[turbofan] Factor out common switch-related code in instruction selectors.

src/compiler/arm64/instruction-selector-arm64.cc

Index: src/compiler/arm64/instruction-selector-arm64.cc
diff --git a/src/compiler/arm64/instruction-selector-arm64.cc b/src/compiler/arm64/instruction-selector-arm64.cc
index 7f5014ee00feeafba038309f0fe41361c4c501d0..e81c5801bc2615348e25c16edea2c66b0bd025ee 100644
--- a/src/compiler/arm64/instruction-selector-arm64.cc
+++ b/src/compiler/arm64/instruction-selector-arm64.cc
@@ -1443,62 +1443,31 @@ void InstructionSelector::VisitBranch(Node* branch, BasicBlock* tbranch,
 }
 
 
-void InstructionSelector::VisitSwitch(Node* node, BasicBlock* default_branch,
-                                      BasicBlock** case_branches,
-                                      int32_t* case_values, size_t case_count,
-                                      int32_t min_value, int32_t max_value) {
+void InstructionSelector::VisitSwitch(Node* node, const SwitchInfo& sw) {
   Arm64OperandGenerator g(this);
   InstructionOperand value_operand = g.UseRegister(node->InputAt(0));
-  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 = 4 + value_range;
+  // Emit either ArchTableSwitch or ArchLookupSwitch.
+  size_t table_space_cost = 4 + sw.value_range;
   size_t table_time_cost = 3;
-  size_t lookup_space_cost = 3 + 2 * case_count;
-  size_t lookup_time_cost = case_count;
-  if (case_count > 0 &&
+  size_t lookup_space_cost = 3 + 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 &&
-      min_value > std::numeric_limits<int32_t>::min()) {
+      sw.min_value > std::numeric_limits<int32_t>::min()) {
     InstructionOperand index_operand = value_operand;
-    if (min_value) {
+    if (sw.min_value) {
       index_operand = g.TempRegister();
       Emit(kArm64Sub32, index_operand, value_operand,
-           g.TempImmediate(min_value));
-    }
-    size_t input_count = 2 + value_range;
-    auto* inputs = zone()->NewArray<InstructionOperand>(input_count);
-    inputs[0] = index_operand;
-    std::fill(&inputs[1], &inputs[input_count], default_operand);
-    for (size_t index = 0; index < case_count; ++index) {
-      size_t value = case_values[index] - min_value;
-      BasicBlock* branch = case_branches[index];
-      DCHECK_LE(0u, value);
-      DCHECK_LT(value + 2, input_count);
-      inputs[value + 2] = g.Label(branch);
+           g.TempImmediate(sw.min_value));
     }
-    Emit(kArchTableSwitch, 0, nullptr, input_count, inputs, 0, nullptr);
-    return;
+    // Generate a table lookup.
+    return EmitTableSwitch(sw, index_operand);
   }
 
   // Generate a sequence of conditional jumps.
-  size_t input_count = 2 + case_count * 2;
-  auto* inputs = zone()->NewArray<InstructionOperand>(input_count);
-  inputs[0] = value_operand;
-  inputs[1] = default_operand;
-  for (size_t index = 0; index < case_count; ++index) {
-    int32_t value = case_values[index];
-    BasicBlock* branch = case_branches[index];
-    inputs[index * 2 + 2 + 0] = g.TempImmediate(value);
-    inputs[index * 2 + 2 + 1] = g.Label(branch);
-  }
-  Emit(kArchLookupSwitch, 0, nullptr, input_count, inputs, 0, nullptr);
+  return EmitLookupSwitch(sw, value_operand);
 }