PrettyPrint enum values as enum values, rather than merely their bit …

…patterns.

Before:
  0020:  let _ = assert_eq(EnumType::FIRST, EnumType::SECOND);
~~~~~~~~~~~~~~~~~~~~~~~^---------------------------------^ FailureError: The program being interpreted failed!
  lhs: u1:0
  rhs: u1:1
  were not equal

After:
0020:  let _ = assert_eq(EnumType::FIRST, EnumType::SECOND);
~~~~~~~~~~~~~~~~~~~~~~~^---------------------------------^ FailureError: The program being interpreted failed!
  lhs: EnumType::FIRST (u1:0)
  rhs: EnumType::SECOND (u1:1)
  were not equal

fixes google#86.

(The titular "signed numbers" portion of the git issue seems to have already been
solved for a while.)

PiperOrigin-RevId: 541067811

xls/dslx/bytecode/BUILD

@@ -150,6 +150,7 @@ cc_library(
         "//xls/dslx:interp_value",
         "//xls/dslx:interp_value_helpers",
         "//xls/dslx/frontend:ast",
+        "//xls/dslx/type_system:concrete_type",
         "//xls/dslx/type_system:parametric_env",
         "//xls/ir:bits_ops",
     ],

xls/dslx/bytecode/bytecode_interpreter.cc

@@ -30,10 +30,10 @@
 #include "absl/memory/memory.h"
 #include "absl/status/status.h"
 #include "absl/status/statusor.h"
+#include "absl/strings/match.h"
 #include "absl/strings/str_cat.h"
 #include "absl/strings/str_format.h"
 #include "absl/strings/str_join.h"
-#include "absl/strings/match.h"
 #include "absl/strings/str_split.h"
 #include "absl/types/optional.h"
 #include "absl/types/span.h"
@@ -44,6 +44,7 @@
 #include "xls/dslx/frontend/ast.h"
 #include "xls/dslx/interp_value.h"
 #include "xls/dslx/interp_value_helpers.h"
+#include "xls/dslx/type_system/concrete_type.h"
 #include "xls/ir/bits_ops.h"
 
 namespace xls::dslx {
@@ -1437,6 +1438,21 @@ absl::StatusOr<std::string> PrettyPrintValue(const InterpValue& value,
                            struct_type->nominal_type().identifier(),
                            absl::StrJoin(members, "\n"), indent_str);
   }
+  if (const auto* enum_type = dynamic_cast<const EnumType*>(type);
+      enum_type != nullptr) {
+    const EnumDef& enum_def = enum_type->nominal_type();
+    int member_index = 0;
+    for (const InterpValue& member : enum_type->members()) {
+      if (member == value) {
+        return absl::StrFormat("%s::%s (%s)", enum_def.identifier(),
+            enum_def.GetMemberName(member_index), member.ToString());
+      }
+      ++member_index;
+    }
+    XLS_RET_CHECK_FAIL()
+        << "Unexpected value " << value.ToString() << " as enum "
+        << enum_def.identifier();
+  }
   return value.ToString();
 }
 

xls/dslx/bytecode/bytecode_interpreter_test.cc

@@ -1535,6 +1535,25 @@ fn doomed() {
   })"))));
 }
 
+TEST(BytecodeInterpreterTest, PrettyPrintsEnums) {
+  constexpr std::string_view kProgram = R"(
+enum Flowers {
+    ROSES = u24:0xFF007F,
+    VIOLETS = u24:0xEE82EE,
+}
+
+fn doomed() {
+    let a = Flowers::ROSES;
+    let b = Flowers::VIOLETS;
+    assert_eq(a, b)
+})";
+  absl::StatusOr<InterpValue> value = Interpret(kProgram, "doomed");
+  EXPECT_THAT(value.status(), StatusIs(absl::StatusCode::kInternal,
+      AllOf(
+          HasSubstr("Flowers::ROSES (u24:16711807"),
+          HasSubstr("Flowers::VIOLETS (u24:15631086"))));
+}
+
 TEST(BytecodeInterpreterTest, TraceChannels) {
   constexpr std::string_view kProgram = R"(
 proc incrementer {