From 473d2d56fc2ef401cccd17ae736330b50c168c4a Mon Sep 17 00:00:00 2001
From: Jade Lovelace <lix@jade.fyi>
Date: Wed, 29 May 2024 21:12:34 -0700
Subject: [PATCH] Remove 100s of CPU time (10%) from build times (1465s ->
 1302s)
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Result's from Mic92's framework 13th Gen Intel Core i7-1360P:

Before: 3595.92s user 183.01s system 1360% cpu 4:37.74 total
After: 3486.07s user 168.93s system 1354% cpu 4:29.79 total

I saw that boost/lexical_cast was costing about 100s in CPU time on our
compiles. We can fix this trivially by doing explicit template
instantiation in exactly one place and eliminating all other includes of
it, which is a code improvement anyway by hiding the boost.

Before:
```
lix/lix2 » ClangBuildAnalyzer --analyze buildtimeold.bin
Analyzing build trace from 'buildtimeold.bin'...
**** Time summary:
Compilation (551 times):
  Parsing (frontend):         1465.3 s
  Codegen & opts (backend):   1110.9 s

<snip>

**** Expensive headers:
178153 ms: ../src/libcmd/installable-value.hh (included 52 times, avg 3426 ms), included via:
  40x: command.hh
  5x: command-installable-value.hh
  3x: installable-flake.hh
  2x: <direct include>
  2x: installable-attr-path.hh

176217 ms: ../src/libutil/error.hh (included 246 times, avg 716 ms), included via:
  36x: command.hh installable-value.hh installables.hh derived-path.hh config.hh experimental-features.hh
  12x: globals.hh config.hh experimental-features.hh
  11x: file-system.hh file-descriptor.hh
  6x: serialise.hh strings.hh
  6x: <direct include>
  6x: archive.hh serialise.hh strings.hh
  ...

173243 ms: ../src/libstore/store-api.hh (included 152 times, avg 1139 ms), included via:
  55x: <direct include>
  39x: command.hh installable-value.hh installables.hh
  7x: libexpr.hh
  4x: local-store.hh
  4x: command-installable-value.hh installable-value.hh installables.hh
  3x: binary-cache-store.hh
  ...

170482 ms: ../src/libutil/serialise.hh (included 201 times, avg 848 ms), included via:
  37x: command.hh installable-value.hh installables.hh built-path.hh realisation.hh hash.hh
  14x: store-api.hh nar-info.hh hash.hh
  11x: <direct include>
  7x: primops.hh eval.hh attr-set.hh nixexpr.hh value.hh source-path.hh archive.hh
  7x: libexpr.hh value.hh source-path.hh archive.hh
  6x: fetchers.hh hash.hh
  ...

169397 ms: ../src/libcmd/installables.hh (included 53 times, avg 3196 ms), included via:
  40x: command.hh installable-value.hh
  5x: command-installable-value.hh installable-value.hh
  3x: installable-flake.hh installable-value.hh
  2x: <direct include>
  1x: installable-derived-path.hh
  1x: installable-value.hh
  ...

159740 ms: ../src/libutil/strings.hh (included 221 times, avg 722 ms), included via:
  37x: command.hh installable-value.hh installables.hh built-path.hh realisation.hh hash.hh serialise.hh
  19x: <direct include>
  14x: store-api.hh nar-info.hh hash.hh serialise.hh
  11x: serialise.hh
  7x: primops.hh eval.hh attr-set.hh nixexpr.hh value.hh source-path.hh archive.hh serialise.hh
  7x: libexpr.hh value.hh source-path.hh archive.hh serialise.hh
  ...

156796 ms: ../src/libcmd/command.hh (included 51 times, avg 3074 ms), included via:
  42x: <direct include>
  7x: command-installable-value.hh
  2x: installable-attr-path.hh

150392 ms: ../src/libutil/types.hh (included 251 times, avg 599 ms), included via:
  36x: command.hh installable-value.hh installables.hh path.hh
  11x: file-system.hh
  10x: globals.hh
  6x: fetchers.hh
  6x: serialise.hh strings.hh error.hh
  5x: archive.hh
  ...

133101 ms: /nix/store/644b90j1vms44nr18yw3520pzkrg4dd1-boost-1.81.0-dev/include/boost/lexical_cast.hpp (included 226 times, avg 588 ms), included via
:
  37x: command.hh installable-value.hh installables.hh built-path.hh realisation.hh hash.hh serialise.hh strings.hh
  19x: file-system.hh
  11x: store-api.hh nar-info.hh hash.hh serialise.hh strings.hh
  7x: primops.hh eval.hh attr-set.hh nixexpr.hh value.hh source-path.hh archive.hh serialise.hh strings.hh
  7x: libexpr.hh value.hh source-path.hh archive.hh serialise.hh strings.hh
  6x: eval.hh attr-set.hh nixexpr.hh value.hh source-path.hh archive.hh serialise.hh strings.hh
  ...

132887 ms: /nix/store/h2abv2l8irqj942i5rq9wbrj42kbsh5y-gcc-12.3.0/include/c++/12.3.0/memory (included 262 times, avg 507 ms), included via:
  36x: command.hh installable-value.hh installables.hh path.hh types.hh ref.hh
  16x: gtest.h
  11x: file-system.hh types.hh ref.hh
  10x: globals.hh types.hh ref.hh
  10x: json.hpp
  6x: serialise.hh
  ...

  done in 0.6s.
```

