GCC 13 Release Series
Changes, New Features, and Fixes

This page is a "brief" summary of some of the huge number of improvements in GCC 13. You may also want to check out our Porting to GCC 13 page and the full GCC documentation.

Note: GCC 13 has not been released yet, so this document is a work-in-progress.

Caveats

• OpenMP offloading to Intel MIC has been removed.
• The support for the cr16-elf, tilegx*-linux, tilepro*-linux, hppa[12]*-*-hpux10*, hppa[12]*-*-hpux11* and m32c-rtems configurations has been removed.
• Support for emitting the STABS debugging format (including the -gstabs and -gxcoff options) has been removed. (This means the dbx debugger is no longer supported, either.)
• Legacy debug info compression option -gz=zlib-gnu was removed and the option is ignored right now.
• New debug info compression option value -gz=zstd has been added.

General Improvements

• OpenMP
  • Reverse offload is now supported and the all clauses to the requires directive are now accepted; however, the requires_offload, unified_address and unified_shared_memory clauses cause that the only available device is the initial device (the host).
  • The following OpenMP 5.1 features have been added: the omp_all_memory reserved locator, the inoutset modifier to the depend clause, the nowait clause for the taskwait directive and the omp_target_is_accessible, omp_target_memcpy_async, omp_target_memcpy_rect_async and omp_get_mapped_ptr API routines. Fortran now supports non-rectangular loop nests, which were added for C/C++ in GCC 11.
  • Initial support for OpenMP 5.2 features have been added: Support for firstprivate and allocate clauses on the scope construct and the OpenMP 5.2 syntax of the linear clause; the new enum/constants omp_initial_device and omp_invalid_device; and optionally omitting the map-type in target enter/exit data. The enter clause (as alias for to) has been added to the declare target directive.
  • For user defined allocators requesting high bandwidth or large capacity memspaces or interleaved partitioning, the memkind library is used, if available at runtime.
• AddressSanitizer defaults to detect_stack_use_after_return=1 on GNU/Linux targets. For compatibility, it can be disabled with env ASAN_OPTIONS=detect_stack_use_after_return=0.
• Link-time optimization improvements:
  • LTO supports the newly added jobserver of GNU make jobserver that uses named pipes (--jobserver-style=fifo) by default.
  • If make's jobserver is active, parallel LTO WPA streaming communicates with it and thus avoids system overcommitting.

New Languages and Language specific improvements

C

• Several C23 features have been implemented:
  • N3042, Introduce the nullptr constant
  • N2963, Enhanced Enumerations (fixed underlying types)
  • N2975, Relax requirements for variadic parameter lists
  • N3007, Type inference for object definitions (auto)
  • N3018, The constexpr specifier for object definitions
  • N3038, Introduce storage-class specifiers for compound literals
  • typeof (previously supported as an extension) and typeof_unqual
  • New keywords alignas, alignof, bool, false, static_assert, thread_local, true
  • N2764, The noreturn attribute
  • Support for empty initializer braces
  • __STDC_VERSION_*_H__ header version macros
  • Removal of ATOMIC_VAR_INIT
  • unreachable macro in <stddef.h>
  • Removal of trigraphs
  • Removal of unprototyped functions
  • printf and scanf format checking with -Wformat for %wN and %wfN format length modifiers
  • N2836, Identifier Syntax using Unicode Standard Annex 31
• In addition to those C23 features, existing features adopted in C23 have been adjusted to follow C23 requirements and are not diagnosed with -std=c2x -Wpedantic.
• New warnings:
  • -Wenum-int-mismatch warns about mismatches between an enumerated type and an integer type (PR105131)

C++

• Several C++23 features have been implemented:
  • P2324R1, Labels at the end of compound statements (PR103539)
  • P2255R2, A type trait to detect reference binding to temporary (PR104477)
  • P2327R1, De-deprecating volatile compound operations
  • P2437R1, Support for #warning (PR106646)
  • P2290R3, Delimited escape sequences (PR106645)
  • P2071R2, Named universal character escapes (PR106648)
  • P2513R3, char8_t Compatibility and Portability Fix (PR106656)
  • P1169R4, static operator() (PR106651)
  • P2266R3, Simpler implicit move (PR101165)
  • P2468R2, The Equality Operator You Are Looking For (PR106644)
• New warnings:
  • -Wself-move warns when a value is moved to itself with std::move (PR81159)
  • -Wdangling-reference warns when a reference is bound to a temporary whose lifetime has ended (PR106393)
• The -Wpessimizing-move and -Wredundant-move warnings have been extended to warn in more contexts.

