build-acceleration

Name: build-acceleration
Author: mohitmishra786

254installs19forks

How to install build-acceleration?

mohitmishra786/low-level-dev-skills/build-acceleration

$npx -y skills add mohitmishra786/low-level-dev-skills --skill build-acceleration

Installs into the current project.

Summary

Build acceleration skill for C/C++ projects. Use when reducing compilation times with ccache, sccache, distcc, unity builds, precompiled headers, split DWARF, or IWYU. Covers caching strategies, distributed compilation, link time reduction, and diagnosing build bottlenecks. Activ

Files · 1

View on GitHub

SKILL.md

1	# Build Acceleration
2
3	## Purpose
4
5	Guide agents through reducing C/C++ build times using caching (ccache/sccache), distributed compilation (distcc), unity/jumbo builds, precompiled headers, split-DWARF for faster linking, and include pruning with IWYU.
6
7	## Triggers
8
9	- "My C++ build is too slow — how do I speed it up?"
10	- "How do I set up ccache / sccache?"
11	- "How do precompiled headers work with CMake?"
12	- "How do I set up distributed compilation with distcc?"
13	- "How do I reduce link times with split-DWARF?"
14	- "How do I find which headers are slowing down compilation?"
15
16	## Workflow
17
18	### 1. Diagnose the bottleneck first
19
20	```bash
21	# Time the full build
22	time cmake --build build -j$(nproc)
23
24	# Find the slowest TUs (CMake ≥3.16 with --profiling-output)
25	cmake -S . -B build -DCMAKE_CXX_FLAGS="-ftime-report"
26	cmake --build build 2>&1 \| grep "Total" \| sort -t: -k2 -rn \| head -20
27
28	# Ninja build timings (use ninja -j1 for serial timing)
29	ninja -C build -j1 2>&1 \| grep "^\[" \| sort -t" " -k2 -rn \| head -20
30	```
31
32	### 2. ccache — compiler cache
33
34	```bash
35	# Install
36	apt-get install ccache # Ubuntu/Debian
37	brew install ccache # macOS
38
39	# Check hit rate
40	ccache -s
41
42	# Configure cache size (default 5GB)
43	ccache -M 20G
44
45	# Invalidate cache if needed
46	ccache -C
47	```
48
49	CMake integration (recommended over prefix hacks):
50
51	```cmake
52	# CMakeLists.txt
53	find_program(CCACHE_PROGRAM ccache)
54	if(CCACHE_PROGRAM)
55	set(CMAKE_C_COMPILER_LAUNCHER ${CCACHE_PROGRAM})
56	set(CMAKE_CXX_COMPILER_LAUNCHER ${CCACHE_PROGRAM})
57	endif()
58	```
59
60	Key `~/.config/ccache/ccache.conf` options:
61
62	```ini
63	max_size = 20G
64	compression = true
65	compression_level = 6
66	# For CI: share cache across jobs
67	cache_dir = /shared/ccache
68	```
69
70	### 3. sccache — cloud-compatible cache (Rust, C/C++)
71
72	```bash
73	cargo install sccache
74	# Or: brew install sccache
75
76	# Set as compiler launcher
77	export RUSTC_WRAPPER=sccache # for Rust
78	export CMAKE_C_COMPILER_LAUNCHER=sccache # for CMake
79
80	# With S3 backend
81	export SCCACHE_BUCKET=my-build-cache
82	export SCCACHE_REGION=us-east-1
