src/compiler/nir/nir_opt_constant_folding.c - platform/external/mesa3d - Git at Google

 /*
  * 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.
  *
  * Authors:
  *    Jason Ekstrand (jason@jlekstrand.net)
  *
  */

 #include "nir_constant_expressions.h"
 #include <math.h>

 /*
  * Implements SSA-based constant folding.
  */

 struct constant_fold_state {
    nir_shader *shader;
    unsigned execution_mode;
    bool has_load_constant;
    bool has_indirect_load_const;
 };

 static bool
 constant_fold_alu_instr(struct constant_fold_state *state, nir_alu_instr *instr)
 {
    nir_const_value src[NIR_MAX_VEC_COMPONENTS][NIR_MAX_VEC_COMPONENTS];

    if (!instr->dest.dest.is_ssa)
       return false;

    /* In the case that any outputs/inputs have unsized types, then we need to
     * guess the bit-size. In this case, the validator ensures that all
     * bit-sizes match so we can just take the bit-size from first
     * output/input with an unsized type. If all the outputs/inputs are sized
     * then we don't need to guess the bit-size at all because the code we
     * generate for constant opcodes in this case already knows the sizes of
     * the types involved and does not need the provided bit-size for anything
     * (although it still requires to receive a valid bit-size).
     */
    unsigned bit_size = 0;
    if (!nir_alu_type_get_type_size(nir_op_infos[instr->op].output_type))
       bit_size = instr->dest.dest.ssa.bit_size;

    for (unsigned i = 0; i < nir_op_infos[instr->op].num_inputs; i++) {
       if (!instr->src[i].src.is_ssa)
          return false;

       if (bit_size == 0 &&
           !nir_alu_type_get_type_size(nir_op_infos[instr->op].input_types[i]))
          bit_size = instr->src[i].src.ssa->bit_size;

       nir_instr *src_instr = instr->src[i].src.ssa->parent_instr;

       if (src_instr->type != nir_instr_type_load_const)
          return false;
       nir_load_const_instr* load_const = nir_instr_as_load_const(src_instr);

       for (unsigned j = 0; j < nir_ssa_alu_instr_src_components(instr, i);
            j++) {
          src[i][j] = load_const->value[instr->src[i].swizzle[j]];
       }

       /* We shouldn't have any source modifiers in the optimization loop. */
       assert(!instr->src[i].abs && !instr->src[i].negate);
    }

    if (bit_size == 0)
       bit_size = 32;

    /* We shouldn't have any saturate modifiers in the optimization loop. */
    assert(!instr->dest.saturate);

    nir_const_value dest[NIR_MAX_VEC_COMPONENTS];
    nir_const_value *srcs[NIR_MAX_VEC_COMPONENTS];
    memset(dest, 0, sizeof(dest));
    for (unsigned i = 0; i < nir_op_infos[instr->op].num_inputs; ++i)
       srcs[i] = src[i];
    nir_eval_const_opcode(instr->op, dest, instr->dest.dest.ssa.num_components,
                          bit_size, srcs, state->execution_mode);

    nir_load_const_instr *new_instr =
       nir_load_const_instr_create(state->shader,
                                   instr->dest.dest.ssa.num_components,
                                   instr->dest.dest.ssa.bit_size);

    memcpy(new_instr->value, dest, sizeof(*new_instr->value) * new_instr->def.num_components);

    nir_instr_insert_before(&instr->instr, &new_instr->instr);

    nir_ssa_def_rewrite_uses(&instr->dest.dest.ssa,
                             nir_src_for_ssa(&new_instr->def));

    nir_instr_remove(&instr->instr);
    ralloc_free(instr);

    return true;
 }

 static bool
 constant_fold_intrinsic_instr(struct constant_fold_state *state, nir_intrinsic_instr *instr)
 {
    bool progress = false;

