[mlir] Make fold result type check more verbose

Print the op and its types when the fold type check fails. This is to
speed up debuging as it should be trivial to map the offending op to its
folder based on the op name.

Author: kuhar

mlir/lib/IR/Operation.cpp

@@ -20,6 +20,7 @@
 #include "mlir/Interfaces/FoldInterfaces.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringExtras.h"
+#include "llvm/Support/ErrorHandling.h"
 #include <numeric>
 #include <optional>
 
@@ -611,11 +612,19 @@ void Operation::setSuccessor(Block *block, unsigned index) {
 /// the results of the given op.
 static void checkFoldResultTypes(Operation *op,
                                  SmallVectorImpl<OpFoldResult> &results) {
-  if (!results.empty())
-    for (auto [ofr, opResult] : llvm::zip_equal(results, op->getResults()))
-      if (auto value = ofr.dyn_cast<Value>())
-        assert(value.getType() == opResult.getType() &&
-               "folder produced value of incorrect type");
+  if (results.empty())
+    return;
+
+  for (auto [ofr, opResult] : llvm::zip_equal(results, op->getResults())) {
+    if (auto value = dyn_cast<Value>(ofr)) {
+      if (value.getType() != opResult.getType()) {
+        llvm::errs() << "Folder produced a value of incorrect type for: "
+                     << *op << "\nOriginal type: '" << value.getType()
+                     << "'\nNew type: '" << opResult.getType() << "'\n";
+        assert(false && "incorrect fold result type");
+      }
+    }
+  }
 }
 #endif // NDEBUG