[Mlir-commits] [mlir] Define a DataFlowSolver helper that loads sensible default analyses (PR #143415)
Jeremy Kun
llvmlistbot at llvm.org
Mon Jun 9 10:42:59 PDT 2025
https://github.com/j2kun created https://github.com/llvm/llvm-project/pull/143415
Cf. https://discourse.llvm.org/t/mlir-dead-code-analysis/67568/10
Custom analysis passes will not work properly unless both DeadCodeAnalysis and SparseConstantPropagation are loaded to the DataFlowSolver. This is intended behavior, but surprising to many users as shown in the thread. In lieu of a longer-term fix (which I am not knowledgeable enough to implement myself, yet), this commit adds a helper function that loads these two analyses, as well as providing breadcrumbs for an explanation of the problem. The existing places in the codebase where these two analyses are loaded for the purpose of running other unrelated analyses are replaced by the use of the helper.
>From 58ce9f80ac9762983422d3616ade85ab54f9b5c9 Mon Sep 17 00:00:00 2001
From: Jeremy Kun <j2kun at users.noreply.github.com>
Date: Mon, 9 Jun 2025 10:38:34 -0700
Subject: [PATCH] Define a DataFlowSolver helper that loads sensible default
analyses
Cf. https://discourse.llvm.org/t/mlir-dead-code-analysis/67568/10
Custom analysis passes will not work properly unless both
DeadCodeAnalysis and SparseConstantPropagation are loaded to the
DataFlowSolver. This is intended behavior, but surprising to many users
as shown in the thread. In lieu of a longer-term fix (which I am not
knowledgeable enough to implement myself, yet), this commit adds a
helper function that loads these two analyses, as well as providing
breadcrumbs for an explanation of the problem. The existing places in
the codebase where these two analyses are loaded for the purpose of
running other unrelated analyses are replaced by the use of the helper.
---
mlir/include/mlir/Analysis/DataFlow/Utils.h | 37 +++++++++++++++++++
.../Analysis/DataFlow/LivenessAnalysis.cpp | 6 +--
.../Transforms/XeGPUSubgroupDistribute.cpp | 6 +--
.../TestDenseBackwardDataFlowAnalysis.cpp | 6 +--
.../TestDenseForwardDataFlowAnalysis.cpp | 6 +--
.../TestSparseBackwardDataFlowAnalysis.cpp | 6 +--
6 files changed, 47 insertions(+), 20 deletions(-)
create mode 100644 mlir/include/mlir/Analysis/DataFlow/Utils.h
diff --git a/mlir/include/mlir/Analysis/DataFlow/Utils.h b/mlir/include/mlir/Analysis/DataFlow/Utils.h
new file mode 100644
index 0000000000000..9955ded0d56c6
--- /dev/null
+++ b/mlir/include/mlir/Analysis/DataFlow/Utils.h
@@ -0,0 +1,37 @@
+//===-Utils.h - DataFlow utility functions -----------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines utility functions for dataflow analyses.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef MLIR_ANALYSIS_DATAFLOW_UTILS_H
+#define MLIR_ANALYSIS_DATAFLOW_UTILS_H
+
+#include "mlir/Analysis/DataFlow/ConstantPropagationAnalysis.h"
+#include "mlir/Analysis/DataFlow/DeadCodeAnalysis.h"
+#include "mlir/Analysis/DataFlowFramework.h"
+
+namespace mlir {
+namespace dataflow {
+
+/// Populates a DataFlowSolver with analyses that are required to ensure
+/// user-defined analyses are run properly.
+///
+/// This helper is intended to be an interim fix until a more robust solution
+/// can be implemented in the DataFlow framework directly. Cf.
