Detemplatize convertRegion in DialectConversion

Originally, FunctionConverter::convertRegion in the DialectConversion framework
    was implemented as a function template because it was creating a new region in
    the parent object, which could have been an op or a function.  Since
    DialectConversion now operates in place, new region is no longer created so
    there is no need for convertRegion to be aware of the parent, only of the error
    reporting location.

--

PiperOrigin-RevId: 249826392

mlir/lib/Transforms/DialectConversion.cpp

@@ -240,10 +240,10 @@ public:
   LogicalResult convertFunction(Function *f);
 
   /// Converts the given region starting from the entry block and following the
-  /// block successors. Returns failure on error, success otherwise.
-  template <typename RegionParent>
+  /// block successors. Returns failure on error, success otherwise. Prints
+  /// error messages at `loc`.
   LogicalResult convertRegion(DialectConversionRewriter &rewriter,
-                              Region &region, RegionParent *parent);
+                              Region &region, Location loc);
 
   /// Converts a block by traversing its operations sequentially, attempting to
   /// match a pattern. If there is no match, recurses the operations regions if
@@ -299,7 +299,8 @@ FunctionConverter::convertBlock(DialectConversionRewriter &rewriter,
 
     // Traverse any held regions.
     for (auto &region : op.getRegions())
-      if (!region.empty() && failed(convertRegion(rewriter, region, &op)))
+      if (!region.empty() &&
+          failed(convertRegion(rewriter, region, op.getLoc())))
         return failure();
   }
 
@@ -313,10 +314,9 @@ FunctionConverter::convertBlock(DialectConversionRewriter &rewriter,
   return success();
 }
 
-template <typename RegionParent>
 LogicalResult
 FunctionConverter::convertRegion(DialectConversionRewriter &rewriter,
-                                 Region &region, RegionParent *parent) {
+                                 Region &region, Location loc) {
   assert(!region.empty() && "expected non-empty region");
 
   // Create the arguments of each of the blocks in the region. If a type
@@ -325,7 +325,7 @@ FunctionConverter::convertRegion(DialectConversionRewriter &rewriter,
   if (dialectConversion) {
     for (Block &block : region)
       for (auto *arg : block.getArguments())
-        if (failed(convertArgument(rewriter, arg, parent->getLoc())))
+        if (failed(convertArgument(rewriter, arg, loc)))
           return failure();
   }
 
@@ -338,7 +338,8 @@ FunctionConverter::convertRegion(DialectConversionRewriter &rewriter,
   // If some blocks are not reachable through successor chains, they should have
   // been removed by the DCE before this.
   if (visitedBlocks.size() != std::distance(region.begin(), region.end()))
-    return parent->emitError("unreachable blocks were not converted");
+    return rewriter.getContext()->emitError(loc)
+           << "unreachable blocks were not converted";
   return success();
 }
 
@@ -349,7 +350,7 @@ LogicalResult FunctionConverter::convertFunction(Function *f) {
 
   // Rewrite the function body.
   DialectConversionRewriter rewriter(f);
-  if (failed(convertRegion(rewriter, f->getBody(), f))) {
+  if (failed(convertRegion(rewriter, f->getBody(), f->getLoc()))) {
     // Reset any of the generated rewrites.
     rewriter.discardRewrites();
     return failure();