[CIR][Lowering] Core dialects: passthrough symbol visibility (llvm#1620)

Fixes llvm#1619
Fixes llvm#1618

Author: felixdaas

clang/lib/CIR/Lowering/ThroughMLIR/LowerCIRToMLIR.cpp

@@ -544,6 +544,12 @@ class CIRFuncOpLowering : public mlir::OpConversionPattern<cir::FuncOp> {
       signatureConversion.addInputs(argType.index(), convertedType);
     }
 
+    SmallVector<mlir::NamedAttribute, 2> passThroughAttrs;
+
+    if (auto symVisibilityAttr = op.getSymVisibilityAttr())
+      passThroughAttrs.push_back(
+          rewriter.getNamedAttr("sym_visibility", symVisibilityAttr));
+
     SmallVector<mlir::Type> resultTypes;
     // Only convert return type if the function is not void
     if (!mlir::isa<cir::VoidType>(fnType.getReturnType())) {
@@ -556,7 +562,8 @@ class CIRFuncOpLowering : public mlir::OpConversionPattern<cir::FuncOp> {
     auto fn = rewriter.create<mlir::func::FuncOp>(
         op.getLoc(), op.getName(),
         rewriter.getFunctionType(signatureConversion.getConvertedTypes(),
-                                 resultTypes));
+                                 resultTypes),
+        passThroughAttrs);
 
     if (failed(rewriter.convertRegionTypes(&op.getBody(), *getTypeConverter(),
                                            &signatureConversion)))

clang/lib/CIR/Lowering/ThroughMLIR/LowerMLIRToLLVM.cpp

@@ -24,6 +24,7 @@
 #include "mlir/Pass/PassManager.h"
 #include "mlir/Target/LLVMIR/Dialect/LLVMIR/LLVMToLLVMIRTranslation.h"
 #include "mlir/Transforms/DialectConversion.h"
+#include "clang/CIR/Dialect/IR/CIRDialect.h"
 #include "clang/CIR/Passes.h"
 
 using namespace cir;
@@ -62,6 +63,17 @@ void ConvertMLIRToLLVMPass::runOnOperation() {
   populateFuncToLLVMConversionPatterns(typeConverter, patterns);
 
   auto module = getOperation();
+
+  // Lower the module attributes to LLVM equivalents.
+  if (auto tripleAttr = module->getAttr(cir::CIRDialect::getTripleAttrName()))
+    module->setAttr(mlir::LLVM::LLVMDialect::getTargetTripleAttrName(),
+                    tripleAttr);
+
+  // Strip the CIR attributes.
+  module->removeAttr(cir::CIRDialect::getSOBAttrName());
+  module->removeAttr(cir::CIRDialect::getLangAttrName());
+  module->removeAttr(cir::CIRDialect::getTripleAttrName());
+
   if (failed(applyFullConversion(module, target, std::move(patterns))))
     signalPassFailure();
 }

clang/test/CIR/Lowering/ThroughMLIR/function-attributes.c

@@ -0,0 +1,9 @@
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir -fno-clangir-direct-lowering -emit-mlir=core %s -o %t.mlir 
+// RUN: FileCheck --input-file=%t.mlir %s
+
+// CHECK: func.func private @declaration(i32) -> i32
+
+int declaration(int x);
+int declaration_test() {
+  return declaration(15);
+}

clang/test/CIR/driver.c

@@ -25,6 +25,7 @@
 // RUN: FileCheck --input-file=%t.cir %s -check-prefix=CIR_MACOS
 // RUN: %clang -target arm64-apple-macosx12.0.0 -fclangir -S -emit-llvm %s -o %t3.ll
 // RUN: FileCheck --input-file=%t3.ll %s -check-prefix=LLVM_MACOS
+// RUN: %clang -target x86_64-unknown-linux-gnu -fclangir -fno-clangir-direct-lowering -c %s -o %t.o
 
 void foo(void) {}