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Re: WIP: Register doco



Sorry, I'm again lost.  I earlier wrote (note edits):

``No, ABI.  For instance mipsIII and o32.  The o32 ABI thinks
registers have 32 bits yet the real register has 64 bits.  This gives
two [cooked] views of the same [raw] register.  When o32 debug info
indicates a value in two adjacent [cooked] registers, it is refering
to 32 bit and not 64 bit registers.''

I'm not discussing which of these should be printed since that is
outside of the scope of this discussion.

(Sorry, the `what would this print' is a distraction.)

Suppose I have a program compiled to the o32 ABI which has a 64-bit
variable that the debug info says is in $a0.  I'm running it on a MIPS
III machine.  This means that half of my variable is in the low 32
bits of $a0, and the the other half is in the low 32 bits of $a1.

So, when you say that cooked registers are "ABI registers", are you
saying that, in the cooked register set, $a0 and $a1 would be 32-bit
registers, even though we're executing a 64-bit instruction set?
Having the register sizes disagree with the actual instructions being
executed is what seems like a bad idea to me.
As I pointed out in the above, there are two cooked $a0's. One is 32 bits and one is 64 bits. With regard to which should be user visible, I wrote:

``(Should user visible registers be displayed according to the underlying ISA or ABI is an item for debate. It has never been specified and I suspect in part because GDB, prior to gdbarch_register_read/write, couldn't handle both.)''

It was in paren because I want to first fix the regcache (and its doco). That debate can be left to when someone has the cycles spare for fixing it.

enjoy,
Andrew



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