10-06-2017, 07:10 AM
A cross compiler is a compiler capable of creating executable code for a platform other than the one on which the compiler is run. They are used to generate executables for embedded system or multiple platforms, to compile for a platform upon which it is not feasible to do the compiling.It has become more common to use this tool for paravirtualization where a system may have one or more platforms in use.This definition does not encompass source to source translators, which are often called by the name of cross compiler.
Uses
major use:-to separate the build environment from the target environment.
1)Embedded computers: Embedded computers have limited resources and will not be powerful enough to run a compiler, a file system, or a development environment. So cross compilation is used. Eg: the case of a microwave oven where the computer can only read its touchpad and door sensor, provide output to a digital display and speaker, and to control the machinery for cooking food.
2)Compiling for multiple machines: using a cross compiler, a single build environment can be set up to compile for several different versions of an operating system or for several different operating systems.
3)Bootstrapping to a new platform:cross compiler to compile necessary tools such as the operating system and a native compiler when developing software for a new platform, or the emulator of a future platform.
4)Compiling on a server farm:many compile operations can be executed across any machine that is free regardless of its brand or current version of an operating system.
5)Compiling native code for emulators for older now-obsolete platforms
the hardware architecture differs but cross-compilation is also applicable when only the operating system environment differs.
Canadian cross
a technique for building cross compilers for other machines. Given three machines X, Y and Z, one uses machine X to build a cross compiler that runs on machine Y to create executables for machine Z.
When done in GCC, four compilers are involved.
GCC and cross compilation
GCC is a free software collection of compilers.It supports many platforms and languages. Many releases are broken due to limited volunteer time and the huge amount of work it takes to maintain working cross compilers.GCC requires that a compiled copy of binutils be available for each targeted platform.important one is the GNU Assembler.Cross compiling GCC requires that a portion of the target platform's C standard library be available on the host platform.The GNU autotools packages (i.e. autoconf, automake, and libtool) use the notion of a build platform, a host platform, and a target platform.
Microsoft C cross compilers
C programs had long been linked with modules written in Assembly Language. C was usually written in Assembly Language, and most C compilers offer an Assembly Language pass. Compilers like Aztec-C converted everything to assembly language as a distinct pass and then assembled the code. 16 bit binary object code written in Assembly Language (MASM) and Microsoft's other languages including Quick Basic, Pascal, and Fortran could be linked together into one program in a process they called "Mixed Language Programming" and now "InterLanguage Calling". The C code in particular needed to be written to pass its variables in "reverse order" on the stack and return its values on the stack rather than in a processor register.
In retail applications that require Handheld Devices like the Symbol Technologies PDT3100, an 8088 based Bar Code Scanner, the same procedure was used.
DotNET
Common Language Runtime(CLR) formed the core for their DotNET (.NET) compiler in the Visual Studio IDE . This layer on the operating system which is in the API allows the mixing of development languages compiled across platforms that run the Windows operating system.Microsoft .NET applications for target platforms like Windows Mobile on the ARM Processor cross-compile on Windows machines.
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