On lun, 2014-09-29 at 13:19 -0400, Connor Abbott wrote:
> On Mon, Sep 29, 2014 at 7:49 AM, Iago Toral Quiroga <ito...@igalia.com> wrote:
> > Original patch by Petri Latvala <petri.latv...@intel.com>:
> >
> > 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.
> >
> > Version 2 by Iago Toral Quiroga <ito...@igalia.com>:
> >
> > Changes from review feedback:
> > - Squashed various cosmetic changes sent by Matt Turner.
> > - Make less_all_components return an enum rather than setting a class
> > member.
> > (Suggested by Mat Turner). Also, renamed it to compare_components.
> > - Make less_all_components, smaller_constant and larger_constant static.
> > (Suggested by Mat Turner)
> > - Change mixmax_range to call its limits "low" and "high" instead of
> > "range[0]" and "range[1]". (Suggested by Connor Abbot).
> > - Use ir_builder swizzle helpers in swizzle_if_required(). (Suggested by
> > Connor Abbot).
> > - Make the logic more clearer by rearrenging the code and commenting.
> > (Suggested by Connor Abbot).
> > - Added comment to explain why we need to recurse twice. (Suggested by
> > Connor Abbot).
> > - If we cannot prune an expression, do not return early. Instead, attempt
> > to prune its children. (Suggested by Connor Abbot).
> >
> > Other changes:
> > - Instead of having a global "valid" visitor member, let the various
> > functions
> > that can determine this status return a boolean and check for its value
> > to decide what to do in each case. This is more flexible and allows to
> > recurse into children of parents that could not be prunned due to invalid
> > ranges (so related to the last bullet in the review feedback).
> > - Make sure we always check if a range is valid before working with it.
> > Since
> > any use of get_range, combine_range or range_intersection can invalidate
> > a range we should check for this situation every time we use any of these
> > functions.
> >
> > Version 3 by Iago Toral Quiroga <ito...@igalia.com>:
> >
> > Changes from review feedback:
> > - Now we can make get_range, combine_range and range_intersection static too
> > (suggested by Connor Abbot).
> > - Do not return NULL when looking for the larger or greater constant into
> > mixed vector constants. Instead, produce a new constant by doing a
> > component-wise minmax. With this we can also remove of the validations
> > when
> > we call into these functions (suggested by Connor Abbot).
> > - Add a comment explaining the meaning of the baserange argument in
> > prune_expression (suggested by Connor Abbot).
> >
> > Other changes:
> > - Eliminate minmax expressions operating on constant vectors with mixed
> > values
> > by resolving them.
> >
> > No piglit regressions observed with Version 3.
> >
> > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=76861
> > ---
> >
> > Version 3 passes all minmax unit tests sent in the original series by Petri,
> > except for the ones aimed at mixed vectors because this version produces
> > better code for these than what is expected by these tests.
>
> Thanks for cleaning this up! This patch is
>
> Reviewed-by: Connor Abbott <cwabbo...@gmail.com>
>
> Dylan had some style comments on the Python patches IIRC, but other
> than that I think they looked good (assuming you fix the broken tests
> you mentioned) - it has been a while though.
Yes, there was some review feedback for those too, I'll look into them
and send updated versions here for review.
Thanks for reviewing this!
Iago
> >
> > src/glsl/Makefile.sources | 1 +
> > src/glsl/glsl_parser_extras.cpp | 1 +
> > src/glsl/ir_optimization.h | 1 +
> > src/glsl/opt_minmax.cpp | 464
> > ++++++++++++++++++++++++++++++++++++++++
> > 4 files changed, 467 insertions(+)
> > create mode 100644 src/glsl/opt_minmax.cpp
> >
> > diff --git a/src/glsl/Makefile.sources b/src/glsl/Makefile.sources
> > index cb8d5a6..1c08697 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 490c3c8..ae19ce4 100644
> > --- a/src/glsl/glsl_parser_extras.cpp
> > +++ b/src/glsl/glsl_parser_extras.cpp
> > @@ -1586,6 +1586,7 @@ 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 369dcd1..8fbd992 100644
> > --- a/src/glsl/ir_optimization.h
> > +++ b/src/glsl/ir_optimization.h
> > @@ -99,6 +99,7 @@ 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..a4fe2bd
> > --- /dev/null
> > +++ b/src/glsl/opt_minmax.cpp
> > @@ -0,0 +1,464 @@
> > +/*
> > + * 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 "ir_builder.h"
> > +#include "program/prog_instruction.h"
> > +#include "glsl_types.h"
> > +#include "main/macros.h"
> > +
> > +using namespace ir_builder;
> > +
> > +namespace {
> > +
> > +enum compare_components_result {
> > + LESS,
> > + LESS_OR_EQUAL,
> > + EQUAL,
> > + GREATER_OR_EQUAL,
> > + GREATER,
> > + MIXED
> > +};
> > +
> > +class minmax_range {
> > +public:
> > + minmax_range(ir_constant *low = NULL, ir_constant *high = NULL)
> > + {
> > + this->low = low;
> > + this->high = high;
> > + }
> > +
> > + /* low is the lower limit of the range, high is the higher limit. NULL
> > on
> > + * low means negative infinity (unlimited) and on high positive infinity
> > + * (unlimited). Because of the two interpretations of the value NULL,
> > + * arbitrary comparison between ir_constants is impossible.
