Fixed an MSAN error.

PiperOrigin-RevId: 694545431
Change-Id: I9fb36f53705e034535beb760695e002264a271b2

mpact/sim/decoder/encoding_group.cc

diff --git a/mpact/sim/decoder/encoding_group.cc b/mpact/sim/decoder/encoding_group.cc
index 39da46b..9238df1 100644
--- a/mpact/sim/decoder/encoding_group.cc
+++ b/mpact/sim/decoder/encoding_group.cc
@@ -725,9 +725,17 @@
         std::string name = constraint->field == nullptr
                                ? constraint->overlay->name()
                                : constraint->field->name;
-        absl::StrAppend(&output, " ", name, " != ",
-                        absl::Hex(constraint->value, absl::PadSpec::kZeroPad8),
-                        " ");
+        std::string rhs_value;
+        if (constraint->rhs_field != nullptr) {
+          rhs_value = constraint->rhs_field->name;
+        } else if (constraint->rhs_overlay != nullptr) {
+          rhs_value = constraint->rhs_overlay->name();
+        } else {
+          rhs_value = absl::StrCat(
+              absl::Hex(constraint->value, absl::PadSpec::kZeroPad8));
+        }
+        absl::StrAppend(&output, " ", name, " ", constraint->type, " ",
+                        rhs_value, " ");
       }
       absl::StrAppend(&output, "\n");
     }