On Sat, 2012-04-28 at 11:42 -0700, Kenneth Graunke wrote:
> On 04/28/2012 11:20 AM, Vadim Girlin wrote:
> > According to GLSL 1.30 specification, initial value for all uniforms
> > without initializer is 0. Some applications rely on this behaviour,
> > e.g. google's MapGL doesn't set all sampler uniforms.
> >
> > (see https://bugs.freedesktop.org/show_bug.cgi?id=49088 )
> >
> > Signed-off-by: Vadim Girlin<vadimgir...@gmail.com>
> > ---
> >
> > Tested with r600g only - no regressions.
>
> Awesome find! I was at a complete loss here. :)
>
> It turns out this is in the 1.20 spec too; it looks like 1.10 doesn't
> say (but that isn't too surprising). I might add a comment:
>
> /* From the GLSL 1.20 specification, page 24, section 4.3.5 "Uniform":
> * "The link time initial value is either the value of the variable's
> * initializer, or 0 if no initializer present. Sampler types cannot
> * have initializers."
> */
>
> Also, do you really need the memsets in ir_to_mesa and st_glsl_to_tgsi?
> Everything should go through the linker, so that seems somewhat
> redundant. I tested with just the link_uniforms change and that was
> enough to fix MapsGL on i965/Sandybridge.
Without the memset in the st_glsl_to_tgsi firefox crashed with MapGL.
Probably some code in the state tracker relies on the synchronized
values of the SamplerUnits arrays in the gl_program and
gl_shader_program. Also, _mesa_uniform function compares these arrays to
check for update, and some piglit test failed due to the following
problem:
First array is initialized: 0, 0, 0, ...
Second (without memset) : 0, 1, 2, ...
The app calls Uniform1i to set sampler[1] to 1, so we do first[1]=1, but
then it's equal with second[1] and update is not detected.
Vadim
>
> Assuming you drop the other hunks and add a comment, you can add:
> Reviewed-and-tested-by: Kenneth Graunke <kenn...@whitecape.org>
>
> Ian, does this look right to you?
>
> > src/glsl/link_uniforms.cpp | 4 +---
> > src/mesa/program/ir_to_mesa.cpp | 1 +
> > src/mesa/state_tracker/st_glsl_to_tgsi.cpp | 1 +
> > 3 files changed, 3 insertions(+), 3 deletions(-)
> >
> > diff --git a/src/glsl/link_uniforms.cpp b/src/glsl/link_uniforms.cpp
> > index 2f1c9f5..cb80caf 100644
> > --- a/src/glsl/link_uniforms.cpp
> > +++ b/src/glsl/link_uniforms.cpp
> > @@ -329,9 +329,7 @@ link_assign_uniform_locations(struct gl_shader_program
> > *prog)
> > prog->UniformHash = new string_to_uint_map;
> > }
> >
> > - for (unsigned i = 0; i< Elements(prog->SamplerUnits); i++) {
> > - prog->SamplerUnits[i] = i;
> > - }
> > + memset(prog->SamplerUnits, 0, sizeof(prog->SamplerUnits));
> >
> > /* First pass: Count the uniform resources used by the user-defined
> > * uniforms. While this happens, each active uniform will have an
> > index
> > diff --git a/src/mesa/program/ir_to_mesa.cpp
> > b/src/mesa/program/ir_to_mesa.cpp
> > index 840648e..685c1b9 100644
> > --- a/src/mesa/program/ir_to_mesa.cpp
> > +++ b/src/mesa/program/ir_to_mesa.cpp
> > @@ -2865,6 +2865,7 @@ get_mesa_program(struct gl_context *ctx,
> > prog = ctx->Driver.NewProgram(ctx, target, shader_program->Name);
> > if (!prog)
> > return NULL;
> > + memset(prog->SamplerUnits, 0, sizeof(prog->SamplerUnits));
> > prog->Parameters = _mesa_new_parameter_list();
> > v.ctx = ctx;
> > v.prog = prog;
> > diff --git a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
> > b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
> > index 9e68deb..7c4275a 100644
> > --- a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
> > +++ b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
> > @@ -4779,6 +4779,7 @@ get_mesa_program(struct gl_context *ctx,
> > prog = ctx->Driver.NewProgram(ctx, target, shader_program->Name);
> > if (!prog)
> > return NULL;
> > + memset(prog->SamplerUnits, 0, sizeof(prog->SamplerUnits));
> > prog->Parameters = _mesa_new_parameter_list();
> > v->ctx = ctx;
> > v->prog = prog;
>
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