[flang][driver] Make `flang-new -fc1` accept MLIR files

This relatively small change will allow Flang's frontend driver,
`flang-new -fc1`, to consume and parse MLIR files.  Semantically (i.e.
from user's perspective) this is identical to reading LLVM IR files.

Two file extensions are associated with MLIR files: .fir and .mlir. Note
that reading MLIR files makes only sense when running one of the
code-generation actions, i.e. when using one of the following action
flags: -S, -emit-obj, -emit-llvm, -emit-llvm-bc.

The majority of tests that required `tco` to run are updated to also run
with `flang-new -fc1`. A few tests are updated to use `fir-opt` instead
of `tco` (that's the preferred choice when testing a particular MLIR
pass). basic-program.fir is not updated as that test is intended to
verify the behaviour of `tco` specifically.

Differential Revision: https://reviews.llvm.org/D126890

1 files changed, 3 insertions, 1 deletions

diff --git a/flang/lib/Frontend/CompilerInvocation.cpp b/flang/lib/Frontend/CompilerInvocation.cpp
index cc376f3..8f2167b 100644
--- a/flang/lib/Frontend/CompilerInvocation.cpp
+++ b/flang/lib/Frontend/CompilerInvocation.cpp
@@ -269,10 +269,12 @@ static bool parseFrontendArgs(FrontendOptions &opts, llvm::opt::ArgList &args,
                 .Case("f95-cpp-input", Language::Fortran)
                 .Default(Language::Unknown);
 
-    // Some special cases cannot be combined with suffixes.
+    // Flang's intermediate representations.
     if (dashX.isUnknown())
       dashX = llvm::StringSwitch<InputKind>(xValue)
                   .Case("ir", Language::LLVM_IR)
+                  .Case("fir", Language::MLIR)
+                  .Case("mlir", Language::MLIR)
                   .Default(Language::Unknown);
 
     if (dashX.isUnknown())