+/// https://discourse.llvm.org/t/mlir-dead-code-analysis/67568
+inline void loadBaselineAnalyses(DataFlowSolver &solver) {
+ solver.load<dataflow::DeadCodeAnalysis>();
+ solver.load<dataflow::SparseConstantPropagation>();
+}
+
+} // end namespace dataflow
+} // end namespace mlir
+
+#endif // MLIR_ANALYSIS_DATAFLOW_INTEGERANGEANALYSIS_H
diff --git a/mlir/lib/Analysis/DataFlow/LivenessAnalysis.cpp b/mlir/lib/Analysis/DataFlow/LivenessAnalysis.cpp
index d61cdb143e7dd..24a78400eb84a 100644
--- a/mlir/lib/Analysis/DataFlow/LivenessAnalysis.cpp
+++ b/mlir/lib/Analysis/DataFlow/LivenessAnalysis.cpp
@@ -10,9 +10,8 @@
#include <cassert>
#include <mlir/Analysis/DataFlow/LivenessAnalysis.h>
-#include <mlir/Analysis/DataFlow/ConstantPropagationAnalysis.h>
-#include <mlir/Analysis/DataFlow/DeadCodeAnalysis.h>
#include <mlir/Analysis/DataFlow/SparseAnalysis.h>
+#include <mlir/Analysis/DataFlow/Utils.h>
#include <mlir/Analysis/DataFlowFramework.h>
#include <mlir/IR/Operation.h>
#include <mlir/IR/Value.h>
@@ -249,8 +248,7 @@ void LivenessAnalysis::setToExitState(Liveness *lattice) {
RunLivenessAnalysis::RunLivenessAnalysis(Operation *op) {
SymbolTableCollection symbolTable;
- solver.load<DeadCodeAnalysis>();
- solver.load<SparseConstantPropagation>();
+ loadBaselineAnalyses(solver);
solver.load<LivenessAnalysis>(symbolTable);
(void)solver.initializeAndRun(op);
}
diff --git a/mlir/lib/Dialect/XeGPU/Transforms/XeGPUSubgroupDistribute.cpp b/mlir/lib/Dialect/XeGPU/Transforms/XeGPUSubgroupDistribute.cpp
index 992700524146a..e4ed77541b0a2 100644
--- a/mlir/lib/Dialect/XeGPU/Transforms/XeGPUSubgroupDistribute.cpp
+++ b/mlir/lib/Dialect/XeGPU/Transforms/XeGPUSubgroupDistribute.cpp
@@ -5,9 +5,8 @@
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
-#include "mlir/Analysis/DataFlow/ConstantPropagationAnalysis.h"
-#include "mlir/Analysis/DataFlow/DeadCodeAnalysis.h"
#include "mlir/Analysis/DataFlow/SparseAnalysis.h"
+#include "mlir/Analysis/DataFlow/Utils.h"
#include "mlir/Analysis/DataFlowFramework.h"
#include "mlir/Dialect/GPU/IR/GPUDialect.h"
#include "mlir/Dialect/GPU/Utils/DistributionUtils.h"
@@ -622,8 +621,7 @@ class RunLayoutInfoPropagation {
RunLayoutInfoPropagation(Operation *op) : target(op) {
SymbolTableCollection symbolTable;
- solver.load<DeadCodeAnalysis>();
- solver.load<SparseConstantPropagation>();
+ loadBaselineAnalyses(solver);
solver.load<LayoutInfoPropagation>(symbolTable);
(void)solver.initializeAndRun(op);
}
diff --git a/mlir/test/lib/Analysis/DataFlow/TestDenseBackwardDataFlowAnalysis.cpp b/mlir/test/lib/Analysis/DataFlow/TestDenseBackwardDataFlowAnalysis.cpp
index da543f4f04f97..d57b41c41de64 100644
--- a/mlir/test/lib/Analysis/DataFlow/TestDenseBackwardDataFlowAnalysis.cpp
+++ b/mlir/test/lib/Analysis/DataFlow/TestDenseBackwardDataFlowAnalysis.cpp
@@ -13,9 +13,8 @@
#include "TestDenseDataFlowAnalysis.h"
#include "TestDialect.h"
#include "TestOps.h"
-#include "mlir/Analysis/DataFlow/ConstantPropagationAnalysis.h"
-#include "mlir/Analysis/DataFlow/DeadCodeAnalysis.h"
