initial import of GCC 10.3.0. main changes include:

caveats:
- ABI issue between c++14 and c++17 fixed
- profile mode is removed from libstdc++
- -fno-common is now the default

new features:
- new flags -fallocation-dce, -fprofile-partial-training,
-fprofile-reproducible, -fprofile-prefix-path, and -fanalyzer
- many new compile and link time optimisations
- enhanced drive optimisations
- openacc 2.6 support
- openmp 5.0 features
- new warnings: -Wstring-compare and -Wzero-length-bounds
- extended warnings: -Warray-bounds, -Wformat-overflow,
-Wrestrict, -Wreturn-local-addr, -Wstringop-overflow,
-Warith-conversion, -Wmismatched-tags, and -Wredundant-tags
- some likely C2X features implemented
- more C++20 implemented
- many new arm & intel CPUs known

hundreds of reported bugs are fixed. full list of changes
can be found at:

https://gcc.gnu.org/gcc-10/changes.html

initial import of GCC 9.3.0. changes include:

- live patching support
- shell completion help
- generally better diagnostic output (less verbose/more useful)
- diagnostics and optimisation choices can be emitted in json
- asan memory usage reduction
- many general, and specific to switch, inter-procedure,
profile and link-time optimisations. from the release notes:
"Overall compile time of Firefox 66 and LibreOffice 6.2.3 on
an 8-core machine was reduced by about 5% compared to GCC 8.3"
- OpenMP 5.0 support
- better spell-guesser
- partial experimental support for c2x and c++2a
- c++17 is no longer experimental
- arm AAPCS GCC 6-8 structure passing bug fixed, may cause
incompatibility (restored compat with GCC 5 and earlier.)
- openrisc support

import GCC 5.3.0. see these urls for details which are too large to
include here:

http://gcc.gnu.org/gcc-4.9/changes.html
http://gcc.gnu.org/gcc-5/changes.html

(note that GCC 5.x is a release stream like GCC 4.9.x, 4.8.x, etc.)


the main issues we will have are:

The default mode for C is now -std=gnu11 instead of -std=gnu89.

ARM:
The deprecated option -mwords-little-endian has been removed.
The options -mapcs, -mapcs-frame, -mtpcs-frame and -mtpcs-leaf-frame
which are only applicable to the old ABI have been deprecated.

MIPS:
The o32 ABI has been modified and extended. The o32 64-bit
floating-point register support is now obsolete and has been removed.
It has been replaced by three ABI extensions FPXX, FP64A, and FP64.
The meaning of the -mfp64 command-line option has changed. It is now
used to enable the FP64A and FP64 ABI extensions.

import GCC 4.8 branch at r206687.

highlights from: http://gcc.gnu.org/gcc-4.6/changes.html

GCC now has stricter checks for invalid command-line options
New -Wunused-but-set-variable and -Wunused-but-set-parameter
warnings
Many platforms have been obsoleted
Link-time optimization improvements
A new switch -fstack-usage has been added
A new function attribute leaf was introduced
A new warning, enabled by -Wdouble-promotion
Support for selectively enabling and disabling warnings via
#pragma GCC diagnostic has been added
There is now experimental support for some features from the
upcoming C1X revision of the ISO C standard
Improved experimental support for the upcoming C++0x ISO C++
standard
G++ now issues clearer diagnostics in several cases
Updates for ARM, x86, MIPS, PPC/PPC64, SPARC
Darwin, FreeBSD, Solaris 2, MinGW and Cygwin now all support
__float128 on 32-bit and 64-bit x86 targets. [*1]

highlights from: http://gcc.gnu.org/gcc-4.7/changes.html

The -fconserve-space flag has been deprecated
Support for a new parameter --param case-values-threshold=n
was added
Interprocedural and Link-time optimization improvements
A new built-in, __builtin_assume_aligned, has been added
A new warning option -Wunused-local-typedefs was added
A new experimental command-line option -ftrack-macro-expansion
was added
Support for atomic operations specifying the C++11/C11 memory
model has been added
There is support for some more features from the C11 revision
of the ISO C standard
Improved experimental support for the new ISO C++ standard,
C++11
Updates for ARM, x86, MIPS, PPC/PPC64, SH, SPARC, TILE*
A new option (-grecord-gcc-switches) was added

