[clangd] Add library to semantically strip flags by name.
Summary:
This is designed for tweaking compile commands by specifying flags to add/remove
in a config file. Something like:
CompileFlags: { Remove: -fcolor-diagnostics }
Having users tweak raw argv (e.g. with a regex) is going to end in tears: bugs
around clang-cl, xclang, aliases, joined-vs-separate args etc are inevitable.
This isn't in tooling because of the performance choices: build a big table
up-front to make subsequent actions fast. Maybe it should be though.
Reviewers: adamcz, hokein
Subscribers: ilya-biryukov, MaskRay, jkorous, arphaman, kadircet, usaxena95, cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D81958
diff --git a/clang-tools-extra/clangd/CompileCommands.cpp b/clang-tools-extra/clangd/CompileCommands.cpp
index 4b69555..4731221 100644
--- a/clang-tools-extra/clangd/CompileCommands.cpp
+++ b/clang-tools-extra/clangd/CompileCommands.cpp
@@ -9,8 +9,12 @@
#include "CompileCommands.h"
#include "Config.h"
#include "support/Logger.h"
+#include "clang/Driver/Options.h"
#include "clang/Frontend/CompilerInvocation.h"
#include "clang/Tooling/ArgumentsAdjusters.h"
+#include "llvm/Option/Option.h"
+#include "llvm/Support/Allocator.h"
+#include "llvm/Support/Debug.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/FileUtilities.h"
#include "llvm/Support/MemoryBuffer.h"
@@ -234,5 +238,269 @@
};
}
+// ArgStripper implementation
+namespace {
+
+// Determine total number of args consumed by this option.
+// Return answers for {Exact, Prefix} match. 0 means not allowed.
+std::pair<unsigned, unsigned> getArgCount(const llvm::opt::Option &Opt) {
+ constexpr static unsigned Rest = 10000; // Should be all the rest!
+ // Reference is llvm::opt::Option::acceptInternal()
+ using llvm::opt::Option;
+ switch (Opt.getKind()) {
+ case Option::FlagClass:
+ return {1, 0};
+ case Option::JoinedClass:
+ case Option::CommaJoinedClass:
+ return {1, 1};
+ case Option::GroupClass:
+ case Option::InputClass:
+ case Option::UnknownClass:
+ case Option::ValuesClass:
+ return {1, 0};
+ case Option::JoinedAndSeparateClass:
+ return {2, 2};
+ case Option::SeparateClass:
+ return {2, 0};
+ case Option::MultiArgClass:
+ return {1 + Opt.getNumArgs(), 0};
+ case Option::JoinedOrSeparateClass:
+ return {2, 1};
+ case Option::RemainingArgsClass:
+ return {Rest, 0};
+ case Option::RemainingArgsJoinedClass:
+ return {Rest, Rest};
+ }
+}
+
+// Flag-parsing mode, which affects which flags are available.
+enum DriverMode : unsigned char {
+ DM_None = 0,
+ DM_GCC = 1, // Default mode e.g. when invoked as 'clang'
+ DM_CL = 2, // MS CL.exe compatible mode e.g. when invoked as 'clang-cl'
+ DM_CC1 = 4, // When invoked as 'clang -cc1' or after '-Xclang'
+ DM_All = 7
+};
+
+// Examine args list to determine if we're in GCC, CL-compatible, or cc1 mode.
+DriverMode getDriverMode(const std::vector<std::string> &Args) {
+ DriverMode Mode = DM_GCC;
+ llvm::StringRef Argv0 = Args.front();
+ if (Argv0.endswith_lower(".exe"))
+ Argv0 = Argv0.drop_back(strlen(".exe"));
+ if (Argv0.endswith_lower("cl"))
+ Mode = DM_CL;
+ for (const llvm::StringRef Arg : Args) {
+ if (Arg == "--driver-mode=cl") {
+ Mode = DM_CL;
+ break;
+ }
+ if (Arg == "-cc1") {
+ Mode = DM_CC1;
+ break;
+ }
+ }
+ return Mode;
+}
+
+// Returns the set of DriverModes where an option may be used.
+unsigned char getModes(const llvm::opt::Option &Opt) {
+ // Why is this so complicated?!
