* 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_FRACT
+ * - LDEXP_TO_ARITH
+ * - BITFIELD_INSERT_TO_BFM_BFI
+ * - CARRY_TO_ARITH
+ * - BORROW_TO_ARITH
+ * - SAT_TO_CLAMP
*
* SUB_TO_ADD_NEG:
* ---------------
* want to recognize add(op0, neg(op1)) or the other way around to
* produce a subtract anyway.
*
- * DIV_TO_MUL_RCP:
- * ---------------
- * Breaks an ir_unop_div expression down to op0 * (rcp(op1)).
+ * DIV_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.
*
+ * DIV_TO_MUL_RCP only lowers floating point division; 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_FRACT:
* -------------
- * Breaks an ir_unop_mod expression down to (op1 * fract(op0 / op1))
+ * Breaks an ir_binop_mod expression down to (op1 * fract(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.
+ *
+ * LDEXP_TO_ARITH:
+ * -------------
+ * Converts ir_binop_ldexp to arithmetic and bit operations.
+ *
+ * BITFIELD_INSERT_TO_BFM_BFI:
+ * ---------------------------
+ * Breaks ir_quadop_bitfield_insert into ir_binop_bfm (bitfield mask) and
+ * ir_triop_bfi (bitfield insert).
+ *
+ * Many GPUs implement the bitfieldInsert() built-in from ARB_gpu_shader_5
+ * with a pair of instructions.
+ *
+ * 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)
+ *
*/
-#include "main/core.h" /* for M_E */
+#include "main/core.h" /* for M_LOG2E */
#include "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)
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_fract(ir_expression *);
void exp_to_exp2(ir_expression *);
+ void pow_to_exp2(ir_expression *);
void log_to_log2(ir_expression *);
+ void bitfield_insert_to_bfm_bfi(ir_expression *);
+ void ldexp_to_arith(ir_expression *);
+ void carry_to_arith(ir_expression *);
+ void borrow_to_arith(ir_expression *);
+ void sat_to_clamp(ir_expression *);
};
+} /* anonymous namespace */
+
/**
* Determine if a particular type of lowering should occur
*/
void
lower_instructions_visitor::div_to_mul_rcp(ir_expression *ir)
{
- if (!ir->operands[1]->type->is_integer()) {
- /* 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],
- NULL);
-
- /* op0 / op1 -> op0 * (1.0 / op1) */
- ir->operation = ir_binop_mul;
- ir->operands[1] = expr;
- } else {
- /* 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;
+ assert(ir->operands[1]->type->is_float());
+
+ /* 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);
- 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);
- 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);
- 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);
- 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);
- 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);
+ 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;
- ir->operands[1] = NULL;
+ } 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(log2f(M_E));
+ 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,
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(1.0f / log2f(M_E));
+ ir->operands[1] = new(ir) ir_constant(float(1.0 / M_LOG2E));
this->progress = true;
}
this->progress = true;
}
+void
+lower_instructions_visitor::bitfield_insert_to_bfm_bfi(ir_expression *ir)
+{
+ /* Translates
+ * ir_quadop_bitfield_insert base insert offset bits
+ * into
+ * ir_triop_bfi (ir_binop_bfm bits offset) insert base
+ */
+
+ ir_rvalue *base_expr = ir->operands[0];
+
+ ir->operation = ir_triop_bfi;
+ ir->operands[0] = new(ir) ir_expression(ir_binop_bfm,
+ ir->type->get_base_type(),
+ ir->operands[3],
+ ir->operands[2]);
+ /* ir->operands[1] is still the value to insert. */
+ ir->operands[2] = base_expr;
+ ir->operands[3] = NULL;
+
+ 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) {
+ * 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 = 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);
+ ir_constant *exp_width = new(ir) ir_constant(8);
+
+ /* 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,
+ 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);
+ 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;
+
+ /* Don't generate new IR that would need to be lowered in an additional
+ * pass.
+ */
+ if (lowering(BITFIELD_INSERT_TO_BFM_BFI))
+ bitfield_insert_to_bfm_bfi(ir->operands[0]->as_expression());
+
+ 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;
+}
+
ir_visitor_status
lower_instructions_visitor::visit_leave(ir_expression *ir)
{
break;
case ir_binop_div:
- if (lowering(DIV_TO_MUL_RCP))
+ 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(DIV_TO_MUL_RCP))
div_to_mul_rcp(ir);
break;
break;
case ir_binop_mod:
- if (lowering(MOD_TO_FRACT))
+ if (lowering(MOD_TO_FRACT) && ir->type->is_float())
mod_to_fract(ir);
break;
+ case ir_binop_pow:
+ if (lowering(POW_TO_EXP2))
+ pow_to_exp2(ir);
+ break;
+
+ case ir_quadop_bitfield_insert:
+ if (lowering(BITFIELD_INSERT_TO_BFM_BFI))
+ bitfield_insert_to_bfm_bfi(ir);
+ break;
+
+ case ir_binop_ldexp:
+ if (lowering(LDEXP_TO_ARITH))
+ ldexp_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;
+
default:
return visit_continue;
}
projects / mesa.git / blobdiff