[MLIR] Fix LivenessAnalysis/RemoveDeadValues handling of dead function arguments

In llvm#153973 I added the correctly handling of block arguments, unfortunately
this was gated on operation that also have results. This wasn't intentional
and this excluded operations like function from being correctly processed.

Author: joker-eph

mlir/lib/Analysis/DataFlow/LivenessAnalysis.cpp

@@ -299,8 +299,6 @@ RunLivenessAnalysis::RunLivenessAnalysis(Operation *op) {
   // The framework doesn't visit operations in dead blocks, so we need to
   // explicitly mark them as dead.
   op->walk([&](Operation *op) {
-    if (op->getNumResults() == 0)
-      return;
     for (auto result : llvm::enumerate(op->getResults())) {
       if (getLiveness(result.value()))
         continue;

mlir/lib/Transforms/RemoveDeadValues.cpp

@@ -287,7 +287,8 @@ static void processSimpleOp(Operation *op, RunLivenessAnalysis &la,
 static void processFuncOp(FunctionOpInterface funcOp, Operation *module,
                           RunLivenessAnalysis &la, DenseSet<Value> &nonLiveSet,
                           RDVFinalCleanupList &cl) {
-  LDBG() << "Processing function op: " << funcOp.getOperation()->getName();
+  LDBG() << "Processing function op: "
+         << OpWithFlags(funcOp, OpPrintingFlags().skipRegions());
   if (funcOp.isPublic() || funcOp.isExternal()) {
     LDBG() << "Function is public or external, skipping: "
            << funcOp.getOperation()->getName();

mlir/test/Transforms/remove-dead-values.mlir

@@ -615,3 +615,37 @@ module @last_block_not_exit {
   // CHECK-LABEL: @call_private_but_not_use
   // CHECK: call @terminated_with_condbr(%false, %true) : (i1, i1)
 }
+
+// -----
+
+// Test the elimination of function arguments.
+
+// CHECK-LABEL: func private @single_parameter
+// CHECK-SAME: () {
+func.func private @single_parameter(%arg0: index) {
+  return
+}
+
+// CHECK-LABEL: func.func private @mutl_parameter(
+// CHECK-SAME: %[[ARG0:.*]]: index)
+// CHECK: return %[[ARG0]]
+func.func private @mutl_parameter(%arg0: index, %arg1: index, %arg2: index) -> index {
+  return %arg1 : index
+}
+
+// CHECK-LABEL: func private @eliminate_parameter
+// CHECK-SAME: () {
+func.func private @eliminate_parameter(%arg0: index, %arg1: index) {
+  call @single_parameter(%arg0) : (index) -> ()
+  return
+}
+
+// CHECK-LABEL: func @callee
+// CHECK-SAME: (%[[ARG0:.*]]: index, %[[ARG1:.*]]: index, %[[ARG2:.*]]: index)
+func.func @callee(%arg0: index, %arg1: index, %arg2: index) -> index {
+// CHECK: call @eliminate_parameter() : () -> ()
+  call @eliminate_parameter(%arg0, %arg1) : (index, index) -> ()
+// CHECK: call @mutl_parameter(%[[ARG1]]) : (index) -> index
+  %res = call @mutl_parameter(%arg0, %arg1, %arg2) : (index, index, index) -> (index)
+  return %res : index
+}