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Diffstat (limited to 'src/compiler/glsl/opt_vectorize.cpp')
| -rw-r--r-- | src/compiler/glsl/opt_vectorize.cpp | 407 |
1 files changed, 407 insertions, 0 deletions
diff --git a/src/compiler/glsl/opt_vectorize.cpp b/src/compiler/glsl/opt_vectorize.cpp new file mode 100644 index 00000000000..88318cd8a6e --- /dev/null +++ b/src/compiler/glsl/opt_vectorize.cpp @@ -0,0 +1,407 @@ +/* + * Copyright © 2013 Intel Corporation + * + * Permission is hereby granted, free of charge, to any person obtaining a + * copy of this software and associated documentation files (the "Software"), + * to deal in the Software without restriction, including without limitation + * the rights to use, copy, modify, merge, publish, distribute, sublicense, + * and/or sell copies of the Software, and to permit persons to whom the + * Software is furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice (including the next + * paragraph) shall be included in all copies or substantial portions of the + * Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER + * DEALINGS IN THE SOFTWARE. + */ + +/** + * \file opt_vectorize.cpp + * + * Combines scalar assignments of the same expression (modulo swizzle) to + * multiple channels of the same variable into a single vectorized expression + * and assignment. + * + * Many generated shaders contain scalarized code. That is, they contain + * + * r1.x = log2(v0.x); + * r1.y = log2(v0.y); + * r1.z = log2(v0.z); + * + * rather than + * + * r1.xyz = log2(v0.xyz); + * + * We look for consecutive assignments of the same expression (modulo swizzle) + * to each channel of the same variable. + * + * For instance, we want to convert these three scalar operations + * + * (assign (x) (var_ref r1) (expression float log2 (swiz x (var_ref v0)))) + * (assign (y) (var_ref r1) (expression float log2 (swiz y (var_ref v0)))) + * (assign (z) (var_ref r1) (expression float log2 (swiz z (var_ref v0)))) + * + * into a single vector operation + * + * (assign (xyz) (var_ref r1) (expression vec3 log2 (swiz xyz (var_ref v0)))) + */ + +#include "ir.h" +#include "ir_visitor.h" +#include "ir_optimization.h" +#include "compiler/glsl_types.h" +#include "program/prog_instruction.h" + +namespace { + +class ir_vectorize_visitor : public ir_hierarchical_visitor { +public: + void clear() + { + assignment[0] = NULL; + assignment[1] = NULL; + assignment[2] = NULL; + assignment[3] = NULL; + current_assignment = NULL; + last_assignment = NULL; + channels = 0; + has_swizzle = false; + } + + ir_vectorize_visitor() + { + clear(); + progress = false; + } + + virtual ir_visitor_status visit_enter(ir_assignment *); + virtual ir_visitor_status visit_enter(ir_swizzle *); + virtual ir_visitor_status visit_enter(ir_dereference_array *); + virtual ir_visitor_status visit_enter(ir_expression *); + virtual ir_visitor_status visit_enter(ir_if *); + virtual ir_visitor_status visit_enter(ir_loop *); + virtual ir_visitor_status visit_enter(ir_texture *); + + virtual ir_visitor_status visit_leave(ir_assignment *); + + void try_vectorize(); + + ir_assignment *assignment[4]; + ir_assignment *current_assignment, *last_assignment; + unsigned channels; + bool has_swizzle; + + bool progress; +}; + +} /* unnamed namespace */ + +/** + * Rewrites the swizzles and types of a right-hand side of an assignment. + * + * From the example above, this function would be called (by visit_tree()) on + * the nodes of the tree (expression float log2 (swiz z (var_ref v0))), + * rewriting it into (expression vec3 log2 (swiz xyz (var_ref v0))). + * + * The function operates on ir_expressions (and its operands) and ir_swizzles. + * For expressions it sets a new type and swizzles any non-expression and non- + * swizzle scalar operands into appropriately sized vector arguments. For + * example, if combining + * + * (assign (x) (var_ref r1) (expression float + (swiz x (var_ref v0) (var_ref v1)))) + * (assign (y) (var_ref r1) (expression float + (swiz y (var_ref v0) (var_ref v1)))) + * + * where