From 6fb5754c5b5198e4e825d4bf91683ba080eee8d3 Mon Sep 17 00:00:00 2001
From: Rui Ueyama <ruiu@cs.stanford.edu>
Date: Tue, 4 May 2021 14:41:32 +0900
Subject: [PATCH] Use u8[] instead of std::vector to avoid zero-initialization
 cost

---
 main.cc        | 10 +++++-----
 mold.h         |  2 +-
 object_file.cc |  8 ++++----
 3 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/main.cc b/main.cc
index e22250d5..7ec5a66d 100644
--- a/main.cc
+++ b/main.cc
@@ -20,11 +20,11 @@ static bool is_text_file(Context<E> &ctx, MemoryMappedFile<E> *mb) {
 
 template <typename E>
 std::string_view save_string(Context<E> &ctx, const std::string &str) {
-  std::vector<u8> *buf = new std::vector<u8>(str.size() + 1);
-  memcpy(buf->data(), str.data(), str.size());
-  (*buf)[str.size()] = '\0';
-  ctx.owning_bufs.push_back(std::unique_ptr<std::vector<u8>>(buf));
-  return {(char *)buf->data(), str.size()};
+  u8 *buf = new u8[str.size() + 1];
+  memcpy(buf, str.data(), str.size());
+  buf[str.size()] = '\0';
+  ctx.owning_bufs.push_back(std::unique_ptr<u8[]>(buf));
+  return {(char *)buf, str.size()};
 }
 
 std::string get_version_string() {
diff --git a/mold.h b/mold.h
index 82939fde..4a34f57f 100644
--- a/mold.h
+++ b/mold.h
@@ -1434,7 +1434,7 @@ struct Context {
 
   tbb::concurrent_vector<std::unique_ptr<ObjectFile<E>>> owning_objs;
   tbb::concurrent_vector<std::unique_ptr<SharedFile<E>>> owning_dsos;
-  tbb::concurrent_vector<std::unique_ptr<std::vector<u8>>> owning_bufs;
+  tbb::concurrent_vector<std::unique_ptr<u8[]>> owning_bufs;
   tbb::concurrent_vector<std::unique_ptr<ElfShdr<E>>> owning_shdrs;
   tbb::concurrent_vector<std::unique_ptr<MemoryMappedFile<E>>> owning_mbs;
 
diff --git a/object_file.cc b/object_file.cc
index 5e3bf99a..0ae17792 100644
--- a/object_file.cc
+++ b/object_file.cc
@@ -193,15 +193,15 @@ std::pair<std::string_view, const ElfShdr<E> *>
 ObjectFile<E>::uncompress_contents(Context<E> &ctx, const ElfShdr<E> &shdr,
                                    std::string_view name) {
   auto do_uncompress = [&](std::string_view data, u64 size) {
-    std::vector<u8> *buf = new std::vector<u8>(size);
-    ctx.owning_bufs.push_back(std::unique_ptr<std::vector<u8>>(buf));
+    u8 *buf = new u8[size];
+    ctx.owning_bufs.push_back(std::unique_ptr<u8[]>(buf));
 
     unsigned long size2 = size;
-    if (uncompress(buf->data(), &size2, (u8 *)&data[0], data.size()) != Z_OK)
+    if (uncompress(buf, &size2, (u8 *)&data[0], data.size()) != Z_OK)
       Fatal(ctx) << *this << ": " << name << ": uncompress failed";
     if (size != size2)
       Fatal(ctx) << *this << ": " << name << ": uncompress: invalid size";
-    return std::string_view((char *)buf->data(), size);
+    return std::string_view((char *)buf, size);
   };
 
   if (name.starts_with(".zdebug")) {