> In fact, you might even consider not allocating a register greedily. What might that look like? I have no idea.
One case I'm aware of: if your ISA supports arbitrary memory operands like x86, rarely-used variables can be operated-on entirely on the stack. Historically this was something ICC did better than GCC, though it became much less relevant with the shift to 64-bit bringing more registers.
Most x86 instructions only support one memory operand so you can’t completely avoid register allocation. It isn’t a full-on hardcore CISC like 68k or VAX.
x86 memory operands are also nice for binary size, my amateur compiler sometimes produces smaller objects than peers despite having no load-store elimination, all by greedily opting for memory operands during instruction selection; kinda amusing 'cause I'm now worrying my future optimization backend might actually cause a regression in size.
One case I'm aware of: if your ISA supports arbitrary memory operands like x86, rarely-used variables can be operated-on entirely on the stack. Historically this was something ICC did better than GCC, though it became much less relevant with the shift to 64-bit bringing more registers.