[flang][driver] Limit the usage of -mvscale-max and -mvscale-min (#77905)

Make sure that `-mvscale-max` and `-mvscale-min` are only available for
targets that are known to support vscale and scalable vectors.

Also fix capitalization of function variables.

1 files changed, 31 insertions, 14 deletions

diff --git a/flang/lib/Frontend/CompilerInvocation.cpp b/flang/lib/Frontend/CompilerInvocation.cpp
index 0732f4b..a3c41fb 100644
--- a/flang/lib/Frontend/CompilerInvocation.cpp
+++ b/flang/lib/Frontend/CompilerInvocation.cpp
@@ -1056,28 +1056,45 @@ static bool parseFloatingPointArgs(CompilerInvocation &invoc,
 /// \param [out] diags DiagnosticsEngine to report erros with
 static bool parseVScaleArgs(CompilerInvocation &invoc, llvm::opt::ArgList &args,
                             clang::DiagnosticsEngine &diags) {
+  const auto *vscaleMin =
+      args.getLastArg(clang::driver::options::OPT_mvscale_min_EQ);
+  const auto *vscaleMax =
+      args.getLastArg(clang::driver::options::OPT_mvscale_max_EQ);
+
+  if (!vscaleMin && !vscaleMax)
+    return true;
+
+  llvm::Triple triple = llvm::Triple(invoc.getTargetOpts().triple);
+  if (!triple.isAArch64() && !triple.isRISCV()) {
+    const unsigned diagID =
+        diags.getCustomDiagID(clang::DiagnosticsEngine::Error,
+                              "`-mvscale-max` and `-mvscale-min` are not "
+                              "supported for this architecture: %0");
+    diags.Report(diagID) << triple.getArchName();
+    return false;
+  }
+
   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)) {
+  if (vscaleMin) {
+    llvm::StringRef argValue = llvm::StringRef(vscaleMin->getValue());
+    unsigned vscaleMinVal;
+    if (argValue.getAsInteger(/*Radix=*/10, vscaleMinVal)) {
       diags.Report(clang::diag::err_drv_unsupported_option_argument)
-          << arg->getSpelling() << argValue;
+          << vscaleMax->getSpelling() << argValue;
       return false;
     }
-    opts.VScaleMin = VScaleMin;
+    opts.VScaleMin = vscaleMinVal;
   }
-  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)) {
+
+  if (vscaleMax) {
+    llvm::StringRef argValue = llvm::StringRef(vscaleMax->getValue());
+    unsigned vscaleMaxVal;
+    if (argValue.getAsInteger(/*Radix=w*/ 10, vscaleMaxVal)) {
       diags.Report(clang::diag::err_drv_unsupported_option_argument)
-          << arg->getSpelling() << argValue;
+          << vscaleMax->getSpelling() << argValue;
       return false;
     }
-    opts.VScaleMax = VScaleMax;
+    opts.VScaleMax = vscaleMaxVal;
   }
   return true;
 }