Revert "Shorten generated code for binary-search switches"

This reverts commit 00a757fa.

Reason for revert: Caused perf regressions, https://crbug.com/1280236

Original change's description:
> Shorten generated code for binary-search switches
>
> On some branches of the search tree for a binary-search switch, the
> input value is sufficiently constrained that we could unconditionally
> jump to the last possible case rather than checking for value equality.
> This shortens some builtins by a few instructions and might speed things
> up, though I expect the effect to be small.
>
> Change-Id: I2313f26976e6d3c182f03bd927b338c8175b3af3
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3335437
> Reviewed-by: Nico Hartmann <nicohartmann@chromium.org>
> Commit-Queue: Seth Brenith <seth.brenith@microsoft.com>
> Cr-Commit-Position: refs/heads/main@{#78376}

Bug: chromium:1280236
Change-Id: I88d9ff64641b85d48198b7012df2eeb9441913b5
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3343234
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Reviewed-by: Nico Hartmann <nicohartmann@chromium.org>
Commit-Queue: Seth Brenith <seth.brenith@microsoft.com>
Cr-Commit-Position: refs/heads/main@{#78397}

src/compiler/backend/arm/code-generator-arm.cc

@@ -3625,9 +3625,9 @@ void CodeGenerator::AssembleArchBoolean(Instruction* instr,
 void CodeGenerator::AssembleArchBinarySearchSwitch(Instruction* instr) {
   ArmOperandConverter i(this, instr);
   Register input = i.InputRegister(0);
-  std::vector<std::pair<int32_t, RpoNumber>> cases;
+  std::vector<std::pair<int32_t, Label*>> cases;
   for (size_t index = 2; index < instr->InputCount(); index += 2) {
-    cases.push_back({i.InputInt32(index + 0), i.InputRpo(index + 1)});
+    cases.push_back({i.InputInt32(index + 0), GetLabel(i.InputRpo(index + 1))});
   }
   AssembleArchBinarySearchSwitchRange(input, i.InputRpo(1), cases.data(),
                                       cases.data() + cases.size());

src/compiler/backend/arm64/code-generator-arm64.cc

@@ -2960,9 +2960,9 @@ void CodeGenerator::AssembleArchSelect(Instruction* instr,
 void CodeGenerator::AssembleArchBinarySearchSwitch(Instruction* instr) {
   Arm64OperandConverter i(this, instr);
   Register input = i.InputRegister32(0);
-  std::vector<std::pair<int32_t, RpoNumber>> cases;
+  std::vector<std::pair<int32_t, Label*>> cases;
   for (size_t index = 2; index < instr->InputCount(); index += 2) {
-    cases.push_back({i.InputInt32(index + 0), i.InputRpo(index + 1)});
+    cases.push_back({i.InputInt32(index + 0), GetLabel(i.InputRpo(index + 1))});
   }
   AssembleArchBinarySearchSwitchRange(input, i.InputRpo(1), cases.data(),
                                       cases.data() + cases.size());

src/compiler/backend/code-generator.cc

@@ -491,23 +491,11 @@ void CodeGenerator::AssembleCode() {
 }
 
 void CodeGenerator::AssembleArchBinarySearchSwitchRange(
-    Register input, RpoNumber def_block, std::pair<int32_t, RpoNumber>* begin,
-    std::pair<int32_t, RpoNumber>* end, int32_t min_possible_value,
-    int32_t max_possible_value) {
+    Register input, RpoNumber def_block, std::pair<int32_t, Label*>* begin,
+    std::pair<int32_t, Label*>* end) {
   if (end - begin < kBinarySearchSwitchMinimalCases) {
     while (begin != end) {
-      if (min_possible_value == begin->first) {
-        if (max_possible_value == begin->first) {
-          // Only one value is possible, so we can jump to it unconditionally.
-          DCHECK_EQ(begin + 1, end);
-          def_block = begin->second;
-          break;
-        }
-        // After emitting the branch for this case, the minimum possible value
-        // is increased.
-        ++min_possible_value;
-      }
-      tasm()->JumpIfEqual(input, begin->first, GetLabel(begin->second));
+      tasm()->JumpIfEqual(input, begin->first, begin->second);
       ++begin;
     }
     AssembleArchJumpRegardlessOfAssemblyOrder(def_block);
@@ -516,11 +504,9 @@ void CodeGenerator::AssembleArchBinarySearchSwitchRange(
   auto middle = begin + (end - begin) / 2;
   Label less_label;
   tasm()->JumpIfLessThan(input, middle->first, &less_label);
-  AssembleArchBinarySearchSwitchRange(input, def_block, middle, end,
-                                      middle->first, max_possible_value);
+  AssembleArchBinarySearchSwitchRange(input, def_block, middle, end);
   tasm()->bind(&less_label);
-  AssembleArchBinarySearchSwitchRange(input, def_block, begin, middle,
-                                      min_possible_value, middle->first - 1);
+  AssembleArchBinarySearchSwitchRange(input, def_block, begin, middle);
 }
 
