Wouldn't something like max(min(x, max(y,z)), min(y, z)) work as well, saving one instruction?
Roland Am 11.12.2013 08:52, schrieb Mario Rugiero: > Why not computing the max3(min(x,y),min(x,z),min(y,z))? > > For the six possible cases: > x < y < z --> max(x, x, y) -> y ==> works > x < z < y --> max(x, z, z) -> z ==> works > y < x < z --> max(y, x, y) -> x ==> works > y < z < x --> max(y, z, y) -> z ==> works > z < x < y --> max(x, z, z) -> x ==> works > z < y < x --> max(y, z, z) -> y ==> works > > > 2013/12/11 Kenneth Graunke <kenn...@whitecape.org > <mailto:kenn...@whitecape.org>> > > On 12/10/2013 02:43 PM, =?UTF-8?q?Maxence=20Le=20Dor=C3=A9?= <Maxence Le > Doré> wrote: > > --- > > src/glsl/builtin_functions.cpp | 44 > ++++++++++++++++++++++++++++++++++++++++++ > > 1 file changed, 44 insertions(+) > > > > diff --git a/src/glsl/builtin_functions.cpp > b/src/glsl/builtin_functions.cpp > > index 1f21a37..b9beffd 100644 > > --- a/src/glsl/builtin_functions.cpp > > +++ b/src/glsl/builtin_functions.cpp > > @@ -404,6 +404,7 @@ private: > > > > ir_expression *min3_expr(ir_variable *x, ir_variable *y, > ir_variable *z); > > ir_expression *max3_expr(ir_variable *x, ir_variable *y, > ir_variable *z); > > + ir_expression *mid3_expr(ir_variable *x, ir_variable *y, > ir_variable *z); > > > > /** > > * Call function \param f with parameters specified as the linked > > @@ -589,6 +590,11 @@ private: > > const glsl_type *y_type, > > const glsl_type *z_type); > > > > + ir_function_signature *_mid3(builtin_available_predicate avail, > > + const glsl_type *x_type, > > + const glsl_type *y_type, > > + const glsl_type *z_type); > > + > > #undef B0 > > #undef B1 > > #undef B2 > > @@ -2159,6 +2165,23 @@ builtin_builder::create_builtins() > > _max3(shader_trinary_mimax, > glsl_type::uvec4_type, glsl_type::uvec4_type, glsl_type::uvec4_type), > > NULL); > > > > + add_function("mid3", > > + _mid3(shader_trinary_mimax, > glsl_type::float_type, glsl_type::float_type, glsl_type::float_type), > > + _mid3(shader_trinary_mimax, glsl_type::vec2_type, > glsl_type::vec2_type, glsl_type::vec2_type), > > + _mid3(shader_trinary_mimax, glsl_type::vec3_type, > glsl_type::vec3_type, glsl_type::vec3_type), > > + _mid3(shader_trinary_mimax, glsl_type::vec4_type, > glsl_type::vec4_type, glsl_type::vec4_type), > > + > > + _mid3(shader_trinary_mimax, glsl_type::int_type, > glsl_type::int_type, glsl_type::int_type), > > + _mid3(shader_trinary_mimax, > glsl_type::ivec2_type, glsl_type::ivec2_type, glsl_type::ivec2_type), > > + _mid3(shader_trinary_mimax, > glsl_type::ivec3_type, glsl_type::ivec3_type, glsl_type::ivec3_type), > > + _mid3(shader_trinary_mimax, > glsl_type::ivec4_type, glsl_type::ivec4_type, glsl_type::ivec4_type), > > + > > + _mid3(shader_trinary_mimax, glsl_type::uint_type, > glsl_type::uint_type, glsl_type::uint_type), > > + _mid3(shader_trinary_mimax, > glsl_type::uvec2_type, glsl_type::uvec2_type, glsl_type::uvec2_type), > > + _mid3(shader_trinary_mimax, > glsl_type::uvec3_type, glsl_type::uvec3_type, glsl_type::uvec3_type), > > + _mid3(shader_trinary_mimax, > glsl_type::uvec4_type, glsl_type::uvec4_type, glsl_type::uvec4_type), > > + NULL); > > + > > #undef F > > #undef FI > > #undef FIU > > @@ -2386,6 +2409,12 @@ builtin_builder::max3_expr(ir_variable *x, > ir_variable *y, ir_variable *z) > > return max(x, max(y,z)); > > } > > > > +ir_expression * > > +builtin_builder::mid3_expr(ir_variable *x, ir_variable *y, > ir_variable *z) > > +{ > > + return max(min(x, y), min(y, z)); > > This is broken if y is the median. Consider the following cases: > > x < y < z --> max(x, y) -> y ==> works > x < z < y --> max(x, z) -> z ==> works > y < x < z --> max(y, y) -> y ==> broken (selects least, not median) > y < z < x --> max(y, y) -> y ==> broken (selects least, not median) > z < x < y --> max(x, z) -> x ==> works > z < y < x --> max(y, z) -> y ==> works > > > +} > > + > > ir_call * > > builtin_builder::call(ir_function *f, ir_variable *ret, exec_list > params) > > { > > @@ -4086,6 +4115,21 @@ > builtin_builder::_max3(builtin_available_predicate avail, > > return sig; > > } > > > > +ir_function_signature * > > +builtin_builder::_mid3(builtin_available_predicate avail, > > + const glsl_type *x_type, const glsl_type > *y_type, > > + const glsl_type *z_type) > > +{ > > + ir_variable *x = in_var(x_type, "x"); > > + ir_variable *y = in_var(y_type, "y"); > > + ir_variable *z = in_var(z_type, "z"); > > + MAKE_SIG(x_type, avail, 3, x, y, z); > > + > > + body.emit(ret(mid3_expr(x, y, z))); > > + > > + return sig; > > +} > > + > > /** @} */ > > > > > > /******************************************************************************/ > > > > _______________________________________________ > mesa-dev mailing list > mesa-dev@lists.freedesktop.org <mailto:mesa-dev@lists.freedesktop.org> > http://lists.freedesktop.org/mailman/listinfo/mesa-dev > > <https://urldefense.proofpoint.com/v1/url?u=http://lists.freedesktop.org/mailman/listinfo/mesa-dev&k=oIvRg1%2BdGAgOoM1BIlLLqw%3D%3D%0A&r=F4msKE2WxRzA%2BwN%2B25muztFm5TSPwE8HKJfWfR2NgfY%3D%0A&m=P0UPWHkjwggjyMzQsGbIJge0JmImxQOJ8abTwIlVgak%3D%0A&s=e5fb02199165025279af0affc1dac271265febe087f6ec38fb650691002164d2> > > > > > _______________________________________________ > mesa-dev mailing list > mesa-dev@lists.freedesktop.org > https://urldefense.proofpoint.com/v1/url?u=http://lists.freedesktop.org/mailman/listinfo/mesa-dev&k=oIvRg1%2BdGAgOoM1BIlLLqw%3D%3D%0A&r=F4msKE2WxRzA%2BwN%2B25muztFm5TSPwE8HKJfWfR2NgfY%3D%0A&m=P0UPWHkjwggjyMzQsGbIJge0JmImxQOJ8abTwIlVgak%3D%0A&s=e5fb02199165025279af0affc1dac271265febe087f6ec38fb650691002164d2 > _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
