Added %_Likely/%_Unlikely intrinsics (special cases of GCC's __builin_expect).

src/compiler/js-intrinsic-lowering.cc

 
 // Copyright 2015 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/js-intrinsic-lowering.h"
 
+#include <stack>
+
 #include "src/compiler/access-builder.h"
 #include "src/compiler/js-graph.h"
 #include "src/compiler/node-matchers.h"
 #include "src/compiler/node-properties.h"
 
 namespace v8 {
 namespace internal {
 namespace compiler {
 
 JSIntrinsicLowering::JSIntrinsicLowering(JSGraph* jsgraph)
@@ skipping 23 matching lines @@
     case Runtime::kInlineIsFunction:
       return ReduceIsInstanceType(node, JS_FUNCTION_TYPE);
     case Runtime::kInlineIsNonNegativeSmi:
       return ReduceIsNonNegativeSmi(node);
     case Runtime::kInlineIsRegExp:
       return ReduceIsInstanceType(node, JS_REGEXP_TYPE);
     case Runtime::kInlineIsSmi:
       return ReduceIsSmi(node);
     case Runtime::kInlineJSValueGetValue:
       return ReduceJSValueGetValue(node);
+    case Runtime::kInlineLikely:
+      return ReduceUnLikely(node, BranchHint::kTrue);
     case Runtime::kInlineMapGetInstanceType:
       return ReduceMapGetInstanceType(node);
     case Runtime::kInlineMathClz32:
       return ReduceMathClz32(node);
     case Runtime::kInlineMathFloor:
       return ReduceMathFloor(node);
     case Runtime::kInlineMathSqrt:
       return ReduceMathSqrt(node);
     case Runtime::kInlineOneByteSeqStringGetChar:
       return ReduceSeqStringGetChar(node, String::ONE_BYTE_ENCODING);
     case Runtime::kInlineOneByteSeqStringSetChar:
       return ReduceSeqStringSetChar(node, String::ONE_BYTE_ENCODING);
     case Runtime::kInlineStringGetLength:
       return ReduceStringGetLength(node);
     case Runtime::kInlineTwoByteSeqStringGetChar:
       return ReduceSeqStringGetChar(node, String::TWO_BYTE_ENCODING);
     case Runtime::kInlineTwoByteSeqStringSetChar:
       return ReduceSeqStringSetChar(node, String::TWO_BYTE_ENCODING);
+    case Runtime::kInlineUnlikely:
+      return ReduceUnLikely(node, BranchHint::kFalse);
     case Runtime::kInlineValueOf:
       return ReduceValueOf(node);
     default:
       break;
   }
   return NoChange();
 }
 
 
 Reduction JSIntrinsicLowering::ReduceConstructDouble(Node* node) {
@@ skipping 207 matching lines @@
 
 Reduction JSIntrinsicLowering::ReduceStringGetLength(Node* node) {
   Node* value = NodeProperties::GetValueInput(node, 0);
   Node* effect = NodeProperties::GetEffectInput(node);
   Node* control = NodeProperties::GetControlInput(node);
   return Change(node, simplified()->LoadField(AccessBuilder::ForStringLength()),
                 value, effect, control);
 }
 
 
+Reduction JSIntrinsicLowering::ReduceUnLikely(Node* node, BranchHint hint) {
+  std::stack<Node*> nodes_to_visit;
+  nodes_to_visit.push(node);
+  while (!nodes_to_visit.empty()) {
+    Node* current = nodes_to_visit.top();
+    nodes_to_visit.pop();
+    for (Node* use : current->uses()) {
+      if (use->opcode() == IrOpcode::kJSToBoolean) {
+        // We have to "look through" ToBoolean calls.
+        nodes_to_visit.push(use);
+      } else if (use->opcode() == IrOpcode::kBranch) {
+        // Actually set the hint on any branch using the intrinsic node.
+        use->set_op(common()->Branch(hint));
+      }
+    }
+  }
+  // Apart from adding hints to branchs nodes, this is the identity function.
+  Node* value = NodeProperties::GetValueInput(node, 0);
+  NodeProperties::ReplaceWithValue(node, value);
+  return Changed(value);
+}
+
+
 Reduction JSIntrinsicLowering::ReduceValueOf(Node* node) {
   // if (%_IsSmi(value)) {
   //   return value;
   // } else if (%_GetInstanceType(%_GetMap(value)) == JS_VALUE_TYPE) {
   //   return %_GetValue(value);
   // } else {
   //   return value;
   // }
   const Operator* const merge_op = common()->Merge(2);
   const Operator* const ephi_op = common()->EffectPhi(2);
@@ skipping 88 matching lines @@
 }
 
 
 MachineOperatorBuilder* JSIntrinsicLowering::machine() const {
   return jsgraph()->machine();
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8