83	sccache --start-server
84
85	sccache --show-stats
86	```
87
88	### 4. Precompiled headers (PCH)
89
90	PCH compiles a large header once and reuses the binary form.
91
92	```cmake
93	# CMake ≥3.16 native PCH support
94	target_precompile_headers(mylib PRIVATE
95	<vector>
96	<string>
97	<unordered_map>
98	"myproject/common.h"
99	)
100
101	# Share PCH across targets (avoids recompilation)
102	target_precompile_headers(myapp REUSE_FROM mylib)
103	```
104
105	```c
106	// Traditional: stdafx.h / pch.h approach
107	// All TUs include pch.h as the very first include
108	// pch.h includes heavy system headers
109	#pragma once
110	#include <stdio.h>
111	#include <stdlib.h>
112	#include <string.h>
113	```
114
115	PCH is most effective when headers are large and stable (STL, Boost, Qt). Avoid PCH for frequently-changing project headers.
116
117	### 5. Unity / jumbo builds
118
119	Combine multiple `.cpp` files into one TU to reduce header parsing overhead and improve inlining.
120
121	```cmake
122	# CMake ≥3.16 unity build
123	set_target_properties(mylib PROPERTIES UNITY_BUILD ON)
124	# Control batch size (default 8 files per unity TU)
125	set_target_properties(mylib PROPERTIES UNITY_BUILD_BATCH_SIZE 16)
126
127	# Exclude specific files from unity (e.g., if they have ODR issues)
128	set_source_files_properties(problem.cpp PROPERTIES SKIP_UNITY_BUILD_INCLUSION ON)
129	```
130
131	Manual unity file:
132
133	```cpp
134	// unity_build.cpp
135	#include "module_a.cpp"
136	#include "module_b.cpp"
137	#include "module_c.cpp"
138	```
139
140	Watch out for: anonymous namespaces (each TU has its own), `using namespace` in headers, duplicate static variables.
141
142	### 6. split-DWARF — reduce link time
143
144	Split DWARF puts debug info in `.dwo` sidecar files, dramatically reducing what the linker must process.
145
146	```bash
147	# GCC / Clang
148	gcc -g -gsplit-dwarf -o prog main.c
149
150	# CMake global
151	add_compile_options(-gsplit-dwarf)
152
153	# Combine .dwo files for distribution (optional)
154	dwp -o prog.dwp prog # GNU dwp tool
155	```
156
157	Pair with `--gdb-index` for faster GDB startup:
158
159	```bash
160	gcc -g -gsplit-dwarf -Wl,--gdb-index -o prog main.c
161	```
162
163	Link time comparison (large project, typical): `-g` full DWARF ~4×–6× longer link vs `-gsplit-dwarf`.
164
165	### 7. distcc — distributed compilation
166
167	```bash
168	# Install on all machines
169	apt-get install distcc
170
171	# Start daemon on worker machines
172	distccd --daemon --allow 192.168.1.0/24 --jobs 8
173
174	# Client: set DISTCC_HOSTS
175	export DISTCC_HOSTS="localhost/4 worker1/8 worker2/8"
176	make -j20 CC="distcc gcc"
177
178	# CMake integration
179	set(CMAKE_C_COMPILER_LAUNCHER distcc)
180	set(CMAKE_CXX_COMPILER_LAUNCHER distcc)
181	```
182
183	Stack with ccache: `CC="ccache distcc gcc"` — ccache checks local cache first, falls

