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android / platform / external / mesa3d / 7f6c6b910156629f988277ef0c177a2e97ca17e0 / . / src / compiler / glsl / lower_instructions.cpp
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/*
* Copyright © 2010 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 lower_instructions.cpp
*
* Many GPUs lack native instructions for certain expression operations, and
* must replace them with some other expression tree. This pass lowers some
* of the most common cases, allowing the lowering code to be implemented once
* rather than in each driver backend.
*
* Currently supported transformations:
* - SUB_TO_ADD_NEG
* - DIV_TO_MUL_RCP
* - INT_DIV_TO_MUL_RCP
* - EXP_TO_EXP2
* - POW_TO_EXP2
* - LOG_TO_LOG2
* - MOD_TO_FLOOR
* - LDEXP_TO_ARITH
* - DFREXP_TO_ARITH
* - CARRY_TO_ARITH
* - BORROW_TO_ARITH
* - SAT_TO_CLAMP
* - DOPS_TO_DFRAC
*
* SUB_TO_ADD_NEG:
* ---------------
* Breaks an ir_binop_sub expression down to add(op0, neg(op1))
*
* This simplifies expression reassociation, and for many backends
* there is no subtract operation separate from adding the negation.
* For backends with native subtract operations, they will probably
* want to recognize add(op0, neg(op1)) or the other way around to
* produce a subtract anyway.
*
* FDIV_TO_MUL_RCP, DDIV_TO_MUL_RCP, and INT_DIV_TO_MUL_RCP:
* ---------------------------------------------------------
* Breaks an ir_binop_div expression down to op0 * (rcp(op1)).
*
* Many GPUs don't have a divide instruction (945 and 965 included),
* but they do have an RCP instruction to compute an approximate
* reciprocal. By breaking the operation down, constant reciprocals
* can get constant folded.
*
* FDIV_TO_MUL_RCP only lowers single-precision floating point division;
* DDIV_TO_MUL_RCP only lowers double-precision floating point division.
* DIV_TO_MUL_RCP is a convenience macro that sets both flags.
* INT_DIV_TO_MUL_RCP handles the integer case, converting to and from floating
* point so that RCP is possible.
*
* EXP_TO_EXP2 and LOG_TO_LOG2:
* ----------------------------
* Many GPUs don't have a base e log or exponent instruction, but they
* do have base 2 versions, so this pass converts exp and log to exp2
* and log2 operations.
*
* POW_TO_EXP2:
* -----------
* Many older GPUs don't have an x**y instruction. For these GPUs, convert
* x**y to 2**(y * log2(x)).
*
* MOD_TO_FLOOR:
* -------------
* Breaks an ir_binop_mod expression down to (op0 - op1 * floor(op0 / op1))
*
* Many GPUs don't have a MOD instruction (945 and 965 included), and
* if we have to break it down like this anyway, it gives an
* opportunity to do things like constant fold the (1.0 / op1) easily.
*
* Note: before we used to implement this as op1 * fract(op / op1) but this
* implementation had significant precision errors.
*
* LDEXP_TO_ARITH:
* -------------
* Converts ir_binop_ldexp to arithmetic and bit operations for float sources.
*
* DFREXP_DLDEXP_TO_ARITH:
* ---------------
* Converts ir_binop_ldexp, ir_unop_frexp_sig, and ir_unop_frexp_exp to
* arithmetic and bit ops for double arguments.
*
* CARRY_TO_ARITH:
* ---------------
* Converts ir_carry into (x + y) < x.
*
* BORROW_TO_ARITH:
* ----------------
* Converts ir_borrow into (x < y).
*
* SAT_TO_CLAMP:
* -------------
* Converts ir_unop_saturate into min(max(x, 0.0), 1.0)
*
* DOPS_TO_DFRAC:
* --------------
* Converts double trunc, ceil, floor, round to fract
*/
#include "c99_math.h"
#include "program/prog_instruction.h" /* for swizzle */
#include "compiler/glsl_types.h"
#include "ir.h"
#include "ir_builder.h"
#include "ir_optimization.h"
using namespace ir_builder;
namespace {
class lower_instructions_visitor : public ir_hierarchical_visitor {
public:
lower_instructions_visitor(unsigned lower)
: progress(false), lower(lower) { }
ir_visitor_status visit_leave(ir_expression *);
bool progress;
private:
unsigned lower; /** Bitfield of which operations to lower */
void sub_to_add_neg(ir_expression *);
void div_to_mul_rcp(ir_expression *);
void int_div_to_mul_rcp(ir_expression *);
void mod_to_floor(ir_expression *);
void exp_to_exp2(ir_expression *);
void pow_to_exp2(ir_expression *);
void log_to_log2(ir_expression *);
void ldexp_to_arith(ir_expression *);
void dldexp_to_arith(ir_expression *);
void dfrexp_sig_to_arith(ir_expression *);
void dfrexp_exp_to_arith(ir_expression *);
void carry_to_arith(ir_expression *);
void borrow_to_arith(ir_expression *);
void sat_to_clamp(ir_expression *);
void double_dot_to_fma(ir_expression *);
void double_lrp(ir_expression *);
void dceil_to_dfrac(ir_expression *);
void dfloor_to_dfrac(ir_expression *);
void dround_even_to_dfrac(ir_expression *);
void dtrunc_to_dfrac(ir_expression *);
void dsign_to_csel(ir_expression *);
void bit_count_to_math(ir_expression *);
void extract_to_shifts(ir_expression *);
void insert_to_shifts(ir_expression *);
void reverse_to_shifts(ir_expression *ir);
void find_lsb_to_float_cast(ir_expression *ir);
void find_msb_to_float_cast(ir_expression *ir);
void imul_high_to_mul(ir_expression *ir);
ir_expression *_carry(operand a, operand b);
};
} /* anonymous namespace */
/**
* Determine if a particular type of lowering should occur
*/
#define lowering(x) (this->lower & x)
bool
lower_instructions(exec_list *instructions, unsigned what_to_lower)
{
lower_instructions_visitor v(what_to_lower);
visit_list_elements(&v, instructions);
return v.progress;
}
void
lower_instructions_visitor::sub_to_add_neg(ir_expression *ir)
{
ir->operation = ir_binop_add;
ir->operands[1] = new(ir) ir_expression(ir_unop_neg, ir->operands[1]->type,
ir->operands[1], NULL);
this->progress = true;
}
void
lower_instructions_visitor::div_to_mul_rcp(ir_expression *ir)
{
assert(ir->operands[1]->type->is_float() || ir->operands[1]->type->is_double());
/* New expression for the 1.0 / op1 */
ir_rvalue *expr;
expr = new(ir) ir_expression(ir_unop_rcp,
ir->operands[1]->type,
ir->operands[1]);
/* op0 / op1 -> op0 * (1.0 / op1) */
ir->operation = ir_binop_mul;
ir->operands[1] = expr;
this->progress = true;
}
void
lower_instructions_visitor::int_div_to_mul_rcp(ir_expression *ir)
{
assert(ir->operands[1]->type->is_integer());
/* Be careful with integer division -- we need to do it as a
* float and re-truncate, since rcp(n > 1) of an integer would
* just be 0.
