Multi-language Runtime Subsystem Changelog

cl.arkcompiler.1 New Alarms and Existing Alarm Enhancements for LLVM

Change Impact

By default, the -Werror option is disabled for the OpenHarmony NDK. If you have enabled the -Werror option, you are advised to correct the code based on the suggestions in the check result or mask the errors.

Changes in Key Compilation Check Rules

Adaptation Guide

1. For issues in the code that are not detected by LLVM 12, check and update the code.
2. Some old implementations are discarded during LLVM update. Adapt to the new rules and update the code.
3. If you believe a certain type of error can be masked, use the -Wno-xxx option to mask the error.

Defective code example

void Heap::Resume(TriggerGCType gcType)
{
    if (mode_ != HeapMode::SPAWN &&
        activeSemiSpace_->AdjustCapacity(inactiveSemiSpace_->GetAllocatedSizeSinceGC())) {
        // If activeSpace capacity changes, oldSpace maximumCapacity should change too.
        size_t multiple = 2;
        // oldSpaceMaxLimit is assigned a value but is not used.
        size_t oldSpaceMaxLimit = 0;
        if (activeSemiSpace_->GetInitialCapacity() >= inactiveSemiSpace_->GetInitialCapacity()) {
            size_t delta = activeSemiSpace_->GetInitialCapacity() - inactiveSemiSpace_->GetInitialCapacity();
            oldSpaceMaxLimit = oldSpace_->GetMaximumCapacity() - delta * multiple;
        } else {
            size_t delta = inactiveSemiSpace_->GetInitialCapacity() - activeSemiSpace_->GetInitialCapacity();
            oldSpaceMaxLimit = oldSpace_->GetMaximumCapacity() + delta * multiple;
        }
        inactiveSemiSpace_->SetInitialCapacity(activeSemiSpace_->GetInitialCapacity());
    }
    // irrelated code ...
}

The oldSpaceMaxLimit variable is not used, and the compiler reports an alarm.

../../arkcompiler/ets_runtime/ecmascript/mem/heap.cpp:247:16: error: variable 'oldSpaceMaxLimit' set but not used [-Werror,-Wunused-but-set-variable]
        size_t oldSpaceMaxLimit = 0;

The error is rectified after the attribute is added.

void Heap::Resume(TriggerGCType gcType)
{
    if (mode_ != HeapMode::SPAWN &&
        activeSemiSpace_->AdjustCapacity(inactiveSemiSpace_->GetAllocatedSizeSinceGC())) {
        // If activeSpace capacity changes, oldSpace maximumCapacity should change too.
        size_t multiple = 2;
        // Add the maybe_unused attribute and declare that the variable oldSpaceMaxLimit may not be used.
        [[maybe_unused]] size_t oldSpaceMaxLimit = 0;
        if (activeSemiSpace_->GetInitialCapacity() >= inactiveSemiSpace_->GetInitialCapacity()) {
            size_t delta = activeSemiSpace_->GetInitialCapacity() - inactiveSemiSpace_->GetInitialCapacity();
            oldSpaceMaxLimit = oldSpace_->GetMaximumCapacity() - delta * multiple;
        } else {
            size_t delta = inactiveSemiSpace_->GetInitialCapacity() - activeSemiSpace_->GetInitialCapacity();
            oldSpaceMaxLimit = oldSpace_->GetMaximumCapacity() + delta * multiple;
        }
        inactiveSemiSpace_->SetInitialCapacity(activeSemiSpace_->GetInitialCapacity());
    }
    // irrelated code ...
}

cl.arkcompiler.2 LLVM Parsing Format Changed

Change Impact

When your code depends on the version-script or -gcc-toolchain option, parsing may fail if you continue to use the original LLVM 12 configuration file or options.

Changes in Key Compilation Rules

1. The symbol representation is changed. In the new version, consecutive greater signs (>) are represented as “>>”, which was represented as “> >” in the old version.
2. The -xx options are deprecated. For example, the -gcc-toolchain option is replaced by the –gcc-toolchain option. (This option has been marked as deprecated in versions later than Clang 3.4 and is officially deprecated in LLVM15.)

Adaptation Guide

If two consecutive greater signs (>) exist in the code (without considering the number of spaces in the middle), they will be parsed as “> >” in the older version and “>>” in the new version in version-script (due to mangling differences). In LLVM15, “>>” must be used.

Original configuration file

{
  global:
  extern "C++" {
    "google::protobuf::TextFormat::ParseFromString(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, google::protobuf::Message*)";
    // In LLVM 12, "> >" can be parsed, but ">>" cannot.
    "google::protobuf::TextFormat::PrintToString(google::protobuf::Message const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >*)";
  };
  local:
    *;
}

Modified configuration file

{
  global:
  extern "C++" {
    "google::protobuf::TextFormat::ParseFromString(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>> const&, google::protobuf::Message*)";
    // In LLVM 15, ">>" can be parsed.
    "google::protobuf::TextFormat::PrintToString(google::protobuf::Message const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>>*)";
  };
  local:
    *;
}

cl.arkcompiler.3 LLVM emu-tls Changed

Change Impact

If you use both LLVM 12 and LLVM 15 (this behavior is prohibited) for your code, the emu-tls symbol cannot be found in libc++.so.

Key Library Dependency Changes

In LLVM 15, the emu-tls symbol is extracted from the target binary file to libc++.so. That is, the __emutls_get_address attribute changes from an internal symbol to an externally visible symbol, which is included in libc++.so. As a result, the compiled dynamic library may depend on libc++.so.

Adaptation Guide

This symbol is also in libclang_rt.builtin.a. If you do not want the compiled dynamic library to depend on libc++.so, statically link the libclang_rt.builtin.a library.

cl.arkcompiler.4 LLVM Official Release Notes

Change Impact

New features are added and internal interfaces are changed (such as IR in LLVM and compiler front-end modification). For details, see the official release notes.

Key Documents

https://releases.llvm.org/13.0.0/docs/ReleaseNotes.html https://releases.llvm.org/14.0.0/docs/ReleaseNotes.html https://releases.llvm.org/15.0.0/docs/ReleaseNotes.html

Adaptation Guide

For details about the updates and adaptation guide, see the official documents.

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