add todo

Author: ergawy

mlir/lib/Target/LLVMIR/Dialect/OpenMP/OpenMPToLLVMIRTranslation.cpp

@@ -1291,6 +1291,11 @@ initReductionVars(OP op, ArrayRef<BlockArgument> reductionArgs,
     mapInitializationArgs(op, moduleTranslation, reductionDecls,
                           reductionVariableMap, i);
 
+    // TODO In some cases (specially on the GPU), the init regions may
+    // contains stack alloctaions. If the region is inlined in a loop, this is
+    // problematic. Instead of just inlining the region, handle allocations by
+    // hoisting fixed length allocations to the function entry and using
+    // stacksave and restore for variable length ones.
     if (failed(inlineConvertOmpRegions(reductionDecls[i].getInitializerRegion(),
                                        "omp.reduction.neutral", builder,
                                        moduleTranslation, &phis)))