[turbofan] Re-enables the jump table emission in the mips instruction selector.

src/compiler/mips64/instruction-selector-mips64.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/base/adapters.h"
 #include "src/base/bits.h"
 #include "src/compiler/instruction-selector-impl.h"
 #include "src/compiler/node-matchers.h"
 #include "src/compiler/node-properties.h"
 
@@ skipping 1693 matching lines @@
 void InstructionSelector::VisitDeoptimizeUnless(Node* node) {
   FlagsContinuation cont =
       FlagsContinuation::ForDeoptimize(kEqual, node->InputAt(1));
   VisitWordCompareZero(this, node, node->InputAt(0), &cont);
 }
 
 void InstructionSelector::VisitSwitch(Node* node, const SwitchInfo& sw) {
   Mips64OperandGenerator g(this);
   InstructionOperand value_operand = g.UseRegister(node->InputAt(0));
 
-  // TODO(mips): TableSwitch is broken, as it messes with ra without saving it
-  // properly (which breaks with frame elision, i.e. inside stubs).
-  if (false) {
-    // Emit either ArchTableSwitch or ArchLookupSwitch.
-    size_t table_space_cost = 10 + 2 * sw.value_range;
-    size_t table_time_cost = 3;
-    size_t lookup_space_cost = 2 + 2 * sw.case_count;
-    size_t lookup_time_cost = sw.case_count;
-    if (sw.case_count > 0 &&
-        table_space_cost + 3 * table_time_cost <=
-            lookup_space_cost + 3 * lookup_time_cost &&
-        sw.min_value > std::numeric_limits<int32_t>::min()) {
-      InstructionOperand index_operand = value_operand;
-      if (sw.min_value) {
-        index_operand = g.TempRegister();
-        Emit(kMips64Sub, index_operand, value_operand,
-             g.TempImmediate(sw.min_value));
-      }
-      // Generate a table lookup.
-      return EmitTableSwitch(sw, index_operand);
+  // Emit either ArchTableSwitch or ArchLookupSwitch.
+  size_t table_space_cost = 10 + 2 * sw.value_range;
+  size_t table_time_cost = 3;
+  size_t lookup_space_cost = 2 + 2 * sw.case_count;
+  size_t lookup_time_cost = sw.case_count;
+  if (sw.case_count > 0 &&
+      table_space_cost + 3 * table_time_cost <=
+          lookup_space_cost + 3 * lookup_time_cost &&
+      sw.min_value > std::numeric_limits<int32_t>::min()) {
+    InstructionOperand index_operand = value_operand;
+    if (sw.min_value) {
+      index_operand = g.TempRegister();
+      Emit(kMips64Sub, index_operand, value_operand,
+           g.TempImmediate(sw.min_value));
     }
+    // Generate a table lookup.
+    return EmitTableSwitch(sw, index_operand);
   }
 
   // Generate a sequence of conditional jumps.
   return EmitLookupSwitch(sw, value_operand);
 }
 
 
 void InstructionSelector::VisitWord32Equal(Node* const node) {
   FlagsContinuation cont = FlagsContinuation::ForSet(kEqual, node);
   Int32BinopMatcher m(node);
@@ skipping 194 matching lines @@
          MachineOperatorBuilder::kFloat32RoundUp |
          MachineOperatorBuilder::kFloat64RoundTruncate |
          MachineOperatorBuilder::kFloat32RoundTruncate |
          MachineOperatorBuilder::kFloat64RoundTiesEven |
          MachineOperatorBuilder::kFloat32RoundTiesEven;
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8