highlights from: http://gcc.gnu.org/gcc-4.8/changes.html

GCC now uses C++ as its implementation language. This means
that to build GCC from sources, you will need a C++
compiler that understands C++ 2003
DWARF4 is now the default when generating DWARF debug
information
A new general optimization level, -Og, has been introduced
A new option -ftree-partial-pre was added
The option -fconserve-space has been removed
The command-line options -fipa-struct-reorg and
-fipa-matrix-reorg have been removed
Interprocedural and Link-time optimization improvements
AddressSanitizer, a fast memory error detector, has been
added [*2]
A new -Wsizeof-pointer-memaccess warning has been added
G++ now supports a -std=c++1y option for experimentation
with features proposed for the next revision of the
standard, expected around 2014
Improved experimental support for the new ISO C++ standard,
C++11
A new port has been added to support AArch64
Updates for ARM, x86, MIPS, PPC/PPC64, SH, SPARC, TILE*


[*1] we should support this too!
[*2] we should look into this.
https://code.google.com/p/address-sanitizer/

branches: 1.1.1.1.2; 1.1.1.1.8;
initial import of GCC 4.5.3 sources. changes since 4.1 are way too numerous
to review, please see http://gcc.gnu.org/gcc-4.5/changes.html (and the 4.2,
4.3 and 4.4 versions, too.)

this includes the core, c++, objc and the non java/ada/fortran parts of the
testsuite.

initial import of GCC 9.3.0. changes include:

- live patching support
- shell completion help
- generally better diagnostic output (less verbose/more useful)
- diagnostics and optimisation choices can be emitted in json
- asan memory usage reduction
- many general, and specific to switch, inter-procedure,
profile and link-time optimisations. from the release notes:
"Overall compile time of Firefox 66 and LibreOffice 6.2.3 on
an 8-core machine was reduced by about 5% compared to GCC 8.3"
- OpenMP 5.0 support
- better spell-guesser
- partial experimental support for c2x and c++2a
- c++17 is no longer experimental
- arm AAPCS GCC 6-8 structure passing bug fixed, may cause
incompatibility (restored compat with GCC 5 and earlier.)
- openrisc support

import GCC 5.3.0. see these urls for details which are too large to
include here:

http://gcc.gnu.org/gcc-4.9/changes.html
http://gcc.gnu.org/gcc-5/changes.html

(note that GCC 5.x is a release stream like GCC 4.9.x, 4.8.x, etc.)


the main issues we will have are:

The default mode for C is now -std=gnu11 instead of -std=gnu89.

ARM:
The deprecated option -mwords-little-endian has been removed.
The options -mapcs, -mapcs-frame, -mtpcs-frame and -mtpcs-leaf-frame
which are only applicable to the old ABI have been deprecated.

MIPS:
The o32 ABI has been modified and extended. The o32 64-bit
floating-point register support is now obsolete and has been removed.
It has been replaced by three ABI extensions FPXX, FP64A, and FP64.
The meaning of the -mfp64 command-line option has changed. It is now
used to enable the FP64A and FP64 ABI extensions.

import GCC 4.8 branch at r206687.

highlights from: http://gcc.gnu.org/gcc-4.6/changes.html

GCC now has stricter checks for invalid command-line options
New -Wunused-but-set-variable and -Wunused-but-set-parameter
warnings
Many platforms have been obsoleted
Link-time optimization improvements
A new switch -fstack-usage has been added
A new function attribute leaf was introduced
A new warning, enabled by -Wdouble-promotion
Support for selectively enabling and disabling warnings via
#pragma GCC diagnostic has been added
There is now experimental support for some features from the
upcoming C1X revision of the ISO C standard
Improved experimental support for the upcoming C++0x ISO C++
standard
G++ now issues clearer diagnostics in several cases
Updates for ARM, x86, MIPS, PPC/PPC64, SPARC
Darwin, FreeBSD, Solaris 2, MinGW and Cygwin now all support
__float128 on 32-bit and 64-bit x86 targets. [*1]

highlights from: http://gcc.gnu.org/gcc-4.7/changes.html

The -fconserve-space flag has been deprecated
Support for a new parameter --param case-values-threshold=n
was added
Interprocedural and Link-time optimization improvements
A new built-in, __builtin_assume_aligned, has been added
A new warning option -Wunused-local-typedefs was added
A new experimental command-line option -ftrack-macro-expansion
was added
Support for atomic operations specifying the C++11/C11 memory
model has been added
There is support for some more features from the C11 revision
of the ISO C standard
Improved experimental support for the new ISO C++ standard,
C++11
Updates for ARM, x86, MIPS, PPC/PPC64, SH, SPARC, TILE*
A new option (-grecord-gcc-switches) was added

