[Mlir-commits] [mlir] 5327c6b - [mlir][SCF] Add pass option to deactivate pattern rollback (#168481)

[llvmlistbot at llvm.org]

Author: Matthias Springer
Date: 2025-11-18T16:08:27+08:00
New Revision: 5327c6b57efba007350ab961899150d3fbfe5b45

URL: https://github.com/llvm/llvm-project/commit/5327c6b57efba007350ab961899150d3fbfe5b45
DIFF: https://github.com/llvm/llvm-project/commit/5327c6b57efba007350ab961899150d3fbfe5b45.diff

LOG: [mlir][SCF] Add pass option to deactivate pattern rollback (#168481)

Add a pass option to `convert-scf-to-cf` to deactivate pattern rollback
for better performance. The lowering patterns from SCF->CF to benefit a
lot from this feature because `splitBlock` is expensive in the rollback
driver.

Added: 
    

Modified: 
    mlir/include/mlir/Conversion/Passes.td
    mlir/lib/Conversion/SCFToControlFlow/SCFToControlFlow.cpp
    mlir/test/Conversion/SCFToControlFlow/convert-to-cfg.mlir

Removed: 
    


################################################################################
diff  --git a/mlir/include/mlir/Conversion/Passes.td b/mlir/include/mlir/Conversion/Passes.td
index 0164a2fb9fa81..75ab4b64b7f38 100644
--- a/mlir/include/mlir/Conversion/Passes.td
+++ b/mlir/include/mlir/Conversion/Passes.td
@@ -1086,6 +1086,10 @@ def SCFToControlFlowPass : Pass<"convert-scf-to-cf"> {
   let summary = "Convert SCF dialect to ControlFlow dialect, replacing structured"
                 " control flow with a CFG";
   let dependentDialects = ["cf::ControlFlowDialect"];
+  let options = [
+    Option<"allowPatternRollback", "allow-pattern-rollback", "bool", "true",
+           "Experimental performance flag to disallow pattern rollback">
+  ];
 }
 
 //===----------------------------------------------------------------------===//

diff  --git a/mlir/lib/Conversion/SCFToControlFlow/SCFToControlFlow.cpp b/mlir/lib/Conversion/SCFToControlFlow/SCFToControlFlow.cpp
index 37cfc9f2c23e6..03842cc9bd3a0 100644
--- a/mlir/lib/Conversion/SCFToControlFlow/SCFToControlFlow.cpp
+++ b/mlir/lib/Conversion/SCFToControlFlow/SCFToControlFlow.cpp
@@ -36,6 +36,7 @@ namespace {
 
 struct SCFToControlFlowPass
     : public impl::SCFToControlFlowPassBase<SCFToControlFlowPass> {
+  using Base::Base;
   void runOnOperation() override;
 };
 
@@ -736,7 +737,9 @@ void SCFToControlFlowPass::runOnOperation() {
   target.addIllegalOp<scf::ForallOp, scf::ForOp, scf::IfOp, scf::IndexSwitchOp,
                       scf::ParallelOp, scf::WhileOp, scf::ExecuteRegionOp>();
   target.markUnknownOpDynamicallyLegal([](Operation *) { return true; });
-  if (failed(
-          applyPartialConversion(getOperation(), target, std::move(patterns))))
+  ConversionConfig config;
+  config.allowPatternRollback = allowPatternRollback;
+  if (failed(applyPartialConversion(getOperation(), target, std::move(patterns),
+                                    config)))
     signalPassFailure();
 }

diff  --git a/mlir/test/Conversion/SCFToControlFlow/convert-to-cfg.mlir b/mlir/test/Conversion/SCFToControlFlow/convert-to-cfg.mlir
index 483c7b35c6ec8..0c4f20e8d1a04 100644
--- a/mlir/test/Conversion/SCFToControlFlow/convert-to-cfg.mlir
+++ b/mlir/test/Conversion/SCFToControlFlow/convert-to-cfg.mlir
@@ -1,4 +1,5 @@
 // RUN: mlir-opt -allow-unregistered-dialect -convert-scf-to-cf -split-input-file %s | FileCheck %s
+// RUN: mlir-opt -allow-unregistered-dialect -convert-scf-to-cf="allow-pattern-rollback=0" -split-input-file %s | FileCheck %s
 
 // CHECK-LABEL: func @simple_std_for_loop(%{{.*}}: index, %{{.*}}: index, %{{.*}}: index) {
 //  CHECK-NEXT:  cf.br ^bb1(%{{.*}} : index)