[mlir][Transforms] Check for correct type converter rule implementation

[matthias-springer]

If a type conversion rule fails to apply, it should not append any types to the result. This commit just adds an assertion to detect such cases of incorrect API usage.

[llvmbot]

@llvm/pr-subscribers-mlir

@llvm/pr-subscribers-mlir-core

Author: Matthias Springer (matthias-springer)

Changes

If a type conversion rule fails to apply, it should not append any types to the result. This commit just adds an assertion to detect such cases of incorrect API usage.

---

Full diff: https://github.com/llvm/llvm-project/pull/140347.diff

1 Files Affected:

• (modified) mlir/lib/Transforms/Utils/DialectConversion.cpp (+5)

diff --git a/mlir/lib/Transforms/Utils/DialectConversion.cpp b/mlir/lib/Transforms/Utils/DialectConversion.cpp
index 0d208ce0f2f25..bd11bbe58a3f6 100644
--- a/mlir/lib/Transforms/Utils/DialectConversion.cpp
+++ b/mlir/lib/Transforms/Utils/DialectConversion.cpp
@@ -2880,6 +2880,8 @@ LogicalResult TypeConverter::convertType(Type t,
       if (t.getContext()->isMultithreadingEnabled())
         cacheWriteLock.lock();
       if (!succeeded(*result)) {
+        assert(results.size() == currentCount &&
+               "failed type conversion should not change results");
         cachedDirectConversions.try_emplace(t, nullptr);
         return failure();
       }
@@ -2889,6 +2891,9 @@ LogicalResult TypeConverter::convertType(Type t,
       else
         cachedMultiConversions.try_emplace(t, llvm::to_vector<2>(newTypes));
       return success();
+    } else {
+      assert(results.size() == currentCount &&
+             "failed type conversion should not change results");
     }
   }
   return failure();

[zero9178]

LGTM!