[llvm-branch-commits] [mlir] [mlir-c] Add 1:N TypeConverter conversion and materialization bindings (PR #208935)

[via llvm-branch-commits]

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@@ -664,50 +680,139 @@ void mlirTypeConverterAddConversion(
           });
 }
 
+void mlirTypeConverterConversionResultsAppend(
+    MlirTypeConverterConversionResults results, MlirType type) {
+  static_cast<SmallVectorImpl<Type> *>(results.ptr)->push_back(unwrap(type));
+}
+
+void mlirTypeConverterAdd1ToNConversion(
+    MlirTypeConverter typeConverter,
+    MlirTypeConverter1ToNConversionCallback convertType, void *userData) {
+  unwrap(typeConverter)
+      ->addConversion(
+          [convertType, userData](Type type, SmallVectorImpl<Type> &results)
+              -> std::optional<LogicalResult> {
+            size_t numPriorResults = results.size();
+            MlirTypeConverterConversionResults wrappedResults{&results};
+            MlirLogicalResult result =
+                convertType(wrap(type), wrappedResults, userData);
+            if (mlirLogicalResultIsFailure(result)) {
+              // The callback declined. Restore any types it appended so the
+              // driver's "try the next conversion" invariant holds (a declining
+              // conversion function must not mutate `results`).
+              results.truncate(numPriorResults);
+              return std::nullopt;
+            }
+            return success();
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PragmaTwice wrote:

It seems that in the C++ API there's three states: `success`, `failure` (don't try another) and `nullopt` (try another) but here users cannot specify a `failure` state?

https://github.com/llvm/llvm-project/pull/208935