highlights from: http://gcc.gnu.org/gcc-4.8/changes.html

GCC now uses C++ as its implementation language. This means
that to build GCC from sources, you will need a C++
compiler that understands C++ 2003
DWARF4 is now the default when generating DWARF debug
information
A new general optimization level, -Og, has been introduced
A new option -ftree-partial-pre was added
The option -fconserve-space has been removed
The command-line options -fipa-struct-reorg and
-fipa-matrix-reorg have been removed
Interprocedural and Link-time optimization improvements
AddressSanitizer, a fast memory error detector, has been
added [*2]
A new -Wsizeof-pointer-memaccess warning has been added
G++ now supports a -std=c++1y option for experimentation
with features proposed for the next revision of the
standard, expected around 2014
Improved experimental support for the new ISO C++ standard,
C++11
A new port has been added to support AArch64
Updates for ARM, x86, MIPS, PPC/PPC64, SH, SPARC, TILE*


[*1] we should support this too!
[*2] we should look into this.
https://code.google.com/p/address-sanitizer/

branches: 1.1.1.1.2; 1.1.1.1.8;
initial import of GCC 4.5.3 sources. changes since 4.1 are way too numerous
to review, please see http://gcc.gnu.org/gcc-4.5/changes.html (and the 4.2,
4.3 and 4.4 versions, too.)

this includes the core, c++, objc and the non java/ada/fortran parts of the
testsuite.

import GCC 5.3.0. see these urls for details which are too large to
include here:

http://gcc.gnu.org/gcc-4.9/changes.html
http://gcc.gnu.org/gcc-5/changes.html

(note that GCC 5.x is a release stream like GCC 4.9.x, 4.8.x, etc.)


the main issues we will have are:

The default mode for C is now -std=gnu11 instead of -std=gnu89.

ARM:
The deprecated option -mwords-little-endian has been removed.
The options -mapcs, -mapcs-frame, -mtpcs-frame and -mtpcs-leaf-frame
which are only applicable to the old ABI have been deprecated.

MIPS:
The o32 ABI has been modified and extended. The o32 64-bit
floating-point register support is now obsolete and has been removed.
It has been replaced by three ABI extensions FPXX, FP64A, and FP64.
The meaning of the -mfp64 command-line option has changed. It is now
used to enable the FP64A and FP64 ABI extensions.

import GCC 4.8 branch at r206687.

highlights from: http://gcc.gnu.org/gcc-4.6/changes.html

GCC now has stricter checks for invalid command-line options
New -Wunused-but-set-variable and -Wunused-but-set-parameter
warnings
Many platforms have been obsoleted
Link-time optimization improvements
A new switch -fstack-usage has been added
A new function attribute leaf was introduced
A new warning, enabled by -Wdouble-promotion
Support for selectively enabling and disabling warnings via
#pragma GCC diagnostic has been added
There is now experimental support for some features from the
upcoming C1X revision of the ISO C standard
Improved experimental support for the upcoming C++0x ISO C++
standard
G++ now issues clearer diagnostics in several cases
Updates for ARM, x86, MIPS, PPC/PPC64, SPARC
Darwin, FreeBSD, Solaris 2, MinGW and Cygwin now all support
__float128 on 32-bit and 64-bit x86 targets. [*1]

highlights from: http://gcc.gnu.org/gcc-4.7/changes.html

The -fconserve-space flag has been deprecated
Support for a new parameter --param case-values-threshold=n
was added
Interprocedural and Link-time optimization improvements
A new built-in, __builtin_assume_aligned, has been added
A new warning option -Wunused-local-typedefs was added
A new experimental command-line option -ftrack-macro-expansion
was added
Support for atomic operations specifying the C++11/C11 memory
model has been added
There is support for some more features from the C11 revision
of the ISO C standard
Improved experimental support for the new ISO C++ standard,
C++11
Updates for ARM, x86, MIPS, PPC/PPC64, SH, SPARC, TILE*
A new option (-grecord-gcc-switches) was added

highlights from: http://gcc.gnu.org/gcc-4.8/changes.html

GCC now uses C++ as its implementation language. This means
that to build GCC from sources, you will need a C++
compiler that understands C++ 2003
DWARF4 is now the default when generating DWARF debug
information
A new general optimization level, -Og, has been introduced
A new option -ftree-partial-pre was added
The option -fconserve-space has been removed
The command-line options -fipa-struct-reorg and
-fipa-matrix-reorg have been removed
Interprocedural and Link-time optimization improvements
AddressSanitizer, a fast memory error detector, has been
added [*2]
A new -Wsizeof-pointer-memaccess warning has been added
G++ now supports a -std=c++1y option for experimentation
with features proposed for the next revision of the
standard, expected around 2014
Improved experimental support for the new ISO C++ standard,
C++11
A new port has been added to support AArch64
Updates for ARM, x86, MIPS, PPC/PPC64, SH, SPARC, TILE*


