From 422090017f3eddb2c33d57c3574920af189e07b0 Mon Sep 17 00:00:00 2001
From: JianxiaoLuIntel <jianxiao.lu@intel.com>
Date: Fri, 3 Feb 2023 14:50:53 +0800
Subject: [PATCH] [x64][codegen] Remove redundant cmp in BinarySearchSwitch

Before:
1b6  cmpl r15,0xb
1ba  jl 0x7f69801dd7d5  <+0x1d5>
1bc  cmpl r15,0xb
1c0  jz 0x7f69801dd842  B200,201,202,203,204,205 <+0x242>

1b6  cmpl r15,0xb
1ba  jl 0x7fa6a00a8591  <+0x1d1>
1bc  jz 0x7fa6a00a85fa  B200,201,202,203,204,205 <+0x23a>

After:
Change-Id: I820c9291638f27750cb77a0dcd5f1108c4ab8115
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/4219940
Commit-Queue: Jianxiao Lu <jianxiao.lu@intel.com>
Reviewed-by: Nico Hartmann <nicohartmann@chromium.org>
Cr-Commit-Position: refs/heads/main@{#85675}
---
 src/compiler/backend/code-generator.cc        |  2 ++
 src/compiler/backend/code-generator.h         |  6 ++++
 .../backend/x64/code-generator-x64.cc         | 33 ++++++++++++++++++-
 3 files changed, 40 insertions(+), 1 deletion(-)

diff --git a/src/compiler/backend/code-generator.cc b/src/compiler/backend/code-generator.cc
index 9f1f45b90c..ee75ca27bc 100644
--- a/src/compiler/backend/code-generator.cc
+++ b/src/compiler/backend/code-generator.cc
@@ -430,6 +430,7 @@ void CodeGenerator::AssembleCode() {
   result_ = kSuccess;
 }
 
+#ifndef V8_TARGET_ARCH_X64
 void CodeGenerator::AssembleArchBinarySearchSwitchRange(
     Register input, RpoNumber def_block, std::pair<int32_t, Label*>* begin,
     std::pair<int32_t, Label*>* end) {
@@ -448,6 +449,7 @@ void CodeGenerator::AssembleArchBinarySearchSwitchRange(
   masm()->bind(&less_label);
   AssembleArchBinarySearchSwitchRange(input, def_block, begin, middle);
 }
+#endif  // V8_TARGET_ARCH_X64
 
 void CodeGenerator::AssembleArchJump(RpoNumber target) {
   if (!IsNextInAssemblyOrder(target))
diff --git a/src/compiler/backend/code-generator.h b/src/compiler/backend/code-generator.h
index f6feb42378..20cc045b11 100644
--- a/src/compiler/backend/code-generator.h
+++ b/src/compiler/backend/code-generator.h
@@ -278,9 +278,15 @@ class V8_EXPORT_PRIVATE CodeGenerator final : public GapResolver::Assembler {
 #if V8_ENABLE_WEBASSEMBLY
   void AssembleArchTrap(Instruction* instr, FlagsCondition condition);
 #endif  // V8_ENABLE_WEBASSEMBLY
+#if V8_TARGET_ARCH_X64
+  void AssembleArchBinarySearchSwitchRange(
+      Register input, RpoNumber def_block, std::pair<int32_t, Label*>* begin,
+      std::pair<int32_t, Label*>* end, base::Optional<int32_t>& last_cmp_value);
+#else
   void AssembleArchBinarySearchSwitchRange(Register input, RpoNumber def_block,
                                            std::pair<int32_t, Label*>* begin,
                                            std::pair<int32_t, Label*>* end);
+#endif  // V8_TARGET_ARCH_X64
   void AssembleArchBinarySearchSwitch(Instruction* instr);
   void AssembleArchTableSwitch(Instruction* instr);
 
diff --git a/src/compiler/backend/x64/code-generator-x64.cc b/src/compiler/backend/x64/code-generator-x64.cc
index 42d846a97f..7924a6fe60 100644
--- a/src/compiler/backend/x64/code-generator-x64.cc
+++ b/src/compiler/backend/x64/code-generator-x64.cc
@@ -4,6 +4,7 @@
 
 #include <limits>
 
+#include "src/base/optional.h"
 #include "src/base/overflowing-math.h"
 #include "src/codegen/assembler.h"
 #include "src/codegen/cpu-features.h"
@@ -4746,6 +4747,34 @@ void CodeGenerator::AssembleArchBoolean(Instruction* instr,
   __ bind(&done);
 }
 
+void CodeGenerator::AssembleArchBinarySearchSwitchRange(
+    Register input, RpoNumber def_block, std::pair<int32_t, Label*>* begin,
+    std::pair<int32_t, Label*>* end, base::Optional<int32_t>& last_cmp_value) {
+  if (end - begin < kBinarySearchSwitchMinimalCases) {
+    if (last_cmp_value && *last_cmp_value == begin->first) {
+      // No need to do another repeat cmp.
+      masm()->j(equal, begin->second);
+      ++begin;
+    }
+
+    while (begin != end) {
+      masm()->JumpIfEqual(input, begin->first, begin->second);
+      ++begin;
+    }
+    AssembleArchJumpRegardlessOfAssemblyOrder(def_block);
+    return;
+  }
+  auto middle = begin + (end - begin) / 2;
+  Label less_label;
+  masm()->JumpIfLessThan(input, middle->first, &less_label);
+  last_cmp_value = middle->first;
+  AssembleArchBinarySearchSwitchRange(input, def_block, middle, end,
+                                      last_cmp_value);
+  masm()->bind(&less_label);
+  AssembleArchBinarySearchSwitchRange(input, def_block, begin, middle,
+                                      last_cmp_value);
+}
+
 void CodeGenerator::AssembleArchBinarySearchSwitch(Instruction* instr) {
   X64OperandConverter i(this, instr);
   Register input = i.InputRegister(0);
@@ -4753,8 +4782,10 @@ void CodeGenerator::AssembleArchBinarySearchSwitch(Instruction* instr) {
   for (size_t index = 2; index < instr->InputCount(); index += 2) {
     cases.push_back({i.InputInt32(index + 0), GetLabel(i.InputRpo(index + 1))});
   }
+  base::Optional<int32_t> last_cmp_value;
   AssembleArchBinarySearchSwitchRange(input, i.InputRpo(1), cases.data(),
-                                      cases.data() + cases.size());
+                                      cases.data() + cases.size(),
+                                      last_cmp_value);
 }
 
 void CodeGenerator::AssembleArchTableSwitch(Instruction* instr) {