*/
ir_rvalue *op0, *op1;
const struct glsl_type *vec_type;
vec_type = glsl_type::get_instance(GLSL_TYPE_FLOAT,
ir->operands[1]->type->vector_elements,
ir->operands[1]->type->matrix_columns);
if (ir->operands[1]->type->base_type == GLSL_TYPE_INT)
op1 = new(ir) ir_expression(ir_unop_i2f, vec_type, ir->operands[1], NULL);
else
op1 = new(ir) ir_expression(ir_unop_u2f, vec_type, ir->operands[1], NULL);
op1 = new(ir) ir_expression(ir_unop_rcp, op1->type, op1, NULL);
vec_type = glsl_type::get_instance(GLSL_TYPE_FLOAT,
ir->operands[0]->type->vector_elements,
ir->operands[0]->type->matrix_columns);
if (ir->operands[0]->type->base_type == GLSL_TYPE_INT)
op0 = new(ir) ir_expression(ir_unop_i2f, vec_type, ir->operands[0], NULL);
else
op0 = new(ir) ir_expression(ir_unop_u2f, vec_type, ir->operands[0], NULL);
vec_type = glsl_type::get_instance(GLSL_TYPE_FLOAT,
ir->type->vector_elements,
ir->type->matrix_columns);
op0 = new(ir) ir_expression(ir_binop_mul, vec_type, op0, op1);
if (ir->operands[1]->type->base_type == GLSL_TYPE_INT) {
ir->operation = ir_unop_f2i;
ir->operands[0] = op0;
} else {
ir->operation = ir_unop_i2u;
ir->operands[0] = new(ir) ir_expression(ir_unop_f2i, op0);
}
ir->operands[1] = NULL;
this->progress = true;
}
void
lower_instructions_visitor::exp_to_exp2(ir_expression *ir)
{
ir_constant *log2_e = new(ir) ir_constant(float(M_LOG2E));
ir->operation = ir_unop_exp2;
ir->operands[0] = new(ir) ir_expression(ir_binop_mul, ir->operands[0]->type,
ir->operands[0], log2_e);
this->progress = true;
}
void
lower_instructions_visitor::pow_to_exp2(ir_expression *ir)
{
ir_expression *const log2_x =
new(ir) ir_expression(ir_unop_log2, ir->operands[0]->type,
ir->operands[0]);
ir->operation = ir_unop_exp2;
ir->operands[0] = new(ir) ir_expression(ir_binop_mul, ir->operands[1]->type,
ir->operands[1], log2_x);
ir->operands[1] = NULL;
this->progress = true;
}
void
lower_instructions_visitor::log_to_log2(ir_expression *ir)
{
ir->operation = ir_binop_mul;
ir->operands[0] = new(ir) ir_expression(ir_unop_log2, ir->operands[0]->type,
ir->operands[0], NULL);
ir->operands[1] = new(ir) ir_constant(float(1.0 / M_LOG2E));
this->progress = true;
}
void
lower_instructions_visitor::mod_to_floor(ir_expression *ir)
{
ir_variable *x = new(ir) ir_variable(ir->operands[0]->type, "mod_x",
ir_var_temporary);
ir_variable *y = new(ir) ir_variable(ir->operands[1]->type, "mod_y",
ir_var_temporary);
this->base_ir->insert_before(x);
this->base_ir->insert_before(y);
ir_assignment *const assign_x =
new(ir) ir_assignment(new(ir) ir_dereference_variable(x),
ir->operands[0], NULL);
ir_assignment *const assign_y =
new(ir) ir_assignment(new(ir) ir_dereference_variable(y),
ir->operands[1], NULL);
this->base_ir->insert_before(assign_x);
this->base_ir->insert_before(assign_y);
ir_expression *const div_expr =
new(ir) ir_expression(ir_binop_div, x->type,
new(ir) ir_dereference_variable(x),
new(ir) ir_dereference_variable(y));
/* Don't generate new IR that would need to be lowered in an additional
* pass.
*/
if ((lowering(FDIV_TO_MUL_RCP) && ir->type->is_float()) ||
(lowering(DDIV_TO_MUL_RCP) && ir->type->is_double()))
div_to_mul_rcp(div_expr);
ir_expression *const floor_expr =
new(ir) ir_expression(ir_unop_floor, x->type, div_expr);
if (lowering(DOPS_TO_DFRAC) && ir->type->is_double())
dfloor_to_dfrac(floor_expr);
ir_expression *const mul_expr =
new(ir) ir_expression(ir_binop_mul,
new(ir) ir_dereference_variable(y),
floor_expr);
ir->operation = ir_binop_sub;
ir->operands[0] = new(ir) ir_dereference_variable(x);
ir->operands[1] = mul_expr;
this->progress = true;
}
void
lower_instructions_visitor::ldexp_to_arith(ir_expression *ir)
{
/* Translates
* ir_binop_ldexp x exp
* into
*
* extracted_biased_exp = rshift(bitcast_f2i(abs(x)), exp_shift);
* resulting_biased_exp = extracted_biased_exp + exp;
*
* if (resulting_biased_exp < 1 || x == 0.0f) {
* return copysign(0.0, x);
* }
*
* return bitcast_u2f((bitcast_f2u(x) & sign_mantissa_mask) |
* lshift(i2u(resulting_biased_exp), exp_shift));
*
* which we can't actually implement as such, since the GLSL IR doesn't
* have vectorized if-statements. We actually implement it without branches
* using conditional-select:
*
* extracted_biased_exp = rshift(bitcast_f2i(abs(x)), exp_shift);
* resulting_biased_exp = extracted_biased_exp + exp;
*
* is_not_zero_or_underflow = logic_and(nequal(x, 0.0f),
* gequal(resulting_biased_exp, 1);
* x = csel(is_not_zero_or_underflow, x, copysign(0.0f, x));
* resulting_biased_exp = csel(is_not_zero_or_underflow,
* resulting_biased_exp, 0);
*
* return bitcast_u2f((bitcast_f2u(x) & sign_mantissa_mask) |
* lshift(i2u(resulting_biased_exp), exp_shift));
*/
const unsigned vec_elem = ir->type->vector_elements;
/* Types */
const glsl_type *ivec = glsl_type::get_instance(GLSL_TYPE_INT, vec_elem, 1);
const glsl_type *bvec = glsl_type::get_instance(GLSL_TYPE_BOOL, vec_elem, 1);
/* Constants */
ir_constant *zeroi = ir_constant::zero(ir, ivec);
ir_constant *sign_mask = new(ir) ir_constant(0x80000000u, vec_elem);
ir_constant *exp_shift = new(ir) ir_constant(23, vec_elem);
/* Temporary variables */
ir_variable *x = new(ir) ir_variable(ir->type, "x", ir_var_temporary);
ir_variable *exp = new(ir) ir_variable(ivec, "exp", ir_var_temporary);
ir_variable *zero_sign_x = new(ir) ir_variable(ir->type, "zero_sign_x",
ir_var_temporary);
ir_variable *extracted_biased_exp =
new(ir) ir_variable(ivec, "extracted_biased_exp", ir_var_temporary);
ir_variable *resulting_biased_exp =
new(ir) ir_variable(ivec, "resulting_biased_exp", ir_var_temporary);
ir_variable *is_not_zero_or_underflow =
new(ir) ir_variable(bvec, "is_not_zero_or_underflow", ir_var_temporary);
ir_instruction &i = *base_ir;
/* Copy <x> and <exp> arguments. */
i.insert_before(x);
i.insert_before(assign(x, ir->operands[0]));
i.insert_before(exp);
i.insert_before(assign(exp, ir->operands[1]));
/* Extract the biased exponent from <x>. */
i.insert_before(extracted_biased_exp);
i.insert_before(assign(extracted_biased_exp,
rshift(bitcast_f2i(abs(x)), exp_shift)));
i.insert_before(resulting_biased_exp);
i.insert_before(assign(resulting_biased_exp,
add(extracted_biased_exp, exp)));
/* Test if result is ±0.0, subnormal, or underflow by checking if the
* resulting biased exponent would be less than 0x1. If so, the result is
* 0.0 with the sign of x. (Actually, invert the conditions so that
* immediate values are the second arguments, which is better for i965)
*/
i.insert_before(zero_sign_x);
i.insert_before(assign(zero_sign_x,
bitcast_u2f(bit_and(bitcast_f2u(x), sign_mask))));
i.insert_before(is_not_zero_or_underflow);
i.insert_before(assign(is_not_zero_or_underflow,
logic_and(nequal(x, new(ir) ir_constant(0.0f, vec_elem)),
gequal(resulting_biased_exp,
new(ir) ir_constant(0x1, vec_elem)))));
i.insert_before(assign(x, csel(is_not_zero_or_underflow,
x, zero_sign_x)));
i.insert_before(assign(resulting_biased_exp,
csel(is_not_zero_or_underflow,
resulting_biased_exp, zeroi)));
/* We could test for overflows by checking if the resulting biased exponent
* would be greater than 0xFE. Turns out we don't need to because the GLSL
* spec says:
*
* "If this product is too large to be represented in the
* floating-point type, the result is undefined."
*/
ir_constant *exp_shift_clone = exp_shift->clone(ir, NULL);
/* Don't generate new IR that would need to be lowered in an additional
* pass.
