There are some bits of this patch I'm trying to understand. I think they can be cleared up by one question below...
On 09/14/2013 01:00 PM, Paul Berry wrote: > From: Bryan Cain <bryanca...@gmail.com> > > This corresponds to the lowering of gl_ClipDistance to > gl_ClipDistanceMESA for vertex and geometry shader outputs. Since > this lowering pass occurs after lower_named_interface blocks, it deals > with 2D arrays (gl_ClipDistance[vertex][clip_plane]) rather than 1D > arrays in an interface block > (gl_in[vertex].gl_ClipDistance[clip_plane]). > > v2 (Paul Berry <stereotype...@gmail.com>): Fix indexing order for > gl_ClipDistance input lowering. Properly lower bulk assignment of > gl_ClipDistance inputs. Rework for GLSL 1.50 style geometry shaders. > --- > src/glsl/lower_clip_distance.cpp | 223 > +++++++++++++++++++++++++++++---------- > 1 file changed, 165 insertions(+), 58 deletions(-) > > diff --git a/src/glsl/lower_clip_distance.cpp > b/src/glsl/lower_clip_distance.cpp > index d6cf944..16eaef6 100644 > --- a/src/glsl/lower_clip_distance.cpp > +++ b/src/glsl/lower_clip_distance.cpp > @@ -53,13 +53,16 @@ > class lower_clip_distance_visitor : public ir_rvalue_visitor { > public: > lower_clip_distance_visitor() > - : progress(false), old_clip_distance_var(NULL), > - new_clip_distance_var(NULL) > + : progress(false), old_clip_distance_1d_var(NULL), > + old_clip_distance_2d_var(NULL), new_clip_distance_1d_var(NULL), > + new_clip_distance_2d_var(NULL) > { > } > > virtual ir_visitor_status visit(ir_variable *); > void create_indices(ir_rvalue*, ir_rvalue *&, ir_rvalue *&); > + bool is_clip_distance_vec8(ir_rvalue *ir); > + ir_rvalue *lower_clip_distance_vec8(ir_rvalue *ir); > virtual ir_visitor_status visit_leave(ir_assignment *); > void visit_new_assignment(ir_assignment *ir); > virtual ir_visitor_status visit_leave(ir_call *); > @@ -73,12 +76,14 @@ public: > /** > * Pointer to the declaration of gl_ClipDistance, if found. > */ > - ir_variable *old_clip_distance_var; > + ir_variable *old_clip_distance_1d_var; > + ir_variable *old_clip_distance_2d_var; > > /** > * Pointer to the newly-created gl_ClipDistanceMESA variable. > */ > - ir_variable *new_clip_distance_var; > + ir_variable *new_clip_distance_1d_var; > + ir_variable *new_clip_distance_2d_var; > }; > > > @@ -89,30 +94,60 @@ public: > ir_visitor_status > lower_clip_distance_visitor::visit(ir_variable *ir) > { > - /* No point in looking for the declaration of gl_ClipDistance if > - * we've already found it. > - */ > - if (this->old_clip_distance_var) > + if (!ir->name || strcmp(ir->name, "gl_ClipDistance") != 0) > return visit_continue; > + assert (ir->type->is_array()); > + > + if (!ir->type->element_type()->is_array()) { > + /* 1D gl_ClipDistance (used for vertex and geometry output, and > fragment > + * input). > + */ > + if (this->old_clip_distance_1d_var) > + return visit_continue; > > - if (ir->name && strcmp(ir->name, "gl_ClipDistance") == 0) { > this->progress = true; > - this->old_clip_distance_var = ir; > - assert (ir->type->is_array()); > + this->old_clip_distance_1d_var = ir; > assert (ir->type->element_type() == glsl_type::float_type); > unsigned new_size = (ir->type->array_size() + 3) / 4; > > /* Clone the old var so that we inherit all of its properties */ > - this->new_clip_distance_var = ir->clone(ralloc_parent(ir), NULL); > + this->new_clip_distance_1d_var = ir->clone(ralloc_parent(ir), NULL); > > /* And change the properties that we need to change */ > - this->new_clip_distance_var->name > - = ralloc_strdup(this->new_clip_distance_var, "gl_ClipDistanceMESA"); > - this->new_clip_distance_var->type > + this->new_clip_distance_1d_var->name > + = ralloc_strdup(this->new_clip_distance_1d_var, > + "gl_ClipDistanceMESA"); > + this->new_clip_distance_1d_var->type > = glsl_type::get_array_instance(glsl_type::vec4_type, new_size); > - this->new_clip_distance_var->max_array_access = ir->max_array_access / > 4; > + this->new_clip_distance_1d_var->max_array_access > + = ir->max_array_access / 4; > + > + ir->replace_with(this->new_clip_distance_1d_var); > + } else { > + /* 2D gl_ClipDistance (used for geometry input). */ > + assert(ir->mode == ir_var_shader_in); > + if (this->old_clip_distance_2d_var) > + return visit_continue; > > - ir->replace_with(this->new_clip_distance_var); > + this->progress = true; > + this->old_clip_distance_2d_var = ir; > + assert (ir->type->element_type()->element_type() == > glsl_type::float_type); > + unsigned new_size = (ir->type->element_type()->array_size() + 3) / 4; > + > + /* Clone the old var so that we inherit all of its properties */ > + this->new_clip_distance_2d_var = ir->clone(ralloc_parent(ir), NULL); > + > + /* And change the properties that we need to change */ > + this->new_clip_distance_2d_var->name > + = ralloc_strdup(this->new_clip_distance_2d_var, > "gl_ClipDistanceMESA"); > + this->new_clip_distance_2d_var->type = glsl_type::get_array_instance( > + glsl_type::get_array_instance(glsl_type::vec4_type, > + new_size), > + ir->type->array_size()); > + this->new_clip_distance_2d_var->max_array_access > + = ir->max_array_access / 4; > + > + ir->replace_with(this->new_clip_distance_2d_var); > } > return visit_continue; > } > @@ -177,39 +212,99 @@ lower_clip_distance_visitor::create_indices(ir_rvalue > *old_index, > } > > > +/** > + * Determine whether the given rvalue describes an array of 8 floats that > + * needs to be lowered to an array of 2 vec4's; that is, determine whether it > + * matches one of the following patterns: > + * > + * - gl_ClipDistance (if gl_ClipDistance is 1D) > + * - gl_ClipDistance[i] (if gl_ClipDistance is 2D) > + */ > +bool > +lower_clip_distance_visitor::is_clip_distance_vec8(ir_rvalue *ir) > +{ Is it ever possible for both of these to be taken? > + if (this->old_clip_distance_1d_var) { > + ir_dereference_variable *var_ref = ir->as_dereference_variable(); > + if (var_ref && var_ref->var == this->old_clip_distance_1d_var) > + return true; > + } > + if (this->old_clip_distance_2d_var) { > + ir_dereference_array *array_ref = ir->as_dereference_array(); > + if (array_ref) { > + ir_dereference_variable *var_ref = > + array_ref->array->as_dereference_variable(); > + if (var_ref && var_ref->var == this->old_clip_distance_2d_var) > + return true; > + } > + } > + return false; > +} > + > + > +/** > + * If the given ir satisfies is_clip_distance_vec8(), return new ir > + * representing its lowered equivalent. That is, map: > + * > + * - gl_ClipDistance => gl_ClipDistanceMESA (if gl_ClipDistance is 1D) > + * - gl_ClipDistance[i] => gl_ClipDistanceMESA[i] (if gl_ClipDistance is 2D) > + * > + * Otherwise return NULL. > + */ > +ir_rvalue * > +lower_clip_distance_visitor::lower_clip_distance_vec8(ir_rvalue *ir) > +{ > + if (this->old_clip_distance_1d_var) { > + ir_dereference_variable *var_ref = ir->as_dereference_variable(); > + if (var_ref && var_ref->var == this->old_clip_distance_1d_var) { > + return new(ralloc_parent(ir)) > + ir_dereference_variable(this->new_clip_distance_1d_var); > + } > + } > + if (this->old_clip_distance_2d_var) { > + ir_dereference_array *array_ref = ir->as_dereference_array(); > + if (array_ref) { > + ir_dereference_variable *var_ref = > + array_ref->array->as_dereference_variable(); > + if (var_ref && var_ref->var == this->old_clip_distance_2d_var) { > + return new(ralloc_parent(ir)) > + ir_dereference_array(this->new_clip_distance_2d_var, > + array_ref->array_index); > + } > + } > + } > + return NULL; > +} > + > + > void > lower_clip_distance_visitor::handle_rvalue(ir_rvalue **rv) > { > - /* If the