[MLIR][ROCDL] Fix BallotOp LLVM translation and add doc

[zahimoud]

This modifies the return type of the intrinsic call to handle 32 and 64 bits
properly and document the MLIR operation.

[llvmbot]

@llvm/pr-subscribers-mlir

@llvm/pr-subscribers-mlir-llvm

Author: Zahi Moudallal (zahimoud)

Changes

---

Full diff: https://github.com/llvm/llvm-project/pull/85116.diff

1 Files Affected:

• (modified) mlir/include/mlir/Dialect/LLVMIR/ROCDLOps.td (+10)

diff --git a/mlir/include/mlir/Dialect/LLVMIR/ROCDLOps.td b/mlir/include/mlir/Dialect/LLVMIR/ROCDLOps.td
index abb38a3df8068c..8c641b931de18e 100644
--- a/mlir/include/mlir/Dialect/LLVMIR/ROCDLOps.td
+++ b/mlir/include/mlir/Dialect/LLVMIR/ROCDLOps.td
@@ -162,10 +162,20 @@ def ROCDL_BallotOp :
   ROCDL_Op<"ballot">,
   Results<(outs LLVM_Type:$res)>,
   Arguments<(ins I1:$pred)> {
+  let summary = "Vote across thread group";
+
+  let description = [{
+      This operation applies a reduction to the source predicate across all the active threads within a warp, 
+      resulting in a destination predicate value that is uniform for every thread in the warp.
+
+      i1 -> i32
+  }];
+
   string llvmBuilder = [{
       $res = createIntrinsicCall(builder,
             llvm::Intrinsic::amdgcn_ballot, {$pred}, {llvm::Type::getInt32Ty(moduleTranslation.getLLVMContext())});
   }];
+
   let assemblyFormat = "$pred attr-dict `:` type($res)";
 }
 

[joker-eph]

Thanks!

In general try to keep the first line of the commit short (<80 chars), and then leave an empty line before providing a contextual description. Also patches are better described in the present tense I believe :)