[Mlir-commits] [mlir] [mlir][scf] fix getSuccessorRegions func in scf.forall (PR #147491)

[llvmlistbot at llvm.org]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-mlir

Author: donald chen (cxy-1993)

<details>
<summary>Changes</summary>

In accordance with the semantics of forall, its body is executed in parallel by multiple threads. We should not expect to branch back into the forall body after the region's execution is complete.

---
Full diff: https://github.com/llvm/llvm-project/pull/147491.diff


1 Files Affected:

- (modified) mlir/lib/Dialect/SCF/IR/SCF.cpp (+7-5) 


``````````diff
diff --git a/mlir/lib/Dialect/SCF/IR/SCF.cpp b/mlir/lib/Dialect/SCF/IR/SCF.cpp
index 5a3bd984530db..2e0a7b85af756 100644
--- a/mlir/lib/Dialect/SCF/IR/SCF.cpp
+++ b/mlir/lib/Dialect/SCF/IR/SCF.cpp
@@ -1927,11 +1927,13 @@ void ForallOp::getCanonicalizationPatterns(RewritePatternSet &results,
 /// not a constant.
 void ForallOp::getSuccessorRegions(RegionBranchPoint point,
                                    SmallVectorImpl<RegionSuccessor> &regions) {
-  // Both the operation itself and the region may be branching into the body or
-  // back into the operation itself. It is possible for loop not to enter the
-  // body.
-  regions.push_back(RegionSuccessor(&getRegion()));
-  regions.push_back(RegionSuccessor());
+  // In accordance with the semantics of forall, its body is executed in
+  // parallel by multiple threads. We should not expect to branch back into
+  // the forall body after the region's execution is complete.
+  if (point.isParent())
+    regions.push_back(RegionSuccessor(&getRegion()));
+  else
+    regions.push_back(RegionSuccessor());
 }
 
 //===----------------------------------------------------------------------===//

``````````

</details>


https://github.com/llvm/llvm-project/pull/147491