[WebAssembly] Make thread-related options consistent
Summary:
There have been three options related to threads and users had to set
all three of them separately to get the correct compilation results.
This makes sure the relationship between the options makes sense and
sets necessary options for users if only part of the necessary options
are specified. This does:
- Remove `-matomics`; this option alone does not enable anything, so
removed it to not confuse users.
- `-mthread-model posix` sets `-target-feature +atomics`
- `-pthread` sets both `-target-feature +atomics` and
`-mthread-model posix`
Also errors out when explicitly given options don't match, such as
`-pthread` is given with `-mthread-model single`.
Reviewers: dschuff, sbc100, tlively, sunfish
Subscribers: jgravelle-google, jfb, cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D57874
llvm-svn: 353761
diff --git a/clang/lib/Driver/ToolChains/WebAssembly.cpp b/clang/lib/Driver/ToolChains/WebAssembly.cpp
index b89e043..f076b52 100644
--- a/clang/lib/Driver/ToolChains/WebAssembly.cpp
+++ b/clang/lib/Driver/ToolChains/WebAssembly.cpp
@@ -20,6 +20,27 @@
using namespace clang;
using namespace llvm::opt;
+void parseThreadArgs(const Driver &Driver, const ArgList &DriverArgs,
+ bool &Pthread, StringRef &ThreadModel,
+ bool CheckForErrors = true) {
+ // Default value for -pthread / -mthread-model options, each being false /
+ // "single".
+ Pthread =
+ DriverArgs.hasFlag(options::OPT_pthread, options::OPT_no_pthread, false);
+ ThreadModel =
+ DriverArgs.getLastArgValue(options::OPT_mthread_model, "single");
+ if (!CheckForErrors)
+ return;
+
+ // Did user explicitly specify -mthread-model / -pthread?
+ bool HasThreadModel = DriverArgs.hasArg(options::OPT_mthread_model);
+ bool HasPthread = Pthread && DriverArgs.hasArg(options::OPT_pthread);
+ // '-pthread' cannot be used with '-mthread-model single'
+ if (HasPthread && HasThreadModel && ThreadModel == "single")
+ Driver.Diag(diag::err_drv_argument_not_allowed_with)
+ << "-pthread" << "-mthread-model single";
+}
+
wasm::Linker::Linker(const ToolChain &TC)
: GnuTool("wasm::Linker", "lld", TC) {}
@@ -123,6 +144,17 @@
if (DriverArgs.hasFlag(clang::driver::options::OPT_fuse_init_array,
options::OPT_fno_use_init_array, true))
CC1Args.push_back("-fuse-init-array");
+
+ // Either '-mthread-model posix' or '-pthread' sets '-target-feature
+ // +atomics'. We intentionally didn't create '-matomics' and set the atomics
+ // target feature here depending on the other two options.
+ bool Pthread = false;
+ StringRef ThreadModel = "";
+ parseThreadArgs(getDriver(), DriverArgs, Pthread, ThreadModel);
+ if (Pthread || ThreadModel != "single") {
+ CC1Args.push_back("-target-feature");
+ CC1Args.push_back("+atomics");
+ }
}
ToolChain::RuntimeLibType WebAssembly::GetDefaultRuntimeLibType() const {
@@ -180,12 +212,15 @@
}
}
-std::string WebAssembly::getThreadModel() const {
- // The WebAssembly MVP does not yet support threads; for now, use the
- // "single" threading model, which lowers atomics to non-atomic operations.
- // When threading support is standardized and implemented in popular engines,
- // this override should be removed.
- return "single";
+std::string WebAssembly::getThreadModel(const ArgList &DriverArgs) const {
+ // The WebAssembly MVP does not yet support threads. We set this to "posix"
+ // when '-pthread' is set.
+ bool Pthread = false;
+ StringRef ThreadModel = "";
+ parseThreadArgs(getDriver(), DriverArgs, Pthread, ThreadModel, false);
+ if (Pthread)
+ return "posix";
+ return ThreadModel;
}
Tool *WebAssembly::buildLinker() const {