> > + */
> > + ir_constant *low;
> > + ir_constant *high;
> > +};
> > +
> > +class ir_minmax_visitor : public ir_rvalue_enter_visitor {
> > +public:
> > + ir_minmax_visitor()
> > + : progress(false)
> > + {
> > + }
> > +
> > + ir_rvalue *prune_expression(ir_expression *expr, minmax_range
> > baserange);
> > +
> > + void handle_rvalue(ir_rvalue **rvalue);
> > +
> > + bool progress;
> > +};
> > +
> > +/*
> > + * Returns LESS if all vector components of `a' are strictly lower than of
> > `b',
> > + * GREATER if all vector components of `a' are strictly greater than of
> > `b',
> > + * MIXED if some vector components of `a' are strictly lower than of `b'
> > while
> > + * others are strictly greater, or EQUAL otherwise.
> > + */
> > +static enum compare_components_result
> > +compare_components(ir_constant *a, ir_constant *b)
> > +{
> > + assert(a != NULL);
> > + assert(b != NULL);
> > +
> > + assert(a->type->base_type == b->type->base_type);
> > +
> > + unsigned a_inc = a->type->is_scalar() ? 0 : 1;
> > + unsigned b_inc = b->type->is_scalar() ? 0 : 1;
> > + unsigned components = MAX2(a->type->components(),
> > b->type->components());
> > +
> > + bool foundless = false;
> > + bool foundgreater = false;
> > + bool foundequal = false;
> > +
> > + for (unsigned i = 0, c0 = 0, c1 = 0;
> > + i < components;
> > + c0 += a_inc, c1 += b_inc, ++i) {
> > + switch (a->type->base_type) {
> > + case GLSL_TYPE_UINT:
> > + if (a->value.u[c0] < b->value.u[c1])
> > + foundless = true;
> > + else if (a->value.u[c0] > b->value.u[c1])
> > + foundgreater = true;
> > + else
> > + foundequal = true;
> > + break;
> > + case GLSL_TYPE_INT:
> > + if (a->value.i[c0] < b->value.i[c1])
> > + foundless = true;
> > + else if (a->value.i[c0] > b->value.i[c1])
> > + foundgreater = true;
> > + else
> > + foundequal = true;
> > + break;
> > + case GLSL_TYPE_FLOAT:
> > + if (a->value.f[c0] < b->value.f[c1])
> > + foundless = true;
> > + else if (a->value.f[c0] > b->value.f[c1])
> > + foundgreater = true;
> > + else
> > + foundequal = true;
> > + break;
> > + default:
> > + unreachable("not reached");
> > + }
> > + }
> > +
> > + if (foundless && foundgreater) {
> > + /* Some components are strictly lower, others are strictly greater */
> > + return MIXED;
> > + }
> > +
> > + if (foundequal) {
> > + /* It is not mixed, but it is not strictly lower or greater */
> > + if (foundless)
> > + return LESS_OR_EQUAL;
> > + if (foundgreater)
> > + return GREATER_OR_EQUAL;
> > + return EQUAL;
> > + }
> > +
> > + /* All components are strictly lower or strictly greater */
> > + return foundless ? LESS : GREATER;
> > +}
> > +
> > +static ir_constant *
> > +combine_constant(bool ismin, ir_constant *a, ir_constant *b)
> > +{
> > + void *mem_ctx = ralloc_parent(a);
> > + ir_constant *c = a->clone(mem_ctx, NULL);
> > + for (unsigned i = 0; i < c->type->components(); i++) {
> > + switch (c->type->base_type) {
> > + case GLSL_TYPE_UINT:
> > + if ((ismin && b->value.u[i] < c->value.u[i]) ||
> > + (!ismin && b->value.u[i] > c->value.u[i]))
> > + c->value.u[i] = b->value.u[i];
> > + break;
> > + case GLSL_TYPE_INT:
> > + if ((ismin && b->value.i[i] < c->value.i[i]) ||
> > + (!ismin && b->value.i[i] > c->value.i[i]))
> > + c->value.i[i] = b->value.i[i];
> > + break;
> > + case GLSL_TYPE_FLOAT:
> > + if ((ismin && b->value.f[i] < c->value.f[i]) ||
