I had a pretty similar patch on the top of my pow-optimization branch.
I also expand x**3 and x**4. I had hoped that would enable some cases
to expand then merge to MADs. It should also be faster on older GENs
where POW perf sucks. I didn't send it out because I wanted to add a
similar optimization in the back end that would turn x*x*x*x back into
x**4 on GPUs where the POW would be faster.
I also didn't have anything in shader-db that benefitted from x**2 or
x**3. It seems like there were a couple that would be modified by a
x**5 flattening, but I think that would universally be slower....
On 03/10/2014 03:54 PM, Matt Turner wrote:
> Cuts two instructions out of SynMark's Gl32VSInstancing benchmark.
> ---
> src/glsl/opt_algebraic.cpp | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/src/glsl/opt_algebraic.cpp b/src/glsl/opt_algebraic.cpp
> index 5c49a78..8494bd9 100644
> --- a/src/glsl/opt_algebraic.cpp
> +++ b/src/glsl/opt_algebraic.cpp
> @@ -528,6 +528,14 @@ ir_algebraic_visitor::handle_expression(ir_expression
> *ir)
> if (is_vec_two(op_const[0]))
> return expr(ir_unop_exp2, ir->operands[1]);
>
> + if (is_vec_two(op_const[1])) {
> + ir_variable *x = new(ir) ir_variable(ir->operands[1]->type, "x",
> + ir_var_temporary);
> + base_ir->insert_before(x);
> + base_ir->insert_before(assign(x, ir->operands[0]));
> + return mul(x, x);
> + }
> +
> break;
>
> case ir_unop_rcp:
>
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