bcahoon marked 4 inline comments as done.
bcahoon added inline comments.

================
Comment at: llvm/test/CodeGen/AMDGPU/GlobalISel/llvm.amdgcn.intersect_ray.ll:4
+; RUN: llc -global-isel -march=amdgcn -mcpu=gfx1013 -verify-machineinstrs < %s 
| FileCheck -check-prefix=GCN %s
+; RUN: llc -global-isel -march=amdgcn -mcpu=gfx1012 -verify-machineinstrs < %s 
| FileCheck -check-prefix=GCN %s
 
----------------
rampitec wrote:
> bcahoon wrote:
> > rampitec wrote:
> > > rampitec wrote:
> > > > foad wrote:
> > > > > This test surely should not pass for gfx1012, since it does not have 
> > > > > these instructions. And with your patch as written it should fail for 
> > > > > gfx1013 too, since they are predicated on HasGFX10_BEncoding.
> > > > > 
> > > > > @rampitec any idea what is wrong here? Apparently the backend will 
> > > > > happily generate image_bvh_intersect_ray instructions even for gfx900!
> > > > Indeed. MIMG_IntersectRay has this:
> > > > 
> > > > ```
> > > >   let SubtargetPredicate = HasGFX10_BEncoding,
> > > >       AssemblerPredicate = HasGFX10_BEncoding,
> > > > ```
> > > > but apparently SubtargetPredicate did not work. It needs to be fixed.
> > > > 
> > > > gfx1012 does not have it, gfx1013 does though. That is what GFX10_A 
> > > > encoding is about, 10_B it has to be replaced with 10_A in BVH and MSAA 
> > > > load.
> > > Image lowering and selection is not really done like everything else. For 
> > > BVH it just lowers intrinsic to opcode. I think the easiest fix is to add 
> > > to SIISelLowering.cpp where we lower 
> > > Intrinsic::amdgcn_image_bvh_intersect_ray something like this:
> > > 
> > > 
> > > ```
> > >   if (!Subtarget->hasGFX10_AEncoding())
> > >     report_fatal_error(
> > >         "requested image instruction is not supported on this GPU");
> > > ```
> > I ended up using emitRemovedIntrinsicError, which uses 
> > DiagnosticInfoUnsupported. This way the failure isn't a crash dump.
> > I ended up using emitRemovedIntrinsicError, which uses 
> > DiagnosticInfoUnsupported. This way the failure isn't a crash dump.
> 
> Diagnostics is a good thing, but we still have to fail the compilation.
The diagnostic is marked as an error, so the compilation fails in that llc 
returns a non-zero return code. This mechanism is used in other places in the 
back-end to report similar types of errors. The alternative, if I understand 
correctly, is that a crash occurs with an error message that indicates that the 
bug is in LLVM (rather the the input source file).


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D103663/new/

https://reviews.llvm.org/D103663

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