> > + (!ismin && b->value.f[i] > c->value.f[i]))
> > + c->value.f[i] = b->value.f[i];
> > + break;
> > + default:
> > + assert(!"not reached");
> > + }
> > + }
> > + return c;
> > +}
> > +
> > +static ir_constant *
> > +smaller_constant(ir_constant *a, ir_constant *b)
> > +{
> > + assert(a != NULL);
> > + assert(b != NULL);
> > +
> > + enum compare_components_result ret = compare_components(a, b);
> > + if (ret == MIXED)
> > + return combine_constant(true, a, b);
> > + else if (ret < EQUAL)
> > + return a;
> > + else
> > + return b;
> > +}
> > +
> > +static ir_constant *
> > +larger_constant(ir_constant *a, ir_constant *b)
> > +{
> > + assert(a != NULL);
> > + assert(b != NULL);
> > +
> > + enum compare_components_result ret = compare_components(a, b);
> > + if (ret == MIXED)
> > + return combine_constant(false, a, b);
> > + else if (ret < EQUAL)
> > + return b;
> > + else
> > + return a;
> > +}
> > +
> > +/* Combines two ranges by doing an element-wise min() / max() depending on
> > the
> > + * operation.
> > + */
> > +static minmax_range
> > +combine_range(minmax_range r0, minmax_range r1, bool ismin)
> > +{
> > + minmax_range ret;
> > +
> > + if (!r0.low) {
> > + ret.low = ismin ? r0.low : r1.low;
> > + } else if (!r1.low) {
> > + ret.low = ismin ? r1.low : r0.low;
> > + } else {
> > + ret.low = ismin ? smaller_constant(r0.low, r1.low) :
> > + larger_constant(r0.low, r1.low);
> > + }
> > +
> > + if (!r0.high) {
> > + ret.high = ismin ? r1.high : r0.high;
> > + } else if (!r1.high) {
> > + ret.high = ismin ? r0.high : r1.high;
> > + } else {
> > + ret.high = ismin ? smaller_constant(r0.high, r1.high) :
> > + larger_constant(r0.high, r1.high);
> > + }
> > +
> > + 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.
> > + */
> > +static minmax_range
> > +range_intersection(minmax_range r0, minmax_range r1)
> > +{
> > + minmax_range ret;
> > +
> > + if (!r0.low)
> > + ret.low = r1.low;
> > + else if (!r1.low)
> > + ret.low = r0.low;
> > + else
> > + ret.low = larger_constant(r0.low, r1.low);
> > +
> > + if (!r0.high)
> > + ret.high = r1.high;
> > + else if (!r1.high)
> > + ret.high = r0.high;
> > + else
> > + ret.high = smaller_constant(r0.high, r1.high);
> > +
> > + return ret;
> > +}
> > +
> > +static minmax_range
> > +get_range(ir_rvalue *rval)
> > +{
> > + ir_expression *expr = rval->as_expression();
> > + if (expr && (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);
> > + }
> > +
> > + ir_constant *c = rval->as_constant();
> > + if (c) {
> > + return minmax_range(c, c);
> > + }
> > +
> > + return minmax_range();
> > +}
> > +
> > +/**
> > + * Prunes a min/max expression considering the base range of the parent
> > + * min/max expression.
> > + *
> > + * @param baserange the range that the parents of this min/max expression
> > + * in the min/max tree will clamp its value to.
> > + */
> > +ir_rvalue *
> > +ir_minmax_visitor::prune_expression(ir_expression *expr, minmax_range
> > baserange)
> > +{
> > + assert(expr->operation == ir_binop_min ||
> > + expr->operation == ir_binop_max);
> > +
> > + bool ismin = expr->operation == ir_binop_min;
> > + minmax_range limits[2];
> > +
> > + /* Recurse to get the ranges for each of the subtrees of this
> > + * expression. We need to do this as a separate step because we need to
> > + * know the ranges of each of the subtrees before we prune either one.
