From 2daa034e87ca1d7d8dcca3540a2373e7ea9b7971 Mon Sep 17 00:00:00 2001
From: xsvm <2479667226@qq.com>
Date: Thu, 8 Oct 2026 10:13:03 +0800
Subject: [PATCH] perf(relinker): write in-place --to-intel substitutions
 directly

Each in-place substitution went through X64InstructionRewriter::Rewrite,
which copies the whole code segment and decodes every instruction in it
to adjust references. The converter only accepts equal-length
replacements, so the adjustment is always zero and the copy and scan are
wasted: conversion time grew by one segment scan per substitution. Copy
the replacement bytes into the segment instead.
---
 core/relinker/codegen/src/Amd64OnlyConverter.cpp | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/core/relinker/codegen/src/Amd64OnlyConverter.cpp b/core/relinker/codegen/src/Amd64OnlyConverter.cpp
index aa0bc0d09..1b97d1853 100644
--- a/core/relinker/codegen/src/Amd64OnlyConverter.cpp
+++ b/core/relinker/codegen/src/Amd64OnlyConverter.cpp
@@ -3,7 +3,6 @@
 #include <codegen/CodegenException.hpp>
 #include <codegen/x86/Amd64OnlySubstitutionTable.hpp>
 #include <codegen/x86/X64InstructionDecoder.hpp>
-#include <codegen/x86/X64InstructionRewriter.hpp>
 #include <codegen/x86/IAmd64OnlyInstructionMatcher.hpp>
 #include <algorithm>
 #include <memory>
@@ -39,7 +38,6 @@ private:
         Amd64OnlyMatch Substitution;
     };
 
-    X64InstructionRewriter _rewriter;
     std::unique_ptr<IAmd64OnlyInstructionMatcher> _matcher = MakeAmd64OnlyInstructionMatcher();
     std::unique_ptr<IInstructionScanner> _scanner = MakeInstructionScanner();
 
@@ -120,7 +118,7 @@ void Amd64OnlyConverter::_convertSegment(
         case Amd64OnlyLowering::InPlace: {
             if (substitution.ReplacementBytes.size() != match.Length)
                 throw CodegenException("Intel substitution changes the instruction length", fileOffset);
-            seg = _atFileOffset(ph.Offset, [&] { return _rewriter.Rewrite(seg, {match.Offset, substitution.ReplacementBytes}).Bytes; });
+            std::copy(substitution.ReplacementBytes.begin(), substitution.ReplacementBytes.end(), seg.begin() + static_cast<std::ptrdiff_t>(match.Offset));
             replacementLength = substitution.ReplacementBytes.size();
             ++result.ReplacedCount;
             break;