From 0f99ed43f15aba7805ebe6d757a2d98418596205 Mon Sep 17 00:00:00 2001
From: Jade Lovelace <lix@jade.fyi>
Date: Thu, 30 May 2024 13:44:01 -0700
Subject: build-time: remove 20% more by PCH'ing C++ stdlib

It seems like someone implemented precompiled headers a long time ago
and then it never got ported to meson or maybe didn't work at all.

This is, however, blessedly easy to simply implement. I went looking for
`#define` that could affect the result of precompiling the headers, and
as far as I can tell we aren't doing any of that, so this should truly
just be free build time savings.

Previous state:
Compilation (551 times):
  Parsing (frontend):         1302.1 s
  Codegen & opts (backend):    956.3 s

New state:
**** Time summary:
Compilation (567 times):
  Parsing (frontend):         1123.0 s
  Codegen & opts (backend):   1078.1 s

I wonder if the "regression" in codegen time is just doing the PCH
operation a few times, because meson does it per-target.

Change-Id: I664366b8069bab4851308b3a7571bea97ac64022
---
 src/pch/precompiled-headers.hh | 60 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 60 insertions(+)
 create mode 100644 src/pch/precompiled-headers.hh

(limited to 'src/pch/precompiled-headers.hh')

diff --git a/src/pch/precompiled-headers.hh b/src/pch/precompiled-headers.hh
new file mode 100644
index 000000000..f52f1cab8
--- /dev/null
+++ b/src/pch/precompiled-headers.hh
@@ -0,0 +1,60 @@
+#include <algorithm>
+#include <array>
+#include <atomic>
+#include <cassert>
+#include <cctype>
+#include <chrono>
+#include <climits>
+#include <cmath>
+#include <condition_variable>
+#include <cstddef>
+#include <cstdint>
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
+#include <exception>
+#include <functional>
+#include <future>
+#include <iostream>
+#include <limits>
+#include <list>
+#include <locale>
+#include <map>
+#include <memory>
+#include <mutex>
+#include <numeric>
+#include <optional>
+#include <queue>
+#include <random>
+#include <regex>
+#include <set>
+#include <sstream>
+#include <stack>
+#include <stdexcept>
+#include <string>
+#include <thread>
+#include <unordered_map>
+#include <unordered_set>
+#include <vector>
+
+#include <boost/format.hpp>
+
+#include <dirent.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <grp.h>
+#include <netdb.h>
+#include <pwd.h>
+#include <signal.h>
+#include <sys/resource.h>
+#include <sys/select.h>
+#include <sys/socket.h>
+#include <sys/stat.h>
+#include <sys/time.h>
+#include <sys/types.h>
+#include <sys/utsname.h>
+#include <sys/wait.h>
+#include <termios.h>
+#include <unistd.h>
+
+#include <nlohmann/json.hpp>
-- 
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