[Mlir-commits] [mlir] [mlir][affine] Fix inverted epilogue check in affineForOpBodySkew (PR #217553)

[Babar Khan]

https://github.com/BabarZKhan created https://github.com/llvm/llvm-project/pull/217553

So, my understanding is, when `unrollPrologueEpilogue` is enabled, `affineForOpBodySkew` aims to fully unroll both the generated prologue and epilogue.  The epilogue condition incorrectly checks `!epilogue`, may be causing valid epilogues to be skipped and passing a null operation to `loopUnrollFull.`

**trivial fix:**
replace the condition with `epilogue && epilogue != prologue`.  So that , a valid epilogue is unrolled exactly once.


>From 65798bd72cb1fdf946e17d26c8e7d166ccb313b2 Mon Sep 17 00:00:00 2001
From: BabarZKhan <bzamankhan at gmail.com>
Date: Thu, 20 Aug 2026 10:06:04 +0200
Subject: [PATCH] [mlir][affine] Fix inverted epilogue check in
 affineForOpBodySkew

---
 mlir/lib/Dialect/Affine/Utils/LoopUtils.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mlir/lib/Dialect/Affine/Utils/LoopUtils.cpp b/mlir/lib/Dialect/Affine/Utils/LoopUtils.cpp
index 90bc57e950cf1..293356b164a36 100644
--- a/mlir/lib/Dialect/Affine/Utils/LoopUtils.cpp
+++ b/mlir/lib/Dialect/Affine/Utils/LoopUtils.cpp
@@ -352,7 +352,7 @@ LogicalResult mlir::affine::affineForOpBodySkew(AffineForOp forOp,
 
   if (unrollPrologueEpilogue && prologue)
     (void)loopUnrollFull(prologue);
-  if (unrollPrologueEpilogue && !epilogue && epilogue != prologue)
+  if (unrollPrologueEpilogue && epilogue && epilogue != prologue)
     (void)loopUnrollFull(epilogue);
 
   return success();