*/
if (!lowering(INSERT_TO_SHIFTS)) {
ir_constant *exp_width = new(ir) ir_constant(8, vec_elem);
ir->operation = ir_unop_bitcast_i2f;
ir->operands[0] = bitfield_insert(bitcast_f2i(x), resulting_biased_exp,
exp_shift_clone, exp_width);
ir->operands[1] = NULL;
} else {
ir_constant *sign_mantissa_mask = new(ir) ir_constant(0x807fffffu, vec_elem);
ir->operation = ir_unop_bitcast_u2f;
ir->operands[0] = bit_or(bit_and(bitcast_f2u(x), sign_mantissa_mask),
lshift(i2u(resulting_biased_exp), exp_shift_clone));
}
this->progress = true;
}
void
lower_instructions_visitor::dldexp_to_arith(ir_expression *ir)
{
/* See ldexp_to_arith for structure. Uses frexp_exp to extract the exponent
* from the significand.
*/
const unsigned vec_elem = ir->type->vector_elements;
/* Types */
const glsl_type *ivec = glsl_type::get_instance(GLSL_TYPE_INT, vec_elem, 1);
const glsl_type *bvec = glsl_type::get_instance(GLSL_TYPE_BOOL, vec_elem, 1);
/* Constants */
ir_constant *zeroi = ir_constant::zero(ir, ivec);
ir_constant *sign_mask = new(ir) ir_constant(0x80000000u);
ir_constant *exp_shift = new(ir) ir_constant(20u);
ir_constant *exp_width = new(ir) ir_constant(11u);
ir_constant *exp_bias = new(ir) ir_constant(1022, vec_elem);
/* Temporary variables */
ir_variable *x = new(ir) ir_variable(ir->type, "x", ir_var_temporary);
ir_variable *exp = new(ir) ir_variable(ivec, "exp", ir_var_temporary);
ir_variable *zero_sign_x = new(ir) ir_variable(ir->type, "zero_sign_x",
ir_var_temporary);
ir_variable *extracted_biased_exp =
new(ir) ir_variable(ivec, "extracted_biased_exp", ir_var_temporary);
ir_variable *resulting_biased_exp =
new(ir) ir_variable(ivec, "resulting_biased_exp", ir_var_temporary);
ir_variable *is_not_zero_or_underflow =
new(ir) ir_variable(bvec, "is_not_zero_or_underflow", ir_var_temporary);
ir_instruction &i = *base_ir;
/* Copy <x> and <exp> arguments. */
i.insert_before(x);
i.insert_before(assign(x, ir->operands[0]));
i.insert_before(exp);
i.insert_before(assign(exp, ir->operands[1]));
ir_expression *frexp_exp = expr(ir_unop_frexp_exp, x);
if (lowering(DFREXP_DLDEXP_TO_ARITH))
dfrexp_exp_to_arith(frexp_exp);
/* Extract the biased exponent from <x>. */
i.insert_before(extracted_biased_exp);
i.insert_before(assign(extracted_biased_exp, add(frexp_exp, exp_bias)));
i.insert_before(resulting_biased_exp);
i.insert_before(assign(resulting_biased_exp,
add(extracted_biased_exp, exp)));
/* Test if result is ±0.0, subnormal, or underflow by checking if the
* resulting biased exponent would be less than 0x1. If so, the result is
* 0.0 with the sign of x. (Actually, invert the conditions so that
* immediate values are the second arguments, which is better for i965)
* TODO: Implement in a vector fashion.
*/
i.insert_before(zero_sign_x);
for (unsigned elem = 0; elem < vec_elem; elem++) {
ir_variable *unpacked =
new(ir) ir_variable(glsl_type::uvec2_type, "unpacked", ir_var_temporary);
i.insert_before(unpacked);
i.insert_before(
assign(unpacked,
expr(ir_unop_unpack_double_2x32, swizzle(x, elem, 1))));
i.insert_before(assign(unpacked, bit_and(swizzle_y(unpacked), sign_mask->clone(ir, NULL)),
WRITEMASK_Y));
i.insert_before(assign(unpacked, ir_constant::zero(ir, glsl_type::uint_type), WRITEMASK_X));
i.insert_before(assign(zero_sign_x,
expr(ir_unop_pack_double_2x32, unpacked),
1 << elem));
}
i.insert_before(is_not_zero_or_underflow);
i.insert_before(assign(is_not_zero_or_underflow,
gequal(resulting_biased_exp,
new(ir) ir_constant(0x1, vec_elem))));
i.insert_before(assign(x, csel(is_not_zero_or_underflow,
x, zero_sign_x)));
i.insert_before(assign(resulting_biased_exp,
csel(is_not_zero_or_underflow,
resulting_biased_exp, zeroi)));
/* We could test for overflows by checking if the resulting biased exponent
* would be greater than 0xFE. Turns out we don't need to because the GLSL
* spec says:
*
* "If this product is too large to be represented in the
* floating-point type, the result is undefined."
*/
ir_rvalue *results[4] = {NULL};
for (unsigned elem = 0; elem < vec_elem; elem++) {
ir_variable *unpacked =
new(ir) ir_variable(glsl_type::uvec2_type, "unpacked", ir_var_temporary);
i.insert_before(unpacked);
i.insert_before(
assign(unpacked,
expr(ir_unop_unpack_double_2x32, swizzle(x, elem, 1))));
ir_expression *bfi = bitfield_insert(
swizzle_y(unpacked),
i2u(swizzle(resulting_biased_exp, elem, 1)),
exp_shift->clone(ir, NULL),
exp_width->clone(ir, NULL));
i.insert_before(assign(unpacked, bfi, WRITEMASK_Y));
results[elem] = expr(ir_unop_pack_double_2x32, unpacked);
}
ir->operation = ir_quadop_vector;
ir->operands[0] = results[0];
ir->operands[1] = results[1];
ir->operands[2] = results[2];
ir->operands[3] = results[3];
/* Don't generate new IR that would need to be lowered in an additional
* pass.
*/
this->progress = true;
}
void
lower_instructions_visitor::dfrexp_sig_to_arith(ir_expression *ir)
{
const unsigned vec_elem = ir->type->vector_elements;
const glsl_type *bvec = glsl_type::get_instance(GLSL_TYPE_BOOL, vec_elem, 1);
/* Double-precision floating-point values are stored as
* 1 sign bit;
* 11 exponent bits;
* 52 mantissa bits.
*
* We're just extracting the significand here, so we only need to modify
* the upper 32-bit uint. Unfortunately we must extract each double
* independently as there is no vector version of unpackDouble.
*/
ir_instruction &i = *base_ir;
ir_variable *is_not_zero =
new(ir) ir_variable(bvec, "is_not_zero", ir_var_temporary);
ir_rvalue *results[4] = {NULL};
ir_constant *dzero = new(ir) ir_constant(0.0, vec_elem);
i.insert_before(is_not_zero);
i.insert_before(
assign(is_not_zero,
nequal(abs(ir->operands[0]->clone(ir, NULL)), dzero)));
/* TODO: Remake this as more vector-friendly when int64 support is
* available.
*/
for (unsigned elem = 0; elem < vec_elem; elem++) {
ir_constant *zero = new(ir) ir_constant(0u, 1);
ir_constant *sign_mantissa_mask = new(ir) ir_constant(0x800fffffu, 1);
/* Exponent of double floating-point values in the range [0.5, 1.0). */
ir_constant *exponent_value = new(ir) ir_constant(0x3fe00000u, 1);
ir_variable *bits =
new(ir) ir_variable(glsl_type::uint_type, "bits", ir_var_temporary);
ir_variable *unpacked =
new(ir) ir_variable(glsl_type::uvec2_type, "unpacked", ir_var_temporary);
ir_rvalue *x = swizzle(ir->operands[0]->clone(ir, NULL), elem, 1);
i.insert_before(bits);
i.insert_before(unpacked);
i.insert_before(assign(unpacked, expr(ir_unop_unpack_double_2x32, x)));
/* Manipulate the high uint to remove the exponent and replace it with
* either the default exponent or zero.
