[turbofan] Improve representation selection for Smi checking.

src/compiler/simplified-lowering.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/compiler/simplified-lowering.h"
 
 #include <limits>
 
 #include "src/address-map.h"
 #include "src/base/bits.h"
@@ skipping 2108 matching lines @@
             // the index is within the bounds of [0.0, length[.
             DeferReplacement(node, node->InputAt(0));
           }
         } else {
           VisitBinop(node, UseInfo::CheckedSigned32AsWord32(),
                      UseInfo::TruncatingWord32(),
                      MachineRepresentation::kWord32);
         }
         return;
       }
+      case IrOpcode::kCheckHeapObject: {
+        if (InputCannotBe(node, Type::SignedSmall())) {
+          VisitUnop(node, UseInfo::AnyTagged(), MachineRepresentation::kTagged);

[Jarin, 2016/09/23 08:31:54]

Move visit binop out of the if?

Can we set the representation to kTaggedPointer here?

[Benedikt Meurer, 2016/09/23 08:39:38]

Not possible (yet), due to InputCannotBe
Not yet, rest of this file blows up.

+          if (lower()) DeferReplacement(node, node->InputAt(0));
+        } else {
+          VisitUnop(node, UseInfo::AnyTagged(), MachineRepresentation::kTagged);
+        }
+        return;
+      }
       case IrOpcode::kCheckIf: {
         ProcessInput(node, 0, UseInfo::Bool());
         ProcessRemainingInputs(node, 1);
         SetOutput(node, MachineRepresentation::kNone);
         return;
       }
       case IrOpcode::kCheckNumber: {
         if (InputIs(node, Type::Number())) {
           if (truncation.IsUsedAsWord32()) {
             VisitUnop(node, UseInfo::TruncatingWord32(),
                       MachineRepresentation::kWord32);
           } else {
             // TODO(jarin,bmeurer): We need to go to Tagged here, because
             // otherwise we cannot distinguish the hole NaN (which might need to
             // be treated as undefined). We should have a dedicated Type for
             // that at some point, and maybe even a dedicated truncation.
             VisitUnop(node, UseInfo::AnyTagged(),
                       MachineRepresentation::kTagged);
           }
           if (lower()) DeferReplacement(node, node->InputAt(0));
         } else {
           VisitUnop(node, UseInfo::AnyTagged(), MachineRepresentation::kTagged);
         }
         return;
       }
+      case IrOpcode::kCheckSmi: {
+        if (SmiValuesAre32Bits() && truncation.IsUsedAsWord32()) {
+          VisitUnop(node, UseInfo::CheckedSignedSmallAsWord32(),
+                    MachineRepresentation::kWord32);
+        } else {
+          VisitUnop(node, UseInfo::CheckedSignedSmallAsTaggedSigned(),
+                    MachineRepresentation::kTaggedSigned);
+        }
+        if (lower()) DeferReplacement(node, node->InputAt(0));
+        return;
+      }
       case IrOpcode::kCheckString: {
         if (InputIs(node, Type::String())) {
           VisitUnop(node, UseInfo::AnyTagged(), MachineRepresentation::kTagged);
           if (lower()) DeferReplacement(node, node->InputAt(0));
         } else {
           VisitUnop(node, UseInfo::AnyTagged(), MachineRepresentation::kTagged);
-        }
-        return;
-      }
-      case IrOpcode::kCheckTaggedPointer: {
-        if (InputCannotBe(node, Type::SignedSmall())) {
-          VisitUnop(node, UseInfo::AnyTagged(), MachineRepresentation::kTagged);
-          if (lower()) DeferReplacement(node, node->InputAt(0));
-        } else {
-          VisitUnop(node, UseInfo::AnyTagged(), MachineRepresentation::kTagged);
-        }
-        return;
-      }
-      case IrOpcode::kCheckTaggedSigned: {
-        if (SmiValuesAre32Bits() && truncation.IsUsedAsWord32()) {
-          VisitUnop(node, UseInfo::CheckedSignedSmallAsWord32(),
-                    MachineRepresentation::kWord32);
-          if (lower()) DeferReplacement(node, node->InputAt(0));
-        } else {
-          VisitUnop(node, UseInfo::AnyTagged(), MachineRepresentation::kTagged);
         }
         return;
       }
 
       case IrOpcode::kAllocate: {
         ProcessInput(node, 0, UseInfo::TruncatingWord32());
         ProcessRemainingInputs(node, 1);
         SetOutput(node, MachineRepresentation::kTagged);
         return;
       }
@@ skipping 1071 matching lines @@
         isolate(), graph()->zone(), callable.descriptor(), 0, flags,
         Operator::kNoProperties);
     to_number_operator_.set(common()->Call(desc));
   }
   return to_number_operator_.get();
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8