    if ((instr->intrinsic == nir_intrinsic_demote_if ||
         instr->intrinsic == nir_intrinsic_discard_if) &&
        nir_src_is_const(instr->src[0])) {
       if (nir_src_as_bool(instr->src[0])) {
          nir_intrinsic_op op = instr->intrinsic == nir_intrinsic_discard_if ?
                                nir_intrinsic_discard :
                                nir_intrinsic_demote;
          nir_intrinsic_instr *new_instr = nir_intrinsic_instr_create(state->shader, op);
          nir_instr_insert_before(&instr->instr, &new_instr->instr);
          nir_instr_remove(&instr->instr);
          progress = true;
       } else {
          /* We're not discarding, just delete the instruction */
          nir_instr_remove(&instr->instr);
          progress = true;
       }
    } else if (instr->intrinsic == nir_intrinsic_load_constant) {
       state->has_load_constant = true;

       if (!nir_src_is_const(instr->src[0])) {
          state->has_indirect_load_const = true;
          return progress;
       }

       unsigned offset = nir_src_as_uint(instr->src[0]);
       unsigned base = nir_intrinsic_base(instr);
       unsigned range = nir_intrinsic_range(instr);
       assert(base + range <= state->shader->constant_data_size);

       nir_instr *new_instr = NULL;
       if (offset >= range) {
          nir_ssa_undef_instr *undef =
             nir_ssa_undef_instr_create(state->shader,
                                        instr->num_components,
                                        instr->dest.ssa.bit_size);

          nir_ssa_def_rewrite_uses(&instr->dest.ssa, nir_src_for_ssa(&undef->def));
          new_instr = &undef->instr;
       } else {
          nir_load_const_instr *load_const =
             nir_load_const_instr_create(state->shader,
                                         instr->num_components,
                                         instr->dest.ssa.bit_size);

          uint8_t *data = (uint8_t*)state->shader->constant_data + base;
          for (unsigned i = 0; i < instr->num_components; i++) {
             unsigned bytes = instr->dest.ssa.bit_size / 8;
             bytes = MIN2(bytes, range - offset);

             memcpy(&load_const->value[i].u64, data + offset, bytes);
             offset += bytes;
          }

          nir_ssa_def_rewrite_uses(&instr->dest.ssa, nir_src_for_ssa(&load_const->def));
          new_instr = &load_const->instr;
       }

       nir_instr_insert_before(&instr->instr, new_instr);
       nir_instr_remove(&instr->instr);
       progress = true;
    }

    return progress;
 }

 static bool
 constant_fold_block(struct constant_fold_state *state, nir_block *block)
 {
    bool progress = false;

    nir_foreach_instr_safe(instr, block) {
       switch (instr->type) {
       case nir_instr_type_alu:
          progress |= constant_fold_alu_instr(state, nir_instr_as_alu(instr));
          break;
       case nir_instr_type_intrinsic:
          progress |=
             constant_fold_intrinsic_instr(state, nir_instr_as_intrinsic(instr));
          break;
       default:
          /* Don't know how to constant fold */
          break;
       }
    }

    return progress;
 }

 static bool
 nir_opt_constant_folding_impl(struct constant_fold_state *state, nir_function_impl *impl)
 {
    bool progress = false;

    nir_foreach_block(block, impl) {
       progress |= constant_fold_block(state, block);
    }

    if (progress) {
       nir_metadata_preserve(impl, nir_metadata_block_index |
                                   nir_metadata_dominance);
    } else {
       nir_metadata_preserve(impl, nir_metadata_all);
    }

    return progress;
 }

 bool
 nir_opt_constant_folding(nir_shader *shader)
 {
    bool progress = false;
    struct constant_fold_state state;
    state.shader = shader;
    state.execution_mode = shader->info.float_controls_execution_mode;
    state.has_load_constant = false;
    state.has_indirect_load_const = false;

    nir_foreach_function(function, shader) {
       if (function->impl)
          progress |= nir_opt_constant_folding_impl(&state, function->impl);
    }

    /* This doesn't free the constant data if there are no constant loads because
     * the data might still be used but the loads have been lowered to load_ubo
     */
    if (state.has_load_constant && !state.has_indirect_load_const &&
        shader->constant_data_size) {
       ralloc_free(shader->constant_data);
       shader->constant_data = NULL;
       shader->constant_data_size = 0;
    }

    return progress;
 }
	/*
	* 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.
	*
	* Authors:
	* Jason Ekstrand (jason@jlekstrand.net)
	*
	*/

