Add an optimization pass that drops min/max expression operands that can be proven to not contribute to the final result. The algorithm is similar to alpha-beta pruning on a minmax search, from the field of AI.
This optimization pass can optimize min/max expressions where operands are min/max expressions. Such code can appear in shaders by itself, or as the result of clamp() or AMD_shader_trinary_minmax functions. This optimization pass improves the generated code for piglit's AMD_shader_trinary_minmax tests as follows: total instructions in shared programs: 75 -> 67 (-10.67%) instructions in affected programs: 60 -> 52 (-13.33%) GAINED: 0 LOST: 0 All tests (max3, min3, mid3) improved. A full shader-db run: total instructions in shared programs: 4293603 -> 4293575 (-0.00%) instructions in affected programs: 1188 -> 1160 (-2.36%) GAINED: 0 LOST: 0 Improvements happen in Guacamelee and Serious Sam 3. One shader from Dungeon Defenders is hurt by shader-db metrics (26 -> 28), because of dropping of a (constant float (0.00000)) operand, which was compiled to a saturate modifier. Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=76861 Signed-off-by: Petri Latvala <petri.latv...@intel.com> --- src/glsl/Makefile.sources | 1 + src/glsl/glsl_parser_extras.cpp | 1 + src/glsl/ir_optimization.h | 1 + src/glsl/opt_minmax.cpp | 395 ++++++++++++++++++++++++++++++++++++++++ 4 files changed, 398 insertions(+) create mode 100644 src/glsl/opt_minmax.cpp diff --git a/src/glsl/Makefile.sources b/src/glsl/Makefile.sources index b54eae7..1ee80a3 100644 --- a/src/glsl/Makefile.sources +++ b/src/glsl/Makefile.sources @@ -95,6 +95,7 @@ LIBGLSL_FILES = \ $(GLSL_SRCDIR)/opt_flip_matrices.cpp \ $(GLSL_SRCDIR)/opt_function_inlining.cpp \ $(GLSL_SRCDIR)/opt_if_simplification.cpp \ + $(GLSL_SRCDIR)/opt_minmax.cpp \ $(GLSL_SRCDIR)/opt_noop_swizzle.cpp \ $(GLSL_SRCDIR)/opt_rebalance_tree.cpp \ $(GLSL_SRCDIR)/opt_redundant_jumps.cpp \ diff --git a/src/glsl/glsl_parser_extras.cpp b/src/glsl/glsl_parser_extras.cpp index 890123a..9f57ef3 100644 --- a/src/glsl/glsl_parser_extras.cpp +++ b/src/glsl/glsl_parser_extras.cpp @@ -1561,6 +1561,7 @@ do_common_optimization(exec_list *ir, bool linked, else progress = do_constant_variable_unlinked(ir) || progress; progress = do_constant_folding(ir) || progress; + progress = do_minmax_prune(ir) || progress; progress = do_cse(ir) || progress; progress = do_rebalance_tree(ir) || progress; progress = do_algebraic(ir, native_integers, options) || progress; diff --git a/src/glsl/ir_optimization.h b/src/glsl/ir_optimization.h index b83c225..9d22585 100644 --- a/src/glsl/ir_optimization.h +++ b/src/glsl/ir_optimization.h @@ -98,6 +98,7 @@ bool opt_flatten_nested_if_blocks(exec_list *instructions); bool do_discard_simplification(exec_list *instructions); bool lower_if_to_cond_assign(exec_list *instructions, unsigned max_depth = 0); bool do_mat_op_to_vec(exec_list *instructions); +bool do_minmax_prune(exec_list *instructions); bool do_noop_swizzle(exec_list *instructions); bool do_structure_splitting(exec_list *instructions); bool do_swizzle_swizzle(exec_list *instructions); diff --git a/src/glsl/opt_minmax.cpp b/src/glsl/opt_minmax.cpp new file mode 100644 index 0000000..5656059 --- /dev/null +++ b/src/glsl/opt_minmax.cpp @@ -0,0 +1,395 @@ +/* + * Copyright © 2014 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_minmax.cpp + * + * Drop operands from an expression tree of only min/max operations if they + * can be proven to not contribute to the final result. + * + * The algorithm is similar to alpha-beta pruning on a minmax search. + */ + +#include "ir.h" +#include "ir_visitor.h" +#include "ir_rvalue_visitor.h" +#include "ir_optimization.h" +#include "glsl_types.h" +#include "main/macros.h" + +namespace +{ +class minmax_range +{ +public: + + minmax_range(ir_constant *low = NULL, ir_constant *high = NULL) + { + range[0] = low; + range[1] = high; + } + + /* [0] is the lower limit of the range, [1] is the higher limit. NULL on + * [0] means negative infinity (unlimited) and on [1] positive infinity + * (unlimited). Because of the two interpretations of the value NULL, + * arbitrary comparison