b4b487e1ad
c_j(al) has a special format, called CJ. The jump offset format is instbits[12:2] --> offset[11|4|9:8|10|6|7|3:1|5] Currently in decoder.isa, c_j format is JOp, the imm and branchTarget are incorrect In the execute section (decoder.isa:228), the imm fields is ignored and the offset is calculated correctlly. As a result, we get decoder flush for each c_j instance I've added CJOp format in compressed.isa, and use it in execute section. In addition, c_j is mappped to jal zero, cj_imm, and actually is neither indirect control nor a function call I fixed the flags accordently. I'll fix all IsRet, IsCall and IsIndirectControl flags for rest of (c_)jal(r) in my next commit. I ran coremark -O0 before my fix and I got 37.7% branch miss-rate, after the fix the branch miss-rate is <13% Change-Id: I608d5894a78a1ebefe36f21e21aaea68b42bccfc Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/17808 Maintainer: Jason Lowe-Power <jason@lowepower.com> Tested-by: kokoro <noreply+kokoro@google.com> Reviewed-by: Jason Lowe-Power <jason@lowepower.com> Reviewed-by: Alec Roelke <alec.roelke@gmail.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.