Add --obfuscate-ids option to driver

include/slang/driver/Driver.h

@@ -261,10 +261,12 @@ class SLANG_EXPORT Driver {
 
     /// Runs the preprocessor on all loaded buffers and outputs the result to stdout.
     /// Any errors encountered will be printed to stderr.
-    /// @param includeComments If true, comments will be included in the output
+    /// @param includeComments If true, comments will be included in the output.
     /// @param includeDirectives If true, preprocessor directives will be included in the output.
+    /// @param obfuscateIds If true, identifiers will be randomized.
     /// @returns true on success and false if errors were encountered.
-    [[nodiscard]] bool runPreprocessor(bool includeComments, bool includeDirectives);
+    [[nodiscard]] bool runPreprocessor(bool includeComments, bool includeDirectives,
+                                       bool obfuscateIds);
 
     /// Prints all macros from all loaded buffers to stdout.
     void reportMacros();

source/driver/Driver.cpp

@@ -8,7 +8,12 @@
 //------------------------------------------------------------------------------
 #include "slang/driver/Driver.h"
 
+#include <array>
+#include <cstring>
 #include <fmt/color.h>
+#include <functional>
+#include <random>
+#include <unordered_map>
 
 #include "slang/ast/symbols/CompilationUnitSymbols.h"
 #include "slang/ast/symbols/InstanceSymbols.h"
@@ -389,7 +394,29 @@ bool Driver::processOptions() {
     return true;
 }
 
-bool Driver::runPreprocessor(bool includeComments, bool includeDirectives) {
+template<typename T = std::mt19937>
+auto randomGenerator() -> T {
+    auto constexpr seedBytes = sizeof(typename T::result_type) * T::state_size;
+    auto constexpr seedLen = seedBytes / sizeof(std::seed_seq::result_type);
+    auto seed = std::array<std::seed_seq::result_type, seedLen>();
+    auto dev = std::random_device();
+    std::generate_n(begin(seed), seedLen, std::ref(dev));
+    auto seedSeq = std::seed_seq(begin(seed), end(seed));
+    return T{seedSeq};
+}
+
+auto generateRandomAlphanumericString(std::size_t len = 16) -> std::string {
+    static constexpr auto chars = "0123456789"
+                                  "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+                                  "abcdefghijklmnopqrstuvwxyz";
+    thread_local auto rng = randomGenerator<>();
+    auto dist = std::uniform_int_distribution{{}, std::strlen(chars) - 1};
+    auto result = std::string(len, '\0');
+    std::generate_n(begin(result), len, [&]() { return chars[dist(rng)]; });
+    return result;
+}
+
+bool Driver::runPreprocessor(bool includeComments, bool includeDirectives, bool obfuscateIds) {
     BumpAllocator alloc;
     Diagnostics diagnostics;
     Preprocessor preprocessor(sourceManager, alloc, diagnostics, createOptionBag());
@@ -401,8 +428,20 @@ bool Driver::runPreprocessor(bool includeComments, bool includeDirectives) {
     output.setIncludeComments(includeComments);
     output.setIncludeDirectives(includeDirectives);
 
+    std::unordered_map<std::string, std::string> translations;
+
     while (true) {
         Token token = preprocessor.next();
+        if (obfuscateIds && token.kind == TokenKind::Identifier) {
+            std::string name = std::string(token.valueText());
+            auto translation = translations.find(name);
+            if (translation == translations.end()) {
+                auto new_name = generateRandomAlphanumericString();
+                auto ret = translations.insert({name, new_name});
+                translation = ret.first;
+            }
+            token = token.withRawText(alloc, translation->second);
+        }
         output.print(token);
         if (token.kind == TokenKind::EndOfFile)
             break;

tests/unittests/DriverTests.cpp

@@ -109,7 +109,7 @@ TEST_CASE("Driver file preprocess") {
     const char* argv[] = {"testfoo", filePath.c_str()};
     CHECK(driver.parseCommandLine(2, argv));
     CHECK(driver.processOptions());
-    CHECK(driver.runPreprocessor(true, false));
+    CHECK(driver.runPreprocessor(true, false, false));
 
     auto output = OS::capturedStdout;
     output = std::regex_replace(output, std::regex("\r\n"), "\n");
@@ -134,7 +134,7 @@ TEST_CASE("Driver file preprocess with error") {
     const char* argv[] = {"testfoo", filePath.c_str()};
     CHECK(driver.parseCommandLine(2, argv));
     CHECK(driver.processOptions());
-    CHECK(!driver.runPreprocessor(true, false));
+    CHECK(!driver.runPreprocessor(true, false, false));
     CHECK(stderrContains("unknown macro"));
 }
 

tools/driver/driver.cpp

@@ -71,10 +71,13 @@ int driverMain(int argc, TArgs argv) try {
 
     std::optional<bool> includeComments;
     std::optional<bool> includeDirectives;
+    std::optional<bool> obfuscateIds;
     driver.cmdLine.add("--comments", includeComments,
                        "Include comments in preprocessed output (with -E)");
     driver.cmdLine.add("--directives", includeDirectives,
                        "Include compiler directives in preprocessed output (with -E)");
+    driver.cmdLine.add("--obfuscate-ids", obfuscateIds,
+                       "Randomize all identifiers in preprocessed output (with -E)");
 
     std::optional<std::string> astJsonFile;
     driver.cmdLine.add(
@@ -127,7 +130,8 @@ int driverMain(int argc, TArgs argv) try {
     bool ok = true;
     try {
         if (onlyPreprocess == true) {
-            ok = driver.runPreprocessor(includeComments == true, includeDirectives == true);
+            ok = driver.runPreprocessor(includeComments == true, includeDirectives == true,
+                                        obfuscateIds == true);
         }
         else if (onlyMacros == true) {
             driver.reportMacros();