After:
```
lix/lix2 » maintainers/buildtime_report.sh build
Processing all files and saving to '/home/jade/lix/lix2/maintainers/../buildtime.bin'...
  done in 0.6s. Run 'ClangBuildAnalyzer --analyze /home/jade/lix/lix2/maintainers/../buildtime.bin' to analyze it.
Analyzing build trace from '/home/jade/lix/lix2/maintainers/../buildtime.bin'...
**** Time summary:
Compilation (551 times):
  Parsing (frontend):         1302.1 s
  Codegen & opts (backend):    956.3 s

<snip>

**** Expensive headers:
178145 ms: ../src/libutil/error.hh (included 246 times, avg 724 ms), included via:
  36x: command.hh installable-value.hh installables.hh derived-path.hh config.hh experimental-features.hh
  12x: globals.hh config.hh experimental-features.hh
  11x: file-system.hh file-descriptor.hh
  6x: <direct include>
  6x: serialise.hh strings.hh
  6x: fetchers.hh hash.hh serialise.hh strings.hh
  ...

154043 ms: ../src/libcmd/installable-value.hh (included 52 times, avg 2962 ms), included via:
  40x: command.hh
  5x: command-installable-value.hh
  3x: installable-flake.hh
  2x: <direct include>
  2x: installable-attr-path.hh

153593 ms: ../src/libstore/store-api.hh (included 152 times, avg 1010 ms), included via:
  55x: <direct include>
  39x: command.hh installable-value.hh installables.hh
  7x: libexpr.hh
  4x: local-store.hh
  4x: command-installable-value.hh installable-value.hh installables.hh
  3x: binary-cache-store.hh
  ...

149948 ms: ../src/libutil/types.hh (included 251 times, avg 597 ms), included via:
  36x: command.hh installable-value.hh installables.hh path.hh
  11x: file-system.hh
  10x: globals.hh
  6x: fetchers.hh
  6x: serialise.hh strings.hh error.hh
  5x: archive.hh
  ...

144560 ms: ../src/libcmd/installables.hh (included 53 times, avg 2727 ms), included via:
  40x: command.hh installable-value.hh
  5x: command-installable-value.hh installable-value.hh
  3x: installable-flake.hh installable-value.hh
  2x: <direct include>
  1x: installable-value.hh
  1x: installable-derived-path.hh
  ...

136585 ms: ../src/libcmd/command.hh (included 51 times, avg 2678 ms), included via:
  42x: <direct include>
  7x: command-installable-value.hh
  2x: installable-attr-path.hh

133394 ms: /nix/store/h2abv2l8irqj942i5rq9wbrj42kbsh5y-gcc-12.3.0/include/c++/12.3.0/memory (included 262 times, avg 509 ms), included via:
  36x: command.hh installable-value.hh installables.hh path.hh types.hh ref.hh
  16x: gtest.h
  11x: file-system.hh types.hh ref.hh
  10x: globals.hh types.hh ref.hh
  10x: json.hpp
  6x: serialise.hh
  ...

89315 ms: ../src/libstore/derived-path.hh (included 178 times, avg 501 ms), included via:
  37x: command.hh installable-value.hh installables.hh
  25x: store-api.hh realisation.hh
  7x: primops.hh eval.hh attr-set.hh nixexpr.hh value.hh context.hh
  6x: eval.hh attr-set.hh nixexpr.hh value.hh context.hh
  6x: libexpr.hh value.hh context.hh
  6x: shared.hh
  ...

87347 ms: /nix/store/h2abv2l8irqj942i5rq9wbrj42kbsh5y-gcc-12.3.0/include/c++/12.3.0/ostream (included 273 times, avg 319 ms), included via:
  35x: command.hh installable-value.hh installables.hh path.hh types.hh ref.hh memory unique_ptr.h
  12x: regex sstream istream
  10x: file-system.hh types.hh ref.hh memory unique_ptr.h
  10x: gtest.h memory unique_ptr.h
  10x: globals.hh types.hh ref.hh memory unique_ptr.h
  6x: fetchers.hh types.hh ref.hh memory unique_ptr.h
  ...

85249 ms: ../src/libutil/config.hh (included 213 times, avg 400 ms), included via:
  37x: command.hh installable-value.hh installables.hh derived-path.hh
  20x: globals.hh
  20x: logging.hh
  16x: store-api.hh logging.hh
  6x: <direct include>
  6x: eval.hh attr-set.hh nixexpr.hh value.hh context.hh derived-path.hh
  ...

  done in 0.5s.
```

