On 08/09/2010 07:20 AM, Claudiu Zissulescu wrote: > I set to zero all CALL_USED_REGISTERS (except the fixed regs), and > then in the expand_call I set CALL_INSN_FUNCTION_USAGE to the list of > clobbered registers (given by attribute attached to a function > declaration). Then, I should be able to achieve the same effect > without touching the IRA.
CALL_INSN_FUNCTION_USAGE says nothing about what registers are clobbered, only that they are *used* by the callee. I.e. they are arguments, either from the user via the declaration of the function or implicit via the ABI. Note that in some ABIs, function arguments may be in call-saved registers. Which implies that the register containing that function argument is unchanged after the call. So I don't see that this is the same effect at all. r~
