Revert "[turbofan] disable indirect jumps in Turbofan generated switches"

This reverts commit 957ac364.

Reason for revert: Breaks roll (crbug.com/v8/7388)

Original change's description:
> [turbofan] disable indirect jumps in Turbofan generated switches
> 
> Bug: 
> Change-Id: I326bf518f895e7c030376210e7797f3dd4a9ae1f
> Reviewed-on: https://chromium-review.googlesource.com/873643
> Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
> Commit-Queue: Tobias Tebbi <tebbi@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#50984}

TBR=jarin@chromium.org,tebbi@chromium.org

Change-Id: Id2546e722179e6d8f2f102ce02fb18d696a79764
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/894385Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Commit-Queue: Jaroslav Sevcik <jarin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#50995}

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

@@ -1980,26 +1980,24 @@ void InstructionSelector::VisitSwitch(Node* node, const SwitchInfo& sw) {
   InstructionOperand value_operand = g.UseRegister(node->InputAt(0));
 
   // Emit either ArchTableSwitch or ArchLookupSwitch.
-  if (!FLAG_turbo_disable_switch_jump_table) {
-    static const size_t kMaxTableSwitchValueRange = 2 << 16;
-    size_t table_space_cost = 4 + sw.value_range;
-    size_t table_time_cost = 3;
-    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 &&
-        sw.min_value > std::numeric_limits<int32_t>::min() &&
-        sw.value_range <= kMaxTableSwitchValueRange) {
-      InstructionOperand index_operand = value_operand;
-      if (sw.min_value) {
-        index_operand = g.TempRegister();
-        Emit(kArmSub | AddressingModeField::encode(kMode_Operand2_I),
-             index_operand, value_operand, g.TempImmediate(sw.min_value));
-      }
-      // Generate a table lookup.
-      return EmitTableSwitch(sw, index_operand);
+  static const size_t kMaxTableSwitchValueRange = 2 << 16;
+  size_t table_space_cost = 4 + sw.value_range;
+  size_t table_time_cost = 3;
+  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 &&
+      sw.min_value > std::numeric_limits<int32_t>::min() &&
+      sw.value_range <= kMaxTableSwitchValueRange) {
+    InstructionOperand index_operand = value_operand;
+    if (sw.min_value) {
+      index_operand = g.TempRegister();
+      Emit(kArmSub | AddressingModeField::encode(kMode_Operand2_I),
+           index_operand, value_operand, g.TempImmediate(sw.min_value));
     }
+    // Generate a table lookup.
+    return EmitTableSwitch(sw, index_operand);
   }
 
   // Generate a sequence of conditional jumps.

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

@@ -2361,26 +2361,24 @@ void InstructionSelector::VisitSwitch(Node* node, const SwitchInfo& sw) {
   InstructionOperand value_operand = g.UseRegister(node->InputAt(0));
 
   // Emit either ArchTableSwitch or ArchLookupSwitch.
-  if (!FLAG_turbo_disable_switch_jump_table) {
-    static const size_t kMaxTableSwitchValueRange = 2 << 16;
-    size_t table_space_cost = 4 + sw.value_range;
-    size_t table_time_cost = 3;
-    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 &&
-        sw.min_value > std::numeric_limits<int32_t>::min() &&
-        sw.value_range <= kMaxTableSwitchValueRange) {
-      InstructionOperand index_operand = value_operand;
-      if (sw.min_value) {
-        index_operand = g.TempRegister();
-        Emit(kArm64Sub32, index_operand, value_operand,
-             g.TempImmediate(sw.min_value));
-      }
-      // Generate a table lookup.
-      return EmitTableSwitch(sw, index_operand);
+  static const size_t kMaxTableSwitchValueRange = 2 << 16;
+  size_t table_space_cost = 4 + sw.value_range;
+  size_t table_time_cost = 3;
+  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 &&
+      sw.min_value > std::numeric_limits<int32_t>::min() &&
+      sw.value_range <= kMaxTableSwitchValueRange) {
+    InstructionOperand index_operand = value_operand;
+    if (sw.min_value) {
+      index_operand = g.TempRegister();
+      Emit(kArm64Sub32, index_operand, value_operand,
+           g.TempImmediate(sw.min_value));
     }
+    // Generate a table lookup.
+    return EmitTableSwitch(sw, index_operand);
   }
 
