[MLIR][NVVM] Print readable modifer (NFC) (#153779)

Currently, modifier is printed as address, so it is not readable and not
useful. This PR adds readable printing for it.

---------

Co-authored-by: Copilot <[email protected]>

Author: grypp

mlir/include/mlir/Dialect/LLVMIR/BasicPtxBuilderInterface.h

@@ -33,6 +33,19 @@ enum class PTXRegisterMod {
   /// set read and write for the same operand.
   ReadWrite = 1,
 };
+
+inline llvm::raw_ostream &operator<<(llvm::raw_ostream &os,
+                                     PTXRegisterMod mod) {
+  switch (mod) {
+  case PTXRegisterMod::Read:
+    return os << "Read";
+  case PTXRegisterMod::Write:
+    return os << "Write";
+  case PTXRegisterMod::ReadWrite:
+    return os << "ReadWrite";
+  }
+  llvm_unreachable("Unknown PTXRegisterMod value");
+}
 } // namespace NVVM
 } // namespace mlir
 

mlir/lib/Conversion/NVVMToLLVM/NVVMToLLVM.cpp

@@ -61,7 +61,7 @@ struct PtxLowering
 
     op.getAsmValues(rewriter, asmValues);
     for (auto &[asmValue, modifier] : asmValues) {
-      LDBG() << asmValue << "\t Modifier : " << &modifier;
+      LDBG() << asmValue << "\t Modifier : " << modifier;
       generator.insertValue(asmValue, modifier);
     }