*/
i.insert_before(assign(bits, swizzle_y(unpacked)));
i.insert_before(assign(bits, bit_and(bits, sign_mantissa_mask)));
i.insert_before(assign(bits, bit_or(bits,
csel(swizzle(is_not_zero, elem, 1),
exponent_value,
zero))));
i.insert_before(assign(unpacked, bits, WRITEMASK_Y));
results[elem] = expr(ir_unop_pack_double_2x32, unpacked);
}
/* Put the dvec back together */
ir->operation = ir_quadop_vector;
ir->operands[0] = results[0];
ir->operands[1] = results[1];
ir->operands[2] = results[2];
ir->operands[3] = results[3];
this->progress = true;
}
void
lower_instructions_visitor::dfrexp_exp_to_arith(ir_expression *ir)
{
const unsigned vec_elem = ir->type->vector_elements;
const glsl_type *bvec = glsl_type::get_instance(GLSL_TYPE_BOOL, vec_elem, 1);
const glsl_type *uvec = glsl_type::get_instance(GLSL_TYPE_UINT, vec_elem, 1);
/* Double-precision floating-point values are stored as
* 1 sign bit;
* 11 exponent bits;
* 52 mantissa bits.
*
* We're just extracting the exponent here, so we only care about the upper
* 32-bit uint.
*/
ir_instruction &i = *base_ir;
ir_variable *is_not_zero =
new(ir) ir_variable(bvec, "is_not_zero", ir_var_temporary);
ir_variable *high_words =
new(ir) ir_variable(uvec, "high_words", ir_var_temporary);
ir_constant *dzero = new(ir) ir_constant(0.0, vec_elem);
ir_constant *izero = new(ir) ir_constant(0, vec_elem);
ir_rvalue *absval = abs(ir->operands[0]);
i.insert_before(is_not_zero);
i.insert_before(high_words);
i.insert_before(assign(is_not_zero, nequal(absval->clone(ir, NULL), dzero)));
/* Extract all of the upper uints. */
for (unsigned elem = 0; elem < vec_elem; elem++) {
ir_rvalue *x = swizzle(absval->clone(ir, NULL), elem, 1);
i.insert_before(assign(high_words,
swizzle_y(expr(ir_unop_unpack_double_2x32, x)),
1 << elem));
}
ir_constant *exponent_shift = new(ir) ir_constant(20, vec_elem);
ir_constant *exponent_bias = new(ir) ir_constant(-1022, vec_elem);
/* For non-zero inputs, shift the exponent down and apply bias. */
ir->operation = ir_triop_csel;
ir->operands[0] = new(ir) ir_dereference_variable(is_not_zero);
ir->operands[1] = add(exponent_bias, u2i(rshift(high_words, exponent_shift)));
ir->operands[2] = izero;
this->progress = true;
}
void
lower_instructions_visitor::carry_to_arith(ir_expression *ir)
{
/* Translates
* ir_binop_carry x y
* into
* sum = ir_binop_add x y
* bcarry = ir_binop_less sum x
* carry = ir_unop_b2i bcarry
*/
ir_rvalue *x_clone = ir->operands[0]->clone(ir, NULL);
ir->operation = ir_unop_i2u;
ir->operands[0] = b2i(less(add(ir->operands[0], ir->operands[1]), x_clone));
ir->operands[1] = NULL;
this->progress = true;
}
void
lower_instructions_visitor::borrow_to_arith(ir_expression *ir)
{
/* Translates
* ir_binop_borrow x y
* into
* bcarry = ir_binop_less x y
* carry = ir_unop_b2i bcarry
*/
ir->operation = ir_unop_i2u;
ir->operands[0] = b2i(less(ir->operands[0], ir->operands[1]));
ir->operands[1] = NULL;
this->progress = true;
}
void
lower_instructions_visitor::sat_to_clamp(ir_expression *ir)
{
/* Translates
* ir_unop_saturate x
* into
* ir_binop_min (ir_binop_max(x, 0.0), 1.0)
*/
ir->operation = ir_binop_min;
ir->operands[0] = new(ir) ir_expression(ir_binop_max, ir->operands[0]->type,
ir->operands[0],
new(ir) ir_constant(0.0f));
ir->operands[1] = new(ir) ir_constant(1.0f);
this->progress = true;
}
void
lower_instructions_visitor::double_dot_to_fma(ir_expression *ir)
{
ir_variable *temp = new(ir) ir_variable(ir->operands[0]->type->get_base_type(), "dot_res",
ir_var_temporary);
this->base_ir->insert_before(temp);
int nc = ir->operands[0]->type->components();
for (int i = nc - 1; i >= 1; i--) {
ir_assignment *assig;
if (i == (nc - 1)) {
assig = assign(temp, mul(swizzle(ir->operands[0]->clone(ir, NULL), i, 1),
swizzle(ir->operands[1]->clone(ir, NULL), i, 1)));
} else {
assig = assign(temp, fma(swizzle(ir->operands[0]->clone(ir, NULL), i, 1),
swizzle(ir->operands[1]->clone(ir, NULL), i, 1),
temp));
}
this->base_ir->insert_before(assig);
}
ir->operation = ir_triop_fma;
ir->operands[0] = swizzle(ir->operands[0], 0, 1);
ir->operands[1] = swizzle(ir->operands[1], 0, 1);
ir->operands[2] = new(ir) ir_dereference_variable(temp);
this->progress = true;
}
void
lower_instructions_visitor::double_lrp(ir_expression *ir)
{
int swizval;
ir_rvalue *op0 = ir->operands[0], *op2 = ir->operands[2];
ir_constant *one = new(ir) ir_constant(1.0, op2->type->vector_elements);
switch (op2->type->vector_elements) {
case 1:
swizval = SWIZZLE_XXXX;
break;
default:
assert(op0->type->vector_elements == op2->type->vector_elements);
swizval = SWIZZLE_XYZW;
break;
}
ir->operation = ir_triop_fma;
ir->operands[0] = swizzle(op2, swizval, op0->type->vector_elements);
ir->operands[2] = mul(sub(one, op2->clone(ir, NULL)), op0);
this->progress = true;
}
void
lower_instructions_visitor::dceil_to_dfrac(ir_expression *ir)
{
/*
* frtemp = frac(x);
* temp = sub(x, frtemp);
* result = temp + ((frtemp != 0.0) ? 1.0 : 0.0);
*/
ir_instruction &i = *base_ir;
ir_constant *zero = new(ir) ir_constant(0.0, ir->operands[0]->type->vector_elements);
ir_constant *one = new(ir) ir_constant(1.0, ir->operands[0]->type->vector_elements);
ir_variable *frtemp = new(ir) ir_variable(ir->operands[0]->type, "frtemp",
ir_var_temporary);
i.insert_before(frtemp);
i.insert_before(assign(frtemp, fract(ir->operands[0])));
ir->operation = ir_binop_add;
ir->operands[0] = sub(ir->operands[0]->clone(ir, NULL), frtemp);
ir->operands[1] = csel(nequal(frtemp, zero), one, zero->clone(ir, NULL));
this->progress = true;
}
void
lower_instructions_visitor::dfloor_to_dfrac(ir_expression *ir)
{
/*
* frtemp = frac(x);
* result = sub(x, frtemp);
*/
ir->operation = ir_binop_sub;
ir->operands[1] = fract(ir->operands[0]->clone(ir, NULL));
this->progress = true;
}
void
lower_instructions_visitor::dround_even_to_dfrac(ir_expression *ir)
{
/*
* insane but works
* temp = x + 0.5;
* frtemp = frac(temp);
* t2 = sub(temp, frtemp);
* if (frac(x) == 0.5)
* result = frac(t2 * 0.5) == 0 ? t2 : t2 - 1;
* else
* result = t2;
*/
ir_instruction &i = *base_ir;
ir_variable *frtemp = new(ir) ir_variable(ir->operands[0]->type, "frtemp",