v1 is a scalar, rewrite_swizzle() would insert a swizzle on + * (var_ref v1) such that the final result was + * + * (assign (xy) (var_ref r1) (expression vec2 + (swiz xy (var_ref v0)) + * (swiz xx (var_ref v1)))) + * + * For swizzles, it sets a new type, and if the variable being swizzled is a + * vector it overwrites the swizzle mask with the ir_swizzle_mask passed as the + * data parameter. If the swizzled variable is scalar, then the swizzle was + * added by an earlier call to rewrite_swizzle() on an expression, so the + * mask should not be modified. + */ +static void +rewrite_swizzle(ir_instruction *ir, void *data) +{ + ir_swizzle_mask *mask = (ir_swizzle_mask *)data; + + switch (ir->ir_type) { + case ir_type_swizzle: { + ir_swizzle *swz = (ir_swizzle *)ir; + if (swz->val->type->is_vector()) { + swz->mask = *mask; + } + swz->type = glsl_type::get_instance(swz->type->base_type, + mask->num_components, 1); + break; + } + case ir_type_expression: { + ir_expression *expr = (ir_expression *)ir; + expr->type = glsl_type::get_instance(expr->type->base_type, + mask->num_components, 1); + for (unsigned i = 0; i < 4; i++) { + if (expr->operands[i]) { + ir_rvalue *rval = expr->operands[i]->as_rvalue(); + if (rval && rval->type->is_scalar() && + !rval->as_expression() && !rval->as_swizzle()) { + expr->operands[i] = new(ir) ir_swizzle(rval, 0, 0, 0, 0, + mask->num_components); + } + } + } + break; + } + default: + break; + } +} + +/** + * Attempt to vectorize the previously saved assignments, and clear them from + * consideration. + * + * If the assignments are able to be combined, it modifies in-place the last + * assignment seen to be an equivalent vector form of the scalar assignments. + * It then removes the other now obsolete scalar assignments. + */ +void +ir_vectorize_visitor::try_vectorize() +{ + if (this->last_assignment && this->channels > 1) { + ir_swizzle_mask mask = {0, 0, 0, 0, channels, 0}; + + this->last_assignment->write_mask = 0; + + for (unsigned i = 0, j = 0; i < 4; i++) { + if (this->assignment[i]) { + this->last_assignment->write_mask |= 1 << i; + + if (this->assignment[i] != this->last_assignment) { + this->assignment[i]->remove(); + } + + switch (j) { + case 0: mask.x = i; break; + case 1: mask.y = i; break; + case 2: mask.z = i; break; + case 3: mask.w = i; break; + } + + j++; + } + } + + visit_tree(this->last_assignment->rhs, rewrite_swizzle, &mask); + + this->progress = true; + } + clear(); +} + +/** + * Returns whether the write mask is a single channel. + */ +static bool +single_channel_write_mask(unsigned write_mask) +{ + return write_mask != 0 && (write_mask & (write_mask - 1)) == 0; +} + +/** + * Translates single-channeled write mask to single-channeled swizzle. + */ +static unsigned +write_mask_to_swizzle(unsigned write_mask) +{ + switch (write_mask) { + case WRITEMASK_X: return SWIZZLE_X; + case WRITEMASK_Y: return SWIZZLE_Y; + case WRITEMASK_Z: return SWIZZLE_Z; + case WRITEMASK_W: return SWIZZLE_W; + } + unreachable("not reached"); +} + +/** + * Returns whether a single-channeled write mask matches a swizzle. + */ +static bool +write_mask_matches_swizzle(unsigned write_mask, + const ir_swizzle *swz) +{ + return ((write_mask == WRITEMASK_X && swz->mask.x == SWIZZLE_X) || + (write_mask == WRITEMASK_Y && swz->mask.x == SWIZZLE_Y) || + (write_mask == WRITEMASK_Z && swz->mask.x == SWIZZLE_Z) || + (write_mask == WRITEMASK_W && swz->mask.x == SWIZZLE_W)); +} + +/** + * Upon entering an ir_assignment, attempt to vectorize the currently tracked + * assignments if the current assignment is not suitable. Keep a pointer to + * the current assignment. + */ +ir_visitor_status +ir_vectorize_visitor::visit_enter(ir_assignment *ir) +{ + ir_dereference *lhs = this->last_assignment != NULL ? + this->last_assignment->lhs : NULL; + ir_rvalue *rhs = this->last_assignment != NULL ? + this->last_assignment->rhs : NULL; + + if (ir->condition || + this->channels >= 4 || + !single_channel_write_mask(ir->write_mask) || + this->assignment[write_mask_to_swizzle(ir->write_mask)] != NULL || + (lhs && !ir->lhs->equals(lhs)) || + (rhs && !ir->rhs->equals(rhs, ir_type_swizzle))) { + try_vectorize(); + } + + this->current_assignment = ir; + + return visit_continue; +} + +/** + * Upon entering an ir_swizzle, set ::has_swizzle if we're visiting from an + * ir_assignment (i.e., that ::current_assignment is set) and the swizzle mask + * matches the current assignment's write mask. + * + * If the write mask doesn't match the swizzle mask, remove the current + * assignment from further consideration. + */ +ir_visitor_status +ir_vectorize_visitor::visit_enter(ir_swizzle *ir) +{ + if (this->current_assignment) { + if (write_mask_matches_swizzle(this->current_assignment->write_mask, ir)) { + this->has_swizzle = true; + } else { + this->current_assignment = NULL; + } + } + return visit_continue; +} + +/* Upon entering an ir_array_dereference, remove the current assignment from + * further consideration. Since the index of an array dereference must scalar, + * we are not able to vectorize it. + * + * FINISHME: If all of scalar indices are identical we could vectorize. + */ +ir_visitor_status +ir_vectorize_visitor::visit_enter(ir_dereference_array *) +{ + this->current_assignment = NULL; + return visit_continue_with_parent; +} + +/** + * Upon entering an ir_expression, remove the current assignment from further + * consideration if the expression operates horizontally on vectors. + */ +ir_visitor_status +ir_vectorize_visitor::visit_enter(ir_expression *ir) +{ + if (ir->is_horizontal()) { + this->current_assignment = NULL; + return visit_continue_with_parent; + } + return visit_continue; +} + +/* Since there is no statement to visit between the "then" and "else" + * instructions try to vectorize before, in between, and after them to avoid + * combining statements from different basic blocks. + */ +ir_visitor_status +ir_vectorize_visitor::visit_enter(ir_if *ir) +{ + try_vectorize(); + + visit_list_elements(this, &ir->then_instructions); + try_vectorize(); + + visit_list_elements(this, &ir->else_instructions); + try_vectorize(); + + return visit_continue_with_parent; +} + +/* Since there is no statement to visit between the instructions in the body of + * the loop and the instructions after it try to vectorize before and after the + * body to avoid combining statements from different basic blocks. + */ +ir_visitor_status +ir_vectorize_visitor::visit_enter(ir_loop *ir) +{ + try_vectorize(); + + visit_list_elements(this, &ir->body_instructions); + try_vectorize(); + + return visit_continue_with_parent; +} + +/** + * Upon entering an ir_texture, remove the current assignment from + * further consideration. Vectorizing multiple texture lookups into one + * is wrong. + */ +ir_visitor_status +ir_vectorize_visitor::visit_enter(ir_texture *) +{ + this->current_assignment = NULL; + return visit_continue_with_parent; +} + +/** + * Upon leaving an ir_assignment, save a pointer to it in ::assignment[] if + * the swizzle mask(s) found were appropriate. Also save a pointer in + * ::last_assignment so that we can compare future assignments with it. + * + * Finally, clear ::current_assignment and ::has_swizzle. + */ +ir_visitor_status +ir_vectorize_visitor::visit_leave(ir_assignment *ir) +{ + if (this->has_swizzle && this->current_assignment) { + assert(this->current_assignment == ir); + + unsigned channel = write_mask_to_swizzle(this->current_assignment->write_mask); + this->assignment[channel] = ir; + this->channels++; + + this->last_assignment = this->current_assignment; + } + this->current_assignment = NULL; + this->has_swizzle = false; + return visit_continue; +} + +/** + * Combines scalar assignments of the same expression (modulo swizzle) to + * multiple channels of the same variable into a single vectorized expression + * and assignment. + */ +bool +do_vectorize(exec_list *instructions) +{ + ir_vectorize_visitor v; + + v.run(instructions); + + /* Try to vectorize the last assignments seen. */ + v.try_vectorize(); + + return v.progress; +} |