between ir_constants is impossible. + */ + ir_constant *range[2]; +}; + +class ir_minmax_visitor : public ir_rvalue_enter_visitor { +public: + ir_minmax_visitor() + : progress(false) + , valid(true) + { + } + + virtual ~ir_minmax_visitor() + { + } + + bool + less_all_components(ir_constant *one, ir_constant *two); + + ir_constant * + smaller_constant(ir_constant *one, ir_constant *two); + + ir_constant * + larger_constant(ir_constant *one, ir_constant *two); + + minmax_range + combine_range(minmax_range r0, minmax_range r1, bool ismin); + + minmax_range + range_intersection(minmax_range r0, minmax_range r1); + + minmax_range + get_range(ir_rvalue *rval); + + ir_rvalue * + prune_expression(ir_expression *expr, minmax_range baserange); + + void + handle_rvalue(ir_rvalue **rvalue); + + bool progress; + bool valid; +}; + +/* + * Returns true if all vector components of `one' are less than of `two'. + * + * If there are vector components that are less while others are greater, the + * visitor is marked invalid and no further changes will be made to the IR. + */ +bool +ir_minmax_visitor::less_all_components(ir_constant *one, ir_constant *two) +{ + assert(one != NULL); + assert(two != NULL); + + assert(one->type->base_type == two->type->base_type); + + unsigned oneinc = one->type->is_scalar() ? 0 : 1; + unsigned twoinc = two->type->is_scalar() ? 0 : 1; + unsigned components = MAX2(one->type->components(), two->type->components()); + + /* No early escape. We need to go through all components and mark the + * visitor as invalid if comparison yields less for some components and + * greater for others. If some components compare as equal, it's not + * invalid. + */ + + bool foundless = false; + bool foundgreater = false; + bool foundequal = false; + + for (unsigned i = 0, c0 = 0, c1 = 0; + i < components; + c0 += oneinc, c1 += twoinc, ++i) { + switch (one->type->base_type) { + case GLSL_TYPE_UINT: + if (one->value.u[c0] < two->value.u[c1]) + foundless = true; + else if (one->value.u[c0] > two->value.u[c1]) + foundgreater = true; + else + foundequal = true; + continue; + case GLSL_TYPE_INT: + if (one->value.i[c0] < two->value.i[c1]) + foundless = true; + else if (one->value.i[c0] > two->value.i[c1]) + foundgreater = true; + else + foundequal = true; + continue; + case GLSL_TYPE_FLOAT: + if (one->value.f[c0] < two->value.f[c1]) + foundless = true; + else if (one->value.f[c0] > two->value.f[c1]) + foundgreater = true; + else + foundequal = true; + continue; + default: + assert(!"not reached"); + } + } + + if (foundless && foundgreater) { + valid = false; + return false; + } + + if (foundequal) + return false; + + return foundless; +} + +ir_constant * +ir_minmax_visitor::smaller_constant(ir_constant *one, ir_constant *two) +{ + assert(one != NULL); + assert(two != NULL); + + if (less_all_components(one, two)) + return one; + else + return two; +} + +ir_constant * +ir_minmax_visitor::larger_constant(ir_constant *one, ir_constant *two) +{ + assert(one != NULL); + assert(two != NULL); + + if (less_all_components(one, two)) + return two; + else + return one; +} + +/* Combines two ranges by doing an element-wise min() / max() depending on the + * operation. + */ +minmax_range +ir_minmax_visitor::combine_range(minmax_range r0, minmax_range r1, bool ismin) +{ + minmax_range ret; + + if (!r0.range[0]) { + ret.range[0] = ismin ? r0.range[0] : r1.range[0]; + } else if (!r1.range[0]) { + ret.range[0] = ismin ? r1.range[0] : r0.range[0]; + } else { + ret.range[0] = ismin ? smaller_constant(r0.range[0], r1.range[0]) : + larger_constant(r0.range[0], r1.range[0]); + } + + if (!r0.range[1]) { + ret.range[1] = ismin ? r1.range[1] : r0.range[1]; + } else if (!r1.range[1]) { + ret.range[1] = ismin ? r0.range[1] : r1.range[1]; + } else { + ret.range[1] = ismin ? smaller_constant(r0.range[1], r1.range[1]) : + larger_constant(r0.range[1], r1.range[1]); + } + + return ret; +} + +/* Returns a range so that lower limit is the larger of the two lower limits, + * and higher limit is the smaller of the two higher limits. + */ +minmax_range +ir_minmax_visitor::range_intersection(minmax_range r0, minmax_range r1) +{ + minmax_range