[Mesa-dev] TGSI declarations missing type info

Dave Airlie airlied at gmail.com
Mon Nov 14 10:40:34 PST 2011

> Having type info in TGSI registers is useless for llvm/llvmpipe, spite what initial appearances may be.

> Imagine indirect addressing on this hypothetical world with typed TGSI declarations:
>  DCL_float TEMP[0]
>  DCL_int   TEMP[1]
>  DCL_float TEMP[2]
>  DCL_int   TEMP[3]
>  DCL_float TEMP[4]
>  DCL_int   TEMP[5]
>  MOV OUT[0], TEMP[ADDR[0]]
> What LLVM type would one declare the TEMP array with? 4 x floats? 4 x int32s? 128bit integers? an union of all these?
> Answer is: it doesn't matter, provided the type has 128bits.

Yeah from my POV It was mainly just how lossy the IR, we drop all this
information at the GLSL->TGSI boundary, and then reconstruct it from
the opcodes on the other side, but I agree now that I've played some
more with llvm that we probably don't require it at this point to the
extent I mentioned, I've been playing with the bitcasts a bit now.

The next open question I have is whether this warrants additions to
the tgsi_opcode_info struct, mainly whether the return value is
and whether then src regs are uint/int/float, I'm not 100% that all
opcodes always take all int/uint/float srcs, but my memory is a bit
hazy on what the outliers might be.


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