Adapated from https://git.lix.systems/lix-project/lix/commit/18aa3e1d570b4ecbb9962376e5fba5757dad8da9
---
 src/libexpr/eval.cc                |  2 +-
 src/libexpr/lexer.l                |  9 +++----
 src/libexpr/nixexpr.cc             |  1 +
 src/libexpr/primops.cc             |  1 +
 src/libexpr/print.cc               |  1 +
 src/libmain/progress-bar.cc        |  1 +
 src/libstore/binary-cache-store.cc |  1 +
 src/libstore/daemon.cc             |  2 ++
 src/libstore/machines.cc           |  2 +-
 src/libutil/current-process.cc     |  1 +
 src/libutil/file-system.hh         |  2 --
 src/libutil/logging.cc             |  1 +
 src/libutil/processes.hh           |  2 --
 src/libutil/util.cc                | 39 ++++++++++++++++++++++++++++++
 src/libutil/util.hh                | 21 ++--------------
 src/nix-env/user-env.cc            |  3 ++-
 src/nix/develop.cc                 |  1 +
 17 files changed, 59 insertions(+), 31 deletions(-)

diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index d7e3a2cdb..c1dadeee0 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -28,13 +28,13 @@
 #include <algorithm>
 #include <chrono>
 #include <iostream>
+#include <sstream>
 #include <cstring>
 #include <optional>
 #include <unistd.h>
 #include <sys/time.h>
 #include <fstream>
 #include <functional>
-#include <iostream>
 
 #include <nlohmann/json.hpp>
 #include <boost/container/small_vector.hpp>
diff --git a/src/libexpr/lexer.l b/src/libexpr/lexer.l
index ee2b6b807..8c0f9d1f2 100644
--- a/src/libexpr/lexer.l
+++ b/src/libexpr/lexer.l
@@ -20,8 +20,6 @@
 #pragma clang diagnostic ignored "-Wunneeded-internal-declaration"
 #endif
 
-#include <boost/lexical_cast.hpp>
-
 #include "nixexpr.hh"
 #include "parser-tab.hh"
 
@@ -129,9 +127,10 @@ or          { return OR_KW; }
 
 {ID}        { yylval->id = {yytext, (size_t) yyleng}; return ID; }
 {INT}       { errno = 0;
-              try {
-                  yylval->n = boost::lexical_cast<int64_t>(yytext);
-              } catch (const boost::bad_lexical_cast &) {
+              std::optional<int64_t> numMay = string2Int<int64_t>(yytext);
+              if (numMay.has_value()) {
+                  yylval->n = *numMay;
+              } else {
                   throw ParseError(ErrorInfo{
                       .msg = HintFmt("invalid integer '%1%'", yytext),
                       .pos = state->positions[CUR_POS],
diff --git a/src/libexpr/nixexpr.cc b/src/libexpr/nixexpr.cc
index c1e2b0448..44198a252 100644
--- a/src/libexpr/nixexpr.cc
+++ b/src/libexpr/nixexpr.cc
@@ -6,6 +6,7 @@
 #include "print.hh"
 
 #include <cstdlib>
+#include <sstream>
 
 namespace nix {
 
diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 1b1a9be3d..7371bd488 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -26,6 +26,7 @@
 
