[Mlir-commits] [mlir] [mlir][ValueBounds] Skip analysis for identical slice components (PR #226894)

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<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-mlir

Author: Ziliang Zhang (ziliangzl)

<details>
<summary>Changes</summary>

One-Shot Bufferize repeatedly compares subset slices whose offsets, sizes, and strides often reuse the same SSA values and attributes. Avoid constructing a ValueBounds constraint set when the two OpFoldResults are already identical, while preserving the existing solver fallback for distinct values.

---
Full diff: https://github.com/llvm/llvm-project/pull/226894.diff


3 Files Affected:

- (modified) mlir/lib/Interfaces/ValueBoundsOpInterface.cpp (+8) 
- (modified) mlir/unittests/Interfaces/CMakeLists.txt (+2) 
- (added) mlir/unittests/Interfaces/ValueBoundsOpInterfaceTest.cpp (+61) 


``````````diff
diff --git a/mlir/lib/Interfaces/ValueBoundsOpInterface.cpp b/mlir/lib/Interfaces/ValueBoundsOpInterface.cpp
index d6d3b4d43cb55..0d22b1d39c14e 100644
--- a/mlir/lib/Interfaces/ValueBoundsOpInterface.cpp
+++ b/mlir/lib/Interfaces/ValueBoundsOpInterface.cpp
@@ -955,6 +955,10 @@ FailureOr<bool> ValueBoundsConstraintSet::areEquivalentSlices(
   // "failure".
   for (auto [offset1, offset2] :
        llvm::zip_equal(slice1.getMixedOffsets(), slice2.getMixedOffsets())) {
+    // Avoid constructing a constraint set for values/attributes that are
+    // already known to be identical.
+    if (offset1 == offset2)
+      continue;
     FailureOr<bool> equal = areEqual(offset1, offset2);
     if (failed(equal))
       return failure();
@@ -963,6 +967,8 @@ FailureOr<bool> ValueBoundsConstraintSet::areEquivalentSlices(
   }
   for (auto [size1, size2] :
        llvm::zip_equal(slice1.getMixedSizes(), slice2.getMixedSizes())) {
+    if (size1 == size2)
+      continue;
     FailureOr<bool> equal = areEqual(size1, size2);
     if (failed(equal))
       return failure();
@@ -971,6 +977,8 @@ FailureOr<bool> ValueBoundsConstraintSet::areEquivalentSlices(
   }
   for (auto [stride1, stride2] :
        llvm::zip_equal(slice1.getMixedStrides(), slice2.getMixedStrides())) {
+    if (stride1 == stride2)
+      continue;
     FailureOr<bool> equal = areEqual(stride1, stride2);
     if (failed(equal))
       return failure();
diff --git a/mlir/unittests/Interfaces/CMakeLists.txt b/mlir/unittests/Interfaces/CMakeLists.txt
index 193edda6bf8d8..5cb2948c814cd 100644
--- a/mlir/unittests/Interfaces/CMakeLists.txt
+++ b/mlir/unittests/Interfaces/CMakeLists.txt
@@ -5,6 +5,7 @@ add_mlir_unittest(MLIRInterfacesTests
   MemorySlotUtilsTest.cpp
   SideEffectInterfacesTest.cpp
   InferTypeOpInterfaceTest.cpp
+  ValueBoundsOpInterfaceTest.cpp
 
   DEPENDS
   MLIRTestInterfaceIncGen
@@ -23,5 +24,6 @@ mlir_target_link_libraries(MLIRInterfacesTests
   MLIRMemorySlotUtils
   MLIRParser
   MLIRSideEffectInterfaces
+  MLIRValueBoundsOpInterface
 )
 target_link_libraries(MLIRInterfacesTests PRIVATE MLIRTestDialect)
diff --git a/mlir/unittests/Interfaces/ValueBoundsOpInterfaceTest.cpp b/mlir/unittests/Interfaces/ValueBoundsOpInterfaceTest.cpp
new file mode 100644
index 0000000000000..1a7de44ecc7da
--- /dev/null
+++ b/mlir/unittests/Interfaces/ValueBoundsOpInterfaceTest.cpp
@@ -0,0 +1,61 @@
+//===- ValueBoundsOpInterfaceTest.cpp - ValueBounds unit tests -----------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "mlir/Dialect/Func/IR/FuncOps.h"
+#include "mlir/Interfaces/ValueBoundsOpInterface.h"
+
+#include <gtest/gtest.h>
+
+using namespace mlir;
+
+namespace {
+
+TEST(ValueBoundsOpInterfaceTest, EquivalentSlices) {
+  MLIRContext context;
+  context.loadDialect<func::FuncDialect>();
+  OpBuilder builder(&context);
+
+  auto function = func::FuncOp::create(
+      builder.getUnknownLoc(), "test",
+      builder.getFunctionType({builder.getIndexType(), builder.getIndexType()},
+                              {}));
+  Block *entryBlock = function.addEntryBlock();
+  Value dynamicValue = entryBlock->getArgument(0);
+  Value otherDynamicValue = entryBlock->getArgument(1);
+
+  OpFoldResult zero = builder.getIndexAttr(0);
+  OpFoldResult one = builder.getIndexAttr(1);
+  OpFoldResult four = builder.getIndexAttr(4);
+  OpFoldResult five = builder.getIndexAttr(5);
+
+  HyperrectangularSlice slice({zero, dynamicValue}, {four, dynamicValue},
+                              {one, one});
+  HyperrectangularSlice identicalSlice({zero, dynamicValue},
+                                       {four, dynamicValue}, {one, one});
+  FailureOr<bool> equivalent = ValueBoundsConstraintSet::areEquivalentSlices(
+      &context, slice, identicalSlice);
+  ASSERT_TRUE(succeeded(equivalent));
+  EXPECT_TRUE(*equivalent);
+
+  // Identical components must not hide a later non-equivalent component.
+  HyperrectangularSlice differentSlice({zero, dynamicValue},
+                                       {five, dynamicValue}, {one, one});
+  equivalent = ValueBoundsConstraintSet::areEquivalentSlices(
+      &context, slice, differentSlice);
+  ASSERT_TRUE(succeeded(equivalent));
+  EXPECT_FALSE(*equivalent);
+
+  // Distinct dynamic values continue to use the ValueBounds fallback.
+  HyperrectangularSlice unknownSlice({zero, otherDynamicValue},
+                                     {four, dynamicValue}, {one, one});
+  equivalent = ValueBoundsConstraintSet::areEquivalentSlices(
+      &context, slice, unknownSlice);
+  EXPECT_TRUE(failed(equivalent));
+}
+
+} // namespace

``````````

</details>


https://github.com/llvm/llvm-project/pull/226894