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/*
* Copyright © 2022 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.
*/
#include "nir.h"
static nir_alu_type
nir_alu_src_type(const nir_alu_instr *instr, unsigned src)
{
return nir_alu_type_get_base_type(nir_op_infos[instr->op].input_types[src]) |
nir_src_bit_size(instr->src[src].src);
}
static nir_ssa_scalar
nir_alu_arg(const nir_alu_instr *alu, unsigned arg, unsigned comp)
{
const nir_alu_src *src = &alu->src[arg];
return nir_get_ssa_scalar(src->src.ssa, src->swizzle[comp]);
}
/* Tries to determine the value of expression "val % div", assuming that val
* is interpreted as value of type "val_type". "div" must be a power of two.
* Returns true if it can statically tell the value of "val % div", false if not.
* Value of *mod is undefined if this function returned false.
*
* Tests are in mod_analysis_tests.cpp.
*/
bool
nir_mod_analysis(nir_ssa_scalar val, nir_alu_type val_type, unsigned div, unsigned *mod)
{
if (div == 1) {
*mod = 0;
return true;
}
assert(util_is_power_of_two_nonzero(div));
switch (val.def->parent_instr->type) {
case nir_instr_type_load_const: {
nir_load_const_instr *load =
nir_instr_as_load_const(val.def->parent_instr);
nir_alu_type base_type = nir_alu_type_get_base_type(val_type);
if (base_type == nir_type_uint) {
assert(val.comp < load->def.num_components);
uint64_t ival = nir_const_value_as_uint(load->value[val.comp],
load->def.bit_size);
*mod = ival % div;
return true;
} else if (base_type == nir_type_int) {
assert(val.comp < load->def.num_components);
int64_t ival = nir_const_value_as_int(load->value[val.comp],
load->def.bit_size);
/* whole analysis collapses the moment we allow negative values */
if (ival < 0)
return false;
*mod = ((uint64_t)ival) % div;
return true;
}
break;
}
case nir_instr_type_alu: {
nir_alu_instr *alu = nir_instr_as_alu(val.def->parent_instr);
if (alu->dest.dest.ssa.num_components != 1)
return false;
switch (alu->op) {
case nir_op_ishr: {
if (nir_src_is_const(alu->src[1].src)) {
assert(alu->src[1].src.ssa->num_components == 1);
uint64_t shift = nir_src_as_uint(alu->src[1].src);
if (util_last_bit(div) + shift > 32)
break;
nir_alu_type type0 = nir_alu_src_type(alu, 0);
if (!nir_mod_analysis(nir_alu_arg(alu, 0, val.comp), type0, div << shift, mod))
return false;
*mod >>= shift;
return true;
}
break;
}
case nir_op_iadd: {
unsigned mod0;
nir_alu_type type0 = nir_alu_src_type(alu, 0);
if (!nir_mod_analysis(nir_alu_arg(alu, 0, val.comp), type0, div, &mod0))
return false;
unsigned mod1;
nir_alu_type type1 = nir_alu_src_type(alu, 1);
if (!nir_mod_analysis(nir_alu_arg(alu, 1, val.comp), type1, div, &mod1))
return false;
*mod = (mod0 + mod1) % div;
return true;
}
case nir_op_ishl: {
if (nir_src_is_const(alu->src[1].src)) {
assert(alu->src[1].src.ssa->num_components == 1);
uint64_t shift = nir_src_as_uint(alu->src[1].src);
if ((div >> shift) == 0) {
*mod = 0;
return true;
}
nir_alu_type type0 = nir_alu_src_type(alu, 0);
return nir_mod_analysis(nir_alu_arg(alu, 0, val.comp), type0, div >> shift, mod);
}
break;
}
case nir_op_imul_32x16: /* multiply 32-bits with low 16-bits */
case nir_op_imul: {
unsigned mod0;
nir_alu_type type0 = nir_alu_src_type(alu, 0);
bool s1 = nir_mod_analysis(nir_alu_arg(alu, 0, val.comp), type0, div, &mod0);
if (s1 && (mod0 == 0)) {
*mod = 0;
return true;
}
/* if divider is larger than 2nd source max (interpreted) value
* then modulo of multiplication is unknown
*/
if (alu->op == nir_op_imul_32x16 && div > (1u << 16))
return false;
unsigned mod1;
nir_alu_type type1 = nir_alu_src_type(alu, 1);
bool s2 = nir_mod_analysis(nir_alu_arg(alu, 1, val.comp), type1, div, &mod1);
if (s2 && (mod1 == 0)) {
*mod = 0;
return true;
}
if (!s1 || !s2)
return false;
*mod = (mod0 * mod1) % div;
return true;
}
default:
break;
}
break;
}
default:
break;
}
return false;
}
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