[clang] [flang] [RFC][flang][runtime] Add FortranFloat128Math wrapper library. (PR #81971)

[Steve Scalpone via cfe-commits]

================
@@ -657,10 +657,61 @@ static llvm::cl::opt<bool>
                                     "instead of libm complex operations"),
                      llvm::cl::init(false));
 
+/// Return a string containing the given Fortran intrinsic name
+/// with the type of its arguments specified in funcType
+/// surrounded by the given prefix/suffix.
+static std::string
+prettyPrintIntrinsicName(fir::FirOpBuilder &builder, mlir::Location loc,
+                         llvm::StringRef prefix, llvm::StringRef name,
+                         llvm::StringRef suffix, mlir::FunctionType funcType) {
+  std::string output = prefix.str();
+  llvm::raw_string_ostream sstream(output);
+  if (name == "pow") {
+    assert(funcType.getNumInputs() == 2 && "power operator has two arguments");
+    std::string displayName{" ** "};
+    sstream << numericMlirTypeToFortran(builder, funcType.getInput(0), loc,
+                                        displayName)
+            << displayName
+            << numericMlirTypeToFortran(builder, funcType.getInput(1), loc,
+                                        displayName);
+  } else {
+    sstream << name.upper() << "(";
+    if (funcType.getNumInputs() > 0)
+      sstream << numericMlirTypeToFortran(builder, funcType.getInput(0), loc,
+                                          name);
+    for (mlir::Type argType : funcType.getInputs().drop_front()) {
+      sstream << ", " << numericMlirTypeToFortran(builder, argType, loc, name);
+    }
+    sstream << ")";
+  }
+  sstream << suffix;
+  return output;
+}
+
+// Generate a call to the Fortran runtime library providing
+// support for 128-bit float math via a third-party library.
+// If the compiler is built without FLANG_RUNTIME_F128_MATH_LIB,
+// this function will report an error.
+static mlir::Value genLibF128Call(fir::FirOpBuilder &builder,
+                                  mlir::Location loc,
+                                  const MathOperation &mathOp,
+                                  mlir::FunctionType libFuncType,
+                                  llvm::ArrayRef<mlir::Value> args) {
+#ifndef FLANG_RUNTIME_F128_MATH_LIB
+  std::string message = prettyPrintIntrinsicName(
+      builder, loc, "compiler is built without support for '", mathOp.key, "'",
----------------
sscalpone wrote:

OK for this message to use a form with "not yet implemented:"?

https://github.com/llvm/llvm-project/pull/81971