+ // Reference is clang::driver::Driver::getIncludeExcludeOptionFlagMasks()
+ unsigned char Result = DM_None;
+ if (Opt.hasFlag(driver::options::CC1Option))
+ Result |= DM_CC1;
+ if (!Opt.hasFlag(driver::options::NoDriverOption)) {
+ if (Opt.hasFlag(driver::options::CLOption)) {
+ Result |= DM_CL;
+ } else {
+ Result |= DM_GCC;
+ if (Opt.hasFlag(driver::options::CoreOption)) {
+ Result |= DM_CL;
+ }
+ }
+ }
+ return Result;
+};
+
+} // namespace
+
+llvm::ArrayRef<ArgStripper::Rule> ArgStripper::rulesFor(llvm::StringRef Arg) {
+ // All the hard work is done once in a static initializer.
+ // We compute a table containing strings to look for and #args to skip.
+ // e.g. "-x" => {-x 2 args, -x* 1 arg, --language 2 args, --language=* 1 arg}
+ using TableTy =
+ llvm::StringMap<llvm::SmallVector<Rule, 4>, llvm::BumpPtrAllocator>;
+ static TableTy *Table = [] {
+ auto &DriverTable = driver::getDriverOptTable();
+ using DriverID = clang::driver::options::ID;
+
+ // Collect sets of aliases, so we can treat -foo and -foo= as synonyms.
+ // Conceptually a double-linked list: PrevAlias[I] -> I -> NextAlias[I].
+ // If PrevAlias[I] is INVALID, then I is canonical.
+ DriverID PrevAlias[DriverID::LastOption] = {DriverID::OPT_INVALID};
+ DriverID NextAlias[DriverID::LastOption] = {DriverID::OPT_INVALID};
+ auto AddAlias = [&](DriverID Self, DriverID T) {
+ if (NextAlias[T]) {
+ PrevAlias[NextAlias[T]] = Self;
+ NextAlias[Self] = NextAlias[T];
+ }
+ PrevAlias[Self] = T;
+ NextAlias[T] = Self;
+ };
+ // Also grab prefixes for each option, these are not fully exposed.
+ const char *const *Prefixes[DriverID::LastOption] = {nullptr};
+#define PREFIX(NAME, VALUE) static const char *const NAME[] = VALUE;
+#define OPTION(PREFIX, NAME, ID, KIND, GROUP, ALIAS, ALIASARGS, FLAGS, PARAM, \
+ HELP, METAVAR, VALUES) \
+ if (DriverID::OPT_##ALIAS != DriverID::OPT_INVALID && ALIASARGS == nullptr) \
+ AddAlias(DriverID::OPT_##ID, DriverID::OPT_##ALIAS); \
+ Prefixes[DriverID::OPT_##ID] = PREFIX;
+#include "clang/Driver/Options.inc"
+#undef OPTION
+#undef PREFIX
+
+ auto Result = std::make_unique<TableTy>();
+ // Iterate over distinct options (represented by the canonical alias).
+ // Every spelling of this option will get the same set of rules.
+ for (unsigned ID = 1 /*Skip INVALID */; ID < DriverID::LastOption; ++ID) {
+ if (PrevAlias[ID] || ID == DriverID::OPT_Xclang)
+ continue; // Not canonical, or specially handled.
+ llvm::SmallVector<Rule, 8> Rules;
+ // Iterate over each alias, to add rules for parsing it.
+ for (unsigned A = ID; A != DriverID::OPT_INVALID; A = NextAlias[A]) {
+ if (Prefixes[A] == nullptr) // option groups.
+ continue;
+ auto Opt = DriverTable.getOption(A);
+ // Exclude - and -foo pseudo-options.
+ if (Opt.getName().empty())
+ continue;
+ auto Modes = getModes(Opt);
+ std::pair<unsigned, unsigned> ArgCount = getArgCount(Opt);
+ // Iterate over each spelling of the alias, e.g. -foo vs --foo.
+ for (auto *Prefix = Prefixes[A]; *Prefix != nullptr; ++Prefix) {
+ llvm::SmallString<64> Buf(*Prefix);
+ Buf.append(Opt.getName());
+ llvm::StringRef Spelling = Result->try_emplace(Buf).first->getKey();
+ Rules.emplace_back();
+ Rule &R = Rules.back();
+ R.Text = Spelling;
+ R.Modes = Modes;
+ R.ExactArgs = ArgCount.first;
+ R.PrefixArgs = ArgCount.second;
+ // Concrete priority is the index into the option table.
+ // Effectively, earlier entries take priority over later ones.
