compiler/doc/Porting.md

Porting to a new platform

Porting to a new 32 or 64 bits platform is usually automatically handled by make full:

• The makefile compiles src/tools/make/configure.c with the platform's default C compiler.
• configure.c determines which types to use for 32 and 64 bit variables, and their alignment.
• configure.c uses a number of strategies to determine the operating system it is running on and what the appropriate installation directory will be.
• configure.c sets makefile variables that are used to select which of 5 sets of preprepared C source files to build to create the bootstrap compiler.

On most systems this will be sufficient for make full to build and install the compiler and libraries.

make full will terminate with a message such as:

--- Branch v2docs freebsd gcc LP64 confidence tests passed ---

Updating configure.c

It should only be necessary to change configure.c if it cannot determine the correct install directory.

In this case add code to src/tools/make/configure.c's function determineOS() to set the os variable to the name of the new OS platform.

The following variables are also set by determineOS() to the followind defaults:

variable	set to	example
platform	Base platform	"unix"
binext	Binary file extension	""
staticlink	Static linking option	"-static"

If your new platform does not support static removing, set the staticlink variable to "".

Then modify determineInstallDirectory() to select the correct instalation root based on the changes you have made to determineOS().

The platform variable selects which variety of the Platform module is compiled. Vishap provides two varieties, one specific to the Windows API (Platformwindows.Mod), and one suitable for Unix-like systems including Linux, BSD, Android and cygwin (Platformunix.Mod).

How to add a new compiler option

• Define it in OPM as a constant before defopt is defined.
• Define a BOOLEAN variable in OPM which will describe if setting is set.
• Add handling of a new option in OPM.ScanOptions
• Set your BOOLEAN value in OPM.OpenPari (or in ScanOptions, after the CASE) so you can check it later.
• Check your boolean when necessary, (see useParFile in OPM.GetOptions)
• Add it in OPC.GenHeaderMsg function.

Known bugs

When using SYSTEM.LSH(s, n) where s is SET, the C compiler generates an error like error: duplicate 'unsigned', that's because SET is defined as unsigned in SYSTEM.h, while LSH is defined in SYSTEM.h as ((t)((unsigned t)(x)<<(n))), and it makes not possible to make SYSTEM.LSH with type SET.

I don't want to prohibit it at the parser level because C backend is only one of possible backends.

The solution currently is to cast set type to longint before lsh-ing it. And then casting it back to set if necessary.