Swift Compiler Driver
本文基于Swift 5.5的源码: https://github.com/apple/swift/tree/release/5.5
1. Driver Tool
Ref[2] 是Driver命令行工具的CMakeLists.txt文件。
add_swift_host_tool(swift-frontend
driver.cpp
autolink_extract_main.cpp
modulewrap_main.cpp
swift_api_digester_main.cpp
swift_indent_main.cpp
swift_symbolgraph_extract_main.cpp
swift_api_extract_main.cpp
SWIFT_COMPONENT compiler
)
target_link_libraries(swift-frontend
PRIVATE
swiftAPIDigester
swiftDriver
swiftFrontendTool
swiftSymbolGraphGen
LLVMBitstreamReader)
1.1 Driver Tool Source Files
Main函数
通过add_swift_host_tool()来定义Driver Tool的源文件，其中driver.cpp为源文件的"入口"，该文件中定义了main()函数。
main()函数的主体逻辑如下所示:
1 int main(int argc_, const char **argv_) {
2 // ... ...
3
4 // Check if this invocation should execute a subcommand.
5 StringRef ExecName = llvm::sys::path::stem(argv[0]);
6 SmallString<256> SubcommandName;
7 bool isRepl = false;
8 if (shouldRunAsSubcommand(ExecName, SubcommandName, argv, isRepl)) { // Branch-A
9 // ... ...
10
11 return 2;
12 }
13
14 if (isRepl) {
15 // Preserve argv for the stack trace.
16 SmallVector<const char *, 256> replArgs(argv.begin(), argv.end());
17 replArgs.erase(&replArgs[1]);
18 return run_driver(ExecName, replArgs); // Branch-B
19 } else {
20 return run_driver(ExecName, argv); // Branch-C
21 }
22
23 }
当以"/usr/bin/swiftc --driver-mode=swift -L /Users/zhangchong/SpareTime/DangerUsage/.build/debug -I /Users/zhangchong/SpareTime/DangerUsage/.build/debug -lDanger /var/folders/g0/wz34vwx54616p8q9thj8yyd00000gp/T/_tmp_dangerfile.swift runner"调用swiftc时, main函数会进入到Branch-C。
run_driver函数
在执行"/usr/bin/swiftc --driver-mode=swift -L /Users/zhangchong/SpareTime/DangerUsage/.build/debug -I /Users/zhangchong/SpareTime/DangerUsage/.build/debug -lDanger /var/folders/g0/wz34vwx54616p8q9thj8yyd00000gp/T/_tmp_dangerfile.swift runner"时，run_driver函数实际上执行Part-D部分。
1 static int run_driver(StringRef ExecName,
2 const ArrayRef<const char *> argv) {
3
4 // Part-A: Check the first argument.
5 // Handle integrated tools.
6 if (argv.size() > 1) {
7 StringRef FirstArg(argv[1]);
8 if (FirstArg == "-frontend") {
9 return performFrontend(llvm::makeArrayRef(argv.data()+2,
10 argv.data()+argv.size()),
11 argv[0], (void *)(intptr_t)getExecutablePath);
12 }
13 if (FirstArg == "-modulewrap") {
14 return modulewrap_main(llvm::makeArrayRef(argv.data()+2,
15 argv.data()+argv.size()),
16 argv[0], (void *)(intptr_t)getExecutablePath);
17 }
18
19 // Run the integrated Swift frontend when called as "swift-frontend" but
20 // without a leading "-frontend".
21 if (!FirstArg.startswith("--driver-mode=")
22 && ExecName == "swift-frontend") {
23 return performFrontend(llvm::makeArrayRef(argv.data()+1,
24 argv.data()+argv.size()),
25 argv[0], (void *)(intptr_t)getExecutablePath);
26 }
27 }
28
29
30 // ... ...
31
32 // Part-B: Should we disable the new swift-driver?
33 if (!shouldDisallowNewDriver(ExecName, argv)) {
34 SmallString<256> NewDriverPath(llvm::sys::path::parent_path(Path));
35 if (appendSwiftDriverName(NewDriverPath) &&
36 llvm::sys::fs::exists(NewDriverPath)) {
37
38 // ... ...
39 return 2;
40 }
41 }
42
43 // Part-C: Select the different tools based on the kind of Driver instance.
44 Driver TheDriver(Path, ExecName, argv, Diags);
45 switch (TheDriver.getDriverKind()) {
46 case Driver::DriverKind::AutolinkExtract:
47 return autolink_extract_main(
48 TheDriver.getArgsWithoutProgramNameAndDriverMode(argv),
49 argv[0], (void *)(intptr_t)getExecutablePath);
50 case Driver::DriverKind::SwiftIndent:
51 return swift_indent_main(
52 TheDriver.getArgsWithoutProgramNameAndDriverMode(argv),
53 argv[0], (void *)(intptr_t)getExecutablePath);
54 case Driver::DriverKind::SymbolGraph:
55 return swift_symbolgraph_extract_main(TheDriver.getArgsWithoutProgramNameAndDriverMode(argv), argv[0], (void *)(intptr_t)getExecutablePath);
56 case Driver::DriverKind::APIExtract:
57 return swift_api_extract_main(
58 TheDriver.getArgsWithoutProgramNameAndDriverMode(argv), argv[0],
59 (void *)(intptr_t)getExecutablePath);
60 case Driver::DriverKind::APIDigester:
61 return swift_api_digester_main(
62 TheDriver.getArgsWithoutProgramNameAndDriverMode(argv), argv[0],
63 (void *)(intptr_t)getExecutablePath);
64 default:
65 break;
66 }
67
68 // Part-D: Do the real compilation. (ignore the error check.)
