[llvm-commits] [llvm] r43918 - in /llvm/trunk/lib/Target/X86: X86RegisterInfo.cpp X86RegisterInfo.td

[Dale Johannesen]

On Nov 8, 2007, at 10:05 PM, Chris Lattner wrote:

>> URL: http://llvm.org/viewvc/llvm-project?rev=43918&view=rev
>> Log:
>> Rewrite Dwarf number handling per review comments.
>
> Hi Dale,
>
> I'm pretty uncomfortable with this, because it means that we're tying
> down the register order.

I tend to agree, but both comments I got on this patch suggested the  
table approach.

Actually the more I look at other people's suggestions the more I  
like my original patch (43844).
Compared to your suggestion below, that has 2 switches instead of 3  
and the switches
are smaller, and it's also proof against reordering of registers.   
What do you think of that one?

> How about something like:
>
>   if (Darwin32) {
>    switch (RegNo) {
>    case X86::AL: case X86::AH: case X86::AX:  return 0;
>    case X86::EDI:  ...
>   } else if (darwin64) {
>    switch (RegNo) {
>    ...
>   } else {
>   }
>
> That way we don't break EH/debug info if registers are reordered or
> added in the future.
>
> -Chris
>
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