gl_ClipDistance var hasn't been declared yet, then > - * there's no way this deref can refer to it. > - */ > - if (!this->old_clip_distance_var || *rv == NULL) > + if (*rv == NULL) > return; > > ir_dereference_array *const array_deref = (*rv)->as_dereference_array(); > if (array_deref == NULL) > return; > > - /* Replace any expression that indexes into the gl_ClipDistance array > + /* Replace any expression that indexes one of the floats in > gl_ClipDistance > * with an expression that indexes into one of the vec4's in > * gl_ClipDistanceMESA and accesses the appropriate component. > */ > - ir_dereference_variable *old_var_ref = > - array_deref->array->as_dereference_variable(); > - if (old_var_ref && old_var_ref->var == this->old_clip_distance_var) { > + ir_rvalue *lowered_vec8 = > + this->lower_clip_distance_vec8(array_deref->array); > + if (lowered_vec8 != NULL) { > this->progress = true; > ir_rvalue *array_index; > ir_rvalue *swizzle_index; > this->create_indices(array_deref->array_index, array_index, > swizzle_index); > void *mem_ctx = ralloc_parent(array_deref); > > - ir_dereference_array *const ClipDistanceMESA_deref = > - new(mem_ctx) ir_dereference_array(this->new_clip_distance_var, > - array_index); > + ir_dereference_array *const new_array_deref = > + new(mem_ctx) ir_dereference_array(lowered_vec8, array_index); > > ir_expression *const expr = > new(mem_ctx) ir_expression(ir_binop_vector_extract, > - ClipDistanceMESA_deref, > + new_array_deref, > swizzle_index); > > *rv = expr; > @@ -243,30 +338,34 @@ lower_clip_distance_visitor::fix_lhs(ir_assignment *ir) > } > > /** > - * Replace any assignment having gl_ClipDistance (undereferenced) as its LHS > - * or RHS with a sequence of assignments, one for each component of the > array. > - * Each of these assignments is lowered to refer to gl_ClipDistanceMESA as > - * appropriate. > + * Replace any assignment having the 1D gl_ClipDistance (undereferenced) as > + * its LHS or RHS with a sequence of assignments, one for each component of > + * the array. Each of these assignments is lowered to refer to > + * gl_ClipDistanceMESA as appropriate. > + * > + * We need to do a similar replacement for 2D gl_ClipDistance, however since > + * it's an input, the only case we need to address is where a 1D slice of it > + * is the entire RHS of an assignment, e.g.: > + * > + * foo = gl_in[i].gl_ClipDistance > */ > ir_visitor_status > lower_clip_distance_visitor::visit_leave(ir_assignment *ir) > { > - ir_dereference_variable *lhs_var = ir->lhs->as_dereference_variable(); > - ir_dereference_variable *rhs_var = ir->rhs->as_dereference_variable(); > - if ((lhs_var && lhs_var->var == this->old_clip_distance_var) > - || (rhs_var && rhs_var->var == this->old_clip_distance_var)) { > - /* LHS or RHS of the assignment is the entire gl_ClipDistance array. > - * Since we are reshaping gl_ClipDistance from an array of floats to an > - * array of vec4's, this isn't going to work as a bulk assignment > - * anymore, so unroll it to element-by-element assignments and lower > - * each of them. > + if (this->is_clip_distance_vec8(ir->lhs) || > + this->is_clip_distance_vec8(ir->rhs)) { > + /* LHS or RHS of the assignment is the entire 1D gl_ClipDistance array > + * (or a 1D slice of a 2D gl_ClipDistance input array). Since we are > + * reshaping gl_ClipDistance from an array of floats to an array of > + * vec4's, this isn't going to work as a bulk assignment anymore, so > + * unroll it to element-by-element assignments and lower each of them. > * > * Note: to unroll into element-by-element assignments, we need to make > * clones of the LHS and RHS. This is safe because expressions and > * l-values are side-effect free. > */ > void *ctx = ralloc_parent(ir); > - int array_size = this->old_clip_distance_var->type->array_size(); > + int