ir_var_temporary);
ir_variable *temp = new(ir) ir_variable(ir->operands[0]->type, "temp",
ir_var_temporary);
ir_variable *t2 = new(ir) ir_variable(ir->operands[0]->type, "t2",
ir_var_temporary);
ir_constant *p5 = new(ir) ir_constant(0.5, ir->operands[0]->type->vector_elements);
ir_constant *one = new(ir) ir_constant(1.0, ir->operands[0]->type->vector_elements);
ir_constant *zero = new(ir) ir_constant(0.0, ir->operands[0]->type->vector_elements);
i.insert_before(temp);
i.insert_before(assign(temp, add(ir->operands[0], p5)));
i.insert_before(frtemp);
i.insert_before(assign(frtemp, fract(temp)));
i.insert_before(t2);
i.insert_before(assign(t2, sub(temp, frtemp)));
ir->operation = ir_triop_csel;
ir->operands[0] = equal(fract(ir->operands[0]->clone(ir, NULL)),
p5->clone(ir, NULL));
ir->operands[1] = csel(equal(fract(mul(t2, p5->clone(ir, NULL))),
zero),
t2,
sub(t2, one));
ir->operands[2] = new(ir) ir_dereference_variable(t2);
this->progress = true;
}
void
lower_instructions_visitor::dtrunc_to_dfrac(ir_expression *ir)
{
/*
* frtemp = frac(x);
* temp = sub(x, frtemp);
* result = x >= 0 ? temp : temp + (frtemp == 0.0) ? 0 : 1;
*/
ir_rvalue *arg = ir->operands[0];
ir_instruction &i = *base_ir;
ir_constant *zero = new(ir) ir_constant(0.0, arg->type->vector_elements);
ir_constant *one = new(ir) ir_constant(1.0, arg->type->vector_elements);
ir_variable *frtemp = new(ir) ir_variable(arg->type, "frtemp",
ir_var_temporary);
ir_variable *temp = new(ir) ir_variable(ir->operands[0]->type, "temp",
ir_var_temporary);
i.insert_before(frtemp);
i.insert_before(assign(frtemp, fract(arg)));
i.insert_before(temp);
i.insert_before(assign(temp, sub(arg->clone(ir, NULL), frtemp)));
ir->operation = ir_triop_csel;
ir->operands[0] = gequal(arg->clone(ir, NULL), zero);
ir->operands[1] = new (ir) ir_dereference_variable(temp);
ir->operands[2] = add(temp,
csel(equal(frtemp, zero->clone(ir, NULL)),
zero->clone(ir, NULL),
one));
this->progress = true;
}
void
lower_instructions_visitor::dsign_to_csel(ir_expression *ir)
{
/*
* temp = x > 0.0 ? 1.0 : 0.0;
* result = x < 0.0 ? -1.0 : temp;
*/
ir_rvalue *arg = ir->operands[0];
ir_constant *zero = new(ir) ir_constant(0.0, arg->type->vector_elements);
ir_constant *one = new(ir) ir_constant(1.0, arg->type->vector_elements);
ir_constant *neg_one = new(ir) ir_constant(-1.0, arg->type->vector_elements);
ir->operation = ir_triop_csel;
ir->operands[0] = less(arg->clone(ir, NULL),
zero->clone(ir, NULL));
ir->operands[1] = neg_one;
ir->operands[2] = csel(greater(arg, zero),
one,
zero->clone(ir, NULL));
this->progress = true;
}
void
lower_instructions_visitor::bit_count_to_math(ir_expression *ir)
{
/* For more details, see:
*
* http://graphics.stanford.edu/~seander/bithacks.html#CountBitsSetPaallel
*/
const unsigned elements = ir->operands[0]->type->vector_elements;
ir_variable *temp = new(ir) ir_variable(glsl_type::uvec(elements), "temp",
ir_var_temporary);
ir_constant *c55555555 = new(ir) ir_constant(0x55555555u);
ir_constant *c33333333 = new(ir) ir_constant(0x33333333u);
ir_constant *c0F0F0F0F = new(ir) ir_constant(0x0F0F0F0Fu);
ir_constant *c01010101 = new(ir) ir_constant(0x01010101u);
ir_constant *c1 = new(ir) ir_constant(1u);
ir_constant *c2 = new(ir) ir_constant(2u);
ir_constant *c4 = new(ir) ir_constant(4u);
ir_constant *c24 = new(ir) ir_constant(24u);
base_ir->insert_before(temp);
if (ir->operands[0]->type->base_type == GLSL_TYPE_UINT) {
base_ir->insert_before(assign(temp, ir->operands[0]));
} else {
assert(ir->operands[0]->type->base_type == GLSL_TYPE_INT);
base_ir->insert_before(assign(temp, i2u(ir->operands[0])));
}
/* temp = temp - ((temp >> 1) & 0x55555555u); */
base_ir->insert_before(assign(temp, sub(temp, bit_and(rshift(temp, c1),
c55555555))));
/* temp = (temp & 0x33333333u) + ((temp >> 2) & 0x33333333u); */
base_ir->insert_before(assign(temp, add(bit_and(temp, c33333333),
bit_and(rshift(temp, c2),
c33333333->clone(ir, NULL)))));
/* int(((temp + (temp >> 4) & 0xF0F0F0Fu) * 0x1010101u) >> 24); */
ir->operation = ir_unop_u2i;
ir->operands[0] = rshift(mul(bit_and(add(temp, rshift(temp, c4)), c0F0F0F0F),
c01010101),
c24);
this->progress = true;
}
void
lower_instructions_visitor::extract_to_shifts(ir_expression *ir)
{
ir_variable *bits =
new(ir) ir_variable(ir->operands[0]->type, "bits", ir_var_temporary);
base_ir->insert_before(bits);
base_ir->insert_before(assign(bits, ir->operands[2]));
if (ir->operands[0]->type->base_type == GLSL_TYPE_UINT) {
ir_constant *c1 =
new(ir) ir_constant(1u, ir->operands[0]->type->vector_elements);
ir_constant *c32 =
new(ir) ir_constant(32u, ir->operands[0]->type->vector_elements);
ir_constant *cFFFFFFFF =
new(ir) ir_constant(0xFFFFFFFFu, ir->operands[0]->type->vector_elements);
/* At least some hardware treats (x << y) as (x << (y%32)). This means
* we'd get a mask of 0 when bits is 32. Special case it.
*
* mask = bits == 32 ? 0xffffffff : (1u << bits) - 1u;
*/
ir_expression *mask = csel(equal(bits, c32),
cFFFFFFFF,
sub(lshift(c1, bits), c1->clone(ir, NULL)));
/* Section 8.8 (Integer Functions) of the GLSL 4.50 spec says:
*
* If bits is zero, the result will be zero.
*
* Since (1 << 0) - 1 == 0, we don't need to bother with the conditional
* select as in the signed integer case.
*
* (value >> offset) & mask;
*/
ir->operation = ir_binop_bit_and;
ir->operands[0] = rshift(ir->operands[0], ir->operands[1]);
ir->operands[1] = mask;
ir->operands[2] = NULL;
} else {
ir_constant *c0 =
new(ir) ir_constant(int(0), ir->operands[0]->type->vector_elements);
ir_constant *c32 =
new(ir) ir_constant(int(32), ir->operands[0]->type->vector_elements);
ir_variable *temp =
new(ir) ir_variable(ir->operands[0]->type, "temp", ir_var_temporary);
/* temp = 32 - bits; */
base_ir->insert_before(temp);
base_ir->insert_before(assign(temp, sub(c32, bits)));
/* expr = value << (temp - offset)) >> temp; */
ir_expression *expr =
rshift(lshift(ir->operands[0], sub(temp, ir->operands[1])), temp);
/* Section 8.8 (Integer Functions) of the GLSL 4.50 spec says:
*
* If bits is zero, the result will be zero.
