[llvm-commits] [llvm] r77499 - /llvm/trunk/utils/TableGen/AsmWriterEmitter.cpp

[Chris Lattner]

On Jul 29, 2009, at 1:10 PM, David Greene wrote:

> Author: greened
> Date: Wed Jul 29 15:10:24 2009
> New Revision: 77499
>
> URL: http://llvm.org/viewvc/llvm-project?rev=77499&view=rev
> Log:
>
> Re-enable comment and operand padding.

Okay, lets go through this again now that I have a better idea of what  
you're trying to do.
>
>
> +    /// MAX_GROUP_NESTING_LEVEL - The maximum number of group nesting
> +    /// levels we ever expect to see in an asm operand.
> +    static const int MAX_GROUP_NESTING_LEVEL = 10;
> +
> +    /// GroupLevel - The level of nesting of the current operand
> +    /// group, such as [reg + (reg + offset)].  -1 means we are not  
> in
> +    /// a group.
> +    int GroupLevel;

Again, the groups.  Why are you doing this?  It appears that you are  
trying to infer from the asmstring that you should not be padding  
operands out when they are parenthesized or square-bracketized etc.

I don't see why tblgen should be having to infer this at this level.   
Why not just make tblgen have an extremely trivial heuristic:

   "If there is a \t in the asm string, pad it to a column".

This would eliminate a ton of this code, a bunch of complexity, and  
make it much more easy to reason about this. This also gives target  
authors a very simple and obvious way to control the formatting of  
their machine code.

What do you think?

-Chris