[Mlir-commits] [mlir] [mlir][Transforms][NFC] Dialect Conversion: Replace after legalizing constants (PR #134384)

[Matthias Springer]

https://github.com/matthias-springer created https://github.com/llvm/llvm-project/pull/134384

When folding an op during a conversion, first try to legalize all generated constants, then replace the original operation. This is slightly more efficient because fewer rewrites must be rolled back in case a generated constant could not be legalized.

Note: This is in preparation of the One-Shot Dialect Conversion refactoring.


>From a68cc737c35e288f498ea9870421a913121a3373 Mon Sep 17 00:00:00 2001
From: Matthias Springer <mspringer at nvidia.com>
Date: Fri, 4 Apr 2025 16:03:16 +0200
Subject: [PATCH] [mlir][Transforms] Dialect Conversion: Replace after
 legalizing constants

---
 mlir/lib/Transforms/Utils/DialectConversion.cpp | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/mlir/lib/Transforms/Utils/DialectConversion.cpp b/mlir/lib/Transforms/Utils/DialectConversion.cpp
index 444c505b64232..0b342a0e5d4bc 100644
--- a/mlir/lib/Transforms/Utils/DialectConversion.cpp
+++ b/mlir/lib/Transforms/Utils/DialectConversion.cpp
@@ -2109,9 +2109,6 @@ OperationLegalizer::legalizeWithFold(Operation *op,
   if (replacementValues.empty())
     return legalize(op, rewriter);
 
-  // Insert a replacement for 'op' with the folded replacement values.
-  rewriter.replaceOp(op, replacementValues);
-
   // Recursively legalize any new constant operations.
   for (unsigned i = curState.numRewrites, e = rewriterImpl.rewrites.size();
        i != e; ++i) {
@@ -2128,6 +2125,9 @@ OperationLegalizer::legalizeWithFold(Operation *op,
     }
   }
 
+  // Insert a replacement for 'op' with the folded replacement values.
+  rewriter.replaceOp(op, replacementValues);
+
   LLVM_DEBUG(logSuccess(rewriterImpl.logger, ""));
   return success();
 }