Adds argument attributes for using LLVM's sret and byval attributes to

the conversion of LLVM IR dialect. These attributes are used in FIR to
support the lowering of Fortran using target-specific calling
conventions.

Add roundtrip tests. Add changes per review comments/concerns.

Reviewed By: ftynse

Differential Revision: https://reviews.llvm.org/D94052

1 files changed, 16 insertions, 0 deletions

diff --git a/mlir/lib/Target/LLVMIR/ModuleTranslation.cpp b/mlir/lib/Target/LLVMIR/ModuleTranslation.cpp
index 7700867bb461..86f4e7e3e2c4 100644
--- a/mlir/lib/Target/LLVMIR/ModuleTranslation.cpp
+++ b/mlir/lib/Target/LLVMIR/ModuleTranslation.cpp
@@ -1102,6 +1102,22 @@ LogicalResult ModuleTranslation::convertOneFunction(LLVMFuncOp func) {
           llvm::AttrBuilder().addAlignmentAttr(llvm::Align(attr.getInt())));
     }
 
+    if (auto attr = func.getArgAttrOfType<UnitAttr>(argIdx, "llvm.sret")) {
+      auto argTy = mlirArg.getType().dyn_cast<LLVM::LLVMType>();
+      if (!argTy.isa<LLVM::LLVMPointerType>())
+        return func.emitError(
+            "llvm.sret attribute attached to LLVM non-pointer argument");
+      llvmArg.addAttr(llvm::Attribute::AttrKind::StructRet);
+    }
+
+    if (auto attr = func.getArgAttrOfType<UnitAttr>(argIdx, "llvm.byval")) {
+      auto argTy = mlirArg.getType().dyn_cast<LLVM::LLVMType>();
+      if (!argTy.isa<LLVM::LLVMPointerType>())
+        return func.emitError(
+            "llvm.byval attribute attached to LLVM non-pointer argument");
+      llvmArg.addAttr(llvm::Attribute::AttrKind::ByVal);
+    }
+
     valueMapping[mlirArg] = &llvmArg;
     argIdx++;
   }