Gabe Black 978782f23c arm: Implement the AAPCS64 ABI.
This implementation has been tested a tiny bit by intercepting a call
which passed an argument of this type to a function.

struct Test
{
    int32_t a;
    float *b;
};

The gem5 intercept printed out the value of a, the value of b, and the
value of the float it pointed to.

I was able to get things to work by commenting out the panic in
fixFuncEventAddr and making it return its argument unmodified, and by
calling addFuncEvent instead of addKernelFuncEvent which injects the
kernel symbol table. I substitured the Process's debugSymbolTable which
had the right symbols.

Note that this implementation is not completely correct. First of all,
I used a dummy type in place of the Short Vector type which is just
a byte array with the appropriate alignment forced on it. It sounds
like this type would be something the compiler would need an intrinsic
and architecture specific type for to behave correctly, and so in
gem5 we'd have to define our own type for ARM which could feed in here.

Also, strictly speaking, it sounds like HVA and HFA category of types,
the Homogeneous Short-Vector Aggregates and Homogeneous Floating-point
Aggregates, are supposed to apply to any type which is an aggregate of
all the same type (short vector for one, floating point for the other)
with 4 or fewer members.

In this implementation, I capture any *array* of 4 or fewer elements of
the appropriate type as an HVA or HFA, but I believe these structures
would also count and are not included in my implementation.

struct {
    float a;
    float b;
    float c;
};

struct {
    ShortVector a;
    ShortVector b;
};

This only matters if those sorts of structures are passed by value as
top level arguments to a function, ie they are not included in some
larger structure.

Also, rule B.6 talks about what to do with an "aignment adjusted type",
and I have no idea what that's supposed to be. Those may not be handled
correctly either.

Change-Id: I5a599a03d38075d7c0a06988c05e7fb5423c68c0
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/23751
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Bobby R. Bruce <bbruce@ucdavis.edu>
Maintainer: Gabe Black <gabeblack@google.com>
2020-03-12 07:21:13 +00:00
2020-03-12 07:21:13 +00:00
2017-03-01 11:58:37 +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, 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.
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