[Mesa-dev] [PATCH] R600/SI: Add pattern for truncating i32 to i1

[Michel Dänzer]

On Fre, 2014-01-24 at 07:40 -0800, Tom Stellard wrote:
> On Fri, Jan 24, 2014 at 01:27:00PM +0900, Michel Dänzer wrote:
> > From: Michel Dänzer <michel.daenzer at amd.com>
> > 
> > Fixes half a dozen piglit tests with radeonsi.
> > 
> > Signed-off-by: Michel Dänzer <michel.daenzer at amd.com>
> > ---
> >  lib/Target/R600/SIInstructions.td |  5 +++++
> >  test/CodeGen/R600/trunc.ll        | 10 ++++++++++
> >  2 files changed, 15 insertions(+)
> > 
> > diff --git a/lib/Target/R600/SIInstructions.td b/lib/Target/R600/SIInstructions.td
> > index 03e7e32..b7b710f 100644
> > --- a/lib/Target/R600/SIInstructions.td
> > +++ b/lib/Target/R600/SIInstructions.td
> > @@ -2126,6 +2126,11 @@ def : Pat <
> >    (EXTRACT_SUBREG $a, sub0)
> >  >;
> >  
> > +def : Pat <
> > +  (i1 (trunc i32:$a)),
> > +  (V_CMP_EQ_I32_e64 (V_AND_B32_e32 (i32 1), $a), 1)
> > +>;
> > +
> 
> I'm guessing you added V_CMP_EQ_I32_e64 in order to make the types match.

Not really. The truncation is used for testing whether the LSB of an i32
value is set, and storing the resulting boolean as an i1 value. My
pattern does this for the VGPRs in all thread of a wavefront in
parallel, storing the resulting boolean bits in a 64-bit SGPR.


> Try this pattern instead:
> 
> def : Pat <
>   (i1 (trunc i32:$a)),
>   (COPY_TO_REGCLASS (V_AND_B32_e32 (i32 1), $a), VReg_32)

I don't understand the idea behind your suggestion, can you elaborate?

Anyway, it fails for one of the relevant piglit tests:

amd_vertex_shader_layer-layered-2d-texture-render: /home/daenzer/src/llvm-git/llvm/lib/Target/R600/SIInstrInfo.cpp:133: virtual void llvm::SIInstrInfo::copyPhysReg(llvm::MachineBasicBlock&, llvm::MachineBasicBlock::iterator, llvm::DebugLoc, unsigned int, unsigned int, bool) const: Assertion `AMDGPU::VReg_64RegClass.contains(SrcReg) || AMDGPU::SReg_64RegClass.contains(SrcReg)' failed.


-- 
Earthling Michel Dänzer            |                  http://www.amd.com
Libre software enthusiast          |                Mesa and X developer