 void CodeGenerator::AssembleArchJump(RpoNumber target) {

src/compiler/backend/code-generator.h

@@ -257,11 +257,9 @@ class V8_EXPORT_PRIVATE CodeGenerator final : public GapResolver::Assembler {
 #if V8_ENABLE_WEBASSEMBLY
   void AssembleArchTrap(Instruction* instr, FlagsCondition condition);
 #endif  // V8_ENABLE_WEBASSEMBLY
-  void AssembleArchBinarySearchSwitchRange(
-      Register input, RpoNumber def_block, std::pair<int32_t, RpoNumber>* begin,
-      std::pair<int32_t, RpoNumber>* end,
-      int32_t min_possible_value = std::numeric_limits<int32_t>::min(),
-      int32_t max_possible_value = std::numeric_limits<int32_t>::max());
+  void AssembleArchBinarySearchSwitchRange(Register input, RpoNumber def_block,
+                                           std::pair<int32_t, Label*>* begin,
+                                           std::pair<int32_t, Label*>* end);
   void AssembleArchBinarySearchSwitch(Instruction* instr);
   void AssembleArchTableSwitch(Instruction* instr);
 

src/compiler/backend/ia32/code-generator-ia32.cc

@@ -3841,9 +3841,9 @@ void CodeGenerator::AssembleArchBoolean(Instruction* instr,
 void CodeGenerator::AssembleArchBinarySearchSwitch(Instruction* instr) {
   IA32OperandConverter i(this, instr);
   Register input = i.InputRegister(0);
-  std::vector<std::pair<int32_t, RpoNumber>> cases;
+  std::vector<std::pair<int32_t, Label*>> cases;
   for (size_t index = 2; index < instr->InputCount(); index += 2) {
-    cases.push_back({i.InputInt32(index + 0), i.InputRpo(index + 1)});
+    cases.push_back({i.InputInt32(index + 0), GetLabel(i.InputRpo(index + 1))});
   }
   AssembleArchBinarySearchSwitchRange(input, i.InputRpo(1), cases.data(),
                                       cases.data() + cases.size());

src/compiler/backend/loong64/code-generator-loong64.cc

@@ -2152,9 +2152,9 @@ void CodeGenerator::AssembleArchBoolean(Instruction* instr,
 void CodeGenerator::AssembleArchBinarySearchSwitch(Instruction* instr) {
   Loong64OperandConverter i(this, instr);
   Register input = i.InputRegister(0);
-  std::vector<std::pair<int32_t, RpoNumber>> cases;
+  std::vector<std::pair<int32_t, Label*>> cases;
   for (size_t index = 2; index < instr->InputCount(); index += 2) {
-    cases.push_back({i.InputInt32(index + 0), i.InputRpo(index + 1)});
+    cases.push_back({i.InputInt32(index + 0), GetLabel(i.InputRpo(index + 1))});
   }
   AssembleArchBinarySearchSwitchRange(input, i.InputRpo(1), cases.data(),
                                       cases.data() + cases.size());

src/compiler/backend/mips/code-generator-mips.cc

@@ -3906,9 +3906,9 @@ void CodeGenerator::AssembleArchBoolean(Instruction* instr,
 void CodeGenerator::AssembleArchBinarySearchSwitch(Instruction* instr) {
   MipsOperandConverter i(this, instr);
   Register input = i.InputRegister(0);
-  std::vector<std::pair<int32_t, RpoNumber>> cases;
+  std::vector<std::pair<int32_t, Label*>> cases;
   for (size_t index = 2; index < instr->InputCount(); index += 2) {
-    cases.push_back({i.InputInt32(index + 0), i.InputRpo(index + 1)});
+    cases.push_back({i.InputInt32(index + 0), GetLabel(i.InputRpo(index + 1))});
   }
   AssembleArchBinarySearchSwitchRange(input, i.InputRpo(1), cases.data(),
                                       cases.data() + cases.size());

