[Mlir-commits] [mlir] 845ee23 - [mlir][LLVM] Disallow opaque struct types as function arguments (#185200)

[llvmlistbot at llvm.org]

Author: Markus Böck
Date: 2026-03-08T15:04:03+01:00
New Revision: 845ee233b86689ad9a81c9668fd10cdb584a466f

URL: https://github.com/llvm/llvm-project/commit/845ee233b86689ad9a81c9668fd10cdb584a466f
DIFF: https://github.com/llvm/llvm-project/commit/845ee233b86689ad9a81c9668fd10cdb584a466f.diff

LOG: [mlir][LLVM] Disallow opaque struct types as function arguments (#185200)

Function types are only allowed to take first-class values as arguments.
The LLVM dialect implemented this correctly so far except for allowing
opaque struct types. When translated to LLVM proper, invalid IR would be
created with confusing assertion errors.

This PR matches LLVM by disallowing opaque struct types as arguments,
allowing users to catch this kind of mistake early while still in the
MLIR world.

The corresponding LLVM logic is here:
https://github.com/llvm/llvm-project/blob/c4898f3f229027e6cbdf8f9db77b8c14d70f6599/llvm/lib/IR/Type.cpp#L404

Added: 
    

Modified: 
    mlir/lib/Dialect/LLVMIR/IR/LLVMTypes.cpp
    mlir/test/Dialect/LLVMIR/types-invalid.mlir

Removed: 
    


################################################################################
diff  --git a/mlir/lib/Dialect/LLVMIR/IR/LLVMTypes.cpp b/mlir/lib/Dialect/LLVMIR/IR/LLVMTypes.cpp
index e24615c8d3046..63acd075c7017 100644
--- a/mlir/lib/Dialect/LLVMIR/IR/LLVMTypes.cpp
+++ b/mlir/lib/Dialect/LLVMIR/IR/LLVMTypes.cpp
@@ -208,6 +208,9 @@ LLVMArrayType::getPreferredAlignment(const DataLayout &dataLayout,
 //===----------------------------------------------------------------------===//
 
 bool LLVMFunctionType::isValidArgumentType(Type type) {
+  if (auto structType = dyn_cast<LLVMStructType>(type))
+    return !structType.isOpaque();
+
   return !llvm::isa<LLVMVoidType, LLVMFunctionType>(type);
 }
 

diff  --git a/mlir/test/Dialect/LLVMIR/types-invalid.mlir b/mlir/test/Dialect/LLVMIR/types-invalid.mlir
index 04710fa6f2396..71ebe4e1b4ef1 100644
--- a/mlir/test/Dialect/LLVMIR/types-invalid.mlir
+++ b/mlir/test/Dialect/LLVMIR/types-invalid.mlir
@@ -14,6 +14,13 @@ func.func @function_returning_function() {
 
 // -----
 
+func.func @function_taking_opaque_struct() {
+  // expected-error @+1 {{invalid function argument type}}
+  "some.op"() : () -> !llvm.func<void(struct<"foo", opaque>)>
+}
+
+// -----
+
 func.func @function_taking_function() {
   // expected-error @+1 {{invalid function argument type}}
   "some.op"() : () -> !llvm.func<void (func<void ()>)>