People who liked this also viewed

6 picks

Type

build-acceleration

254installs19forks

View on GitHub

How to install build-acceleration?

mohitmishra786/low-level-dev-skills/build-acceleration

$npx -y skills add mohitmishra786/low-level-dev-skills --skill build-acceleration

Installs into the current project.

Summary

Files · 1

View on GitHub

SKILL.md

1	# Build Acceleration
2
3	## Purpose
4
5	Guide agents through reducing C/C++ build times using caching (ccache/sccache), distributed compilation (distcc), unity/jumbo builds, precompiled headers, split-DWARF for faster linking, and include pruning with IWYU.
6
7	## Triggers
8
9	- "My C++ build is too slow — how do I speed it up?"
10	- "How do I set up ccache / sccache?"
11	- "How do precompiled headers work with CMake?"
12	- "How do I set up distributed compilation with distcc?"
13	- "How do I reduce link times with split-DWARF?"
14	- "How do I find which headers are slowing down compilation?"
15
16	## Workflow
17
18	### 1. Diagnose the bottleneck first
19
20	```bash
21	# Time the full build
22	time cmake --build build -j$(nproc)
23
24	# Find the slowest TUs (CMake ≥3.16 with --profiling-output)
25	cmake -S . -B build -DCMAKE_CXX_FLAGS="-ftime-report"
26	cmake --build build 2>&1 \| grep "Total" \| sort -t: -k2 -rn \| head -20
27
28	# Ninja build timings (use ninja -j1 for serial timing)
29	ninja -C build -j1 2>&1 \| grep "^\[" \| sort -t" " -k2 -rn \| head -20
30	```
31
32	### 2. ccache — compiler cache
33
34	```bash
35	# Install
36	apt-get install ccache # Ubuntu/Debian
37	brew install ccache # macOS
38
39	# Check hit rate
40	ccache -s
41
42	# Configure cache size (default 5GB)
43	ccache -M 20G
44
45	# Invalidate cache if needed
46	ccache -C
47	```
48
49	CMake integration (recommended over prefix hacks):
50
51	```cmake
52	# CMakeLists.txt
53	find_program(CCACHE_PROGRAM ccache)
54	if(CCACHE_PROGRAM)
55	set(CMAKE_C_COMPILER_LAUNCHER ${CCACHE_PROGRAM})
56	set(CMAKE_CXX_COMPILER_LAUNCHER ${CCACHE_PROGRAM})
57	endif()
58	```
59
60	Key `~/.config/ccache/ccache.conf` options:
61
62	```ini
63	max_size = 20G
64	compression = true
65	compression_level = 6
66	# For CI: share cache across jobs
67	cache_dir = /shared/ccache
68	```
69
70	### 3. sccache — cloud-compatible cache (Rust, C/C++)
71
72	```bash
73	cargo install sccache
74	# Or: brew install sccache
75
76	# Set as compiler launcher
77	export RUSTC_WRAPPER=sccache # for Rust
78	export CMAKE_C_COMPILER_LAUNCHER=sccache # for CMake
79
80	# With S3 backend
81	export SCCACHE_BUCKET=my-build-cache
82	export SCCACHE_REGION=us-east-1
83	sccache --start-server
84
85	sccache --show-stats
86	```
87
88	### 4. Precompiled headers (PCH)
89
90	PCH compiles a large header once and reuses the binary form.
91
92	```cmake
93	# CMake ≥3.16 native PCH support
94	target_precompile_headers(mylib PRIVATE
95	<vector>
96	<string>
97	<unordered_map>
98	"myproject/common.h"
99	)
100
101	# Share PCH across targets (avoids recompilation)
102	target_precompile_headers(myapp REUSE_FROM mylib)
103	```
104
105	```c
106	// Traditional: stdafx.h / pch.h approach
107	// All TUs include pch.h as the very first include
108	// pch.h includes heavy system headers
109	#pragma once
110	#include <stdio.h>
111	#include <stdlib.h>
112	#include <string.h>
113	```
114
115	PCH is most effective when headers are large and stable (STL, Boost, Qt). Avoid PCH for frequently-changing project headers.
116
117	### 5. Unity / jumbo builds
118
119	Combine multiple `.cpp` files into one TU to reduce header parsing overhead and improve inlining.
120
121	```cmake
122	# CMake ≥3.16 unity build
123	set_target_properties(mylib PROPERTIES UNITY_BUILD ON)
124	# Control batch size (default 8 files per unity TU)
125	set_target_properties(mylib PROPERTIES UNITY_BUILD_BATCH_SIZE 16)
126
127	# Exclude specific files from unity (e.g., if they have ODR issues)
128	set_source_files_properties(problem.cpp PROPERTIES SKIP_UNITY_BUILD_INCLUSION ON)
129	```
130
131	Manual unity file:
132
133	```cpp
134	// unity_build.cpp
135	#include "module_a.cpp"
136	#include "module_b.cpp"
137	#include "module_c.cpp"
138	```
139
140	Watch out for: anonymous namespaces (each TU has its own), `using namespace` in headers, duplicate static variables.
141
142	### 6. split-DWARF — reduce link time
143
144	Split DWARF puts debug info in `.dwo` sidecar files, dramatically reducing what the linker must process.
145
146	```bash
147	# GCC / Clang
148	gcc -g -gsplit-dwarf -o prog main.c
149
150	# CMake global
151	add_compile_options(-gsplit-dwarf)
152
153	# Combine .dwo files for distribution (optional)
154	dwp -o prog.dwp prog # GNU dwp tool
155	```
156
157	Pair with `--gdb-index` for faster GDB startup:
158
159	```bash
160	gcc -g -gsplit-dwarf -Wl,--gdb-index -o prog main.c
161	```
162
163	Link time comparison (large project, typical): `-g` full DWARF ~4×–6× longer link vs `-gsplit-dwarf`.
164
165	### 7. distcc — distributed compilation
166
167	```bash
168	# Install on all machines
169	apt-get install distcc
170
171	# Start daemon on worker machines
172	distccd --daemon --allow 192.168.1.0/24 --jobs 8
173
174	# Client: set DISTCC_HOSTS
175	export DISTCC_HOSTS="localhost/4 worker1/8 worker2/8"
176	make -j20 CC="distcc gcc"
177
178	# CMake integration
179	set(CMAKE_C_COMPILER_LAUNCHER distcc)
180	set(CMAKE_CXX_COMPILER_LAUNCHER distcc)
181	```
182
183	Stack with ccache: `CC="ccache distcc gcc"` — ccache checks local cache first, falls

People who liked this also viewed

6 picks

Type