diff options
| author | Marek Olšák <[email protected]> | 2010-08-31 05:38:50 +0200 |
|---|---|---|
| committer | Marek Olšák <[email protected]> | 2010-08-31 06:36:52 +0200 |
| commit | 4f189b3bf57a6500953dac49105f160af5fa6468 (patch) | |
| tree | 6e406eb6f33443db25d95b6f7808c19fcaedd97b | |
| parent | 2619b1c96feed72444499021d8a870eab1c37e00 (diff) | |
ir_to_mesa: use RSQ+MUL instead of RSQ+RCP for SQRT
sqrt(x) = 1/rsq(x) = x*rsq(x)
This optimization already was in the old GLSL compiler.
Acked on irc by Eric Anholt.
| -rw-r--r-- | src/mesa/program/ir_to_mesa.cpp | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/src/mesa/program/ir_to_mesa.cpp b/src/mesa/program/ir_to_mesa.cpp index af6d7345a54..516c991855d 100644 --- a/src/mesa/program/ir_to_mesa.cpp +++ b/src/mesa/program/ir_to_mesa.cpp @@ -880,8 +880,9 @@ ir_to_mesa_visitor::visit(ir_expression *ir) break; case ir_unop_sqrt: + /* sqrt(x) = x * rsq(x). */ ir_to_mesa_emit_scalar_op1(ir, OPCODE_RSQ, result_dst, op[0]); - ir_to_mesa_emit_scalar_op1(ir, OPCODE_RCP, result_dst, result_src); + ir_to_mesa_emit_op2(ir, OPCODE_MUL, result_dst, result_src, op[0]); /* For incoming channels < 0, set the result to 0. */ ir_to_mesa_emit_op3(ir, OPCODE_CMP, result_dst, op[0], src_reg_for_float(0.0), result_src); |