> > + * Consider something like this:
> > + *
> > + * max
> > + * / \
> > + * max max
> > + * / \ / \
> > + * 3 a b 2
> > + *
> > + * We would like to prune away the max on the bottom-right, but to do so
> > + * we need to know the range of the expression on the left beforehand,
> > + * and there's no guarantee that we will visit either subtree in a
> > + * particular order.
> > + */
> > + for (unsigned i = 0; i < 2; ++i)
> > + limits[i] = get_range(expr->operands[i]);
> > +
> > + for (unsigned i = 0; i < 2; ++i) {
> > + bool is_redundant = false;
> > +
> > + enum compare_components_result cr = LESS;
> > + if (ismin) {
> > + /* If this operand will always be greater than the other one, it's
> > + * redundant.
> > + */
> > + if (limits[i].low && limits[1 - i].high) {
> > + cr = compare_components(limits[i].low, limits[1 - i].high);
> > + if (cr >= EQUAL && cr != MIXED)
> > + is_redundant = true;
> > + }
> > + /* If this operand is always greater than baserange, then even if
> > + * it's smaller than the other one it'll get clamped, so it's
> > + * redundant.
> > + */
> > + if (!is_redundant && limits[i].low && baserange.high) {
> > + cr = compare_components(limits[i].low, baserange.high);
> > + if (cr >= EQUAL && cr != MIXED)
> > + is_redundant = true;
> > + }
> > + } else {
> > + /* If this operand will always be lower than the other one, it's
> > + * redundant.
> > + */
> > + if (limits[i].high && limits[1 - i].low) {
> > + cr = compare_components(limits[i].high, limits[1 - i].low);
> > + if (cr <= EQUAL)
> > + is_redundant = true;
> > + }
> > + /* If this operand is always lower than baserange, then even if
> > + * it's greater than the other one it'll get clamped, so it's
> > + * redundant.
> > + */
> > + if (!is_redundant && limits[i].high && baserange.low) {
> > + cr = compare_components(limits[i].high, baserange.low);
> > + if (cr <= EQUAL)
> > + is_redundant = true;
> > + }
> > + }
> > +
> > + if (is_redundant) {
> > + progress = true;
> > +
> > + /* Recurse if necessary. */
> > + ir_expression *op_expr = expr->operands[1 - i]->as_expression();
> > + if (op_expr && (op_expr->operation == ir_binop_min ||
> > + op_expr->operation == ir_binop_max)) {
> > + return prune_expression(op_expr, baserange);
> > + }
> > +
> > + return expr->operands[1 - i];
> > + } else if (cr == MIXED) {
> > + /* If we have mixed vector operands, we can try to resolve the
> > minmax
> > + * expression by doing a component-wise minmax:
> > + *
> > + * min min
> > + * / \ / \
> > + * min a ===> [1,1] a
> > + * / \
> > + * [1,3] [3,1]
> > + *
> > + */
> > + ir_constant *a = expr->operands[0]->as_constant();
> > + ir_constant *b = expr->operands[1]->as_constant();
> > + if (a && b)
> > + return combine_constant(ismin, a, b);
> > + }
> > + }
> > +
> > + /* 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. If we can't compute a valid
> > + * intersection, we use the current baserange.
> > + */
> > + for (unsigned i = 0; i < 2; ++i) {
> > + ir_expression *op_expr = expr->operands[i]->as_expression();
> > + if (op_expr && (op_expr->operation == ir_binop_min ||
> > + op_expr->operation == ir_binop_max)) {
> > + /* We can only compute a new baserange for this operand if we
> > managed
> > + * to compute a valid range for the other operand.
> > + */
> > + if (ismin)
> > + limits[1 - i].low = NULL;
> > + else
> > + limits[1 - i].high = NULL;
> > + minmax_range base = range_intersection(limits[1 - i], baserange);
> > + expr->operands[i] = prune_expression(op_expr, base);
> > + }
> > + }
> > +
> > + return expr;
> > +}
> > +
> > +static ir_rvalue *
> > +swizzle_if_required(ir_expression *expr, ir_rvalue *rval)
> > +{
> > + if (expr->type->is_vector() && rval->type->is_scalar()) {
> > + return swizzle(rval, SWIZZLE_XXXX, 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 (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;
> > +}
> > --
> > 1.9.1
> >
>
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