[Mlir-commits] [mlir] [mlir][Transforms] Dialect Conversion: Simplify block conversion API (PR #94866)

[Matthias Springer]

================
@@ -1330,42 +1281,29 @@ FailureOr<Block *> ConversionPatternRewriterImpl::convertRegionTypes(
   if (region->empty())
     return nullptr;
 
-  if (failed(convertNonEntryRegionTypes(rewriter, region, converter)))
-    return failure();
-
-  FailureOr<Block *> newEntry = convertBlockSignature(
-      rewriter, &region->front(), &converter, entryConversion);
-  return newEntry;
-}
-
-LogicalResult ConversionPatternRewriterImpl::convertNonEntryRegionTypes(
-    ConversionPatternRewriter &rewriter, Region *region,
-    const TypeConverter &converter,
-    ArrayRef<TypeConverter::SignatureConversion> blockConversions) {
-  regionToConverter[region] = &converter;
-  if (region->empty())
-    return success();
-
-  // Convert the arguments of each block within the region.
-  int blockIdx = 0;
-  assert((blockConversions.empty() ||
-          blockConversions.size() == region->getBlocks().size() - 1) &&
-         "expected either to provide no SignatureConversions at all or to "
-         "provide a SignatureConversion for each non-entry block");
-
+  // Convert the arguments of each non-entry block within the region.
   for (Block &block :
        llvm::make_early_inc_range(llvm::drop_begin(*region, 1))) {
-    TypeConverter::SignatureConversion *blockConversion =
-        blockConversions.empty()
-            ? nullptr
-            : const_cast<TypeConverter::SignatureConversion *>(
-                  &blockConversions[blockIdx++]);
-
-    if (failed(convertBlockSignature(rewriter, &block, &converter,
-                                     blockConversion)))
+    // Compute the signature for the block with the provided converter.
+    std::optional<TypeConverter::SignatureConversion> conversion =
+        converter.convertBlockSignature(&block);
+    if (!conversion)
       return failure();
-  }
-  return success();
+    // Convert the block with the computed signature.
+    applySignatureConversion(rewriter, &block, &converter, *conversion);
----------------
matthias-springer wrote:

Side note: There were some cases like these that were confusing in the old code. E.g., `FailureOr<Block *> ConversionPatternRewriterImpl::convertBlockSignature()` was sometimes called in a way that we know that it always succeeds. But in other cases, you actually needed error checking.

https://github.com/llvm/llvm-project/pull/94866