[PATCH] R600/SI: Display neg/abs operand the same way as R600

[Owen Anderson]

On Oct 22, 2013, at 7:50 PM, Tom Stellard <tom at stellard.net> wrote:

> On Mon, Oct 21, 2013 at 09:36:05PM -0700, Owen Anderson wrote:
>> 
>> On Oct 21, 2013, at 12:29 PM, Tom Stellard <tom at stellard.net> wrote:
>> 
>>> On Mon, Oct 21, 2013 at 03:03:46PM +0200, Vincent Lejeune wrote:
>>>> ---
>>>> lib/Target/R600/AMDGPUInstructions.td |  9 +++++-
>>>> lib/Target/R600/R600Instructions.td   |  7 -----
>>>> lib/Target/R600/SIISelLowering.cpp    | 45 +++++++++++++++++++++++---
>>>> lib/Target/R600/SIInstrFormats.td     | 24 ++++++++++----
>>>> lib/Target/R600/SIInstrInfo.td        | 59 ++++++++++++++++++++++++-----------
>>>> lib/Target/R600/SIInstructions.td     | 24 ++++++--------
>>>> test/CodeGen/R600/fabs.ll             |  2 +-
>>>> test/CodeGen/R600/fneg.ll             | 23 ++++++++------
>>>> test/CodeGen/R600/fsub64.ll           |  2 +-
>>>> test/CodeGen/R600/seto.ll             |  2 +-
>>>> test/CodeGen/R600/setuo.ll            |  2 +-
>>>> 11 files changed, 136 insertions(+), 63 deletions(-)
>>>> 
>>> 
>>> I'm not a huge fan of adding all these extra operands, but I'm not sure
>>> there is a better way to get the assembly output we want.
>> 
>> You could consider batching them up.  For instance, all the modifiers to operand 1 could be bits in a single immediate operand.  This ends up looking like the ComplexPattern's that most targets use for addressing modes.
>> 
> 
> This would work except that the abs modifier needs to be printed before
> and after the operand, but the negate modifier only needs to be printed
> before.  For example, we want to print the abs modifier like this:
> 
> |VGPR0|
> 
> and this requires defining an assembly string in tablegen like this:
> 
> $src0_abs$src0$src0_abs
> 
> If we merged them all together and did something like:
> 
> $src0_mod$src0$src0_mod, we would end up with negated operands that look
> like this:
> 
> -VGPR0-
> 
> I know next to nothing about the assembly printer, so maybe there is a
> more elegant way to implement this, but I'm not sure what it is.

The way this is handled for addressing modes on CPU targets is that the assembly printing hook is defined on the ComplexOperand, which is basically a tuple of multiple normal operands taken together.  The assembly printer is given the offset on the MCInstr to the first element of the tuple, and is can parse whatever it needs to make that work.

--Owen
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