 #include <algorithm>
 #include <cstring>
+#include <sstream>
 #include <regex>
 
 #ifndef _WIN32
diff --git a/src/libexpr/print.cc b/src/libexpr/print.cc
index d53fadac7..920490cfa 100644
--- a/src/libexpr/print.cc
+++ b/src/libexpr/print.cc
@@ -1,5 +1,6 @@
 #include <limits>
 #include <unordered_set>
+#include <sstream>
 
 #include "print.hh"
 #include "ansicolor.hh"
diff --git a/src/libmain/progress-bar.cc b/src/libmain/progress-bar.cc
index ce45eae2b..bb4c52ef7 100644
--- a/src/libmain/progress-bar.cc
+++ b/src/libmain/progress-bar.cc
@@ -7,6 +7,7 @@
 #include <atomic>
 #include <map>
 #include <thread>
+#include <sstream>
 #include <iostream>
 #include <chrono>
 
diff --git a/src/libstore/binary-cache-store.cc b/src/libstore/binary-cache-store.cc
index 5153ca64f..56e47697c 100644
--- a/src/libstore/binary-cache-store.cc
+++ b/src/libstore/binary-cache-store.cc
@@ -18,6 +18,7 @@
 #include <future>
 #include <regex>
 #include <fstream>
+#include <sstream>
 
 #include <nlohmann/json.hpp>
 
diff --git a/src/libstore/daemon.cc b/src/libstore/daemon.cc
index eb6a4e690..4e231ca99 100644
--- a/src/libstore/daemon.cc
+++ b/src/libstore/daemon.cc
@@ -19,6 +19,8 @@
 # include "monitor-fd.hh"
 #endif
 
+#include <sstream>
+
 namespace nix::daemon {
 
 Sink & operator << (Sink & sink, const Logger::Fields & fields)
diff --git a/src/libstore/machines.cc b/src/libstore/machines.cc
index 20f24e883..256cf9188 100644
--- a/src/libstore/machines.cc
+++ b/src/libstore/machines.cc
@@ -148,7 +148,7 @@ static Machine parseBuilderLine(const std::set<std::string> & defaultSystems, co
     };
 
     auto parseFloatField = [&](size_t fieldIndex) {
-        const auto result = string2Int<float>(tokens[fieldIndex]);
+        const auto result = string2Float<float>(tokens[fieldIndex]);
         if (!result) {
             throw FormatError("bad machine specification: failed to convert column #%lu in a row: '%s' to 'float'", fieldIndex, line);
         }
diff --git a/src/libutil/current-process.cc b/src/libutil/current-process.cc
index 9efb68d47..6ca48220d 100644
--- a/src/libutil/current-process.cc
+++ b/src/libutil/current-process.cc
@@ -7,6 +7,7 @@
 #include "file-system.hh"
 #include "processes.hh"
 #include "signals.hh"
+#include <math.h>
 
 #ifdef __APPLE__
 # include <mach-o/dyld.h>
diff --git a/src/libutil/file-system.hh b/src/libutil/file-system.hh
index 933e88441..c6b6ecedb 100644
--- a/src/libutil/file-system.hh
+++ b/src/libutil/file-system.hh
@@ -20,8 +20,6 @@
 #endif
 #include <signal.h>
 
-#include <boost/lexical_cast.hpp>
-
 #include <atomic>
 #include <functional>
 #include <map>
diff --git a/src/libutil/logging.cc b/src/libutil/logging.cc
index 2511c8849..5fa01f0d9 100644
--- a/src/libutil/logging.cc
+++ b/src/libutil/logging.cc
@@ -8,6 +8,7 @@
 #include "position.hh"
 
 #include <atomic>
+#include <sstream>
 #include <nlohmann/json.hpp>
 #include <iostream>
 
diff --git a/src/libutil/processes.hh b/src/libutil/processes.hh
index 9d5367b02..168fcaa55 100644
--- a/src/libutil/processes.hh
+++ b/src/libutil/processes.hh
@@ -12,8 +12,6 @@
 #include <unistd.h>
 #include <signal.h>
 
-#include <boost/lexical_cast.hpp>
-
 #include <atomic>
 #include <functional>
 #include <map>
diff --git a/src/libutil/util.cc b/src/libutil/util.cc
index 103ce4232..99fbcaf9d 100644
--- a/src/libutil/util.cc
+++ b/src/libutil/util.cc
@@ -7,6 +7,8 @@
 #include <regex>
 
