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glsl: Add lowering pass for ir_unop_bit_count

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Signed-off-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Matt Turner <mattst88@gmail.com>
This commit is contained in:
Ian Romanick 2016-06-23 16:16:21 -07:00
parent 806add360f
commit 7340be8a01
2 changed files with 54 additions and 0 deletions
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1
src/compiler/glsl/ir_optimization.h
View file

@ -42,6 +42,7 @@
#define SAT_TO_CLAMP 0x400
#define DOPS_TO_DFRAC 0x800
#define DFREXP_DLDEXP_TO_ARITH 0x1000
#define BIT_COUNT_TO_MATH 0x02000
/**
* \see class lower_packing_builtins_visitor

53
src/compiler/glsl/lower_instructions.cpp
View file

@ -159,6 +159,7 @@ private:
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 *);
};
} /* anonymous namespace */
@ -954,6 +955,52 @@ lower_instructions_visitor::dsign_to_csel(ir_expression *ir)
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;
}
ir_visitor_status
lower_instructions_visitor::visit_leave(ir_expression *ir)
{
@ -1055,6 +1102,12 @@ lower_instructions_visitor::visit_leave(ir_expression *ir)
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;
default:
return visit_continue;
}