i have a windows machine(intel processor) and gcc installed.
gcc -save-temps "filename.c"
generated the intermediate files and i viewed the assembly file (.s file)
which is intel x86 instructions.
my question is how to generate the assembly which is ARM instruction set architecture equivalent on the same machine?
gcc is always built for a single target. https://developer.arm.com/open-source/gnu-toolchain is where you get your arm-gcc cross-compiler toolchain. Clang on the other hand can generate code for multiple targets.
Both are available on https://www.godbolt.org to see the assembly directly.
Related
I am using aarch64-none-linux-gnu-gcc for compiling the applications on my Ubuntu 20.04. It has support for cortex-a and few other processor cores. But not on cortex-m4 (or cores which use armv7. Can anyone recommend or provide a link to the compiler installer which supports cortex-m4?
The compiler for 32-bit ARM on Ubuntu is arm-linux-gnueabihf-gcc or arm-none-eabi-gcc, roughly according to whether you want to compile code to run on a Linux OS or on bare metal. Look for the packages gcc-arm-linux-gnueabihf or gcc-arm-none-eabi.
The aarch64 compilers only support 64-bit ARM.
I want to compile my C code into 64-bit dll file. I used this command in cmd:
gcc main.c --shared -o main.dll
and it compiles my code into a 32-bit dll file. How should I compile it into 64-bit one? (or even is it possible to convert the 32-bit dll file into the 64-bit one?)
Note that I'm using windows 10 x64.
If you use MS C compiler, it does not have 64bit compiler.
GCC has both 32bit and 64bit compiler. So you can use 64bit compiler to run your program 64bit.
By the way, you can give a try to Clang compiler. It has also 64bit operations.
To install GCC and Clang your can use MinGW-w64.
I'm trying to compile a single codebase for both ArmV8 aarch64 and aarch32 with GCC. My code requires the -mfloat-abi=hard flag and possibly others when compiled for aarch32, but not for aarch64.
I have multiple toolchains so I created two toolchain files.
What's the most idiomatic CMake way to add this flag only when the aarch32 toolchain file is used?
Of course I could do this inside the project CMakeLists.txt file, at the point where I already created the target and I'm setting other compiler flags.
But then I would have to add this flag conditionally depending on the toolchain, which seems to defeat the point of having two neatly separated toolchain files.
I am trying to convert .c files for ARM (ARMv7l for Raspberry Pi2) but I could not find any online converter or understand how it works. Previously these .c files were executable in Windows platform and thus unable to execute on Pi's arm architecture. Does anybody can assist me in this?
Any c compiler can generate assembly code from C code, if your objective is specifically to generate assembly code for arm then you'll need a cross compiler such as the GNU arm embedded toolchain.
For gcc on particular you just need to use the -S option when compiling, so the line looks something like:
gcc -S -source.c -o output.s
Of course you'll need to include any headers and include directories for it to compile.
if you simply want to cross compile it, then simply do the full compilation assemblage and linking process. Depending on how low level the c code is it's actually possible for it not to work on the pi 2 (but it will compile)
I am trying to build a gcc cross compiler. I understand that before compiling the cross compiler I need to have the target binutils built already. why the building of the compiler need the target binutils ? the compiler alone only takes high level code and turn it to the assembly that I defined it in the compiler sources. so why do I need the target bintools for compiling the cross compiler ? It is written in all of the cross compiler documentation that I need them to be build before compiling the cross compiler. (e.g. http://wiki.osdev.org/Building_GCC and http://www.ifp.illinois.edu/~nakazato/tips/xgcc.html).
GCC needs an assembler to transform the assembly it generates into object files (machine code), and a linker to link object files together to produce executables and shared libraries. It also needs an archiver to produce static libraries/archives.
Those three are usually provided by the binutils package (among other useful tools): the GNU assembler as, linker ld and the ar archiver.
Your key question seems to be:
why the building of the compiler need the target binutils ?
As described in Building a cross compiler, part of the build process for a GNU cross-compiler is to build runtime libraries for the target using the newly-compiled cross-compiler. So the binutils for the target need to be present for that step to succeed.
It may be possible to build the cross-compiler first, using empty files for the subset of binutils components that gcc needs - such as as and ld and ar and ranlib - then build and install the target binutils components into the proper locations, then build the target runtime libraries.
But it would be less error-prone to do things the following way (and the documentation recommends this): build binutils for the target first, place the specified executables in gcc's source tree, then build the cross-compiler.
The binutils (binary utilities) provide low-level handling of
binary files, such as linking, assembling, and parsing ELF files. The GCC
compiler depends on these tools to create an executable, because it generates
object files that binutils assemble into an executable image.
ELF is the format that Linux uses for binary executable
files. The GCC compiler relies on binutils to provide much of the platform-specific functionality.
Here your are cross-compiling for some other architecture not for x86. So resulting binutils are platform-specific
while configuring has to give --host!=target. i.e --host=i686-pc-linux-gnu
where --target=arm-none-linux-gnueabi.
So resulting executable are not same which host already having binutils.
addition
the basic things needs to be known.
The build machine, where the toolchain is built.
The host machine, where the toolchain will be executed.
The target machine, where the binaries created by the
toolchain are executed.
So binutils will be having tools to generate and manipulate binaries
for a given CPU architecture. Not for the one host is using