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Re: [RFA patch i386]: Prepare x64 prologue using positive offsets for frame-pointer

On 07/18/2010 03:42 AM, Kai Tietz wrote:
> +mframe-x64
> +Target Report Var(flag_framex64) Init(0)
> +Set the frame-pointer to the stack location at the end of prologue for 64-bit.

Modulo testing purposes, a command-line switch makes no sense.  We'll want to
key this off SEH enabled, or at least TARGET_64BIT_MS_ABI.

The state of ix86_expand_prologue/epilogue is... what's a kind word... chaotic?
This isn't your fault, but your patch doesn't help either.  It's extremely
difficult to tell if your patch is correct.  I'm pretty sure it isn't correct
for any case of stack re-alignment, for instance.

I spent an hour or three attempting to tidy up these functions and handle the
frame pointer at the bottom of the frame.  I have some ideas now for how to
clean things up, but I think they'll really need to be staged in in phases.
One big patch would simply be too unwieldy.

I'll work on this cleanup over the next couple of days.


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