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[MLIR][BufferResultsToOutParamsPass] Add Option to Modify Public Function's Signature #167248

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Merged
merged 2 commits into from
Nov 10, 2025
Merged

[MLIR][BufferResultsToOutParamsPass] Add Option to Modify Public Function's Signature #167248

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Add Test
veera-sivarajan Nov 9, 2025
d22137e
[MLIR][BufferResultsToOutParamsPass] Add Option to Modify Public Func…
veera-sivarajan Nov 9, 2025
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3 changes: 3 additions & 0 deletions mlir/include/mlir/Dialect/Bufferization/Transforms/Passes.h
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Original file line number Diff line number Diff line change
Expand Up @@ -171,6 +171,9 @@ struct BufferResultsToOutParamsOpts {
/// If true, the pass eliminates the memref.alloc and memcpy if the returned
/// memref is allocated in the current function and has dynamic shape.
bool hoistDynamicAllocs = false;

/// If true, the pass modifies the function signatures of public functions.
bool modifyPublicFunctions = false;
};

/// Replace buffers that are returned from a function with an out parameter.
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3 changes: 3 additions & 0 deletions mlir/include/mlir/Dialect/Bufferization/Transforms/Passes.td
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Expand Up @@ -258,6 +258,9 @@ def BufferResultsToOutParamsPass
/*default=*/"false", "Hoist static allocations to call sites.">,
Option<"hoistDynamicAllocs", "hoist-dynamic-allocs", "bool",
/*default=*/"false", "Hoist dynamic allocations to call sites.">,
Option<"modifyPublicFunctions", "modify-public-functions", "bool",
/*default=*/"false", "Modify function signatures of public "
"functions.">,
];
let dependentDialects = ["memref::MemRefDialect"];
}
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10 changes: 8 additions & 2 deletions mlir/lib/Dialect/Bufferization/Transforms/BufferResultsToOutParams.cpp
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Expand Up @@ -217,7 +217,9 @@ updateCalls(ModuleOp module, const AllocDynamicSizesMap &map,
}
if (!options.filterFn(&callee))
return;
if (callee.isExternal() || callee.isPublic())
if (callee.isPublic() && !options.modifyPublicFunctions)
return;
if (callee.isExternal())
return;

SmallVector<Value, 6> replaceWithNewCallResults;
Expand Down Expand Up @@ -295,7 +297,9 @@ LogicalResult mlir::bufferization::promoteBufferResultsToOutParams(
// function.
AllocDynamicSizesMap map;
for (auto func : module.getOps<func::FuncOp>()) {
if (func.isExternal() || func.isPublic())
if (func.isPublic() && !options.modifyPublicFunctions)
continue;
if (func.isExternal())
continue;
if (!options.filterFn(&func))
continue;
Expand Down Expand Up @@ -326,6 +330,8 @@ struct BufferResultsToOutParamsPass
options.hoistStaticAllocs = true;
if (hoistDynamicAllocs)
options.hoistDynamicAllocs = true;
if (modifyPublicFunctions)
options.modifyPublicFunctions = true;

if (failed(bufferization::promoteBufferResultsToOutParams(getOperation(),
options)))
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40 changes: 40 additions & 0 deletions mlir/test/Transforms/buffer-results-to-out-params-modify-public-functions.mlir
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@@ -0,0 +1,40 @@
// RUN: mlir-opt -p 'builtin.module(buffer-results-to-out-params{modify-public-functions})' %s | FileCheck %s
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@matthias-springer matthias-springer Nov 9, 2025

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This file should be in the Bufferization directory. But since the tests for this pass are also here, let's leave it here for now.


// Test if `public` functions' return values are transformed into out parameters
// when `buffer-results-to-out-params` is invoked with `modifyPublicFunctions`.

// CHECK-LABEL: func.func @basic(
// CHECK-SAME: %[[ARG0:.*]]: memref<f32>) {
// CHECK: %[[VAL_0:.*]] = "test.source"() : () -> memref<f32>
// CHECK: memref.copy %[[VAL_0]], %[[ARG0]] : memref<f32> to memref<f32>
// CHECK: return
// CHECK: }
func.func @basic() -> (memref<f32>) {
%0 = "test.source"() : () -> (memref<f32>)
return %0 : memref<f32>
}

// CHECK-LABEL: func.func @presence_of_existing_arguments(
// CHECK-SAME: %[[ARG0:.*]]: memref<1xf32>,
// CHECK-SAME: %[[ARG1:.*]]: memref<2xf32>) {
// CHECK: %[[VAL_0:.*]] = "test.source"() : () -> memref<2xf32>
// CHECK: memref.copy %[[VAL_0]], %[[ARG1]] : memref<2xf32> to memref<2xf32>
// CHECK: return
// CHECK: }
func.func @presence_of_existing_arguments(%arg0: memref<1xf32>) -> (memref<2xf32>) {
%0 = "test.source"() : () -> (memref<2xf32>)
return %0 : memref<2xf32>
}

// CHECK-LABEL: func.func @multiple_results(
// CHECK-SAME: %[[ARG0:.*]]: memref<1xf32>,
// CHECK-SAME: %[[ARG1:.*]]: memref<2xf32>) {
// CHECK: %[[VAL_0:.*]]:2 = "test.source"() : () -> (memref<1xf32>, memref<2xf32>)
// CHECK: memref.copy %[[VAL_0]]#0, %[[ARG0]] : memref<1xf32> to memref<1xf32>
// CHECK: memref.copy %[[VAL_0]]#1, %[[ARG1]] : memref<2xf32> to memref<2xf32>
// CHECK: return
// CHECK: }
func.func @multiple_results() -> (memref<1xf32>, memref<2xf32>) {
%0, %1 = "test.source"() : () -> (memref<1xf32>, memref<2xf32>)
return %0, %1 : memref<1xf32>, memref<2xf32>
}