69 // Parse the arguments that from the command line.
70 std::unique_ptr<llvm::opt::InputArgList> ArgList =
71 TheDriver.parseArgStrings(ArrayRef<const char*>(argv).slice(1));
72 // Build a ToolChain instance.
73 std::unique_ptr<ToolChain> TC = TheDriver.buildToolChain(*ArgList);
74 // Build a Compilation instance.
75 std::unique_ptr<Compilation> C =
76 TheDriver.buildCompilation(*TC, std::move(ArgList));
77 if (C) {
78 // Build the task queue from the Compilation instance.
79 std::unique_ptr<sys::TaskQueue> TQ = TheDriver.buildTaskQueue(*C);
80 if (!TQ)
81 return 1;
82 // Run the jobs which are generated from the task queue.
83 return C->performJobs(std::move(TQ)).exitCode;
84 }
85
86 return 0;
87
88 }
1.2 Driver Tool Dependencies
2. swiftDriver library
Ref[1] 是swiftDriver库的CMakeLists.txt文件。
3. Driver Mode
`--driver-mode`的定义在Options.inc文件中, Options.inc文件是生成的。
TODO: 如何生成Options.inc文件?
从https://gist.github.com/vitonzhangtt/7f6f6feaa0e61373d90bbf9291d2b66b#file-options-inc-L322 可以看出
`--driver-mode`的值可以为: swift, 或者swiftc。
3.1 Driver Kind
Driver是整个编译过程的"驱动器"，Driver Kind保存Driver的类型。
Driver Kind有一些作用:
1. 决定Driver对命令行参数的解析
2. 影响OutputInput的生成
https://github1s.com/apple/swift/blob/release/5.5/lib/Driver/Driver.cpp#L1472-L1475
1 2 // OutputInfo &OI 3 OI.CompilerOutputType = driverKind == DriverKind::Interactive 4 ? file_types::TY_Nothing 5 : CompilerOutputType;
3. 影响Compiler Mode
https://github1s.com/apple/swift/blob/release/5.5/lib/Driver/Driver.cpp#L1854-L1857
// const InputFileList &Inputs
if (driverKind == Driver::DriverKind::Interactive)
return Inputs.empty() ? OutputInfo::Mode::REPL
: OutputInfo::Mode::Immediate;
4. 影响-help选项的输出
https://github1s.com/apple/swift/blob/release/5.5/lib/Driver/Driver.cpp#L3535-L3540
3.2 DriverKind的计算
Driver Mode决定了部分DriverKind的取值。
在Driver的构造函数中，首先进行DriverKind的计算:
1 Driver::Driver(StringRef DriverExecutable,
2 StringRef Name,
3 ArrayRef<const char *> Args,
4 DiagnosticEngine &Diags)
5 : Opts(createSwiftOptTable()), Diags(Diags),
6 Name(Name), DriverExecutable(DriverExecutable),
7 DefaultTargetTriple(llvm::sys::getDefaultTargetTriple()) {
8
9 // The driver kind must be parsed prior to parsing arguments, since that
10 // affects how arguments are parsed.
11 parseDriverKind(Args.slice(1));
12 }
13
14 void Driver::parseDriverKind(ArrayRef<const char *> Args) {
15 // The default driver kind is determined by Name.
16 StringRef DriverName = Name;
17
18 std::string OptName;
19 // However, the driver kind may be overridden if the first argument is
20 // --driver-mode.
21 if (!Args.empty()) {
22 OptName = getOpts().getOption(options::OPT_driver_mode).getPrefixedName();
23
24 StringRef FirstArg(Args[0]);
25 if (FirstArg.startswith(OptName))
26 DriverName = FirstArg.drop_front(OptName.size());
27 }
28
29 Optional<DriverKind> Kind =
30 llvm::StringSwitch<Optional<DriverKind>>(DriverName)
31 .Case("swift", DriverKind::Interactive) // --driver-mode=swift
32 .Case("swiftc", DriverKind::Batch). // --driver-mode=swiftc
33 .Case("swift-autolink-extract", DriverKind::AutolinkExtract)
34 .Case("swift-indent", DriverKind::SwiftIndent)
35 .Case("swift-symbolgraph-extract", DriverKind::SymbolGraph)
36 .Case("swift-api-extract", DriverKind::APIExtract)
37 .Case("swift-api-digester", DriverKind::APIDigester)
38 .Default(None);
39
40 if (Kind.hasValue())
41 driverKind = Kind.getValue(); // driverKind is member of Driver Class.
42 else if (!OptName.empty())
43 Diags.diagnose({}, diag::error_invalid_arg_value, OptName, DriverName);
44 }
Interactive: swift --driver-mode=swift
Batch: swift --driver-mode=swiftc
1. --driver-mode=swiftc
swiftc --driver-mode=swiftc hello.swift
编译hello.swift文件，生成可执行文件hello。
2. --driver-mode=swift
swiftc --driver-mode=swift hello.swift
编译并执行hello.swift文件。
Next: swift-driver
Reference
1. CMakeLists.txt for swiftDriver
https://github.com/apple/swift/blob/release/5.5/lib/Driver/CMakeLists.txt
2. CMakeLists.txt for swift-frontend
https://github.com/apple/swift/blob/release/5.5/tools/driver/CMakeLists.txt
3. Headers file for swiftDriver
https://github.com/apple/swift/tree/release/5.5/include/swift/Driver
4. Options.inc
https://gist.github.com/vitonzhangtt/7f6f6feaa0e61373d90bbf9291d2b66b