2fbd03599d
Some compilers won't build ARM due to how guest ABI
has been implemented.
The error is: "left shift count >= width of type"
[-Werror=shift-count-overflow]
The error is triggered when there is a left shift > the variable size
(in bits); this leads to undefined behaviour.
This is a compile time vs run time problem; the code is technically
fine, but the compiler is not able to understand this.
For example in aapcs64:
struct Argument<Aapcs64, Integer, typename std::enable_if<
std::is_integral<Integer>::value>::type> : public Aapcs64ArgumentBase
{
[...]
if (sizeof(Integer) == 16 && state.ngrn + 1 <= state.MAX_GRN) {
Integer low = tc->readIntReg(state.ngrn++);
Integer high = tc->readIntReg(state.ngrn++);
high = high << 64;
return high | low;
}
}
Even if the sizeof operator will be evaluated at compile time,
the block will be executed at runtime: the block will still be part of
the code if Integer = uint32_t.
The compiler will then throw an error because we are left shifting an
uint32_t by 64 bits.
Error arising on:
Compiler: gcc/5.4.0
Distro: Ubuntu 16.04 LTS
Change-Id: Iaafe030b7262c5fb162afe7118ae592a1a759a58
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/26990
Reviewed-by: Gabe Black <gabeblack@google.com>
Tested-by: kokoro <noreply+kokoro@google.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/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, SWIG, 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 the aforementioned tools. Once you have all dependencies resolved, type 'scons build/<ARCH>/gem5.opt' where ARCH is one of 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/documentation/general_docs/building for more details and options. 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. If you have questions, please send mail to gem5-users@gem5.org Enjoy using gem5 and please share your modifications and extensions.