which registers must be preserved for the caller

[Andrew Makhorin]

Hello,

The document "System V ABI: Intel386 Architecture Processor Supplement"
says that contents of %ebx, %esi, and %edi must be preserved for the
caller. Does GCC for 32-bit GNU/Linux and for 32-bit Cygwin conform to
this ABI? If not, how to determine which registers are expected to be
saved by calling C functions?

Thank you,

Andrew Makhorin