 #include <sodium.h>
+#include <boost/lexical_cast.hpp>
+#include <stdint.h>
 
 #ifdef NDEBUG
 #error "Nix may not be built with assertions disabled (i.e. with -DNDEBUG)."
@@ -111,6 +113,43 @@ std::string rewriteStrings(std::string s, const StringMap & rewrites)
     return s;
 }
 
+template<class N>
+std::optional<N> string2Int(const std::string_view s)
+{
+    if (s.substr(0, 1) == "-" && !std::numeric_limits<N>::is_signed)
+        return std::nullopt;
+    try {
+        return boost::lexical_cast<N>(s.data(), s.size());
+    } catch (const boost::bad_lexical_cast &) {
+        return std::nullopt;
+    }
+}
+
+// Explicitly instantiated in one place for faster compilation
+template std::optional<unsigned char>  string2Int<unsigned char>(const std::string_view s);
+template std::optional<unsigned short> string2Int<unsigned short>(const std::string_view s);
+template std::optional<unsigned int> string2Int<unsigned int>(const std::string_view s);
+template std::optional<unsigned long> string2Int<unsigned long>(const std::string_view s);
+template std::optional<unsigned long long> string2Int<unsigned long long>(const std::string_view s);
+template std::optional<signed char> string2Int<signed char>(const std::string_view s);
+template std::optional<signed short> string2Int<signed short>(const std::string_view s);
+template std::optional<signed int> string2Int<signed int>(const std::string_view s);
+template std::optional<signed long> string2Int<signed long>(const std::string_view s);
+template std::optional<signed long long> string2Int<signed long long>(const std::string_view s);
+
+template<class N>
+std::optional<N> string2Float(const std::string_view s)
+{
+    try {
+        return boost::lexical_cast<N>(s.data(), s.size());
+    } catch (const boost::bad_lexical_cast &) {
+        return std::nullopt;
+    }
+}
+
+template std::optional<double> string2Float<double>(const std::string_view s);
+template std::optional<float> string2Float<float>(const std::string_view s);
+
 
 bool hasPrefix(std::string_view s, std::string_view prefix)
 {
diff --git a/src/libutil/util.hh b/src/libutil/util.hh
index 8b049875a..0919f43c3 100644
--- a/src/libutil/util.hh
+++ b/src/libutil/util.hh
@@ -5,7 +5,6 @@
 #include "error.hh"
 #include "logging.hh"
 
-#include <boost/lexical_cast.hpp>
 
 #include <functional>
 #include <map>
@@ -102,16 +101,7 @@ std::string rewriteStrings(std::string s, const StringMap & rewrites);
  * Parse a string into an integer.
  */
 template<class N>
-std::optional<N> string2Int(const std::string_view s)
-{
-    if (s.substr(0, 1) == "-" && !std::numeric_limits<N>::is_signed)
-        return std::nullopt;
-    try {
-        return boost::lexical_cast<N>(s.data(), s.size());
-    } catch (const boost::bad_lexical_cast &) {
-        return std::nullopt;
-    }
-}
+std::optional<N> string2Int(const std::string_view s);
 
 /**
  * Like string2Int(), but support an optional suffix 'K', 'M', 'G' or
@@ -141,14 +131,7 @@ N string2IntWithUnitPrefix(std::string_view s)
  * Parse a string into a float.
  */
 template<class N>
-std::optional<N> string2Float(const std::string_view s)
-{
-    try {
-        return boost::lexical_cast<N>(s.data(), s.size());
-    } catch (const boost::bad_lexical_cast &) {
-        return std::nullopt;
-    }
-}
+std::optional<N> string2Float(const std::string_view s);
 
 
 /**
diff --git a/src/nix-env/user-env.cc b/src/nix-env/user-env.cc
index f7b091f8f..5246b03e4 100644
--- a/src/nix-env/user-env.cc
+++ b/src/nix-env/user-env.cc
@@ -9,8 +9,9 @@
 #include "eval-inline.hh"
 #include "profiles.hh"
 #include "print-ambiguous.hh"
-#include <limits>
 
+#include <limits>
+#include <sstream>
 
 namespace nix {
 
diff --git a/src/nix/develop.cc b/src/nix/develop.cc
index 0363ca829..27287a1a8 100644
--- a/src/nix/develop.cc
+++ b/src/nix/develop.cc
@@ -14,6 +14,7 @@
 
 #include <iterator>
 #include <memory>
+#include <sstream>
 #include <nlohmann/json.hpp>
 #include <algorithm>