[flang][driver] Fix support for `-x`

Until now, `-x` wasn't really taken into account in Flang's compiler and
frontend drivers. `flang-new` and `flang-new -fc1` only recently gained
powers to consume inputs other than Fortran files and that's probably
why this hasn't been noticed yet.

This patch makes sure that `-x` is supported correctly and consistently
with Clang. To this end, verification is added when reading LLVM IR
files (i.e. IR modules are verified with `llvm::verifyModule`). This
way, LLVM IR parsing errors are correctly reported to Flang users. This
also aids testing.

With the new functionality, we can verify that `-x ir` breaks
compilation for e.g. Fortran files and vice-versa. Tests are updated
accordingly.

Differential Revision: https://reviews.llvm.org/D127207

1 files changed, 4 insertions, 1 deletions

diff --git a/flang/lib/Frontend/CompilerInvocation.cpp b/flang/lib/Frontend/CompilerInvocation.cpp
index 9ea4810..cc376f3 100644
--- a/flang/lib/Frontend/CompilerInvocation.cpp
+++ b/flang/lib/Frontend/CompilerInvocation.cpp
@@ -263,7 +263,10 @@ static bool parseFrontendArgs(FrontendOptions &opts, llvm::opt::ArgList &args,
     llvm::StringRef xValue = a->getValue();
     // Principal languages.
     dashX = llvm::StringSwitch<InputKind>(xValue)
-                .Case("f90", Language::Fortran)
+                // Flang does not differentiate between pre-processed and not
+                // pre-processed inputs.
+                .Case("f95", Language::Fortran)
+                .Case("f95-cpp-input", Language::Fortran)
                 .Default(Language::Unknown);
 
     // Some special cases cannot be combined with suffixes.