src/compiler/backend/mips64/code-generator-mips64.cc

@@ -4110,9 +4110,9 @@ void CodeGenerator::AssembleArchBoolean(Instruction* instr,
 void CodeGenerator::AssembleArchBinarySearchSwitch(Instruction* instr) {
   MipsOperandConverter i(this, instr);
   Register input = i.InputRegister(0);
-  std::vector<std::pair<int32_t, RpoNumber>> cases;
+  std::vector<std::pair<int32_t, Label*>> cases;
   for (size_t index = 2; index < instr->InputCount(); index += 2) {
-    cases.push_back({i.InputInt32(index + 0), i.InputRpo(index + 1)});
+    cases.push_back({i.InputInt32(index + 0), GetLabel(i.InputRpo(index + 1))});
   }
   AssembleArchBinarySearchSwitchRange(input, i.InputRpo(1), cases.data(),
                                       cases.data() + cases.size());

src/compiler/backend/ppc/code-generator-ppc.cc

@@ -3926,9 +3926,9 @@ void CodeGenerator::AssembleArchBoolean(Instruction* instr,
 void CodeGenerator::AssembleArchBinarySearchSwitch(Instruction* instr) {
   PPCOperandConverter i(this, instr);
   Register input = i.InputRegister(0);
-  std::vector<std::pair<int32_t, RpoNumber>> cases;
+  std::vector<std::pair<int32_t, Label*>> cases;
   for (size_t index = 2; index < instr->InputCount(); index += 2) {
-    cases.push_back({i.InputInt32(index + 0), i.InputRpo(index + 1)});
+    cases.push_back({i.InputInt32(index + 0), GetLabel(i.InputRpo(index + 1))});
   }
   AssembleArchBinarySearchSwitchRange(input, i.InputRpo(1), cases.data(),
                                       cases.data() + cases.size());

src/compiler/backend/riscv64/code-generator-riscv64.cc

@@ -3764,9 +3764,9 @@ void CodeGenerator::AssembleArchBoolean(Instruction* instr,
 void CodeGenerator::AssembleArchBinarySearchSwitch(Instruction* instr) {
   RiscvOperandConverter i(this, instr);
   Register input = i.InputRegister(0);
-  std::vector<std::pair<int32_t, RpoNumber>> cases;
+  std::vector<std::pair<int32_t, Label*>> cases;
   for (size_t index = 2; index < instr->InputCount(); index += 2) {
-    cases.push_back({i.InputInt32(index + 0), i.InputRpo(index + 1)});
+    cases.push_back({i.InputInt32(index + 0), GetLabel(i.InputRpo(index + 1))});
   }
   AssembleArchBinarySearchSwitchRange(input, i.InputRpo(1), cases.data(),
                                       cases.data() + cases.size());

src/compiler/backend/s390/code-generator-s390.cc

@@ -3793,9 +3793,9 @@ void CodeGenerator::AssembleArchBoolean(Instruction* instr,
 void CodeGenerator::AssembleArchBinarySearchSwitch(Instruction* instr) {
   S390OperandConverter i(this, instr);
   Register input = i.InputRegister(0);
-  std::vector<std::pair<int32_t, RpoNumber>> cases;
+  std::vector<std::pair<int32_t, Label*>> cases;
   for (size_t index = 2; index < instr->InputCount(); index += 2) {
-    cases.push_back({i.InputInt32(index + 0), i.InputRpo(index + 1)});
+    cases.push_back({i.InputInt32(index + 0), GetLabel(i.InputRpo(index + 1))});
   }
   AssembleArchBinarySearchSwitchRange(input, i.InputRpo(1), cases.data(),
                                       cases.data() + cases.size());

src/compiler/backend/x64/code-generator-x64.cc

@@ -4478,9 +4478,9 @@ void CodeGenerator::AssembleArchBoolean(Instruction* instr,
 void CodeGenerator::AssembleArchBinarySearchSwitch(Instruction* instr) {
   X64OperandConverter i(this, instr);
   Register input = i.InputRegister(0);
-  std::vector<std::pair<int32_t, RpoNumber>> cases;
+  std::vector<std::pair<int32_t, Label*>> cases;
   for (size_t index = 2; index < instr->InputCount(); index += 2) {
-    cases.push_back({i.InputInt32(index + 0), i.InputRpo(index + 1)});
+    cases.push_back({i.InputInt32(index + 0), GetLabel(i.InputRpo(index + 1))});
   }
   AssembleArchBinarySearchSwitchRange(input, i.InputRpo(1), cases.data(),
                                       cases.data() + cases.size());