   // Generate a sequence of conditional jumps.

src/compiler/ia32/instruction-selector-ia32.cc

@@ -1431,26 +1431,24 @@ void InstructionSelector::VisitSwitch(Node* node, const SwitchInfo& sw) {
   InstructionOperand value_operand = g.UseRegister(node->InputAt(0));
 
   // Emit either ArchTableSwitch or ArchLookupSwitch.
-  if (!FLAG_turbo_disable_switch_jump_table) {
-    static const size_t kMaxTableSwitchValueRange = 2 << 16;
-    size_t table_space_cost = 4 + sw.value_range;
-    size_t table_time_cost = 3;
-    size_t lookup_space_cost = 3 + 2 * sw.case_count;
-    size_t lookup_time_cost = sw.case_count;
-    if (sw.case_count > 4 &&
-        table_space_cost + 3 * table_time_cost <=
-            lookup_space_cost + 3 * lookup_time_cost &&
-        sw.min_value > std::numeric_limits<int32_t>::min() &&
-        sw.value_range <= kMaxTableSwitchValueRange) {
-      InstructionOperand index_operand = value_operand;
-      if (sw.min_value) {
-        index_operand = g.TempRegister();
-        Emit(kIA32Lea | AddressingModeField::encode(kMode_MRI), index_operand,
-             value_operand, g.TempImmediate(-sw.min_value));
-      }
-      // Generate a table lookup.
-      return EmitTableSwitch(sw, index_operand);
+  static const size_t kMaxTableSwitchValueRange = 2 << 16;
+  size_t table_space_cost = 4 + sw.value_range;
+  size_t table_time_cost = 3;
+  size_t lookup_space_cost = 3 + 2 * sw.case_count;
+  size_t lookup_time_cost = sw.case_count;
+  if (sw.case_count > 4 &&
+      table_space_cost + 3 * table_time_cost <=
+          lookup_space_cost + 3 * lookup_time_cost &&
+      sw.min_value > std::numeric_limits<int32_t>::min() &&
+      sw.value_range <= kMaxTableSwitchValueRange) {
+    InstructionOperand index_operand = value_operand;
+    if (sw.min_value) {
+      index_operand = g.TempRegister();
+      Emit(kIA32Lea | AddressingModeField::encode(kMode_MRI), index_operand,
+           value_operand, g.TempImmediate(-sw.min_value));
     }
+    // Generate a table lookup.
+    return EmitTableSwitch(sw, index_operand);
   }
 
   // Generate a sequence of conditional jumps.

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

@@ -1608,26 +1608,24 @@ void InstructionSelector::VisitSwitch(Node* node, const SwitchInfo& sw) {
   InstructionOperand value_operand = g.UseRegister(node->InputAt(0));
 
   // Emit either ArchTableSwitch or ArchLookupSwitch.
-  if (!FLAG_turbo_disable_switch_jump_table) {
-    static const size_t kMaxTableSwitchValueRange = 2 << 16;
-    size_t table_space_cost = 9 + 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() &&
-        sw.value_range <= kMaxTableSwitchValueRange) {
-      InstructionOperand index_operand = value_operand;
-      if (sw.min_value) {
-        index_operand = g.TempRegister();
-        Emit(kMipsSub, index_operand, value_operand,
-             g.TempImmediate(sw.min_value));
-      }
-      // Generate a table lookup.
-      return EmitTableSwitch(sw, index_operand);
+  static const size_t kMaxTableSwitchValueRange = 2 << 16;
+  size_t table_space_cost = 9 + 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() &&
+      sw.value_range <= kMaxTableSwitchValueRange) {
+    InstructionOperand index_operand = value_operand;
+    if (sw.min_value) {
+      index_operand = g.TempRegister();
+      Emit(kMipsSub, index_operand, value_operand,
+           g.TempImmediate(sw.min_value));
     }
+    // Generate a table lookup.
+    return EmitTableSwitch(sw, index_operand);
   }
 
   // Generate a sequence of conditional jumps.