[*1] we should support this too!
[*2] we should look into this.
https://code.google.com/p/address-sanitizer/

branches: 1.1.1.1.2; 1.1.1.1.8;
initial import of GCC 4.5.3 sources. changes since 4.1 are way too numerous
to review, please see http://gcc.gnu.org/gcc-4.5/changes.html (and the 4.2,
4.3 and 4.4 versions, too.)

this includes the core, c++, objc and the non java/ada/fortran parts of the
testsuite.

branches: 1.1.1;
Initial revision

import GCC 4.8 branch at r206687.

highlights from: http://gcc.gnu.org/gcc-4.6/changes.html

GCC now has stricter checks for invalid command-line options
New -Wunused-but-set-variable and -Wunused-but-set-parameter
warnings
Many platforms have been obsoleted
Link-time optimization improvements
A new switch -fstack-usage has been added
A new function attribute leaf was introduced
A new warning, enabled by -Wdouble-promotion
Support for selectively enabling and disabling warnings via
#pragma GCC diagnostic has been added
There is now experimental support for some features from the
upcoming C1X revision of the ISO C standard
Improved experimental support for the upcoming C++0x ISO C++
standard
G++ now issues clearer diagnostics in several cases
Updates for ARM, x86, MIPS, PPC/PPC64, SPARC
Darwin, FreeBSD, Solaris 2, MinGW and Cygwin now all support
__float128 on 32-bit and 64-bit x86 targets. [*1]

highlights from: http://gcc.gnu.org/gcc-4.7/changes.html

The -fconserve-space flag has been deprecated
Support for a new parameter --param case-values-threshold=n
was added
Interprocedural and Link-time optimization improvements
A new built-in, __builtin_assume_aligned, has been added
A new warning option -Wunused-local-typedefs was added
A new experimental command-line option -ftrack-macro-expansion
was added
Support for atomic operations specifying the C++11/C11 memory
model has been added
There is support for some more features from the C11 revision
of the ISO C standard
Improved experimental support for the new ISO C++ standard,
C++11
Updates for ARM, x86, MIPS, PPC/PPC64, SH, SPARC, TILE*
A new option (-grecord-gcc-switches) was added

highlights from: http://gcc.gnu.org/gcc-4.8/changes.html

GCC now uses C++ as its implementation language. This means
that to build GCC from sources, you will need a C++
compiler that understands C++ 2003
DWARF4 is now the default when generating DWARF debug
information
A new general optimization level, -Og, has been introduced
A new option -ftree-partial-pre was added
The option -fconserve-space has been removed
The command-line options -fipa-struct-reorg and
-fipa-matrix-reorg have been removed
Interprocedural and Link-time optimization improvements
AddressSanitizer, a fast memory error detector, has been
added [*2]
A new -Wsizeof-pointer-memaccess warning has been added
G++ now supports a -std=c++1y option for experimentation
with features proposed for the next revision of the
standard, expected around 2014
Improved experimental support for the new ISO C++ standard,
C++11
A new port has been added to support AArch64
Updates for ARM, x86, MIPS, PPC/PPC64, SH, SPARC, TILE*


[*1] we should support this too!
[*2] we should look into this.
https://code.google.com/p/address-sanitizer/

branches: 1.1.1.1.2; 1.1.1.1.8;
initial import of GCC 4.5.3 sources. changes since 4.1 are way too numerous
to review, please see http://gcc.gnu.org/gcc-4.5/changes.html (and the 4.2,
4.3 and 4.4 versions, too.)

this includes the core, c++, objc and the non java/ada/fortran parts of the
testsuite.

Rebase to HEAD as of a few days ago.

sync with head.

for a reference, the tree before this commit was tagged
as yamt-pagecache-tag8.

this commit was splitted into small chunks to avoid
a limitation of cvs. ("Protocol error: too many arguments")