*
* Due to the (x << (y%32)) behavior mentioned before, the (value <<
* (32-0)) doesn't "erase" all of the data as we would like, so finish
* up with:
*
* (bits == 0) ? 0 : e;
*/
ir->operation = ir_triop_csel;
ir->operands[0] = equal(c0, bits);
ir->operands[1] = c0->clone(ir, NULL);
ir->operands[2] = expr;
}
this->progress = true;
}
void
lower_instructions_visitor::insert_to_shifts(ir_expression *ir)
{
ir_constant *c1;
ir_constant *c32;
ir_constant *cFFFFFFFF;
ir_variable *offset =
new(ir) ir_variable(ir->operands[0]->type, "offset", ir_var_temporary);
ir_variable *bits =
new(ir) ir_variable(ir->operands[0]->type, "bits", ir_var_temporary);
ir_variable *mask =
new(ir) ir_variable(ir->operands[0]->type, "mask", ir_var_temporary);
if (ir->operands[0]->type->base_type == GLSL_TYPE_INT) {
c1 = new(ir) ir_constant(int(1), ir->operands[0]->type->vector_elements);
c32 = new(ir) ir_constant(int(32), ir->operands[0]->type->vector_elements);
cFFFFFFFF = new(ir) ir_constant(int(0xFFFFFFFF), ir->operands[0]->type->vector_elements);
} else {
assert(ir->operands[0]->type->base_type == GLSL_TYPE_UINT);
c1 = new(ir) ir_constant(1u, ir->operands[0]->type->vector_elements);
c32 = new(ir) ir_constant(32u, ir->operands[0]->type->vector_elements);
cFFFFFFFF = new(ir) ir_constant(0xFFFFFFFFu, ir->operands[0]->type->vector_elements);
}
base_ir->insert_before(offset);
base_ir->insert_before(assign(offset, ir->operands[2]));
base_ir->insert_before(bits);
base_ir->insert_before(assign(bits, ir->operands[3]));
/* At least some hardware treats (x << y) as (x << (y%32)). This means
* we'd get a mask of 0 when bits is 32. Special case it.
*
* mask = (bits == 32 ? 0xffffffff : (1u << bits) - 1u) << offset;
*
* Section 8.8 (Integer Functions) of the GLSL 4.50 spec says:
*
* The result will be undefined if offset or bits is negative, or if the
* sum of offset and bits is greater than the number of bits used to
* store the operand.
*
* Since it's undefined, there are a couple other ways this could be
* implemented. The other way that was considered was to put the csel
* around the whole thing:
*
* final_result = bits == 32 ? insert : ... ;
*/
base_ir->insert_before(mask);
base_ir->insert_before(assign(mask, csel(equal(bits, c32),
cFFFFFFFF,
lshift(sub(lshift(c1, bits),
c1->clone(ir, NULL)),
offset))));
/* (base & ~mask) | ((insert << offset) & mask) */
ir->operation = ir_binop_bit_or;
ir->operands[0] = bit_and(ir->operands[0], bit_not(mask));
ir->operands[1] = bit_and(lshift(ir->operands[1], offset), mask);
ir->operands[2] = NULL;
ir->operands[3] = NULL;
this->progress = true;
}
void
lower_instructions_visitor::reverse_to_shifts(ir_expression *ir)
{
/* For more details, see:
*
* http://graphics.stanford.edu/~seander/bithacks.html#ReverseParallel
*/
ir_constant *c1 =
new(ir) ir_constant(1u, ir->operands[0]->type->vector_elements);
ir_constant *c2 =
new(ir) ir_constant(2u, ir->operands[0]->type->vector_elements);
ir_constant *c4 =
new(ir) ir_constant(4u, ir->operands[0]->type->vector_elements);
ir_constant *c8 =
new(ir) ir_constant(8u, ir->operands[0]->type->vector_elements);
ir_constant *c16 =
new(ir) ir_constant(16u, ir->operands[0]->type->vector_elements);
ir_constant *c33333333 =
new(ir) ir_constant(0x33333333u, ir->operands[0]->type->vector_elements);
ir_constant *c55555555 =
new(ir) ir_constant(0x55555555u, ir->operands[0]->type->vector_elements);
ir_constant *c0F0F0F0F =
new(ir) ir_constant(0x0F0F0F0Fu, ir->operands[0]->type->vector_elements);
ir_constant *c00FF00FF =
new(ir) ir_constant(0x00FF00FFu, ir->operands[0]->type->vector_elements);
ir_variable *temp =
new(ir) ir_variable(glsl_type::uvec(ir->operands[0]->type->vector_elements),
"temp", ir_var_temporary);
ir_instruction &i = *base_ir;
i.insert_before(temp);
if (ir->operands[0]->type->base_type == GLSL_TYPE_UINT) {
i.insert_before(assign(temp, ir->operands[0]));
} else {
assert(ir->operands[0]->type->base_type == GLSL_TYPE_INT);
i.insert_before(assign(temp, i2u(ir->operands[0])));
}
/* Swap odd and even bits.
*
* temp = ((temp >> 1) & 0x55555555u) | ((temp & 0x55555555u) << 1);
*/
i.insert_before(assign(temp, bit_or(bit_and(rshift(temp, c1), c55555555),
lshift(bit_and(temp, c55555555->clone(ir, NULL)),
c1->clone(ir, NULL)))));
/* Swap consecutive pairs.
*
* temp = ((temp >> 2) & 0x33333333u) | ((temp & 0x33333333u) << 2);
*/
i.insert_before(assign(temp, bit_or(bit_and(rshift(temp, c2), c33333333),
lshift(bit_and(temp, c33333333->clone(ir, NULL)),
c2->clone(ir, NULL)))));
/* Swap nibbles.
*
* temp = ((temp >> 4) & 0x0F0F0F0Fu) | ((temp & 0x0F0F0F0Fu) << 4);
*/
i.insert_before(assign(temp, bit_or(bit_and(rshift(temp, c4), c0F0F0F0F),
lshift(bit_and(temp, c0F0F0F0F->clone(ir, NULL)),
c4->clone(ir, NULL)))));
/* The last step is, basically, bswap. Swap the bytes, then swap the
* words. When this code is run through GCC on x86, it does generate a
* bswap instruction.
*
* temp = ((temp >> 8) & 0x00FF00FFu) | ((temp & 0x00FF00FFu) << 8);
* temp = ( temp >> 16 ) | ( temp << 16);
*/
i.insert_before(assign(temp, bit_or(bit_and(rshift(temp, c8), c00FF00FF),
lshift(bit_and(temp, c00FF00FF->clone(ir, NULL)),
c8->clone(ir, NULL)))));
if (ir->operands[0]->type->base_type == GLSL_TYPE_UINT) {
ir->operation = ir_binop_bit_or;
ir->operands[0] = rshift(temp, c16);
ir->operands[1] = lshift(temp, c16->clone(ir, NULL));
} else {
ir->operation = ir_unop_u2i;
ir->operands[0] = bit_or(rshift(temp, c16),
lshift(temp, c16->clone(ir, NULL)));
}
this->progress = true;
}
void
lower_instructions_visitor::find_lsb_to_float_cast(ir_expression *ir)
{
/* For more details, see:
*
* http://graphics.stanford.edu/~seander/bithacks.html#ZerosOnRightFloatCast
*/
const unsigned elements = ir->operands[0]->type->vector_elements;
ir_constant *c0 = new(ir) ir_constant(unsigned(0), elements);
ir_constant *cminus1 = new(ir) ir_constant(int(-1), elements);
ir_constant *c23 = new(ir) ir_constant(int(23), elements);
ir_constant *c7F = new(ir) ir_constant(int(0x7F), elements);
ir_variable *temp =
new(ir) ir_variable(glsl_type::ivec(elements), "temp", ir_var_temporary);
ir_variable *lsb_only =
new(ir) ir_variable(glsl_type::uvec(elements), "lsb_only", ir_var_temporary);
ir_variable *as_float =
new(ir) ir_variable(glsl_type::vec(elements), "as_float", ir_var_temporary);
ir_variable *lsb =
new(ir) ir_variable(glsl_type::ivec(elements), "lsb", ir_var_temporary);
ir_instruction &i = *base_ir;
i.insert_before(temp);
if (ir->operands[0]->type->base_type == GLSL_TYPE_INT) {
i.insert_before(assign(temp, ir->operands[0]));
} else {
assert(ir->operands[0]->type->base_type == GLSL_TYPE_UINT);
i.insert_before(assign(temp, u2i(ir->operands[0])));
}
/* The int-to-float conversion is lossless because (value & -value) is
* either a power of two or zero. We don't use the result in the zero
* case. The uint() cast is necessary so that 0x80000000 does not
* generate a negative value.
*
* uint lsb_only = uint(value & -value);
* float as_float = float(lsb_only);
*/
i.insert_before(lsb_only);
i.insert_before(assign(lsb_only, i2u(bit_and(temp, neg(temp)))));
i.insert_before(as_float);
i.insert_before(assign(as_float, u2f(lsb_only)));
/* This is basically an open-coded frexp. Implementations that have a
* native frexp instruction would be better served by that. This is
* optimized versus a full-featured open-coded implementation in two ways:
*
* - We don't care about a correct result from subnormal numbers (including
* 0.0), so the raw exponent can always be safely unbiased.
