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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>
This is the gem5 simulator. The main website can be found at http://www.gem5.org A good starting point is http://www.gem5.org/Introduction, and for more information about building the simulator and getting started please see http://www.gem5.org/Documentation and http://www.gem5.org/Tutorials. To build gem5, you will need the following software: g++ or clang, Python (gem5 links in the Python interpreter), SCons, SWIG, zlib, m4, and lastly protobuf if you want trace capture and playback support. Please see http://www.gem5.org/Dependencies for more details concerning the minimum versions of the aforementioned tools. Once you have all dependencies resolved, type 'scons build/<ARCH>/gem5.opt' where ARCH is one of ALPHA, ARM, NULL, MIPS, POWER, SPARC, or X86. This will build an optimized version of the gem5 binary (gem5.opt) for the the specified architecture. See http://www.gem5.org/Build_System for more details and options. With the simulator built, have a look at http://www.gem5.org/Running_gem5 for more information on how to use gem5. The basic source release includes these subdirectories: - configs: example simulation configuration scripts - ext: less-common external packages needed to build gem5 - src: source code of the gem5 simulator - system: source for some optional system software for simulated systems - tests: regression tests - util: useful utility programs and files To run full-system simulations, you will need compiled system firmware (console and PALcode for Alpha), kernel binaries and one or more disk images. Please see the gem5 download page for these items at http://www.gem5.org/Download If you have questions, please send mail to gem5-users@gem5.org Enjoy using gem5 and please share your modifications and extensions.