================
@@ -1465,6 +1465,101 @@ bool
DisassemblerLLVMC::MCDisasmInstance::IsAuthenticated(
return InstrDesc.isAuthenticated() || IsBrkC47x;
}
+static void
+UpdateSubtargetFeatures(const llvm::SubtargetFeatures &subtarget_features,
+ std::string &user_feature_overrides) {
+
+ // Extract the default features string from the SubtargetFeatures object.
+ // We must store this in a std::string variable to ensure the memory exists
+ // for the StringRef to point to during the execution of this function.
+ std::string default_features_storage = subtarget_features.getString();
+ llvm::StringRef default_features = default_features_storage;
+
+ // If the user has not provided any overrides AND defaults exist,
+ // then simply use the default feature string.
+ if (user_feature_overrides.empty() && !default_features.empty()) {
+ user_feature_overrides = default_features.str();
+ return;
+ }
+
+ std::string warning_reason;
+ std::vector<std::string> valid_user_flags;
+ std::set<std::string> user_disabled_features;
+
+ for (llvm::StringRef flag : llvm::split(user_feature_overrides, ",")) {
+ bool is_valid = true;
+ flag = flag.trim();
+
+ // If we don't do this, flag.front() below will crash.
+ if (flag.empty())
+ continue;
+
+ // 1. Must be at least 2 chars (e.g., "+a").
+ // 2. Must start with '+' or '-' (Users can enable OR disable).
+ // 3. Name cannot start with a digit (e.g. "+123" is invalid)
+ // 4. All characters after the sign must be alphabets.
+ if (flag.front() != '+' && flag.front() != '-') {
+ is_valid = false;
+ warning_reason = "must start with '+' or '-'";
+ } else if (flag.size() < 2) {
+ is_valid = false;
+ warning_reason = "must have a name";
+ } else if (std::isdigit(static_cast<unsigned char>(flag[1]))) {
+ is_valid = false;
+ warning_reason = "name cannot start with a digit";
+ } else if (!std::all_of(flag.begin() + 1, flag.end(), [](unsigned char c) {
+ return std::isalnum(c) || c == '_';
+ })) {
+ is_valid = false;
+ warning_reason = "contains invalid characters";
+ }
+ if (!is_valid) {
+ llvm::errs() << "Warning: Malformed feature '" << flag
+ << "': " << warning_reason << ". Ignoring.\n";
+ continue; // Skip this flag, continue to the next
+ }
+ valid_user_flags.push_back(flag.str());
+
+ if (flag.starts_with('-')) {
+ user_disabled_features.insert(flag.substr(1).str());
+ }
+ }
+
+ // Rebuild the user string with ONLY valid flags.
+ std::vector<std::string> final_features;
+
+ // Allow users to override default additional features.
+ if (!default_features.empty()) {
+ for (llvm::StringRef flag : llvm::split(default_features, ",")) {
+ flag = flag.trim();
+ if (flag.empty())
+ continue;
+ // By default, if both +flag and -flag are present in the feature string,
+ // disassembler keeps the feature enabled (+flag).
+ // To respect user intent, we make -flag(user) take priority over the
+ // default +flag coming from ELF.
+ bool add_flag = true;
+ // flag starts with plus and it's at least two characters.
+ // We check size >= 2 to ensure we have '+' AND a feature name (e.g.,
+ // "+m").
+ if (flag.size() >= 2 && flag.starts_with('+')) {
+ llvm::StringRef feature_name = flag.substr(1);
+ if (user_disabled_features.count(feature_name.str())) {
+ add_flag = false;
+ }
+ }
+ if (add_flag) {
+ final_features.push_back(flag.str());
+ }
+ }
+ }
+
+ // Append User Flags (User overrides come after defaults)
----------------
JDevlieghere wrote:
Missing period.
https://github.com/llvm/llvm-project/pull/147990
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