[MLIR] Allow setting "CodeView" flag in LLVMIR translation on MSVC.

Reviewed By: ftynse, mehdi_amini

Differential Revision: https://reviews.llvm.org/D91365

Author: ScottTodd

mlir/include/mlir/Dialect/LLVMIR/LLVMOpBase.td

@@ -37,6 +37,9 @@ def LLVM_Dialect : Dialect {
     /// Uses `reportError` to report errors.
     static LogicalResult verifyDataLayoutString(
         StringRef descr, llvm::function_ref<void (const Twine &)> reportError);
+
+    /// Name of the target triple attribute.
+    static StringRef getTargetTripleAttrName() { return "llvm.target_triple"; }
   }];
 }
 

mlir/lib/Target/LLVMIR/DebugTranslation.cpp

@@ -48,6 +48,17 @@ DebugTranslation::DebugTranslation(Operation *module, llvm::Module &llvmModule)
   if (!llvmModule.getModuleFlag(debugVersionKey))
     llvmModule.addModuleFlag(llvm::Module::Warning, debugVersionKey,
                              llvm::DEBUG_METADATA_VERSION);
+
+  if (auto targetTripleAttr =
+          module->getAttr(LLVM::LLVMDialect::getTargetTripleAttrName())) {
+    auto targetTriple =
+        llvm::Triple(targetTripleAttr.cast<StringAttr>().getValue());
+    if (targetTriple.isKnownWindowsMSVCEnvironment()) {
+      // Dwarf debugging files will be generated by default, unless "CodeView"
+      // is set explicitly. Windows/MSVC should use CodeView instead.
+      llvmModule.addModuleFlag(llvm::Module::Warning, "CodeView", 1);
+    }
+  }
 }
 
 /// Finalize the translation of debug information.

mlir/test/Target/llvmir.mlir

@@ -1311,3 +1311,17 @@ module attributes {llvm.data_layout = "E"} {
   llvm.func @module_big_endian()
 }
 
+// -----
+
+// CHECK: "CodeView", i32 1
+module attributes {llvm.target_triple = "x86_64-pc-windows-msvc"} {}
+
+// -----
+
+// CHECK-NOT: "CodeView", i32 1
+module attributes {llvm.target_triple = "aarch64-linux-android"} {}
+
+// -----
+
+// CHECK-NOT: "CodeView", i32 1
+module attributes {} {}