[flang] Add Win32 to the list of supported triples

This patch adds Win32 to the list of supported triples in
`fir::CodeGenSpecifics`. This change means that we can use the "native"
triple, even when running tests on Windows. Currently this affects only
1 test, but it will change once we start adding more tests for lowering
and code-generation.

Differential Revision: https://reviews.llvm.org/D119332

flang/lib/Optimizer/CodeGen/Target.cpp

@@ -238,9 +238,7 @@ struct TargetPPC64le : public GenericTarget<TargetPPC64le> {
 } // namespace
 
 // Instantiate the overloaded target instance based on the triple value.
-// Currently, the implementation only instantiates `i386-unknown-linux-gnu`,
-// `x86_64-unknown-linux-gnu`, aarch64 and ppc64le like triples. Other targets
-// should be added to this file as needed.
+// TODO: Add other targets to this file as needed.
 std::unique_ptr<fir::CodeGenSpecifics>
 fir::CodeGenSpecifics::get(mlir::MLIRContext *ctx, llvm::Triple &&trp,
                            KindMapping &&kindMap) {
@@ -253,6 +251,7 @@ fir::CodeGenSpecifics::get(mlir::MLIRContext *ctx, llvm::Triple &&trp,
       break;
     case llvm::Triple::OSType::Linux:
     case llvm::Triple::OSType::Darwin:
+    case llvm::Triple::OSType::Win32:
       return std::make_unique<TargetI386>(ctx, std::move(trp),
                                           std::move(kindMap));
     }
@@ -263,6 +262,7 @@ fir::CodeGenSpecifics::get(mlir::MLIRContext *ctx, llvm::Triple &&trp,
       break;
     case llvm::Triple::OSType::Linux:
     case llvm::Triple::OSType::Darwin:
+    case llvm::Triple::OSType::Win32:
       return std::make_unique<TargetX86_64>(ctx, std::move(trp),
                                             std::move(kindMap));
     }
@@ -273,6 +273,7 @@ fir::CodeGenSpecifics::get(mlir::MLIRContext *ctx, llvm::Triple &&trp,
       break;
     case llvm::Triple::OSType::Linux:
     case llvm::Triple::OSType::Darwin:
+    case llvm::Triple::OSType::Win32:
       return std::make_unique<TargetAArch64>(ctx, std::move(trp),
                                              std::move(kindMap));
     }

flang/test/Fir/basic-program.fir

@@ -1,4 +1,4 @@
-// RUN: tco --target=x86_64-unknown-linux-gnu %s | FileCheck %s
+// RUN: tco %s | FileCheck %s
 
 // Check that tco is working with a basic test.