[Flang] Fix options for FunctionAttr pass (llvm#126819)

For non-basic types GenericOptionParser::findArgStrForValue will return
null, ultimately an llvm_unreachable, when the specific values are not
found. Add the enum, much like the debug-level option in AddDebugInfo to
resolve this problem. Also change tuneCPU to be std::string or it will
also fail.

Author: rscottmanley

flang/include/flang/Optimizer/Transforms/Passes.td

@@ -383,30 +383,33 @@ def FunctionAttr : Pass<"function-attr", "mlir::func::FuncOp"> {
      freeing up an additional register in numerous functions. However, this
      approach can make debugging unfeasible on certain machines.
   }];
-  let options = [
-    Option<"framePointerKind", "frame-pointer",
-           "mlir::LLVM::framePointerKind::FramePointerKind", 
-           /*default=*/"mlir::LLVM::framePointerKind::FramePointerKind{}",
-           "frame pointer">,
-    Option<"noInfsFPMath", "no-infs-fp-math",
-           "bool", /*default=*/"false",
-           "Set the no-infs-fp-math attribute on functions in the module.">,
-    Option<"noNaNsFPMath", "no-nans-fp-math",
-           "bool", /*default=*/"false",
-           "Set the no-nans-fp-math attribute on functions in the module.">,
-    Option<"approxFuncFPMath", "approx-func-fp-math",
-           "bool", /*default=*/"false",
+  let options =
+      [Option<"framePointerKind", "frame-pointer",
+              "mlir::LLVM::framePointerKind::FramePointerKind",
+              /*default=*/"mlir::LLVM::framePointerKind::FramePointerKind{}",
+              "frame pointer", [{::llvm::cl::values(
+            clEnumValN(mlir::LLVM::framePointerKind::FramePointerKind::None, "None", ""),
+            clEnumValN(mlir::LLVM::framePointerKind::FramePointerKind::NonLeaf, "NonLeaf", ""),
+            clEnumValN(mlir::LLVM::framePointerKind::FramePointerKind::All, "All", ""),
+            clEnumValN(mlir::LLVM::framePointerKind::FramePointerKind::Reserved, "Reserved", "")
+          )}]>,
+       Option<"noInfsFPMath", "no-infs-fp-math", "bool", /*default=*/"false",
+              "Set the no-infs-fp-math attribute on functions in the module.">,
+       Option<"noNaNsFPMath", "no-nans-fp-math", "bool", /*default=*/"false",
+              "Set the no-nans-fp-math attribute on functions in the module.">,
+       Option<
+           "approxFuncFPMath", "approx-func-fp-math", "bool",
+           /*default=*/"false",
            "Set the approx-func-fp-math attribute on functions in the module.">,
-    Option<"noSignedZerosFPMath", "no-signed-zeros-fp-math",
-           "bool", /*default=*/"false",
-           "Set the no-signed-zeros-fp-math attribute on functions in the module.">,
-    Option<"unsafeFPMath", "unsafe-fp-math",
-           "bool", /*default=*/"false",
-           "Set the unsafe-fp-math attribute on functions in the module.">,
-    Option<"tuneCPU", "tune-cpu",
-           "llvm::StringRef", /*default=*/"llvm::StringRef{}",
-           "Set the tune-cpu attribute on functions in the module.">,
-];
+       Option<"noSignedZerosFPMath", "no-signed-zeros-fp-math", "bool",
+              /*default=*/"false",
+              "Set the no-signed-zeros-fp-math attribute on functions in the "
+              "module.">,
+       Option<"unsafeFPMath", "unsafe-fp-math", "bool", /*default=*/"false",
+              "Set the unsafe-fp-math attribute on functions in the module.">,
+       Option<"tuneCPU", "tune-cpu", "std::string", /*default=*/"",
+              "Set the tune-cpu attribute on functions in the module.">,
+  ];
 }
 
 def AssumedRankOpConversion : Pass<"fir-assumed-rank-op", "mlir::ModuleOp"> {