Runtime Library (libstdc++)

• Improved experimental support for C++23, including:
  • Additions to the <ranges> header: views::zip, views::zip_transform, views::adjacent, views::adjacent_transform views::pairwise, views::slide, views::chunk, views::chunk_by.
• Support for the <experimental/scope> header from v3 of the Library Fundamentals Technical Specification.

New Targets and Target Specific Improvements

AArch64

• A number of new CPUs are supported through the -mcpu and -mtune options (GCC identifiers in parentheses).
  • Ampere-1A (ampere1a).
  • Arm Cortex-A715 (cortex-a715).
  • Arm Cortex-X1C (cortex-x1c).
  • Arm Cortex-X3 (cortex-x3).
  • Arm Neoverse V2 (neoverse-v2).

AMD Radeon (GCN)

• Support for the Instinct MI200 series devices ( gfx90a) has been added.

arm

• The STAR-MC1 CPU is now supported through the star-mc1 argument to the -mcpu and -mtune options.

IA-32/x86-64

• For both C and C++ the __bf16 type is supported on x86 systems with SSE2 and above enabled.
• Use real __bf16 type for AVX512BF16 intrinsics. Previously we use __bfloat16 which is typedef of short. Now we introduced real __bf16 type to x86 psABI. Users need to adjust their AVX512BF16-related source code when upgrading GCC12 to GCC13.
• New ISA extension support for Intel AVX-IFMA was added. AVX-IFMA intrinsics are available via the -mavxifma compiler switch.
• New ISA extension support for Intel AVX-VNNI-INT8 was added. AVX-VNNI-INT8 intrinsics are available via the -mavxvnniint8 compiler switch.
• New ISA extension support for Intel AVX-NE-CONVERT was added. AVX-NE-CONVERT intrinsics are available via the -mavxneconvert compiler switch.
• New ISA extension support for Intel CMPccXADD was added. CMPccXADD intrinsics are available via the -mcmpccxadd compiler switch.
• New ISA extension support for Intel AMX-FP16 was added. AMX-FP16 intrinsics are available via the -mamx-fp16 compiler switch.
• New ISA extension support for Intel PREFETCHI was added. PREFETCHI intrinsics are available via the -mprefetchi compiler switch.
• New ISA extension support for Intel RAO-INT was added. RAO-INT intrinsics are available via the -mraoint compiler switch.
• GCC now supports the Intel CPU named Raptor Lake through -march=raptorlake. Raptor Lake is based on Alder Lake.
• GCC now supports the Intel CPU named Meteor Lake through -march=meteorlake. Meteor Lake is based on Alder Lake.
• GCC now supports the Intel CPU named Sierra Forest through -march=sierraforest. The switch enables the AVX-IFMA, AVX-VNNI-INT8, AVX-NE-CONVERT and CMPccXADD ISA extensions.
• GCC now supports the Intel CPU named Grand Ridge through -march=grandridge. The switch enables the AVX-IFMA, AVX-VNNI-INT8, AVX-NE-CONVERT, CMPccXADD and RAO-INT ISA extensions.
• GCC now supports the Intel CPU named Granite Rapids through -march=graniterapids. The switch enables the AMX-FP16 and PREFETCHI ISA extensions.

NVPTX

• The default value for the -march option can be now changed when building GCC using the --with-arch= configure option. GCC's target libraries are then build both with sm_30 and the specified target architecture. If not specified, GCC defaults to sm_30.

RISC-V

• New ISA extension support for zawrs.

Operating Systems

Other significant improvements