	#include "nir_constant_expressions.h"
	#include <math.h>

	/*
	* Implements SSA-based constant folding.
	*/

	struct constant_fold_state {
	nir_shader *shader;
	unsigned execution_mode;
	bool has_load_constant;
	bool has_indirect_load_const;
	};

	static bool
	constant_fold_alu_instr(struct constant_fold_state state, nir_alu_instr instr)
	{
	nir_const_value src[NIR_MAX_VEC_COMPONENTS][NIR_MAX_VEC_COMPONENTS];

	if (!instr->dest.dest.is_ssa)
	return false;

	/* In the case that any outputs/inputs have unsized types, then we need to
	* guess the bit-size. In this case, the validator ensures that all
	* bit-sizes match so we can just take the bit-size from first
	* output/input with an unsized type. If all the outputs/inputs are sized
	* then we don't need to guess the bit-size at all because the code we
	* generate for constant opcodes in this case already knows the sizes of
	* the types involved and does not need the provided bit-size for anything
	* (although it still requires to receive a valid bit-size).
	*/
	unsigned bit_size = 0;
	if (!nir_alu_type_get_type_size(nir_op_infos[instr->op].output_type))
	bit_size = instr->dest.dest.ssa.bit_size;

	for (unsigned i = 0; i < nir_op_infos[instr->op].num_inputs; i++) {
	if (!instr->src[i].src.is_ssa)
	return false;

	if (bit_size == 0 &&
	!nir_alu_type_get_type_size(nir_op_infos[instr->op].input_types[i]))
	bit_size = instr->src[i].src.ssa->bit_size;

	nir_instr *src_instr = instr->src[i].src.ssa->parent_instr;

	if (src_instr->type != nir_instr_type_load_const)
	return false;
	nir_load_const_instr* load_const = nir_instr_as_load_const(src_instr);

	for (unsigned j = 0; j < nir_ssa_alu_instr_src_components(instr, i);
	j++) {
	src[i][j] = load_const->value[instr->src[i].swizzle[j]];
	}

	/* We shouldn't have any source modifiers in the optimization loop. */
	assert(!instr->src[i].abs && !instr->src[i].negate);
	}

	if (bit_size == 0)
	bit_size = 32;

	/* We shouldn't have any saturate modifiers in the optimization loop. */
	assert(!instr->dest.saturate);

	nir_const_value dest[NIR_MAX_VEC_COMPONENTS];
	nir_const_value *srcs[NIR_MAX_VEC_COMPONENTS];
	memset(dest, 0, sizeof(dest));
	for (unsigned i = 0; i < nir_op_infos[instr->op].num_inputs; ++i)
	srcs[i] = src[i];
	nir_eval_const_opcode(instr->op, dest, instr->dest.dest.ssa.num_components,
	bit_size, srcs, state->execution_mode);

	nir_load_const_instr *new_instr =
	nir_load_const_instr_create(state->shader,
	instr->dest.dest.ssa.num_components,
	instr->dest.dest.ssa.bit_size);

	memcpy(new_instr->value, dest, sizeof(new_instr->value) new_instr->def.num_components);

	nir_instr_insert_before(&instr->instr, &new_instr->instr);

	nir_ssa_def_rewrite_uses(&instr->dest.dest.ssa,
	nir_src_for_ssa(&new_instr->def));

	nir_instr_remove(&instr->instr);
	ralloc_free(instr);

	return true;
	}

	static bool
	constant_fold_intrinsic_instr(struct constant_fold_state state, nir_intrinsic_instr instr)
	{
	bool progress = false;