#include "mlir/Analysis/DataFlow/DenseAnalysis.h"
+#include "mlir/Analysis/DataFlow/Utils.h"
#include "mlir/Analysis/DataFlowFramework.h"
#include "mlir/IR/Builders.h"
#include "mlir/IR/SymbolTable.h"
@@ -283,9 +282,8 @@ struct TestNextAccessPass
auto config = DataFlowConfig().setInterprocedural(interprocedural);
DataFlowSolver solver(config);
- solver.load<DeadCodeAnalysis>();
+ loadBaselineAnalyses(solver);
solver.load<NextAccessAnalysis>(symbolTable, assumeFuncReads);
- solver.load<SparseConstantPropagation>();
solver.load<UnderlyingValueAnalysis>();
if (failed(solver.initializeAndRun(op))) {
emitError(op->getLoc(), "dataflow solver failed");
diff --git a/mlir/test/lib/Analysis/DataFlow/TestDenseForwardDataFlowAnalysis.cpp b/mlir/test/lib/Analysis/DataFlow/TestDenseForwardDataFlowAnalysis.cpp
index f4f8e9115a3fa..a88ed7f8dea8b 100644
--- a/mlir/test/lib/Analysis/DataFlow/TestDenseForwardDataFlowAnalysis.cpp
+++ b/mlir/test/lib/Analysis/DataFlow/TestDenseForwardDataFlowAnalysis.cpp
@@ -13,9 +13,8 @@
#include "TestDenseDataFlowAnalysis.h"
#include "TestDialect.h"
#include "TestOps.h"
-#include "mlir/Analysis/DataFlow/ConstantPropagationAnalysis.h"
-#include "mlir/Analysis/DataFlow/DeadCodeAnalysis.h"
#include "mlir/Analysis/DataFlow/DenseAnalysis.h"
+#include "mlir/Analysis/DataFlow/Utils.h"
#include "mlir/Interfaces/SideEffectInterfaces.h"
#include "mlir/Pass/Pass.h"
#include "mlir/Support/LLVM.h"
@@ -240,8 +239,7 @@ struct TestLastModifiedPass
Operation *op = getOperation();
DataFlowSolver solver(DataFlowConfig().setInterprocedural(interprocedural));
- solver.load<DeadCodeAnalysis>();
- solver.load<SparseConstantPropagation>();
+ loadBaselineAnalyses(solver);
solver.load<LastModifiedAnalysis>(assumeFuncWrites);
solver.load<UnderlyingValueAnalysis>();
if (failed(solver.initializeAndRun(op)))
diff --git a/mlir/test/lib/Analysis/DataFlow/TestSparseBackwardDataFlowAnalysis.cpp b/mlir/test/lib/Analysis/DataFlow/TestSparseBackwardDataFlowAnalysis.cpp
index 4b02865b6ae19..0bdb7c25c3b5f 100644
--- a/mlir/test/lib/Analysis/DataFlow/TestSparseBackwardDataFlowAnalysis.cpp
+++ b/mlir/test/lib/Analysis/DataFlow/TestSparseBackwardDataFlowAnalysis.cpp
@@ -6,9 +6,8 @@
//
//===----------------------------------------------------------------------===//
-#include "mlir/Analysis/DataFlow/ConstantPropagationAnalysis.h"
-#include "mlir/Analysis/DataFlow/DeadCodeAnalysis.h"
#include "mlir/Analysis/DataFlow/SparseAnalysis.h"
+#include "mlir/Analysis/DataFlow/Utils.h"
#include "mlir/Dialect/MemRef/IR/MemRef.h"
#include "mlir/Interfaces/SideEffectInterfaces.h"
#include "mlir/Pass/Pass.h"
@@ -182,8 +181,7 @@ struct TestWrittenToPass
SymbolTableCollection symbolTable;
DataFlowSolver solver(DataFlowConfig().setInterprocedural(interprocedural));
- solver.load<DeadCodeAnalysis>();
- solver.load<SparseConstantPropagation>();
+ loadBaselineAnalyses(solver);
solver.load<WrittenToAnalysis>(symbolTable, assumeFuncWrites);
if (failed(solver.initializeAndRun(op)))
return signalPassFailure();
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