On 03/16/2012 11:08 AM, Richard Guenther wrote:
> Your patch as-is is not safe at the moment.  But why is casting a pointer
> to an integer prohibitly expensive?  That fact should be an implementation
> detail of GIMPLE.  Or is it the issue that IVOPTs chooses an integer
> type that does not necessarily match the mode we'll use on RTL?
> (thus, ptr_mode vs. Pmode issues, and/or sizeof (sizetype) != sizeof (void *)
> issues?)

The machine is "special". Pointer addition is a different operation than
integer addition. It'll also need a new ptr_plus rtx code which takes a
Pmode and an SImode operand. Pmode is larger than SImode but fits in a
single register; intptr_t (which is what we'd need to use if we freely
cast between pointers and integers is DImode - that requires two regs
and can't be used for memory addressing.


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