+ assert(ID < std::numeric_limits<decltype(R.Priority)>::max() &&
+ "Rules::Priority overflowed by options table");
+ R.Priority = ID;
+ }
+ }
+ // Register the set of rules under each possible name.
+ for (const auto &R : Rules)
+ Result->find(R.Text)->second.append(Rules.begin(), Rules.end());
+ }
+#ifndef NDEBUG
+ // Dump the table and various measures of its size.
+ unsigned RuleCount = 0;
+ dlog("ArgStripper Option spelling table");
+ for (const auto &Entry : *Result) {
+ dlog("{0}", Entry.first());
+ RuleCount += Entry.second.size();
+ for (const auto &R : Entry.second)
+ dlog(" {0} #={1} *={2} Mode={3}", R.Text, R.ExactArgs, R.PrefixArgs,
+ int(R.Modes));
+ }
+ dlog("Table spellings={0} rules={1} string-bytes={2}", Result->size(),
+ RuleCount, Result->getAllocator().getBytesAllocated());
+#endif
+ // The static table will never be destroyed.
+ return Result.release();
+ }();
+
+ auto It = Table->find(Arg);
+ return (It == Table->end()) ? llvm::ArrayRef<Rule>() : It->second;
+}
+
+void ArgStripper::strip(llvm::StringRef Arg) {
+ auto OptionRules = rulesFor(Arg);
+ if (OptionRules.empty()) {
+ // Not a recognized flag. Strip it literally.
+ Storage.emplace_back(Arg);
+ Rules.emplace_back();
+ Rules.back().Text = Storage.back();
+ Rules.back().ExactArgs = 1;
+ if (Rules.back().Text.consume_back("*"))
+ Rules.back().PrefixArgs = 1;
+ Rules.back().Modes = DM_All;
+ Rules.back().Priority = -1; // Max unsigned = lowest priority.
+ } else {
+ Rules.append(OptionRules.begin(), OptionRules.end());
+ }
+}
+
+const ArgStripper::Rule *ArgStripper::matchingRule(llvm::StringRef Arg,
+ unsigned Mode,
+ unsigned &ArgCount) const {
+ const ArgStripper::Rule *BestRule = nullptr;
+ for (const Rule &R : Rules) {
+ // Rule can fail to match if...
+ if (!(R.Modes & Mode))
+ continue; // not applicable to current driver mode
+ if (BestRule && BestRule->Priority < R.Priority)
+ continue; // lower-priority than best candidate.
+ if (!Arg.startswith(R.Text))
+ continue; // current arg doesn't match the prefix string
+ bool PrefixMatch = Arg.size() > R.Text.size();
+ // Can rule apply as an exact/prefix match?
+ if (unsigned Count = PrefixMatch ? R.PrefixArgs : R.ExactArgs) {
+ BestRule = &R;
+ ArgCount = Count;
+ }
+ // Continue in case we find a higher-priority rule.
+ }
+ return BestRule;
+}
+
+void ArgStripper::process(std::vector<std::string> &Args) const {
+ if (Args.empty())
+ return;
+
+ // We're parsing the args list in some mode (e.g. gcc-compatible) but may
+ // temporarily switch to another mode with the -Xclang flag.
+ DriverMode MainMode = getDriverMode(Args);
+ DriverMode CurrentMode = MainMode;
+
+ // Read and write heads for in-place deletion.
+ unsigned Read = 0, Write = 0;
+ bool WasXclang = false;
+ while (Read < Args.size()) {
+ unsigned ArgCount = 0;
+ if (const Rule *R = matchingRule(Args[Read], CurrentMode, ArgCount)) {
+ // Delete it and its args.
+ if (WasXclang) {
+ assert(Write > 0);
+ --Write; // Drop previous -Xclang arg
+ CurrentMode = MainMode;
+ WasXclang = false;
+ }
+ // Advance to last arg. An arg may be foo or -Xclang foo.
+ for (unsigned I = 1; Read < Args.size() && I < ArgCount; ++I) {
+ ++Read;
+ if (Read < Args.size() && Args[Read] == "-Xclang")
+ ++Read;
+ }
+ } else {
+ // No match, just copy the arg through.
+ WasXclang = Args[Read] == "-Xclang";
+ CurrentMode = WasXclang ? DM_CC1 : MainMode;
+ if (Write != Read)
+ Args[Write] = std::move(Args[Read]);
+ ++Write;
+ }
+ ++Read;
+ }
+ Args.resize(Write);
+}
+
} // namespace clangd
} // namespace clang
