base: Replace cppversion == version with >= version

For forward compatibility with later compilers, we should have a greater
than comparison instead of an explicit equality with a particular C++
version.

Change-Id: If848097420b9575f80134986410da3dab32567da
Signed-off-by: Bradley Wang <radwang@ucdavis.edu>
Reviewed-on: https://gem5-review.googlesource.com/11871
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Reviewed-by: Gabe Black <gabeblack@google.com>
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Maintainer: Gabe Black <gabeblack@google.com>

base: Add a M5_PUBLIC and M5_LOCAL attribute macro

There are cases where we need to limit the symbol visibility to avoid
compilation errors. This is a problem for Python code that relies on
PyBind11 since recent versions enforce hidden symbols. As a
consequence, classes that have member variables from PyBind11 need to
be declared with the hidden attribute (or gem5 needs to be compiled
with -fvisibility=hidden).

Change-Id: I30e582fde494ff61ab7a596a595efc26a2952a5f
Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/11513
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>

base: Add M5 flag for [[nodiscard]] attribute

This change adds the M5_NODISCARD keyword to allow use of the
[[nodiscard]] attribute with compilers that support C++17. Currently,
C++17 is not a requirement and therefore the M5_NODISCARD has not
effect and does not break compilation for older compilers.

Change-Id: Ifc5c8f34764da3c7291066dcb2ff908c97738c3d
Reviewed-on: https://gem5-review.googlesource.com/10441
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Reviewed-by: Anthony Gutierrez <anthony.gutierrez@amd.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Anthony Gutierrez <anthony.gutierrez@amd.com>

arm: Fix implicit-fallthrough warnings when building with gcc-7+

gcc 7 onwards have additional heuristics to detect implicit
fallthroughs and it fails the build with warnings for ARM as a result.
There was one gcc bug[1] that I fixed but the rest are cases that gcc
cannot detect due to the point at which it does the fallthrough check.
Most of this patch adds __builtin_unreachable() hints in places that throw
this warning to indicate to gcc that the fallthrough will never
happen.

The remaining cases are actually possible fallthroughs due to
incorrect code running on the simulator; in which case an Unknown
instruction is returned.

[1] https://gcc.gnu.org/ml/gcc-patches/2018-02/msg01105.html

Change-Id: I1baa9fa0ed15181c10c755c0bd777f88b607c158
Signed-off-by: Siddhesh Poyarekar <siddhesh.poyarekar@gmail.com>
Reviewed-on: https://gem5-review.googlesource.com/8541
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Maintainer: Giacomo Travaglini <giacomo.travaglini@arm.com>

misc: Updates for gcc7.2 for x86

GCC 7.2 is much stricter than previous GCC versions. The following changes
are needed:

* There is now a warning if there is an implicit fallthrough between two
case statments. C++17 adds the [[fallthrough]]; declaration. However,
to support non C++17 standards (i.e., C++11), we use M5_FALLTHROUGH.
M5_FALLTHROUGH checks for [[fallthrough]] compliant C++17 compiler and
if that doesn't exist, it defaults to nothing (no older compilers
generate warnings).
* The above resulted in a couple of bugs that were found. This is noted
in the review request on gerrit.
* throw() for dynamic exception specification is deprecated
* There were a couple of new uninitialized variable warnings
* Can no longer perform bitwise operations on a bool.
* Must now include <functional> for std::function
* Compiler bug for void* lambda. Changed to auto as work around. See
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82878

Change-Id: I5d4c782a4e133fa4cdb119e35d9aff68c6e2958e
Signed-off-by: Jason Lowe-Power <jason@lowepower.com>
Reviewed-on: https://gem5-review.googlesource.com/5802
Reviewed-by: Gabe Black <gabeblack@google.com>

base: Defining make_unique for C++11

std::make_unique is not available for C++11 compilers, and it has been
introduced only in C++14. Since gem5 is not officially supporting the
latter at the moment, this patch allows to use it in gem5 if including
base/compiler.hh. If compiled under C++14, std::make_unique will be
used instead.

Change-Id: Ibf1897fad0a1eb1cb0c683cc25170feaa6841997
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/5201
Reviewed-by: Anthony Gutierrez <anthony.gutierrez@amd.com>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>

misc: Remove redundant compiler-specific defines

This patch moves away from using M5_ATTR_OVERRIDE and the m5::hashmap
(and similar) abstractions, as these are no longer needed with gcc 4.7
and clang 3.1 as minimum compiler versions.

base: Add compiler macros to add deprecation warnings

Gcc and clang both provide an attribute that can be used to flag a
function as deprecated at compile time. This changeset adds a gem5
compiler macro for that compiler feature. The macro can be used to
indicate that a legacy API within gem5 has been deprecated and provide
a graceful migration to the new API.

base: Add compiler macros for C++11 final/override

Add the macros M5_ATTR_FINAL and M5_ATTR_OVERRIDE which are defined to
final and override respectively if supported by the compiler. This is
done to allow a smooth transition to gcc >= 4.7.

base: Remove unused M5_PRAGMA_NORETURN

The M5_PRAGMA_NORETURN macro was only used in for
__exit_message. Since the macro only holds a stub definition and all
functions with noreturn semantics use the M5_ATTR_NORETURN, this
macros is completely redundant.

scons: Fixes uninitialized warnings issued by clang

Small fixes to appease recent clang versions.

scons: Enforce gcc >= 4.4 or clang >= 2.9 and c++0x support

This patch checks that the compiler in use is either gcc >= 4.4 or
clang >= 2.9. and enables building with --std=c++0x in all cases. As a
consequence, we can tidy up the hashmap and always have static_assert
available. If anyone wants to use alternative compilers, icc for
example supports c++0x to a similar level and could be added if
needed.

This patch opens up for a more elaborate use of c++0x features that
are present in gcc 4.4 and clang 2.9, e.g. auto typed variables,
variadic templates, rvalues and move semantics, and strongly typed
enums. There will be no going back on this one...

scons: Remove stale compiler options

This patch simply prunes the SUNCC and ICC compiler options as they
are both sufficiently stale that they would have to be re-written from
scratch anyhow. The patch serves to clean things up before shifting to
a build environment that enforces basic c++11 compliance as done in
the following patch.

base: Check for static_assert support and provide fallback

C++11 has support for static_asserts to provide compile-time assertion
checking. This is very useful when testing, for example, structure
sizes to make sure that the compiler got the right alignment or vector
sizes.

Compiler: Add an M5_NO_INLINE define.

VNC: Add VNC server to M5

Bus: Only call end() on an stl object once in a loop

While I'm waiting for legion to run make m5 compile with a few more compilers

SConstruct:
src/SConscript:
Add flags for Intel CC while i'm at it
src/base/compiler.hh:
the _Pragma stuff needst to be called this way unless someone happens to have a cleaner way
src/base/cprintf_formats.hh:
add std:: where appropriate
src/base/statistics.hh:
use this->map since icc was getting confused about std::map vs the locally defined map
src/cpu/static_inst.hh:
Add some more dummy returns where needed
src/mem/packet.hh:
add more dummy returns where needed
src/sim/host.hh:
use limits to come up with max tick

forgot to include this file