array_size = ir->lhs->type->array_size(); > for (int i = 0; i < array_size; ++i) { > ir_dereference_array *new_lhs = new(ctx) ir_dereference_array( > ir->lhs->clone(ctx, NULL), new(ctx) ir_constant(i)); > @@ -326,11 +425,17 @@ > lower_clip_distance_visitor::visit_new_assignment(ir_assignment *ir) > > > /** > - * If gl_ClipDistance appears as an argument in an ir_call expression, > replace > - * it with a temporary variable, and make sure the ir_call is preceded and/or > - * followed by assignments that copy the contents of the temporary variable > to > - * and/or from gl_ClipDistance. Each of these assignments is then lowered to > - * refer to gl_ClipDistanceMESA. > + * If a 1D gl_ClipDistance variable appears as an argument in an ir_call > + * expression, replace it with a temporary variable, and make sure the > ir_call > + * is preceded and/or followed by assignments that copy the contents of the > + * temporary variable to and/or from gl_ClipDistance. Each of these > + * assignments is then lowered to refer to gl_ClipDistanceMESA. > + * > + * We need to do a similar replacement for 2D gl_ClipDistance, however since > + * it's an input, the only case we need to address is where a 1D slice of it > + * is passed as an "in" parameter to an ir_call, e.g.: > + * > + * foo(gl_in[i].gl_ClipDistance) > */ > ir_visitor_status > lower_clip_distance_visitor::visit_leave(ir_call *ir) > @@ -349,12 +454,12 @@ lower_clip_distance_visitor::visit_leave(ir_call *ir) > formal_param_node = formal_param_node->next; > actual_param_node = actual_param_node->next; > > - ir_dereference_variable *deref = > actual_param->as_dereference_variable(); > - if (deref && deref->var == this->old_clip_distance_var) { > - /* User is trying to pass the whole gl_ClipDistance array to a > - * function call. Since we are reshaping gl_ClipDistance from an > - * array of floats to an array of vec4's, this isn't going to work > - * anymore, so use a temporary array instead. > + if (this->is_clip_distance_vec8(actual_param)) { > + /* User is trying to pass the whole 1D gl_ClipDistance array (or a > 1D > + * slice of a 2D gl_ClipDistance array) to a function call. Since > we > + * are reshaping gl_ClipDistance from an array of floats to an array > + * of vec4's, this isn't going to work anymore, so use a temporary > + * array instead. > */ > ir_variable *temp_clip_distance = new(ctx) ir_variable( > actual_param->type, "temp_clip_distance", ir_var_temporary); > @@ -370,7 +475,7 @@ lower_clip_distance_visitor::visit_leave(ir_call *ir) > */ > ir_assignment *new_assignment = new(ctx) ir_assignment( > new(ctx) ir_dereference_variable(temp_clip_distance), > - new(ctx) ir_dereference_variable(old_clip_distance_var)); > + actual_param->clone(ctx, NULL)); > this->base_ir->insert_before(new_assignment); > this->visit_new_assignment(new_assignment); > } > @@ -382,7 +487,7 @@ lower_clip_distance_visitor::visit_leave(ir_call *ir) > * afterwards to make sure it gets lowered. > */ > ir_assignment *new_assignment = new(ctx) ir_assignment( > - new(ctx) ir_dereference_variable(old_clip_distance_var), > + actual_param->clone(ctx, NULL), > new(ctx) ir_dereference_variable(temp_clip_distance)); > this->base_ir->insert_after(new_assignment); > this->visit_new_assignment(new_assignment); > @@ -401,8 +506,10 @@ lower_clip_distance(gl_shader *shader) > > visit_list_elements(&v, shader->ir); > > - if (v.new_clip_distance_var) > - shader->symbols->add_variable(v.new_clip_distance_var); > + if (v.new_clip_distance_1d_var) > + shader->symbols->add_variable(v.new_clip_distance_1d_var); > + if (v.new_clip_distance_2d_var) > + shader->symbols->add_variable(v.new_clip_distance_2d_var); > > return v.progress; > } > _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev