t numTemps = 0;
+  const intptr_t kNumTemps = 0;
   LocationSummary* locs =
-      new LocationSummary(kNumInputs, numTemps, LocationSummary::kNoCall);
+      new LocationSummary(kNumInputs, kNumTemps, LocationSummary::kNoCall);
+  // The smi index is either untagged and tagged again at the end of the
+  // operation (element size == 1), or it is left smi tagged (for all element
+  // sizes > 1).
   locs->set_in(0, Location::RequiresRegister());
   locs->set_in(1, CanBeImmediateIndex(index(), class_id())
                     ? Location::RegisterOrSmiConstant(index())
@@ -1095,11 +1121,18 @@
                         ? Location::WritableRegister()
                         : Location::RegisterOrConstant(value()));
       break;
+    case kInt8ArrayCid:
     case kUint8ArrayCid:
+    case kUint8ClampedArrayCid:
       // TODO(fschneider): Add location constraint for byte registers (RAX,
       // RBX, RCX, RDX) instead of using a fixed register.
       locs->set_in(2, Location::FixedRegisterOrSmiConstant(value(), RAX));
       break;
+    case kInt16ArrayCid:
+    case kUint16ArrayCid:
+      // Writable register because the value must be untagged before storing.
+      locs->set_in(2, Location::WritableRegister());
+      break;
     case kFloat32ArrayCid:
       // Need temp register for float-to-double conversion.
       locs->AddTemp(Location::RequiresXmmRegister());
@@ -1139,6 +1172,7 @@
         __ StoreIntoObjectNoBarrier(array, element_address, value);
       }
       break;
+    case kInt8ArrayCid:
     case kUint8ArrayCid:
       if (index.IsRegister()) {
         __ SmiUntag(index.reg());
@@ -1156,6 +1190,48 @@
         __ 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() == RAX);
+        Label store_value, store_0xff;
+        __ SmiUntag(RAX);
+        __ cmpq(RAX, Immediate(0xFF));
+        __ j(BELOW_EQUAL, &store_value, Assembler::kNearJump);
+        // Clamp to 0x0 or 0xFF respectively.
+        __ j(GREATER, &store_0xff);
+        __ xorq(RAX, RAX);
+        __ jmp(&store_value, Assembler::kNearJump);
+        __ Bind(&store_0xff);
+        __ movq(RAX, Immediate(0xFF));
+        __ Bind(&store_value);
+        __ movb(element_address, RAX);
+      }
+      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());