C main 32/64 bit prologues differ

[Andrew Haley]

Bob Plantz wrote:
> The prologues for the main function in C differ (at the assembly
> language level) depending on whether it is compiled for 32-bit or 64-bit
> in the x86 architecture.
> 
> Also, adding a dwarf2 unwind table is the default in 64-bit mode, but
> not in 32-bit.
> 
> Can anyone point me to discussions about why it's done this way?

The DWARF question I can answer: it's required by the processor-
specific ABI.

Andrew.