Here&there I find the likes of mulqi3.S & divmodhi4.S.
Is there a reference anywhere on gnu.org on how to browse current official revisions of such architecture specific source code? What is the relation to LLVM?
If not, can you point me to a current resource? Download, if browsing is not supported.
What do "they" use for regression testing architecture specific routines;
is there something I could easily use myself?
You can browse using gitweb at https://gcc.gnu.org/git/gitweb.cgi?p=gcc.git
From there, goto tree views and navigate to the parts of the AVR backend:
gcc/config/avr/: The GCC AVR backendlibgcc/config/avr/: The AVR specific part of the libgcc runtimegcc/testsuite/gcc.target/avr/: AVR-specific parts of the test suitegcc/common/config/avr/: Part of the backend that's common to the compiler proper (cc1, cc1plus) and the compiler driver (avr-gcc, avr-g++).Most convenient is to browse on file, so you would
$ git clone git://gcc.gnu.org/git/gcc.git SomeLocalDir
When you are interested in a specific branch or tag, like branches/releases/gcc-14 or tags/releases/gcc-14.1.0, you can navigate to that ref and browse from there.
What is the relation to LLVM?
I don't understand that question. LLVM is a different compiler (infrastructure) with it's own runtime. It has nothing to do with GCC (claims at least).
What do "they" use for regression testing architecture specific routines;
See Installing GCC: Testing → How to test GCC on a simulator → avr → AVRtest → README: Running the avr-gcc Testsuite using the AVRtest Simulator
is there something I could easily use myself?
Yes it's easy enough to compile AVRtest, for example. Notice that AVRtest is just an AVR core simulator; no peripherals are simulated. When you prefer avr-gdb, see SimulAVR and AVaRICE.
gcc/configure.ac and gcc/config.gcc.
What is the relation to LLVM?There is no relation to LLVM. What do you mean?can you point me to a current resource?gcc.gnu.org/releases.html shows how to use git and FTP mirrors. However, most commonly I use mirror on github github.com/gcc-mirror/gcc .What do "they" use for regression testing architecture specific routineswhat? see github.com/gcc-mirror/gcc/tree/master/gcc/testsuite readme and gnu.org/software/dejagnu .I could easily use myself?no. Use cmake and ctest. | Please keep one question per question. You ask how to get official source code of GCC, how to test GCC code, if you can use testing fromework from GCC yourself, how to browse the source code, and about some files, mulqi?