本地构建 d8
按照 https://v8.dev/docs/source-code 拉最新代码，
推荐使用 gm 生成构建参数
Windows 可直接在 PowerShell 中执行
1python3 /path/to/v8/tools/dev/gm.py
正常情况可以看到 gm 帮助信息
1Convenience wrapper for compiling V8 with gn/ninja and running tests.
2Sets up build output directories if they don't exist.
3Produces simulator builds for non-Intel target architectures.
4Uses Goma by default if it is detected (at output directory setup time).
5Expects to be run from the root of a V8 checkout.
6
7Usage:
8 gm.py [<arch>].[<mode>[-<suffix>]].[<target>] [testname...] [--flag]
9
10All arguments are optional. Most combinations should work, e.g.:
11 gm.py ia32.debug x64.release x64.release-my-custom-opts d8
12 gm.py android_arm.release.check --progress=verbose
13 gm.py x64 mjsunit/foo cctest/test-bar/*
14
15For a less automated experience, pass an existing output directory (which
16must contain an existing args.gn), e.g.:
17 gm.py out/foo unittests
18
19Flags are passed unchanged to the test runner. They must start with -- and must
20not contain spaces.
21
22<arch> can be any of: ia32 x64 arm arm64 mips64el ppc ppc64 riscv32 riscv64 s390 s390x android_arm android_arm64 loong64 fuchsia_x64 fuchsia_arm64
23<mode> can be any of: release rel debug dbg optdebug opt
24<target> can be any of:
25 - d8, cctest, v8_unittests, v8_fuzzers, wasm_api_tests, wee8, mkgrokdump, generate-bytecode-expectations, inspector-test, bigint_shell, wami (build respective binary)
26 - all (build all binaries)
27 - tests (build test binaries)
28 - check (build test binaries, run most tests)
29 - checkall (build all binaries, run more tests)
根据平台选择参数
.release 模式已经包含我们所需的参数，一般情况不需要手动指定参数
1is_component_build = false # 必要，用于 profile 的 d8 需要关闭 is_component_build
2is_debug = false
3target_cpu = "x64"
4v8_enable_sandbox = true
5use_goma = false
6v8_enable_backtrace = true
7v8_enable_disassembler = true # 必要，启用反汇编程序以生成机器码
8v8_enable_object_print = true
9v8_enable_verify_heap = true
10dcheck_always_on = false
等一会儿构建应该成功了
1Done. Made 481 targets from 135 files in 343ms
2# autoninja -C out/arm64.release d8
3ninja: Entering directory `out/arm64.release'
4[2370/2370] LINK ./d8
5Done! - V8 compilation finished successfully.
最后记得指定 D8_PATH 环境变量为构建产物目录。
如果需要更多调试信息，例如查看字节码、解释执行过程，gm 默认的构建参数是不够的，可以手动配置构建参数，例如 Apple silicon 环境下
1gn gen out/arm64.debug --args='is_component_build = false is_debug = true symbol_level = 2 target_cpu = "arm64" v8_target_cpu = "arm64" use_goma = false v8_enable_backtrace = true v8_enable_fast_mksnapshot = true v8_enable_slow_dchecks = true v8_optimized_debug = false v8_enable_disassembler = true v8_enable_trace_ignition = true v8_enable_trace_baseline_exec = true v8_enable_trace_feedback_updates=true'
Windows 使用上述命令会提示不支持 “–args” 参数
1ERROR at the command-line "--args":1:27: Undefined identifier
可以使用
1gn args .\out\x64.debug
命令创建构建参数文件，执行后 Windows 会弹出记事本，把构建参数一行一行粘贴进去即可，关闭记事本 gn 会继续创建构建目录，完成后使用 gn args 查看配置
1gn args .\out\x64.debug\ --list --short --overrides-only # 查看指定目录的覆盖性配置
2
3PS C:\Users\zheng\Code\v8\v8> gn args .\out\x64.debug\ --list --short --overrides-only
4enable_rust = false
5is_component_build = false
6is_debug = true
7symbol_level = 2
8target_cpu = "x64"
9use_goma = false
10v8_enable_backtrace = true
11v8_enable_disassembler = true
12v8_enable_fast_mksnapshot = true
13v8_enable_slow_dchecks = true
14v8_enable_trace_baseline_exec = true
15v8_enable_trace_feedback_updates = true
16v8_enable_trace_ignition = true
17v8_optimized_debug = false
18v8_target_cpu = "x64"
确认是你刚才输入的即可。
构建参数中包含一些关键配置例如：
- is_debug = true, debug 模式下才可以看字节码
- v8_enable_trace_ignition = true 允许追踪 ignition 执行流程
生成构建目录后使用 ninja 构建即可
1ninja -C out/arm64.debug d8