src/compiler/mips64/instruction-selector-mips64.cc

@@ -2216,26 +2216,24 @@ void InstructionSelector::VisitSwitch(Node* node, const SwitchInfo& sw) {
   InstructionOperand value_operand = g.UseRegister(node->InputAt(0));
 
   // Emit either ArchTableSwitch or ArchLookupSwitch.
-  if (!FLAG_turbo_disable_switch_jump_table) {
-    static const size_t kMaxTableSwitchValueRange = 2 << 16;
-    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() &&
-        sw.value_range <= kMaxTableSwitchValueRange) {
-      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);
+  static const size_t kMaxTableSwitchValueRange = 2 << 16;
+  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() &&
+      sw.value_range <= kMaxTableSwitchValueRange) {
+    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.

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

@@ -1762,26 +1762,24 @@ void InstructionSelector::VisitSwitch(Node* node, const SwitchInfo& sw) {
   InstructionOperand value_operand = g.UseRegister(node->InputAt(0));
 
   // Emit either ArchTableSwitch or ArchLookupSwitch.
-  if (!FLAG_turbo_disable_switch_jump_table) {
-    static const size_t kMaxTableSwitchValueRange = 2 << 16;
-    size_t table_space_cost = 4 + sw.value_range;
-    size_t table_time_cost = 3;
-    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 &&
-        sw.min_value > std::numeric_limits<int32_t>::min() &&
-        sw.value_range <= kMaxTableSwitchValueRange) {
-      InstructionOperand index_operand = value_operand;
-      if (sw.min_value) {
-        index_operand = g.TempRegister();
-        Emit(kPPC_Sub, index_operand, value_operand,
-             g.TempImmediate(sw.min_value));
-      }
-      // Generate a table lookup.
-      return EmitTableSwitch(sw, index_operand);
+  static const size_t kMaxTableSwitchValueRange = 2 << 16;
+  size_t table_space_cost = 4 + sw.value_range;
+  size_t table_time_cost = 3;
+  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 &&
+      sw.min_value > std::numeric_limits<int32_t>::min() &&
+      sw.value_range <= kMaxTableSwitchValueRange) {
+    InstructionOperand index_operand = value_operand;
+    if (sw.min_value) {
+      index_operand = g.TempRegister();
+      Emit(kPPC_Sub, index_operand, value_operand,
+           g.TempImmediate(sw.min_value));
     }
+    // Generate a table lookup.
+    return EmitTableSwitch(sw, index_operand);
   }
 
   // Generate a sequence of conditional jumps.

src/compiler/s390/instruction-selector-s390.cc

@@ -2138,23 +2138,22 @@ void InstructionSelector::VisitSwitch(Node* node, const SwitchInfo& sw) {
   InstructionOperand value_operand = g.UseRegister(node->InputAt(0));
 
   // Emit either ArchTableSwitch or ArchLookupSwitch.
-  if (!FLAG_turbo_disable_switch_jump_table) {
-    static const size_t kMaxTableSwitchValueRange = 2 << 16;
-    size_t table_space_cost = 4 + sw.value_range;
-    size_t table_time_cost = 3;
-    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 &&
-        sw.min_value > std::numeric_limits<int32_t>::min() &&
-        sw.value_range <= kMaxTableSwitchValueRange) {
-      InstructionOperand index_operand = value_operand;
-      if (sw.min_value) {
-        index_operand = g.TempRegister();
-        Emit(kS390_Lay | AddressingModeField::encode(kMode_MRI), index_operand,
-             value_operand, g.TempImmediate(-sw.min_value));
-      }
+  static const size_t kMaxTableSwitchValueRange = 2 << 16;
+  size_t table_space_cost = 4 + sw.value_range;
+  size_t table_time_cost = 3;
+  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 &&
+      sw.min_value > std::numeric_limits<int32_t>::min() &&
+      sw.value_range <= kMaxTableSwitchValueRange) {
+    InstructionOperand index_operand = value_operand;
+    if (sw.min_value) {
+      index_operand = g.TempRegister();
+      Emit(kS390_Lay | AddressingModeField::encode(kMode_MRI), index_operand,
+           value_operand, g.TempImmediate(-sw.min_value));
+    }
 #if V8_TARGET_ARCH_S390X
     InstructionOperand index_operand_zero_ext = g.TempRegister();
     Emit(kS390_Uint32ToUint64, index_operand_zero_ext, index_operand);
@@ -2163,7 +2162,6 @@ void InstructionSelector::VisitSwitch(Node* node, const SwitchInfo& sw) {
     // Generate a table lookup.
     return EmitTableSwitch(sw, index_operand);
   }
-  }
 
