RHEA-2015:2040 - Product Enhancement Advisory

Topic

New devtoolset-4-gcc packages are now available as a part of Red Hat Developer
Toolset 4.0 for Red Hat Enterprise Linux.

Description

The GNU Compiler Collection (GCC) is a portable compiler suite with support for
various programming languages, including C, C++, and Fortran. The
devtoolset-4-gcc packages provide the Red Hat Developer Toolset version of GCC,
as well as related libraries.

This enhancement update adds the devtoolset-4-gcc packages to Red Hat Developer
Toolset 4.0 for Red Hat Enterprise Linux. These packages include GCC 5.2.1,
which is the latest stable release of GCC. It provides numerous bug fixes and
enhancements over the version included in Red Hat Developer Toolset 3.1.
Notably:

• Various inter-procedural optimization improvements.
• Various link-time optimization improvements.
• Various register-allocation improvements.
• The Undefined Behavior Sanitizer (ubsan) has gained a few new sanitization

options. It is now able to detect out-of-bounds accesses and detect various
misaligned objects. It is also capable of virtual-pointer checking for C++ code.

• Pointer Bounds Checker has been added to GCC, which serves as a bounds

violation detector. This tool only works on 32-bit a 64-bit Intel and AMD Linux
targets with the new ISA extension Intel MPX support.

• Offloading features of the OpenMP 4.0 specification are now supported by the

C, C++, and Fortran compilers.

• Several new warnings options have been added, including, "-Wswitch-bool",

"-Wlogical-not-parentheses", "-Wsizeof-array-argument", and - "-Wbool-compare".

• The preprocessor has gained support for the "__has_include" and

"__has_include_next" macros, which can be used to test the availability of
headers, as well as the "__has_attribute" macro used to determine whether a
specified attribute exists.

• A new set of built-in functions for arithmetics with overflow checking has

been added: "__builtin_add_overflow", "__builtin_sub_overflow", and
"__builtin_mul_overflow".

• The default mode for C is now "-std=gnu11" instead of "-std=gnu89".
• The C++ compiler now supports many C++14 features, for instance: variable

templates, aggregates with non-static data member initializers, the extended
constexpr specifier, sized deallocation functions, and others. The C++ compiler
also supports several new warnings, for example, to help developers annotate
programs with final specifiers.

• The Runtime Library (libstdc++) has been greatly improved.
• GCC now contains the libgccjit library, which allows users to build GCC as a

shared library for embedding in other processes, suitable for Just-In-Time (JIT)
compilation to machine code.

For details, see Appendix A.2. Changes in GCC in the Red Hat Developer Toolset
4.0 User Guide linked from the References section.

(BZ#1223952)

• GCC now supports Decimal Floating Point in C++ as specified by ISO/IEC TR

24733. (BZ#976094)

• GCC now supports new Intel AVX-512 Instruction Set Architecture (ISA)

extensions. (BZ#1003612)

• GCC now contains support for AVX512-VL (Vector Length Extensions), AVX512-BW

(Byte and Word Instructions) and AVX512-DQ (Doubleword and Quadword
Instructions) extensions on top of already existing AVX-512 extensions.
(BZ#1174950)

• The Intel Memory Protection Extensions (MPX) support has been added to GCC in

Developer Toolset 4.0 for use with future releases of Red Hat Enterprise Linux 7
(beyond Red Hat Enterprise Linux 7.2) when the kernel enablement is complete.
This feature will provide a set of extensions to the x86 Instruction Set
Architecture (ISA), which can be used for bounds checking when performing
pointer accesses. This feature will not be supported on Red Hat Enterprise Linux
6. Note that to use the Memory Protection Extensions (MPX) feature in GCC, the
Red Hat Developer Toolset version of the libmpx library is required, otherwise
the application might not link properly. (BZ#1003616)

All users who require devtoolset-4-gcc are advised to install these new
packages.

Solution

Before applying this update, make sure all previously released errata
relevant to your system have been applied.

For details on how to apply this update, refer to:

https://access.redhat.com/articles/11258

Affected Products

• Red Hat Software Collections (for RHEL Server) 1 for RHEL 7.7 x86_64
• Red Hat Software Collections (for RHEL Server) 1 for RHEL 7.6 x86_64
• Red Hat Software Collections (for RHEL Server) 1 for RHEL 7.5 x86_64
• Red Hat Software Collections (for RHEL Server) 1 for RHEL 7.4 x86_64
• Red Hat Software Collections (for RHEL Server) 1 for RHEL 7.3 x86_64
• Red Hat Software Collections (for RHEL Server) 1 for RHEL 7.2 x86_64
• Red Hat Software Collections (for RHEL Server) 1 for RHEL 7.1 x86_64
• Red Hat Software Collections (for RHEL Server) 1 for RHEL 7 x86_64
• Red Hat Software Collections (for RHEL Server) 1 for RHEL 6.7 x86_64
• Red Hat Software Collections (for RHEL Server) 1 for RHEL 6.6 x86_64
• Red Hat Software Collections (for RHEL Server) 1 for RHEL 6 x86_64
• Red Hat Software Collections (for RHEL Workstation) 1 for RHEL 7 x86_64
• Red Hat Software Collections (for RHEL Workstation) 1 for RHEL 6 x86_64
• Red Hat Software Collections (for RHEL Server) from RHUI 1 for RHEL 7 x86_64
• Red Hat Software Collections (for RHEL Server) from RHUI 1 for RHEL 6 x86_64

Fixes

• BZ - 1269279 - GCC does not find gold linker if it is not in PATH

CVEs

(none)

References

• https://access.redhat.com/documentation/en-US/Red_Hat_Developer_Toolset/4/html/User_Guide/sect-Changes_in_Version_4.0-GCC.html