Ping. This is a more accurate version than RSQ+MUL+CMP. Marek
On Tue, May 31, 2016 at 1:19 AM, Marek Olšák <mar...@gmail.com> wrote: > From: Marek Olšák <marek.ol...@amd.com> > > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=94627 > (against nouveau) > --- > src/mesa/state_tracker/st_glsl_to_tgsi.cpp | 16 +++++++++------- > 1 file changed, 9 insertions(+), 7 deletions(-) > > diff --git a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp > b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp > index aa443a5..0f5ee02 100644 > --- a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp > +++ b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp > @@ -1901,13 +1901,15 @@ glsl_to_tgsi_visitor::visit_expression(ir_expression* > ir, st_src_reg *op) > if (have_sqrt) { > emit_scalar(ir, TGSI_OPCODE_SQRT, result_dst, op[0]); > } else { > - /* sqrt(x) = x * rsq(x). */ > - emit_scalar(ir, TGSI_OPCODE_RSQ, result_dst, op[0]); > - emit_asm(ir, TGSI_OPCODE_MUL, result_dst, result_src, op[0]); > - /* For incoming channels <= 0, set the result to 0. */ > - op[0].negate = ~op[0].negate; > - emit_asm(ir, TGSI_OPCODE_CMP, result_dst, > - op[0], result_src, st_src_reg_for_float(0.0)); > + /* This is the only instruction sequence that makes the game "Risen" > + * render correctly. ABS is not required for the game, but since > GLSL > + * declares negative values as "undefined", allowing us to do > whatever > + * we want, I choose to use ABS to match DX9 and pre-GLSL RSQ > + * behavior. > + */ > + emit_scalar(ir, TGSI_OPCODE_ABS, result_dst, op[0]); > + emit_scalar(ir, TGSI_OPCODE_RSQ, result_dst, result_src); > + emit_scalar(ir, TGSI_OPCODE_RCP, result_dst, result_src); > } > break; > case ir_unop_rsq: > -- > 2.7.4 > _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/mesa-dev
