[Mlir-commits] [mlir] 7ab7bc7 - [MLIR] Fix LivenessAnalysis/RemoveDeadValues handling of dead function arguments (#160755)

[llvmlistbot at llvm.org]

Author: Mehdi Amini
Date: 2025-09-26T13:47:46Z
New Revision: 7ab7bc7274dcb2c429bf85cf3488c0627b4f04f7

URL: https://github.com/llvm/llvm-project/commit/7ab7bc7274dcb2c429bf85cf3488c0627b4f04f7
DIFF: https://github.com/llvm/llvm-project/commit/7ab7bc7274dcb2c429bf85cf3488c0627b4f04f7.diff

LOG: [MLIR] Fix LivenessAnalysis/RemoveDeadValues handling of dead function arguments (#160755)

In #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.

Added: 
    

Modified: 
    mlir/lib/Analysis/DataFlow/LivenessAnalysis.cpp
    mlir/lib/Transforms/RemoveDeadValues.cpp
    mlir/test/Transforms/remove-dead-values.mlir

Removed: 
    


################################################################################
diff  --git a/mlir/lib/Analysis/DataFlow/LivenessAnalysis.cpp b/mlir/lib/Analysis/DataFlow/LivenessAnalysis.cpp
index 65df355216f74..fdb97d5963299 100644
--- a/mlir/lib/Analysis/DataFlow/LivenessAnalysis.cpp
+++ b/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;

diff  --git a/mlir/lib/Transforms/RemoveDeadValues.cpp b/mlir/lib/Transforms/RemoveDeadValues.cpp
index fe74f3d4632a6..e0c65b0e09774 100644
--- a/mlir/lib/Transforms/RemoveDeadValues.cpp
+++ b/mlir/lib/Transforms/RemoveDeadValues.cpp
@@ -289,7 +289,8 @@ 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();

diff  --git a/mlir/test/Transforms/remove-dead-values.mlir b/mlir/test/Transforms/remove-dead-values.mlir
index fa2c145bd3701..56449469dc29f 100644
--- a/mlir/test/Transforms/remove-dead-values.mlir
+++ b/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
+}