ret; + + if (!r0.range[0]) + ret.range[0] = r1.range[0]; + else if (!r1.range[0]) + ret.range[0] = r0.range[0]; + else + ret.range[0] = larger_constant(r0.range[0], r1.range[0]); + + if (!r0.range[1]) + ret.range[1] = r1.range[1]; + else if (!r1.range[1]) + ret.range[1] = r0.range[1]; + else + ret.range[1] = smaller_constant(r0.range[1], r1.range[1]); + + return ret; +} + +minmax_range +ir_minmax_visitor::get_range(ir_rvalue *rval) +{ + if (ir_expression *expr = rval->as_expression()) { + if (expr->operation == ir_binop_min || + expr->operation == ir_binop_max) { + minmax_range r0 = get_range(expr->operands[0]); + minmax_range r1 = get_range(expr->operands[1]); + + return combine_range(r0, r1, expr->operation == ir_binop_min); + } + } + + if (ir_constant *c = rval->as_constant()) { + return minmax_range(c, c); + } + + return minmax_range(); +} + +ir_rvalue * +ir_minmax_visitor::prune_expression(ir_expression *expr, minmax_range baserange) +{ + assert(expr->operation == ir_binop_min || + expr->operation == ir_binop_max); + + if (!valid) + return expr; + + bool ismin = expr->operation == ir_binop_min; + minmax_range limits[2]; + + for (unsigned i = 0; i < 2; ++i) { + limits[i] = get_range(expr->operands[i]); + } + + for (unsigned i = 0; i < 2; ++i) { + /* Operands are dropped if their range doesn't reach the given baserange + * or the other operand's limit from the appropriate direction. + */ + + minmax_range basereach; + minmax_range otherreach; + + if (ismin) { + basereach.range[0] = limits[i].range[0]; + otherreach.range[0] = limits[i].range[0]; + basereach.range[1] = baserange.range[1]; + otherreach.range[1] = limits[1 - i].range[1]; + } else { + basereach.range[0] = baserange.range[0]; + otherreach.range[0] = limits[1 - i].range[0]; + basereach.range[1] = limits[i].range[1]; + otherreach.range[1] = limits[i].range[1]; + } + + if ((basereach.range[0] && basereach.range[1] && + !less_all_components(basereach.range[0], basereach.range[1])) || + (otherreach.range[0] && otherreach.range[1] && + !less_all_components(otherreach.range[0], otherreach.range[1]))) { + /* Bail out if those comparisons made the visitor invalid. */ + if (!valid) + return expr; + + progress = true; + + /* Recurse if necessary. */ + if (ir_expression* opexpr = expr->operands[1 - i]->as_expression()) { + if (opexpr->operation == ir_binop_min || + opexpr->operation == ir_binop_max) { + return prune_expression(opexpr, baserange); + } + } + + return expr->operands[1 - i]; + } + } + + /* Now recurse to operands giving them the proper baserange. The baserange + * to pass is the intersection of our baserange and the other operand's + * limit with one of the ranges unlimited. + */ + + unsigned clear = (ismin ? 0 : 1); + + for (unsigned i = 0; i < 2; ++i) { + if (ir_expression *opexpr = expr->operands[i]->as_expression()) { + if (opexpr->operation == ir_binop_min || + opexpr->operation == ir_binop_max) { + limits[1 - i].range[clear] = NULL; + minmax_range base = range_intersection(limits[1 - i], baserange); + expr->operands[i] = prune_expression(opexpr, base); + } + } + } + + return expr; +} + +ir_rvalue * +swizzle_if_required(ir_expression *expr, + ir_rvalue *rval) +{ + if (expr->type->is_vector() && rval->type->is_scalar()) { + return new(expr) ir_swizzle(rval, 0, 0, 0, 0, + expr->type->vector_elements); + } else { + return rval; + } +} + +void +ir_minmax_visitor::handle_rvalue(ir_rvalue **rvalue) +{ + if (!*rvalue) + return; + + ir_expression *expr = (*rvalue)->as_expression(); + if (!expr || (expr->operation != ir_binop_min && + expr->operation != ir_binop_max)) + return; + + ir_rvalue *new_rvalue = prune_expression(expr, minmax_range()); + if (!valid || new_rvalue == *rvalue) { + return; + } + + /* If the expression type is a vector and the optimization leaves a scalar + * as the result, we need to turn it into a vector. + */ + *rvalue = swizzle_if_required(expr, new_rvalue); + + progress = true; +} + +} + +bool +do_minmax_prune(exec_list *instructions) +{ + ir_minmax_visitor v; + + visit_list_elements(&v, instructions); + + return v.progress; +} -- 2.0.1 _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev