[Mlir-commits] [mlir] b21949e - Revert "[mlir][memref]: Collapse strided unit dim even if strides are dynamic" (#166448)

[llvmlistbot at llvm.org]

Author: Han-Chung Wang
Date: 2025-11-04T21:49:46Z
New Revision: b21949eb34037aa1811cc55609ab46c577feab63

URL: https://github.com/llvm/llvm-project/commit/b21949eb34037aa1811cc55609ab46c577feab63
DIFF: https://github.com/llvm/llvm-project/commit/b21949eb34037aa1811cc55609ab46c577feab63.diff

LOG: Revert "[mlir][memref]: Collapse strided unit dim even if strides are dynamic" (#166448)

Reverts llvm/llvm-project#157330

The original revision introduces a bug in `isGuaranteedCollapsible`. The
`memref<3x3x1x96xf32, strided<[288, 96, 96, 1], offset: 864>>` is no
longer collapsable with the change. The revision reverts the change to
bring back correct behavior. `stride` should be computed as `96` like
the old behavior in the failed iteration.


https://github.com/llvm/llvm-project/blob/92a1eb37122fa24e3045fbabdea2bf87127cace5/mlir/lib/Dialect/MemRef/IR/MemRefOps.cpp#L2597-L2605

Added: 
    

Modified: 
    mlir/lib/Dialect/MemRef/IR/MemRefOps.cpp
    mlir/test/Dialect/MemRef/ops.mlir

Removed: 
    


################################################################################
diff  --git a/mlir/lib/Dialect/MemRef/IR/MemRefOps.cpp b/mlir/lib/Dialect/MemRef/IR/MemRefOps.cpp
index e271ac58db327..1c21a2f270da6 100644
--- a/mlir/lib/Dialect/MemRef/IR/MemRefOps.cpp
+++ b/mlir/lib/Dialect/MemRef/IR/MemRefOps.cpp
@@ -2568,11 +2568,6 @@ computeCollapsedLayoutMap(MemRefType srcType,
     auto trailingReassocs = ArrayRef<int64_t>(reassoc).drop_front();
     auto stride = SaturatedInteger::wrap(resultStrides[resultStrideIndex--]);
     for (int64_t idx : llvm::reverse(trailingReassocs)) {
-      // Dimensions of size 1 should be skipped, because their strides are
-      // meaningless and could have any arbitrary value.
-      if (srcShape[idx - 1] == 1)
-        continue;
-
       stride = stride * SaturatedInteger::wrap(srcShape[idx]);
 
       // Both source and result stride must have the same static value. In that
@@ -2587,6 +2582,11 @@ computeCollapsedLayoutMap(MemRefType srcType,
       if (strict && (stride.saturated || srcStride.saturated))
         return failure();
 
+      // Dimensions of size 1 should be skipped, because their strides are
+      // meaningless and could have any arbitrary value.
+      if (srcShape[idx - 1] == 1)
+        continue;
+
       if (!stride.saturated && !srcStride.saturated && stride != srcStride)
         return failure();
     }

diff  --git a/mlir/test/Dialect/MemRef/ops.mlir b/mlir/test/Dialect/MemRef/ops.mlir
index b1db99bb3ad08..a90c9505a8405 100644
--- a/mlir/test/Dialect/MemRef/ops.mlir
+++ b/mlir/test/Dialect/MemRef/ops.mlir
@@ -440,8 +440,7 @@ func.func @expand_collapse_shape_dynamic(%arg0: memref<?x?x?xf32>,
          %arg4: index,
          %arg5: index,
          %arg6: index,
-         %arg7: memref<4x?x4xf32>,
-         %arg8: memref<1x1x18x?xsi8, strided<[?, ?, ?, 1], offset: ?>>) {
+         %arg7: memref<4x?x4xf32>) {
 //       CHECK:   memref.collapse_shape {{.*}} {{\[}}[0, 1], [2]]
 //  CHECK-SAME:     memref<?x?x?xf32> into memref<?x?xf32>
   %0 = memref.collapse_shape %arg0 [[0, 1], [2]] :
@@ -490,10 +489,6 @@ func.func @expand_collapse_shape_dynamic(%arg0: memref<?x?x?xf32>,
 //       CHECK:   memref.expand_shape {{.*}} {{\[}}[0, 1], [2], [3, 4]]
   %4 = memref.expand_shape %arg7 [[0, 1], [2], [3, 4]] output_shape [2, 2, %arg4, 2, 2]
         : memref<4x?x4xf32> into memref<2x2x?x2x2xf32>
-
-//       CHECK:   memref.collapse_shape {{.*}} {{\[}}[0, 1], [2], [3]]
-//  CHECK-SAME:     memref<1x1x18x?xsi8, strided<[?, ?, ?, 1], offset: ?>> into memref<1x18x?xsi8, strided<[?, ?, 1], offset: ?>>
-  %5 = memref.collapse_shape %arg8 [[0, 1], [2], [3]] : memref<1x1x18x?xsi8, strided<[?, ?, ?, 1], offset: ?>> into memref<1x18x?xsi8, strided<[?, ?, 1], offset: ?>>
   return
 }