[Mesa-dev] [PATCH 08/10] radeonsi: re-enable unsafe-fp-math for LLVM 3.8

[Nick Sarnie]

Hi Marek,

I don't get the hang on Dota 2 Reborn with this patch and LLVM/Mesa git.

Tested-by: Nick Sarnie <commendsarnex at gmail.com>

Thanks!

On Sat, Oct 10, 2015 at 10:12 PM, Connor Abbott <cwabbott0 at gmail.com> wrote:

> FWIW, this isn't quite correct with ARB_shader_precision or GL4.1 --
> it specifies that infinities should be correctly generated through
> division by 0, which unsafe-fp-math doesn't guarantee. At least,
> that's assuming this is similar to the "fast" per-instruction flag
> (http://llvm.org/docs/LangRef.html#fast-math-flags) which says "This
> flag implies all the others."
>
> On Sat, Oct 10, 2015 at 9:29 PM, Marek Olšák <maraeo at gmail.com> wrote:
> > From: Marek Olšák <marek.olsak at amd.com>
> >
> > Required for 1/sqrt ==> rsq.
> >
> > We should finally fix the hang instead of running away from the issue.
> This
> > assumes the bug is in LLVM and we have time to fix it before the release.
> > Include compute shaders as well, which only affects TGSI and thus OpenGL.
> >
> > Totals:
> > SGPRS: 344368 -> 345104 (0.21 %)
> > VGPRS: 197552 -> 197420 (-0.07 %)
> > Code Size: 7366304 -> 7324692 (-0.56 %) bytes
> > LDS: 91 -> 91 (0.00 %) blocks
> > Scratch: 1615872 -> 1524736 (-5.64 %) bytes per wave
> >
> > Totals from affected shaders:
> > SGPRS: 146696 -> 147432 (0.50 %)
> > VGPRS: 87212 -> 87080 (-0.15 %)
> > Code Size: 3852664 -> 3811052 (-1.08 %) bytes
> > LDS: 48 -> 48 (0.00 %) blocks
> > Scratch: 1179648 -> 1088512 (-7.73 %) bytes per wave
> > ---
> >  src/gallium/drivers/radeon/radeon_llvm_emit.c | 7 +++++++
> >  1 file changed, 7 insertions(+)
> >
> > diff --git a/src/gallium/drivers/radeon/radeon_llvm_emit.c
> b/src/gallium/drivers/radeon/radeon_llvm_emit.c
> > index 6b2ebde..4bda4a4 100644
> > --- a/src/gallium/drivers/radeon/radeon_llvm_emit.c
> > +++ b/src/gallium/drivers/radeon/radeon_llvm_emit.c
> > @@ -84,6 +84,13 @@ void radeon_llvm_shader_type(LLVMValueRef F, unsigned
> type)
> >         sprintf(Str, "%1d", llvm_type);
> >
> >         LLVMAddTargetDependentFunctionAttr(F, "ShaderType", Str);
> > +
> > +#if HAVE_LLVM >= 0x0308
> > +       /* This only affects TGSI (OpenGL), so it's okay to set it for
> > +        * compute shaders too.
> > +        */
> > +       LLVMAddTargetDependentFunctionAttr(F, "unsafe-fp-math", "true");
> > +#endif
> >  }
> >
> >  static void init_r600_target()
> > --
> > 2.1.4
> >
> > _______________________________________________
> > mesa-dev mailing list
> > mesa-dev at lists.freedesktop.org
> > http://lists.freedesktop.org/mailman/listinfo/mesa-dev
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