[flang]Add vscale argument parsing (#67676)

Support for vector scale range arguments, for AArch64 scalable vector
extension (SVE) support.

Adds -msve-vector-bits to the flang frontend, and for flang fc1 the
options are -mvscale-min and -mvscale-max (optional). These match the
clang and clang cc1 options for the same purposes.

A further patch will actually USE these arguments.

1 files changed, 37 insertions, 0 deletions

diff --git a/flang/lib/Frontend/CompilerInvocation.cpp b/flang/lib/Frontend/CompilerInvocation.cpp
index 6c0b90c..37315e0 100644
--- a/flang/lib/Frontend/CompilerInvocation.cpp
+++ b/flang/lib/Frontend/CompilerInvocation.cpp
@@ -986,6 +986,41 @@ static bool parseFloatingPointArgs(CompilerInvocation &invoc,
   return true;
 }
 
+/// Parses vscale range options and populates the CompilerInvocation
+/// accordingly.
+/// Returns false if new errors are generated.
+///
+/// \param [out] invoc Stores the processed arguments
+/// \param [in] args The compiler invocation arguments to parse
+/// \param [out] diags DiagnosticsEngine to report erros with
+static bool parseVScaleArgs(CompilerInvocation &invoc, llvm::opt::ArgList &args,
+                            clang::DiagnosticsEngine &diags) {
+  LangOptions &opts = invoc.getLangOpts();
+  if (const auto arg =
+          args.getLastArg(clang::driver::options::OPT_mvscale_min_EQ)) {
+    llvm::StringRef argValue = llvm::StringRef(arg->getValue());
+    unsigned VScaleMin;
+    if (argValue.getAsInteger(/*Radix=*/10, VScaleMin)) {
+      diags.Report(clang::diag::err_drv_unsupported_option_argument)
+          << arg->getSpelling() << argValue;
+      return false;
+    }
+    opts.VScaleMin = VScaleMin;
+  }
+  if (const auto arg =
+          args.getLastArg(clang::driver::options::OPT_mvscale_max_EQ)) {
+    llvm::StringRef argValue = llvm::StringRef(arg->getValue());
+    unsigned VScaleMax;
+    if (argValue.getAsInteger(/*Radix=w*/ 10, VScaleMax)) {
+      diags.Report(clang::diag::err_drv_unsupported_option_argument)
+          << arg->getSpelling() << argValue;
+      return false;
+    }
+    opts.VScaleMax = VScaleMax;
+  }
+  return true;
+}
+
 bool CompilerInvocation::createFromArgs(
     CompilerInvocation &res, llvm::ArrayRef<const char *> commandLineArgs,
     clang::DiagnosticsEngine &diags, const char *argv0) {
@@ -1079,6 +1114,8 @@ bool CompilerInvocation::createFromArgs(
 
   success &= parseFloatingPointArgs(res, args, diags);
 
+  success &= parseVScaleArgs(res, args, diags);
+
   // Set the string to be used as the return value of the COMPILER_OPTIONS
   // intrinsic of iso_fortran_env. This is either passed in from the parent
   // compiler driver invocation with an environment variable, or failing that