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glsl: Use bitfieldInsert in ldexp() lowering.

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Shaves a few instructions off of lowered ldexp().

Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
This commit is contained in:
Matt Turner 2014-01-27 11:56:14 -08:00
parent 3ea64f9093
commit 57109d57f8
1 changed files with 10 additions and 4 deletions
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14
src/glsl/lower_instructions.cpp
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@ -384,10 +384,10 @@ lower_instructions_visitor::ldexp_to_arith(ir_expression *ir)
/* Constants */
ir_constant *zeroi = ir_constant::zero(ir, ivec);
ir_constant *sign_mantissa_mask = new(ir) ir_constant(0x807fffffu, vec_elem);
ir_constant *sign_mask = new(ir) ir_constant(0x80000000u, vec_elem);
ir_constant *exp_shift = new(ir) ir_constant(23u, vec_elem);
ir_constant *exp_width = new(ir) ir_constant(8u, vec_elem);
/* Temporary variables */
ir_variable *x = new(ir) ir_variable(ir->type, "x", ir_var_temporary);
@ -449,11 +449,17 @@ lower_instructions_visitor::ldexp_to_arith(ir_expression *ir)
*/
ir_constant *exp_shift_clone = exp_shift->clone(ir, NULL);
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));
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;
}