*
* - The value cannot be negative, so it does not need to be masked off to
* extract the exponent.
*
* int lsb = (floatBitsToInt(as_float) >> 23) - 0x7f;
*/
i.insert_before(lsb);
i.insert_before(assign(lsb, sub(rshift(bitcast_f2i(as_float), c23), c7F)));
/* Use lsb_only in the comparison instead of temp so that the & (far above)
* can possibly generate the result without an explicit comparison.
*
* (lsb_only == 0) ? -1 : lsb;
*
* Since our input values are all integers, the unbiased exponent must not
* be negative. It will only be negative (-0x7f, in fact) if lsb_only is
* 0. Instead of using (lsb_only == 0), we could use (lsb >= 0). Which is
* better is likely GPU dependent. Either way, the difference should be
* small.
*/
ir->operation = ir_triop_csel;
ir->operands[0] = equal(lsb_only, c0);
ir->operands[1] = cminus1;
ir->operands[2] = new(ir) ir_dereference_variable(lsb);
this->progress = true;
}
void
lower_instructions_visitor::find_msb_to_float_cast(ir_expression *ir)
{
/* For more details, see:
*
* http://graphics.stanford.edu/~seander/bithacks.html#ZerosOnRightFloatCast
*/
const unsigned elements = ir->operands[0]->type->vector_elements;
ir_constant *c0 = new(ir) ir_constant(int(0), elements);
ir_constant *cminus1 = new(ir) ir_constant(int(-1), elements);
ir_constant *c23 = new(ir) ir_constant(int(23), elements);
ir_constant *c7F = new(ir) ir_constant(int(0x7F), elements);
ir_constant *c000000FF = new(ir) ir_constant(0x000000FFu, elements);
ir_constant *cFFFFFF00 = new(ir) ir_constant(0xFFFFFF00u, elements);
ir_variable *temp =
new(ir) ir_variable(glsl_type::uvec(elements), "temp", ir_var_temporary);
ir_variable *as_float =
new(ir) ir_variable(glsl_type::vec(elements), "as_float", ir_var_temporary);
ir_variable *msb =
new(ir) ir_variable(glsl_type::ivec(elements), "msb", ir_var_temporary);
ir_instruction &i = *base_ir;
i.insert_before(temp);
if (ir->operands[0]->type->base_type == GLSL_TYPE_UINT) {
i.insert_before(assign(temp, ir->operands[0]));
} else {
assert(ir->operands[0]->type->base_type == GLSL_TYPE_INT);
/* findMSB(uint(abs(some_int))) almost always does the right thing.
* There are two problem values:
*
* * 0x80000000. Since abs(0x80000000) == 0x80000000, findMSB returns
* 31. However, findMSB(int(0x80000000)) == 30.
*
* * 0xffffffff. Since abs(0xffffffff) == 1, findMSB returns
* 31. Section 8.8 (Integer Functions) of the GLSL 4.50 spec says:
*
* For a value of zero or negative one, -1 will be returned.
*
* For all negative number cases, including 0x80000000 and 0xffffffff,
* the correct value is obtained from findMSB if instead of negating the
* (already negative) value the logical-not is used. A conditonal
* logical-not can be achieved in two instructions.
*/
ir_variable *as_int =
new(ir) ir_variable(glsl_type::ivec(elements), "as_int", ir_var_temporary);
ir_constant *c31 = new(ir) ir_constant(int(31), elements);
i.insert_before(as_int);
i.insert_before(assign(as_int, ir->operands[0]));
i.insert_before(assign(temp, i2u(expr(ir_binop_bit_xor,
as_int,
rshift(as_int, c31)))));
}
/* The int-to-float conversion is lossless because bits are conditionally
* masked off the bottom of temp to ensure the value has at most 24 bits of
* data or is zero. We don't use the result in the zero case. The uint()
* cast is necessary so that 0x80000000 does not generate a negative value.
*
* float as_float = float(temp > 255 ? temp & ~255 : temp);
*/
i.insert_before(as_float);
i.insert_before(assign(as_float, u2f(csel(greater(temp, c000000FF),
bit_and(temp, cFFFFFF00),
temp))));
/* This is basically an open-coded frexp. Implementations that have a
* native frexp instruction would be better served by that. This is
* optimized versus a full-featured open-coded implementation in two ways:
*
* - We don't care about a correct result from subnormal numbers (including
* 0.0), so the raw exponent can always be safely unbiased.
*
* - The value cannot be negative, so it does not need to be masked off to
* extract the exponent.
*
* int msb = (floatBitsToInt(as_float) >> 23) - 0x7f;
*/
i.insert_before(msb);
i.insert_before(assign(msb, sub(rshift(bitcast_f2i(as_float), c23), c7F)));
/* Use msb in the comparison instead of temp so that the subtract can
* possibly generate the result without an explicit comparison.
*
* (msb < 0) ? -1 : msb;
*
* Since our input values are all integers, the unbiased exponent must not
* be negative. It will only be negative (-0x7f, in fact) if temp is 0.
*/
ir->operation = ir_triop_csel;
ir->operands[0] = less(msb, c0);
ir->operands[1] = cminus1;
ir->operands[2] = new(ir) ir_dereference_variable(msb);
this->progress = true;
}
ir_expression *
lower_instructions_visitor::_carry(operand a, operand b)
{
if (lowering(CARRY_TO_ARITH))
return i2u(b2i(less(add(a, b),
a.val->clone(ralloc_parent(a.val), NULL))));
else
return carry(a, b);
}
void
lower_instructions_visitor::imul_high_to_mul(ir_expression *ir)
{
/* ABCD
* * EFGH
* ======
* (GH * CD) + (GH * AB) << 16 + (EF * CD) << 16 + (EF * AB) << 32
*
* In GLSL, (a * b) becomes
*
* uint m1 = (a & 0x0000ffffu) * (b & 0x0000ffffu);
* uint m2 = (a & 0x0000ffffu) * (b >> 16);
* uint m3 = (a >> 16) * (b & 0x0000ffffu);
* uint m4 = (a >> 16) * (b >> 16);
*
* uint c1;
* uint c2;
* uint lo_result;
* uint hi_result;
*
* lo_result = uaddCarry(m1, m2 << 16, c1);
* hi_result = m4 + c1;
* lo_result = uaddCarry(lo_result, m3 << 16, c2);
* hi_result = hi_result + c2;
* hi_result = hi_result + (m2 >> 16) + (m3 >> 16);
*/
const unsigned elements = ir->operands[0]->type->vector_elements;
ir_variable *src1 =
new(ir) ir_variable(glsl_type::uvec(elements), "src1", ir_var_temporary);
ir_variable *src1h =
new(ir) ir_variable(glsl_type::uvec(elements), "src1h", ir_var_temporary);
ir_variable *src1l =
new(ir) ir_variable(glsl_type::uvec(elements), "src1l", ir_var_temporary);
ir_variable *src2 =
new(ir) ir_variable(glsl_type::uvec(elements), "src2", ir_var_temporary);
ir_variable *src2h =
new(ir) ir_variable(glsl_type::uvec(elements), "src2h", ir_var_temporary);
ir_variable *src2l =
new(ir) ir_variable(glsl_type::uvec(elements), "src2l", ir_var_temporary);
ir_variable *t1 =
new(ir) ir_variable(glsl_type::uvec(elements), "t1", ir_var_temporary);
ir_variable *t2 =
new(ir) ir_variable(glsl_type::uvec(elements), "t2", ir_var_temporary);
ir_variable *lo =
