[Mlir-commits] [mlir] [mlir] Revert to old fold logic in IR::Dialect::addTypes() (PR #79582)

[llvmlistbot at llvm.org]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-mlir

Author: Andrei Golubev (andrey-golubev)

<details>
<summary>Changes</summary>

Fold expressions on Clang are limited to 256 elements. This causes compilation errors in cases when the amount of elements added exceeds this limit. Side-step the issue by restoring the original trick that would use the std::initializer_list. For instance, in our downstream Clang 16 gives:

mlir/include/mlir/IR/Dialect.h:269:23: fatal error: instantiating fold expression with 688 arguments exceeded expression nesting limit of 256
    (addType<Args>(), ...);

Partially reverts 26d811b3ecd2fa1ca3d9b41e17fb42b8c7ad03d6.

---
Full diff: https://github.com/llvm/llvm-project/pull/79582.diff


1 Files Affected:

- (modified) mlir/include/mlir/IR/Dialect.h (+5-1) 


``````````diff
diff --git a/mlir/include/mlir/IR/Dialect.h b/mlir/include/mlir/IR/Dialect.h
index 45f29f37dd3b97c..9fe1e1c89b228cb 100644
--- a/mlir/include/mlir/IR/Dialect.h
+++ b/mlir/include/mlir/IR/Dialect.h
@@ -281,7 +281,11 @@ class Dialect {
   /// Register a set of type classes with this dialect.
   template <typename... Args>
   void addTypes() {
-    (addType<Args>(), ...);
+    // This initializer_list argument pack expansion is essentially equal to
+    // using a fold expression with a comma operator. Clang however, refuses
+    // to compile a fold expression with a depth of more than 256 by default.
+    // There seem to be no such limitations for initializer_list.
+    (void)std::initializer_list<int>{0, (addType<Args>(), 0)...};
   }
 
   /// Register a type instance with this dialect.

``````````

</details>


https://github.com/llvm/llvm-project/pull/79582