   // Generate a sequence of conditional jumps.
   return EmitLookupSwitch(sw, value_operand);

src/compiler/x64/instruction-selector-x64.cc

@@ -1959,30 +1959,27 @@ void InstructionSelector::VisitSwitch(Node* node, const SwitchInfo& sw) {
   InstructionOperand value_operand = g.UseRegister(node->InputAt(0));
 
   // Emit either ArchTableSwitch or ArchLookupSwitch.
-  if (!FLAG_turbo_disable_switch_jump_table) {
-    static const size_t kMaxTableSwitchValueRange = 2 << 16;
-    size_t table_space_cost = 4 + sw.value_range;
-    size_t table_time_cost = 3;
-    size_t lookup_space_cost = 3 + 2 * sw.case_count;
-    size_t lookup_time_cost = sw.case_count;
-    if (sw.case_count > 4 &&
-        table_space_cost + 3 * table_time_cost <=
-            lookup_space_cost + 3 * lookup_time_cost &&
-        sw.min_value > std::numeric_limits<int32_t>::min() &&
-        sw.value_range <= kMaxTableSwitchValueRange) {
-      InstructionOperand index_operand = g.TempRegister();
-      if (sw.min_value) {
-        // The leal automatically zero extends, so result is a valid 64-bit
-        // index.
-        Emit(kX64Lea32 | AddressingModeField::encode(kMode_MRI), index_operand,
-             value_operand, g.TempImmediate(-sw.min_value));
-      } else {
-        // Zero extend, because we use it as 64-bit index into the jump table.
-        Emit(kX64Movl, index_operand, value_operand);
-      }
-      // Generate a table lookup.
-      return EmitTableSwitch(sw, index_operand);
+  static const size_t kMaxTableSwitchValueRange = 2 << 16;
+  size_t table_space_cost = 4 + sw.value_range;
+  size_t table_time_cost = 3;
+  size_t lookup_space_cost = 3 + 2 * sw.case_count;
+  size_t lookup_time_cost = sw.case_count;
+  if (sw.case_count > 4 &&
+      table_space_cost + 3 * table_time_cost <=
+          lookup_space_cost + 3 * lookup_time_cost &&
+      sw.min_value > std::numeric_limits<int32_t>::min() &&
+      sw.value_range <= kMaxTableSwitchValueRange) {
+    InstructionOperand index_operand = g.TempRegister();
+    if (sw.min_value) {
+      // The leal automatically zero extends, so result is a valid 64-bit index.
+      Emit(kX64Lea32 | AddressingModeField::encode(kMode_MRI), index_operand,
+           value_operand, g.TempImmediate(-sw.min_value));
+    } else {
+      // Zero extend, because we use it as 64-bit index into the jump table.
+      Emit(kX64Movl, index_operand, value_operand);
     }
+    // Generate a table lookup.
+    return EmitTableSwitch(sw, index_operand);
   }
 
   // Generate a sequence of conditional jumps.

src/flag-definitions.h

@@ -490,10 +490,6 @@ DEFINE_BOOL(untrusted_code_mitigations, V8_DEFAULT_UNTRUSTED_CODE_MITIGATIONS,
             "Enable mitigations for executing untrusted code")
 #undef V8_DEFAULT_UNTRUSTED_CODE_MITIGATIONS
 
-DEFINE_BOOL(turbo_disable_switch_jump_table, false,
-            "do not emit jump-tables in Turbofan")
-DEFINE_IMPLICATION(untrusted_code_mitigations, turbo_disable_switch_jump_table)
-
 // Flags to help platform porters
 DEFINE_BOOL(minimal, false,
             "simplifies execution model to make porting "