[mlir][Linalg] Bugfix in decompose generic by unfolding permutation #126737
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The pattern was returning success() by default which made the greedy pattern application act as if the IR was modified and even though nothing was changed and thus it can prevent it from converging for no legitimate reason. The patch makes the rewrite pattern return failure() by default and success() if and only if the IR changed
gdehame
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dcaballe,
nicolasvasilache and
rengolin
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@llvm/pr-subscribers-mlir-linalg @llvm/pr-subscribers-mlir Author: None (gdehame) ChangesThe pattern was returning success() by default which made the greedy pattern application act as if the IR was modified and even though nothing was changed and thus it can prevent it from converging for no legitimate reason. The patch makes the rewrite pattern return failure() by default and success() if and only if the IR changed. An example of unexpected behavior is by running If we add the Output of Full diff: https://github.com/llvm/llvm-project/pull/126737.diff 1 Files Affected:
diff --git a/mlir/lib/Dialect/Linalg/Transforms/DecomposeGenericByUnfoldingPermutation.cpp b/mlir/lib/Dialect/Linalg/Transforms/DecomposeGenericByUnfoldingPermutation.cpp
index 83c4b5bdf109765..281a248681792ab 100644
--- a/mlir/lib/Dialect/Linalg/Transforms/DecomposeGenericByUnfoldingPermutation.cpp
+++ b/mlir/lib/Dialect/Linalg/Transforms/DecomposeGenericByUnfoldingPermutation.cpp
@@ -237,8 +237,9 @@ LogicalResult DecomposeProjectedPermutation::matchAndRewrite(
newOp.getRegion().takeBody(op->getRegion(0));
rewriter.replaceOp(op, newOp->getResults());
+ return success();
}
- return success();
+ return failure();
}
} // namespace
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Thanks, makes sense!
[nit] Would you mind updating the condition to:
if (!isChanged)
return failure();That would make more sense to me. Also, the summary will be used as the commit message. And the commit message should not include that lengthy debug dump. Steps to reproduce would be sufficient.
Thanks!
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I changed the code to use an early exit and removed the dump from the summary |
banach-space
approved these changes
Feb 14, 2025
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✅ With the latest revision this PR passed the C/C++ code formatter. |
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@gdehame Please fix formatting :) |
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banach-space
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Feb 18, 2025
Following on from llvm#126737, adds a negative test that: * prior to llvm#126737, would incorrectly generated empty output, * with the fix in-tree, simply outputs the input IR (i.e. the specialization "fails"). I've also made minor editorial changes.
wldfngrs
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Feb 19, 2025
…lvm#127600) Following on from llvm#126737, adds a negative test that: * prior to llvm#126737, would incorrectly generated empty output, * with the fix in-tree, simply outputs the input IR (i.e. the specialization "fails"). I've also made minor editorial changes.
sivan-shani
pushed a commit
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that referenced
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Feb 24, 2025
…lvm#126737) The pattern was returning success() by default which made the greedy pattern application act as if the IR was modified and even though nothing was changed and thus it can prevent it from converging for no legitimate reason. The patch makes the rewrite pattern return failure() by default and success() if and only if the IR changed. An example of unexpected behavior is by running `mlir-opt input.mlir --linalg-specialize-generic-ops`, we obtain an empty mlir as output with `input.mlir` as follows: ``` #map = affine_map<(d0) -> (d0)> func.func @f(%arg0: tensor<8xi32>, %arg1: tensor<8xi32>) -> tensor<8xi32> { %0 = tensor.empty() : tensor<8xi32> %1 = linalg.generic {indexing_maps = [#map, #map, #map], iterator_types = ["parallel"]} ins(%arg0, %arg1: tensor<8xi32>, tensor<8xi32>) outs(%0: tensor<8xi32>) { ^bb0(%in: i32, %in_0: i32, %out: i32): %2 = arith.addi %in, %in_0: i32 linalg.yield %2: i32 } -> tensor<8xi32> return %1 : tensor<8xi32> } ```
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The pattern was returning success() by default which made the greedy pattern application act as if the IR was modified and even though nothing was changed and thus it can prevent it from converging for no legitimate reason.
The patch makes the rewrite pattern return failure() by default and success() if and only if the IR changed.
An example of unexpected behavior is by running
mlir-opt input.mlir --linalg-specialize-generic-ops, we obtain an empty mlir as output withinput.mliras follows: