[Flang][Driver] Handle target CPU and features

This patch:

- Adds target-feature and target-cpu to FC1Options.
- Moves getTargetFeatures() from Clang.cpp to CommonArgs.cpp.
- Processes target cpu and features in the flang driver. Right now
  features are only added for AArch64/x86 because I only did basic
  testing on them but it should generally work for others as well.
  Option handling is similar to clang.
- Adds appropriate structures in TargetOptions and passes them to
  the target machine.

What's missing:

- Adding the CPU info and the features as attributes in the LLVM IR
  module.
- Processing target specific flags, e.g. SVE vector bits for AArch64,
  ABI etc.

Differential Revision: https://reviews.llvm.org/D137995

Change-Id: Ib081a74ea98617674845518a5d2754edba596418

1 files changed, 8 insertions, 0 deletions

diff --git a/flang/lib/Frontend/CompilerInvocation.cpp b/flang/lib/Frontend/CompilerInvocation.cpp
index b8f4ad7..e24d816 100644
--- a/flang/lib/Frontend/CompilerInvocation.cpp
+++ b/flang/lib/Frontend/CompilerInvocation.cpp
@@ -171,6 +171,14 @@ static void parseTargetArgs(TargetOptions &opts, llvm::opt::ArgList &args) {
   if (const llvm::opt::Arg *a =
           args.getLastArg(clang::driver::options::OPT_triple))
     opts.triple = a->getValue();
+
+  if (const llvm::opt::Arg *a =
+          args.getLastArg(clang::driver::options::OPT_target_cpu))
+    opts.cpu = a->getValue();
+
+  for (const llvm::opt::Arg *currentArg :
+       args.filtered(clang::driver::options::OPT_target_feature))
+    opts.featuresAsWritten.emplace_back(currentArg->getValue());
 }
 
 // Tweak the frontend configuration based on the frontend action