Gabe Black f12c330f40 arch-x86: Use different tables for 64 bit prefixes in the decoder.
There are instructions in 64 bit mode which have been turned into the
REX and VEX prefixes, and which should no longer behave as instructions.
When not in 64 bit mode however, those instructions still need to behave
properly.

We were handling that for the REX prefixes by explicitly checking if the
prefix we found was one of those, and then whether we were in 64 bit
mode or not. We were not handling the VEX prefixes at all, so those were
always acting as prefixes, even when not in 64 bit mode.

This change replaces the REX check and possible VEX check by having two
prefix tables, one for 64 bit mode, and one for otherwise. The REX and
VEX prefixes are simply left out of the non 64b it mode table, making an
explicit check for them unnecessary.

Change-Id: Ia2fc17074015e074d1f156177bd499d67da5411d
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/55587
Maintainer: Gabe Black <gabe.black@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Gabe Black <gabe.black@gmail.com>
2022-02-26 02:00:06 +00:00
2020-10-22 01:01:46 +00:00
2020-07-14 18:41:37 +00:00
2017-03-01 11:58:37 +00:00
2021-09-23 23:14:55 +00:00

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/about, and for
more information about building the simulator and getting started
please see http://www.gem5.org/documentation and
http://www.gem5.org/documentation/learning_gem5/introduction.

To build gem5, you will need the following software: g++ or clang,
Python (gem5 links in the Python interpreter), SCons, zlib, m4, and lastly
protobuf if you want trace capture and playback support. Please see
http://www.gem5.org/documentation/general_docs/building for more details
concerning the minimum versions of these tools.

Once you have all dependencies resolved, type 'scons
build/<CONFIG>/gem5.opt' where CONFIG is one of the options in build_opts like
ARM, NULL, MIPS, POWER, SPARC, X86, Garnet_standalone, etc. This will build an
optimized version of the gem5 binary (gem5.opt) with the the specified
configuration. See http://www.gem5.org/documentation/general_docs/building for
more details and options.

The main source tree includes these subdirectories:
   - build_opts: pre-made default configurations for gem5
   - build_tools: tools used internally by gem5's build process.
   - configs: example simulation configuration scripts
   - ext: less-common external packages needed to build gem5
   - include: include files for use in other programs
   - site_scons: modular components of the build system
   - 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 may need compiled system firmware, kernel
binaries and one or more disk images, depending on gem5's configuration and
what type of workload you're trying to run. Many of those resources can be
downloaded from http://resources.gem5.org, and/or from the git repository here:
https://gem5.googlesource.com/public/gem5-resources/

If you have questions, please send mail to gem5-users@gem5.org

Enjoy using gem5 and please share your modifications and extensions.
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