[Flang][OpenMP] Move assert for wrapper syms and block args to genLoo…

…pNestOp (#103731)

This patch adds an assert to `genLoopNestClauses` to ensure the number
of symbols and corresponding loop wrapper entry block arguments have the
same size. This is checked by some of the callers, but it makes more
sense moving it into the function itself and avoid having to replicate
it.

flang/lib/Lower/OpenMP/OpenMP.cpp

@@ -1371,6 +1371,9 @@ genLoopNestOp(lower::AbstractConverter &converter, lower::SymMap &symTable,
               llvm::ArrayRef<const semantics::Symbol *> wrapperSyms,
               llvm::ArrayRef<mlir::BlockArgument> wrapperArgs,
               llvm::omp::Directive directive, DataSharingProcessor &dsp) {
+  assert(wrapperSyms.size() == wrapperArgs.size() &&
+         "Number of symbols and wrapper block arguments must match");
+
   auto ivCallback = [&](mlir::Operation *op) {
     genLoopVars(op, converter, loc, iv, wrapperSyms, wrapperArgs);
     return llvm::SmallVector<const semantics::Symbol *>(iv);
@@ -2083,8 +2086,6 @@ static void genCompositeDistributeSimd(
       llvm::concat<mlir::BlockArgument>(distributeOp.getRegion().getArguments(),
                                         simdOp.getRegion().getArguments()));
 
-  assert(wrapperArgs.empty() &&
-         "Block args for omp.simd and omp.distribute currently not expected");
   genLoopNestOp(converter, symTable, semaCtx, eval, loc, queue, item,
                 loopNestClauseOps, iv, /*wrapperSyms=*/{}, wrapperArgs,
                 llvm::omp::Directive::OMPD_distribute_simd, dsp);
@@ -2132,8 +2133,6 @@ static void genCompositeDoSimd(lower::AbstractConverter &converter,
   auto wrapperArgs = llvm::to_vector(llvm::concat<mlir::BlockArgument>(
       wsloopOp.getRegion().getArguments(), simdOp.getRegion().getArguments()));
 
-  assert(wsloopReductionSyms.size() == wrapperArgs.size() &&
-         "Number of symbols and wrapper block arguments must match");
   genLoopNestOp(converter, symTable, semaCtx, eval, loc, queue, item,
                 loopNestClauseOps, iv, wsloopReductionSyms, wrapperArgs,
                 llvm::omp::Directive::OMPD_do_simd, dsp);