From: Ian Romanick <ian.d.roman...@intel.com>
Continue using ADD in the other case because a fragment shader backend
could fuse the ADD with a MUL to generate a MAD for ((x && y) || z).
Signed-off-by: Ian Romanick <ian.d.roman...@intel.com>
---
src/mesa/program/ir_to_mesa.cpp | 26 +++++++++++---------------
1 file changed, 11 insertions(+), 15 deletions(-)
diff --git a/src/mesa/program/ir_to_mesa.cpp b/src/mesa/program/ir_to_mesa.cpp
index d5b3693..7f24a9e 100644
--- a/src/mesa/program/ir_to_mesa.cpp
+++ b/src/mesa/program/ir_to_mesa.cpp
@@ -1212,24 +1212,20 @@ ir_to_mesa_visitor::visit(ir_expression *ir)
break;
case ir_binop_logic_or: {
- /* After the addition, the value will be an integer on the
- * range [0,2]. Zero stays zero, and positive values become 1.0.
- */
- ir_to_mesa_instruction *add =
- emit(ir, OPCODE_ADD, result_dst, op[0], op[1]);
if (this->prog->Target == GL_FRAGMENT_PROGRAM_ARB) {
- /* The clamping to [0,1] can be done for free in the fragment
- * shader with a saturate.
- */
+ /* After the addition, the value will be an integer on the
+ * range [0,2]. Zero stays zero, and positive values become 1.0.
+ */
+ ir_to_mesa_instruction *add =
+ emit(ir, OPCODE_ADD, result_dst, op[0], op[1]);
add->saturate = true;
} else {
- /* Negating the result of the addition gives values on the range
- * [-2, 0]. Zero stays zero, and negative values become 1.0. This
- * is achieved using SLT.
- */
- src_reg slt_src = result_src;
- slt_src.negate = ~slt_src.negate;
- emit(ir, OPCODE_SLT, result_dst, slt_src, src_reg_for_float(0.0));
+ /* The Boolean arguments are stored as float 0.0 and 1.0. If either
+ * value is 1.0, the result of the logcal-or should be 1.0. If both
+ * values are 0.0, the result should be 0.0. This is exactly what
+ * MAX does.
+ */
+ emit(ir, OPCODE_MAX, result_dst, op[0], op[1]);
}
break;
}
--
2.5.5
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