/* * 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); void sqrt_to_abs_sqrt(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->init_num_operands(); 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->init_num_operands(); 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->init_num_operands(); 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->init_num_operands(); 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->init_num_operands(); 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->init_num_operands(); 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->init_num_operands(); 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 = min(extracted_biased_exp + exp, 255); * * if (extracted_biased_exp >= 255) * return x; // +/-inf, NaN * * sign_mantissa = bitcast_f2u(x) & sign_mantissa_mask; * * if (min(resulting_biased_exp, extracted_biased_exp) < 1) * resulting_biased_exp = 0; * if (resulting_biased_exp >= 255 || * min(resulting_biased_exp, extracted_biased_exp) < 1) { * sign_mantissa &= sign_mask; * } * * return bitcast_u2f(sign_mantissa | * 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 = min(extracted_biased_exp + exp, 255); * * sign_mantissa = bitcast_f2u(x) & sign_mantissa_mask; * * flush_to_zero = lequal(min(resulting_biased_exp, extracted_biased_exp), 0); * resulting_biased_exp = csel(flush_to_zero, 0, resulting_biased_exp) * zero_mantissa = logic_or(flush_to_zero, * gequal(resulting_biased_exp, 255)); * sign_mantissa = csel(zero_mantissa, sign_mantissa & sign_mask, sign_mantissa); * * result = sign_mantissa | * lshift(i2u(resulting_biased_exp), exp_shift)); * * return csel(extracted_biased_exp >= 255, x, bitcast_u2f(result)); * * The definition of ldexp in the GLSL spec says: * * "If this product is too large to be represented in the * floating-point type, the result is undefined." * * However, the definition of ldexp in the GLSL ES spec does not contain * this sentence, so we do need to handle overflow correctly. * * There is additional language limiting the defined range of exp, but this * is merely to allow implementations that store 2^exp in a temporary * variable. */ 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 *uvec = glsl_type::get_instance(GLSL_TYPE_UINT, vec_elem, 1); const glsl_type *bvec = glsl_type::get_instance(GLSL_TYPE_BOOL, vec_elem, 1); /* 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 *result = new(ir) ir_variable(uvec, "result", 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 *sign_mantissa = new(ir) ir_variable(uvec, "sign_mantissa", ir_var_temporary); ir_variable *flush_to_zero = new(ir) ir_variable(bvec, "flush_to_zero", ir_var_temporary); ir_variable *zero_mantissa = new(ir) ir_variable(bvec, "zero_mantissa", ir_var_temporary); ir_instruction &i = *base_ir; /* Copy and 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 . */ i.insert_before(extracted_biased_exp); i.insert_before(assign(extracted_biased_exp, rshift(bitcast_f2i(abs(x)), new(ir) ir_constant(23, vec_elem)))); /* The definition of ldexp in the GLSL 4.60 spec says: * * "If exp is greater than +128 (single-precision) or +1024 * (double-precision), the value returned is undefined. If exp is less * than -126 (single-precision) or -1022 (double-precision), the value * returned may be flushed to zero." * * So we do not have to guard against the possibility of addition overflow, * which could happen when exp is close to INT_MAX. Addition underflow * cannot happen (the worst case is 0 + (-INT_MAX)). */ i.insert_before(resulting_biased_exp); i.insert_before(assign(resulting_biased_exp, min2(add(extracted_biased_exp, exp), new(ir) ir_constant(255, vec_elem)))); i.insert_before(sign_mantissa); i.insert_before(assign(sign_mantissa, bit_and(bitcast_f2u(x), new(ir) ir_constant(0x807fffffu, vec_elem)))); /* We flush to zero if the original or resulting biased exponent is 0, * indicating a +/-0.0 or subnormal input or output. * * The mantissa is set to 0 if the resulting biased exponent is 255, since * an overflow should produce a +/-inf result. * * Note that NaN inputs are handled separately. */ i.insert_before(flush_to_zero); i.insert_before(assign(flush_to_zero, lequal(min2(resulting_biased_exp, extracted_biased_exp), ir_constant::zero(ir, ivec)))); i.insert_before(assign(resulting_biased_exp, csel(flush_to_zero, ir_constant::zero(ir, ivec), resulting_biased_exp))); i.insert_before(zero_mantissa); i.insert_before(assign(zero_mantissa, logic_or(flush_to_zero, equal(resulting_biased_exp, new(ir) ir_constant(255, vec_elem))))); i.insert_before(assign(sign_mantissa, csel(zero_mantissa, bit_and(sign_mantissa, new(ir) ir_constant(0x80000000u, vec_elem)), sign_mantissa))); /* Don't generate new IR that would need to be lowered in an additional * pass. */ i.insert_before(result); if (!lowering(INSERT_TO_SHIFTS)) { i.insert_before(assign(result, bitfield_insert(sign_mantissa, i2u(resulting_biased_exp), new(ir) ir_constant(23u, vec_elem), new(ir) ir_constant(8u, vec_elem)))); } else { i.insert_before(assign(result, bit_or(sign_mantissa, lshift(i2u(resulting_biased_exp), new(ir) ir_constant(23, vec_elem))))); } ir->operation = ir_triop_csel; ir->init_num_operands(); ir->operands[0] = gequal(extracted_biased_exp, new(ir) ir_constant(255, vec_elem)); ir->operands[1] = new(ir) ir_dereference_variable(x); ir->operands[2] = bitcast_u2f(result); 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 and 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 . */ 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->init_num_operands(); 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->init_num_operands(); 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->init_num_operands(); 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->init_num_operands(); 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->init_num_operands(); 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->init_num_operands(); 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->init_num_operands(); 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->init_num_operands(); 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->init_num_operands(); 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->init_num_operands(); 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->init_num_operands(); 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->init_num_operands(); 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->init_num_operands(); 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->init_num_operands(); 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->init_num_operands(); 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->init_num_operands(); 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->init_num_operands(); 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->init_num_operands(); ir->operands[0] = rshift(temp, c16); ir->operands[1] = lshift(temp, c16->clone(ir, NULL)); } else { ir->operation = ir_unop_u2i; ir->init_num_operands(); 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->init_num_operands(); 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->init_num_operands(); 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->init_num_operands(); 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->init_num_operands(); 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); } } void lower_instructions_visitor::sqrt_to_abs_sqrt(ir_expression *ir) { ir->operands[0] = new(ir) ir_expression(ir_unop_abs, ir->operands[0]); this->progress = true; } 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; case ir_unop_rsq: case ir_unop_sqrt: if (lowering(SQRT_TO_ABS_SQRT)) sqrt_to_abs_sqrt(ir); break; default: return visit_continue; } return visit_continue; }