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//===-- CacheBuildSession.cpp - cache-build-session tool ------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// Accepts a command that triggers a build and, while the command is running,
// all the compiler invocations that are part of that build will be sharing the
// same dependency scanning daemon.
//
//===----------------------------------------------------------------------===//
#include "CMakeFileAPI.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/StringSet.h"
#include "llvm/Config/config.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/InitLLVM.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/Process.h"
#include "llvm/Support/StringSaver.h"
using namespace llvm;
static Error inferCMakePathPrefixes(StringRef CMakeBuildPath,
SmallVectorImpl<StringRef> &PrefixMaps,
StringSaver &Saver) {
cmake_file_api::Index Index;
if (Error E = cmake_file_api::Index::fromPath(CMakeBuildPath).moveInto(Index))
return E;
cmake_file_api::CodeModel CodeModel;
if (Error E = Index.getCodeModel().moveInto(CodeModel))
return E;
StringRef BuildPath;
if (Error E = CodeModel.getBuildPath().moveInto(BuildPath))
return E;
StringRef SourcePath;
if (Error E = CodeModel.getSourcePath().moveInto(SourcePath))
return E;
SmallVector<StringRef, 8> ExtraSourcePaths;
if (Error E = CodeModel.getExtraTopLevelSourcePaths(ExtraSourcePaths))
return E;
StringSet<> SeenMapNames;
auto getUniqueMapName = [&](StringRef SourcePath) -> StringRef {
StringRef Filename = sys::path::filename(SourcePath);
StringRef MapName = Filename;
unsigned Count = 0;
while (SeenMapNames.contains(MapName)) {
MapName = Saver.save(Filename + "-" + utostr(++Count));
}
SeenMapNames.insert(MapName);
return MapName;
};
PrefixMaps.push_back(Saver.save(BuildPath + "=/^build"));
PrefixMaps.push_back(Saver.save(SourcePath + "=/^src"));
for (StringRef SourcePath : ExtraSourcePaths) {
PrefixMaps.push_back(
Saver.save(SourcePath + "=/^src-" + getUniqueMapName(SourcePath)));
}
return Error::success();
}
int main(int Argc, const char **Argv) {
InitLLVM X(Argc, Argv);
cl::OptionCategory OptCategory("cache-build-session options");
cl::extrahelp MoreHelp("\n"
"Accepts a command that triggers a build and, while "
"the command is running,\n"
"all the compiler invocations that are part of that "
"build will share the same\n"
"dependency scanning daemon.\n"
"\n");
cl::opt<bool> InferCMakePrefixMaps(
"prefix-map-cmake",
cl::desc("Infer source and build prefixes from a CMake build directory"),
cl::cat(OptCategory));
cl::opt<bool> Verbose("v", cl::desc("Verbose output"), cl::cat(OptCategory));
// This is here only to improve the help message (for "USAGE:" line).
cl::list<std::string> Inputs(cl::Positional, cl::desc("command ..."));
int CmdArgsI = 1;
while (CmdArgsI < Argc && Argv[CmdArgsI][0] == '-')
++CmdArgsI;
cl::HideUnrelatedOptions(OptCategory);
cl::ParseCommandLineOptions(CmdArgsI, Argv, "cache-build-session");
SmallVector<const char *, 256> CmdArgs(Argv + CmdArgsI, Argv + Argc);
if (CmdArgs.empty()) {
cl::PrintHelpMessage();
return 1;
}
auto setEnvVar = [&Verbose](const char *Var, const char *Value) {
#if HAVE_SETENV
::setenv(Var, Value, 1);
#elif defined(_WIN32)
_putenv_s(Var, Value);
#else
#error "unsupported environment"
#endif
if (Verbose) {
errs() << "note: setting " << Var << '=' << Value << '\n';
}
};
BumpPtrAllocator Alloc;
StringSaver Saver(Alloc);
if (InferCMakePrefixMaps) {
SmallString<128> WorkingDirectory;
if (Error E = errorCodeToError(sys::fs::current_path(WorkingDirectory))) {
errs() << "error: failed getting working directory: "
<< toString(std::move(E)) << '\n';
return 1;
}
SmallVector<StringRef, 8> PrefixMaps;
if (Error E = inferCMakePathPrefixes(WorkingDirectory, PrefixMaps, Saver)) {
errs() << "error: could not infer prefix map for CMake build: "
<< toString(std::move(E)) << '\n';
return 1;
}
if (!PrefixMaps.empty()) {
constexpr const char *PrefixMapEnvVar = "LLVM_CACHE_PREFIX_MAPS";
SmallString<128> PrefixMapsConcat;
const char *PriorPrefixMaps = ::getenv(PrefixMapEnvVar);
if (PriorPrefixMaps) {
// Merge the derived prefix maps with the pre-existing ones from the
// environment variable.
PrefixMapsConcat.append(PriorPrefixMaps);
PrefixMapsConcat.push_back(';');
}
for (StringRef PrefixMap : PrefixMaps) {
PrefixMapsConcat.append(PrefixMap);
PrefixMapsConcat.push_back(';');
}
assert(PrefixMapsConcat.back() == ';');
PrefixMapsConcat.pop_back();
setEnvVar(PrefixMapEnvVar, Saver.save(PrefixMapsConcat.str()).data());
}
}
// Set 'LLVM_CACHE_BUILD_SESSION_ID' to a unique identifier so that compiler
// invocations under the given command share the same depscan daemon while the
// command is running.
// Uses the process id to ensure parallel invocations of
// `cache-build-session` will not share the same identifier, and
// 'elapsed nanoseconds since epoch' to ensure the same for consecutive
// invocations.
SmallString<32> SessionId;
raw_svector_ostream(SessionId)
<< sys::Process::getProcessId() << '-'
<< std::chrono::system_clock::now().time_since_epoch().count();
setEnvVar("LLVM_CACHE_BUILD_SESSION_ID", SessionId.c_str());
ErrorOr<std::string> ExecPathOrErr = sys::findProgramByName(CmdArgs.front());
if (!ExecPathOrErr) {
errs() << "error: cannot find executable " << CmdArgs.front() << '\n';
return 1;
}
std::string ExecPath = std::move(*ExecPathOrErr);
CmdArgs[0] = ExecPath.c_str();
SmallVector<StringRef, 16> RefArgs;
RefArgs.reserve(CmdArgs.size());
for (const char *Arg : CmdArgs) {
RefArgs.push_back(Arg);
}
std::string ErrMsg;
int Result =
sys::ExecuteAndWait(RefArgs.front(), RefArgs, /*Env*/ std::nullopt,
/*Redirects*/ {}, /*SecondsToWait*/ 0,
/*MemoryLimit*/ 0, &ErrMsg);
if (!ErrMsg.empty()) {
errs() << "error: failed executing command: " << ErrMsg << '\n';
}
return Result;
}
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