new(ir) ir_variable(glsl_type::uvec(elements), "lo", ir_var_temporary);
ir_variable *hi =
new(ir) ir_variable(glsl_type::uvec(elements), "hi", ir_var_temporary);
ir_variable *different_signs = NULL;
ir_constant *c0000FFFF = new(ir) ir_constant(0x0000FFFFu, elements);
ir_constant *c16 = new(ir) ir_constant(16u, elements);
ir_instruction &i = *base_ir;
i.insert_before(src1);
i.insert_before(src2);
i.insert_before(src1h);
i.insert_before(src2h);
i.insert_before(src1l);
i.insert_before(src2l);
if (ir->operands[0]->type->base_type == GLSL_TYPE_UINT) {
i.insert_before(assign(src1, ir->operands[0]));
i.insert_before(assign(src2, ir->operands[1]));
} else {
assert(ir->operands[0]->type->base_type == GLSL_TYPE_INT);
ir_variable *itmp1 =
new(ir) ir_variable(glsl_type::ivec(elements), "itmp1", ir_var_temporary);
ir_variable *itmp2 =
new(ir) ir_variable(glsl_type::ivec(elements), "itmp2", ir_var_temporary);
ir_constant *c0 = new(ir) ir_constant(int(0), elements);
i.insert_before(itmp1);
i.insert_before(itmp2);
i.insert_before(assign(itmp1, ir->operands[0]));
i.insert_before(assign(itmp2, ir->operands[1]));
different_signs =
new(ir) ir_variable(glsl_type::bvec(elements), "different_signs",
ir_var_temporary);
i.insert_before(different_signs);
i.insert_before(assign(different_signs, expr(ir_binop_logic_xor,
less(itmp1, c0),
less(itmp2, c0->clone(ir, NULL)))));
i.insert_before(assign(src1, i2u(abs(itmp1))));
i.insert_before(assign(src2, i2u(abs(itmp2))));
}
i.insert_before(assign(src1l, bit_and(src1, c0000FFFF)));
i.insert_before(assign(src2l, bit_and(src2, c0000FFFF->clone(ir, NULL))));
i.insert_before(assign(src1h, rshift(src1, c16)));
i.insert_before(assign(src2h, rshift(src2, c16->clone(ir, NULL))));
i.insert_before(lo);
i.insert_before(hi);
i.insert_before(t1);
i.insert_before(t2);
i.insert_before(assign(lo, mul(src1l, src2l)));
i.insert_before(assign(t1, mul(src1l, src2h)));
i.insert_before(assign(t2, mul(src1h, src2l)));
i.insert_before(assign(hi, mul(src1h, src2h)));
i.insert_before(assign(hi, add(hi, _carry(lo, lshift(t1, c16->clone(ir, NULL))))));
i.insert_before(assign(lo, add(lo, lshift(t1, c16->clone(ir, NULL)))));
i.insert_before(assign(hi, add(hi, _carry(lo, lshift(t2, c16->clone(ir, NULL))))));
i.insert_before(assign(lo, add(lo, lshift(t2, c16->clone(ir, NULL)))));
if (different_signs == NULL) {
assert(ir->operands[0]->type->base_type == GLSL_TYPE_UINT);
ir->operation = ir_binop_add;
ir->operands[0] = add(hi, rshift(t1, c16->clone(ir, NULL)));
ir->operands[1] = rshift(t2, c16->clone(ir, NULL));
} else {
assert(ir->operands[0]->type->base_type == GLSL_TYPE_INT);
i.insert_before(assign(hi, add(add(hi, rshift(t1, c16->clone(ir, NULL))),
rshift(t2, c16->clone(ir, NULL)))));
/* For channels where different_signs is set we have to perform a 64-bit
* negation. This is *not* the same as just negating the high 32-bits.
* Consider -3 * 2. The high 32-bits is 0, but the desired result is
* -1, not -0! Recall -x == ~x + 1.
*/
ir_variable *neg_hi =
new(ir) ir_variable(glsl_type::ivec(elements), "neg_hi", ir_var_temporary);
ir_constant *c1 = new(ir) ir_constant(1u, elements);
i.insert_before(neg_hi);
i.insert_before(assign(neg_hi, add(bit_not(u2i(hi)),
u2i(_carry(bit_not(lo), c1)))));
ir->operation = ir_triop_csel;
ir->operands[0] = new(ir) ir_dereference_variable(different_signs);
ir->operands[1] = new(ir) ir_dereference_variable(neg_hi);
ir->operands[2] = u2i(hi);
}
}
ir_visitor_status
lower_instructions_visitor::visit_leave(ir_expression *ir)
{
switch (ir->operation) {
case ir_binop_dot:
if (ir->operands[0]->type->is_double())
double_dot_to_fma(ir);
break;
case ir_triop_lrp:
if (ir->operands[0]->type->is_double())
double_lrp(ir);
break;
case ir_binop_sub:
if (lowering(SUB_TO_ADD_NEG))
sub_to_add_neg(ir);
break;
case ir_binop_div:
if (ir->operands[1]->type->is_integer() && lowering(INT_DIV_TO_MUL_RCP))
int_div_to_mul_rcp(ir);
else if ((ir->operands[1]->type->is_float() && lowering(FDIV_TO_MUL_RCP)) ||
(ir->operands[1]->type->is_double() && lowering(DDIV_TO_MUL_RCP)))
div_to_mul_rcp(ir);
break;
case ir_unop_exp:
if (lowering(EXP_TO_EXP2))
exp_to_exp2(ir);
break;
case ir_unop_log:
if (lowering(LOG_TO_LOG2))
log_to_log2(ir);
break;
case ir_binop_mod:
if (lowering(MOD_TO_FLOOR) && (ir->type->is_float() || ir->type->is_double()))
mod_to_floor(ir);
break;
case ir_binop_pow:
if (lowering(POW_TO_EXP2))
pow_to_exp2(ir);
break;
case ir_binop_ldexp:
if (lowering(LDEXP_TO_ARITH) && ir->type->is_float())
ldexp_to_arith(ir);
if (lowering(DFREXP_DLDEXP_TO_ARITH) && ir->type->is_double())
dldexp_to_arith(ir);
break;
case ir_unop_frexp_exp:
if (lowering(DFREXP_DLDEXP_TO_ARITH) && ir->operands[0]->type->is_double())
dfrexp_exp_to_arith(ir);
break;
case ir_unop_frexp_sig:
if (lowering(DFREXP_DLDEXP_TO_ARITH) && ir->operands[0]->type->is_double())
dfrexp_sig_to_arith(ir);
break;
case ir_binop_carry:
if (lowering(CARRY_TO_ARITH))
carry_to_arith(ir);
break;
case ir_binop_borrow:
if (lowering(BORROW_TO_ARITH))
borrow_to_arith(ir);
break;
case ir_unop_saturate:
if (lowering(SAT_TO_CLAMP))
sat_to_clamp(ir);
break;
case ir_unop_trunc:
if (lowering(DOPS_TO_DFRAC) && ir->type->is_double())
dtrunc_to_dfrac(ir);
break;
case ir_unop_ceil:
if (lowering(DOPS_TO_DFRAC) && ir->type->is_double())
dceil_to_dfrac(ir);
break;
case ir_unop_floor:
if (lowering(DOPS_TO_DFRAC) && ir->type->is_double())
dfloor_to_dfrac(ir);
break;
case ir_unop_round_even:
if (lowering(DOPS_TO_DFRAC) && ir->type->is_double())
dround_even_to_dfrac(ir);
break;
case ir_unop_sign:
if (lowering(DOPS_TO_DFRAC) && ir->type->is_double())
dsign_to_csel(ir);
break;
case ir_unop_bit_count:
if (lowering(BIT_COUNT_TO_MATH))
bit_count_to_math(ir);
break;
case ir_triop_bitfield_extract:
if (lowering(EXTRACT_TO_SHIFTS))
extract_to_shifts(ir);
break;
case ir_quadop_bitfield_insert:
if (lowering(INSERT_TO_SHIFTS))
insert_to_shifts(ir);
break;
case ir_unop_bitfield_reverse:
if (lowering(REVERSE_TO_SHIFTS))
reverse_to_shifts(ir);
break;
case ir_unop_find_lsb:
if (lowering(FIND_LSB_TO_FLOAT_CAST))
find_lsb_to_float_cast(ir);
break;
case ir_unop_find_msb:
if (lowering(FIND_MSB_TO_FLOAT_CAST))
find_msb_to_float_cast(ir);
break;
case ir_binop_imul_high:
if (lowering(IMUL_HIGH_TO_MUL))
imul_high_to_mul(ir);
break;
default:
return visit_continue;
}
return visit_continue;
}