On Wed, Apr 8, 2015 at 4:38 PM, Ian Romanick <i...@freedesktop.org> wrote:
> From: Ian Romanick <ian.d.roman...@intel.com>
>
> ir_rvalue_visitor visits each rvalue on exit. When visiting a large
> expression, the leaf expressions will be visited and eliminated first.
> Once one leaf expression was replaced, it would no longer match a
> potentially much larger tree. This means that code like:
>
> x = a + (b * c);
> y = -(a + (b * c));
>
> would effectively be replaced by
>
> tmp = b * c;
> x = a + tmp;
> y = -(a + tmp);
>
> As a result both opportunities for generating a MAD would be lost, and
> we would generate worse code.
>
> Using ir_rvalue_enter_visitor means that larger expression trees will be
> checked first, and we have the potential to eliminate much larger
> expressions.
>
> I believe that opt_cse.cpp predates the existence of
> ir_rvalue_enter_visitor.
Nope, git disagrees.
Reviewed-by: Matt Turner <matts...@gmail.com>
>
> Shader-db results:
>
> GM45:
> total instructions in shared programs: 4063165 -> 4061744 (-0.03%)
> instructions in affected programs: 21664 -> 20243 (-6.56%)
> helped: 259
>
> GM45 NIR:
> total instructions in shared programs: 4082044 -> 4080646 (-0.03%)
> instructions in affected programs: 21091 -> 19693 (-6.63%)
> helped: 255
> HURT: 1
>
> Iron Lake:
> total instructions in shared programs: 5480334 -> 5478897 (-0.03%)
> instructions in affected programs: 25798 -> 24361 (-5.57%)
> helped: 273
> HURT: 1
>
> Iron Lake NIR:
> total instructions in shared programs: 5678776 -> 5677395 (-0.02%)
> instructions in affected programs: 21744 -> 20363 (-6.35%)
> helped: 263
> HURT: 2
>
> Sandy Bridge:
> total instructions in shared programs: 7318903 -> 7316983 (-0.03%)
> instructions in affected programs: 37937 -> 36017 (-5.06%)
> helped: 398
> HURT: 26
>
> Sandy Bridge NIR:
> total instructions in shared programs: 7329995 -> 7328069 (-0.03%)
> instructions in affected programs: 32487 -> 30561 (-5.93%)
> helped: 384
> HURT: 6
>
> Ivy Bridge:
> total instructions in shared programs: 6766579 -> 6765409 (-0.02%)
> instructions in affected programs: 18110 -> 16940 (-6.46%)
> helped: 288
> HURT: 16
> GAINED: 1
>
> Ivy Bridge NIR:
> total instructions in shared programs: 6769314 -> 6768159 (-0.02%)
> instructions in affected programs: 11063 -> 9908 (-10.44%)
> helped: 264
> HURT: 6
>
> Haswell:
> total instructions in shared programs: 6226294 -> 6225102 (-0.02%)
> instructions in affected programs: 17555 -> 16363 (-6.79%)
> helped: 297
> HURT: 10
> GAINED: 1
>
> Haswell NIR:
> total instructions in shared programs: 6183693 -> 6182538 (-0.02%)
> instructions in affected programs: 10990 -> 9835 (-10.51%)
> helped: 264
> HURT: 6
>
> Broadwell:
> total instructions in shared programs: 7285895 -> 7284537 (-0.02%)
> instructions in affected programs: 31977 -> 30619 (-4.25%)
> helped: 357
> HURT: 6
>
> Broadwell NIR:
> total instructions in shared programs: 7501711 -> 7501544 (-0.00%)
> instructions in affected programs: 7174 -> 7007 (-2.33%)
> helped: 87
> HURT: 2
>
> Signed-off-by: Ian Romanick <ian.d.roman...@intel.com>
> ---
> src/glsl/opt_cse.cpp | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/src/glsl/opt_cse.cpp b/src/glsl/opt_cse.cpp
> index 4b8e9a0..425eebc 100644
> --- a/src/glsl/opt_cse.cpp
> +++ b/src/glsl/opt_cse.cpp
> @@ -99,7 +99,7 @@ public:
> ir_variable *var;
> };
>
> -class cse_visitor : public ir_rvalue_visitor {
> +class cse_visitor : public ir_rvalue_enter_visitor {
> public:
> cse_visitor(exec_list *validate_instructions)
> : validate_instructions(validate_instructions)
> --
> 2.1.0
>
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