[turbofan] Optimize certain chains of Branch into a Switch.

src/compiler/common-operator.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/common-operator.h"
 
 #include "src/assembler.h"
 #include "src/base/lazy-instance.h"
 #include "src/compiler/linkage.h"
 #include "src/compiler/opcodes.h"
@@ skipping 18 matching lines @@
   return os;
 }
 
 
 BranchHint BranchHintOf(const Operator* const op) {
   DCHECK_EQ(IrOpcode::kBranch, op->opcode());
   return OpParameter<BranchHint>(op);
 }
 
 
-size_t CaseIndexOf(const Operator* const op) {
-  DCHECK_EQ(IrOpcode::kCase, op->opcode());
-  return OpParameter<size_t>(op);
-}
-
-
 bool operator==(SelectParameters const& lhs, SelectParameters const& rhs) {
   return lhs.type() == rhs.type() && lhs.hint() == rhs.hint();
 }
 
 
 bool operator!=(SelectParameters const& lhs, SelectParameters const& rhs) {
   return !(lhs == rhs);
 }
 
 
@@ skipping 59 matching lines @@
   return OpParameter<size_t>(op);
 }
 
 
 #define CACHED_OP_LIST(V)                                  \
   V(Always, Operator::kPure, 0, 0, 0, 1, 0, 0)             \
   V(Dead, Operator::kFoldable, 0, 0, 0, 0, 0, 1)           \
   V(End, Operator::kKontrol, 0, 0, 1, 0, 0, 0)             \
   V(IfTrue, Operator::kKontrol, 0, 0, 1, 0, 0, 1)          \
   V(IfFalse, Operator::kKontrol, 0, 0, 1, 0, 0, 1)         \
+  V(IfDefault, Operator::kKontrol, 0, 0, 1, 0, 0, 1)       \
   V(Throw, Operator::kFoldable, 1, 1, 1, 0, 0, 1)          \
   V(Return, Operator::kNoThrow, 1, 1, 1, 0, 0, 1)          \
   V(OsrNormalEntry, Operator::kFoldable, 0, 1, 1, 0, 1, 1) \
   V(OsrLoopEntry, Operator::kFoldable, 0, 1, 1, 0, 1, 1)
 
 
 #define CACHED_LOOP_LIST(V) \
   V(1)                      \
   V(2)
 
@@ skipping 115 matching lines @@
       return &cache_.kBranchTrueOperator;
     case BranchHint::kFalse:
       return &cache_.kBranchFalseOperator;
   }
   UNREACHABLE();
   return nullptr;
 }
 
 
 const Operator* CommonOperatorBuilder::Switch(size_t control_output_count) {
-  DCHECK_GE(control_output_count, 2u);        // Disallow trivial switches.
+  DCHECK_GE(control_output_count, 3u);        // Disallow trivial switches.
   return new (zone()) Operator(               // --
       IrOpcode::kSwitch, Operator::kKontrol,  // opcode
       "Switch",                               // name
       1, 0, 1, 0, 0, control_output_count);   // counts
 }
 
 
-const Operator* CommonOperatorBuilder::Case(size_t index) {
-  return new (zone()) Operator1<size_t>(    // --
-      IrOpcode::kCase, Operator::kKontrol,  // opcode
-      "Case",                               // name
-      0, 0, 1, 0, 0, 1,                     // counts
-      index);                               // parameter
+const Operator* CommonOperatorBuilder::IfValue(int32_t index) {
+  return new (zone()) Operator1<int32_t>(      // --
+      IrOpcode::kIfValue, Operator::kKontrol,  // opcode
+      "IfValue",                               // name
+      0, 0, 1, 0, 0, 1,                        // counts
+      index);                                  // parameter
 }
 
 
 const Operator* CommonOperatorBuilder::Start(int num_formal_parameters) {
   // Outputs are formal parameters, plus context, receiver, and JSFunction.
   const int value_output_count = num_formal_parameters + 3;
   return new (zone()) Operator(               // --
       IrOpcode::kStart, Operator::kFoldable,  // opcode
       "Start",                                // name
       0, 0, 0, value_output_count, 1, 1);     // counts
@@ skipping 250 matching lines @@
   } else {
     UNREACHABLE();
     return nullptr;
   }
 }
 
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8