MIPS: Tweak constants to be in favor of table switch.

src/compiler/mips/instruction-selector-mips.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/bits.h"
 #include "src/compiler/instruction-selector-impl.h"
 #include "src/compiler/node-matchers.h"
 #include "src/compiler/node-properties.h"
 
 namespace v8 {
@@ skipping 766 matching lines @@
   InstructionOperand default_operand = g.Label(default_branch);
 
   // Note that {value_range} can be 0 if {min_value} is -2^31 and {max_value}
   // is 2^31-1, so don't assume that it's non-zero below.
   size_t value_range =
       1u + bit_cast<uint32_t>(max_value) - bit_cast<uint32_t>(min_value);
 
   // Determine whether to issue an ArchTableSwitch or an ArchLookupSwitch
   // instruction.
   size_t table_space_cost = 9 + value_range;
-  size_t table_time_cost = 9;
+  size_t table_time_cost = 3;
   size_t lookup_space_cost = 2 + 2 * case_count;
   size_t lookup_time_cost = case_count;
   if (case_count > 0 &&
       table_space_cost + 3 * table_time_cost <=
           lookup_space_cost + 3 * lookup_time_cost &&
       min_value > std::numeric_limits<int32_t>::min()) {
     InstructionOperand index_operand = value_operand;
     if (min_value) {
       index_operand = g.TempRegister();
       Emit(kMipsSub, index_operand, value_operand, g.TempImmediate(min_value));
@@ skipping 140 matching lines @@
   if (IsMipsArchVariant(kMips32r2) || IsMipsArchVariant(kMips32r6)) {
     return MachineOperatorBuilder::kFloat64RoundDown |
            MachineOperatorBuilder::kFloat64RoundTruncate;
   }
   return MachineOperatorBuilder::kNoFlags;
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8