On Mon, Mar 10, 2014 at 11:54 PM, Matt Turner <matts...@gmail.com> 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);
> + }
> +
Is this safe? Since many GPUs implement pow(x, y) as exp2(log2(x) *
y), this will give different results for if y comes from a uniform vs
if it's a constant, no?
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