	if ((instr->intrinsic == nir_intrinsic_demote_if \|\|
	instr->intrinsic == nir_intrinsic_discard_if) &&
	nir_src_is_const(instr->src[0])) {
	if (nir_src_as_bool(instr->src[0])) {
	nir_intrinsic_op op = instr->intrinsic == nir_intrinsic_discard_if ?
	nir_intrinsic_discard :
	nir_intrinsic_demote;
	nir_intrinsic_instr *new_instr = nir_intrinsic_instr_create(state->shader, op);
	nir_instr_insert_before(&instr->instr, &new_instr->instr);
	nir_instr_remove(&instr->instr);
	progress = true;
	} else {
	/* We're not discarding, just delete the instruction */
	nir_instr_remove(&instr->instr);
	progress = true;
	}
	} else if (instr->intrinsic == nir_intrinsic_load_constant) {
	state->has_load_constant = true;

	if (!nir_src_is_const(instr->src[0])) {
	state->has_indirect_load_const = true;
	return progress;
	}

	unsigned offset = nir_src_as_uint(instr->src[0]);
	unsigned base = nir_intrinsic_base(instr);
	unsigned range = nir_intrinsic_range(instr);
	assert(base + range <= state->shader->constant_data_size);

	nir_instr *new_instr = NULL;
	if (offset >= range) {
	nir_ssa_undef_instr *undef =
	nir_ssa_undef_instr_create(state->shader,
	instr->num_components,
	instr->dest.ssa.bit_size);

	nir_ssa_def_rewrite_uses(&instr->dest.ssa, nir_src_for_ssa(&undef->def));
	new_instr = &undef->instr;
	} else {
	nir_load_const_instr *load_const =
	nir_load_const_instr_create(state->shader,
	instr->num_components,
	instr->dest.ssa.bit_size);

	uint8_t data = (uint8_t)state->shader->constant_data + base;
	for (unsigned i = 0; i < instr->num_components; i++) {
	unsigned bytes = instr->dest.ssa.bit_size / 8;
	bytes = MIN2(bytes, range - offset);

	memcpy(&load_const->value[i].u64, data + offset, bytes);
	offset += bytes;
	}

	nir_ssa_def_rewrite_uses(&instr->dest.ssa, nir_src_for_ssa(&load_const->def));
	new_instr = &load_const->instr;
	}

	nir_instr_insert_before(&instr->instr, new_instr);
	nir_instr_remove(&instr->instr);
	progress = true;
	}

	return progress;
	}

	static bool
	constant_fold_block(struct constant_fold_state state, nir_block block)
	{
	bool progress = false;

	nir_foreach_instr_safe(instr, block) {
	switch (instr->type) {
	case nir_instr_type_alu:
	progress \|= constant_fold_alu_instr(state, nir_instr_as_alu(instr));
	break;
	case nir_instr_type_intrinsic:
	progress \|=
	constant_fold_intrinsic_instr(state, nir_instr_as_intrinsic(instr));
	break;
	default:
	/* Don't know how to constant fold */
	break;
	}
	}

	return progress;
	}

	static bool
	nir_opt_constant_folding_impl(struct constant_fold_state state, nir_function_impl impl)
	{
	bool progress = false;

	nir_foreach_block(block, impl) {
	progress \|= constant_fold_block(state, block);
	}

	if (progress) {
	nir_metadata_preserve(impl, nir_metadata_block_index \|
	nir_metadata_dominance);
	} else {
	nir_metadata_preserve(impl, nir_metadata_all);
	}

	return progress;
	}

	bool
	nir_opt_constant_folding(nir_shader *shader)
	{
	bool progress = false;
	struct constant_fold_state state;
	state.shader = shader;
	state.execution_mode = shader->info.float_controls_execution_mode;
	state.has_load_constant = false;
	state.has_indirect_load_const = false;

	nir_foreach_function(function, shader) {
	if (function->impl)
	progress \|= nir_opt_constant_folding_impl(&state, function->impl);
	}

	/* This doesn't free the constant data if there are no constant loads because
	* the data might still be used but the loads have been lowered to load_ubo
	*/
	if (state.has_load_constant && !state.has_indirect_load_const &&
	shader->constant_data_size) {
	ralloc_free(shader->constant_data);
	shader->constant_data = NULL;
	shader->constant_data_size = 0;
	}

	return progress;
	}