Mesa (main): mesa: don't add attenuation constants if ffvp doesn't use them

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Module: Mesa
Branch: main
Commit: 09342dcfc0e45fbbe4a019a7e8086780aebd8336
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=09342dcfc0e45fbbe4a019a7e8086780aebd8336

Author: Marek Olšák <marek.olsak at amd.com>
Date:   Mon Nov  1 12:00:06 2021 -0400

mesa: don't add attenuation constants if ffvp doesn't use them

This slightly decreases the size of constant buffers.

Acked-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer at amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/13872>

---

 src/mesa/main/ffvertex_prog.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/src/mesa/main/ffvertex_prog.c b/src/mesa/main/ffvertex_prog.c
index f38c6a3d36e..2f8b721a2f8 100644
--- a/src/mesa/main/ffvertex_prog.c
+++ b/src/mesa/main/ffvertex_prog.c
@@ -939,8 +939,7 @@ static struct ureg calculate_light_attenuation( struct tnl_program *p,
 						struct ureg VPpli,
 						struct ureg dist )
 {
-   struct ureg attenuation = register_param3(p, STATE_LIGHT, i,
-					     STATE_ATTENUATION);
+   struct ureg attenuation = undef;
    struct ureg att = undef;
 
    /* Calculate spot attenuation:
@@ -950,6 +949,7 @@ static struct ureg calculate_light_attenuation( struct tnl_program *p,
       struct ureg spot = get_temp(p);
       struct ureg slt = get_temp(p);
 
+      attenuation = register_param3(p, STATE_LIGHT, i, STATE_ATTENUATION);
       att = get_temp(p);
 
       emit_op2(p, OPCODE_DP3, spot, 0, negate(VPpli), spot_dir_norm);
@@ -969,6 +969,10 @@ static struct ureg calculate_light_attenuation( struct tnl_program *p,
    if (p->state->unit[i].light_attenuated && !is_undef(dist)) {
       if (is_undef(att))
          att = get_temp(p);
+
+      if (is_undef(attenuation))
+         attenuation = register_param3(p, STATE_LIGHT, i, STATE_ATTENUATION);
+
       /* 1/d,d,d,1/d */
       emit_op1(p, OPCODE_RCP, dist, WRITEMASK_YZ, dist);
       /* 1,d,d*d,1/d */
@@ -1141,7 +1145,10 @@ static void build_lighting( struct tnl_program *p )
       }
    }
    for (i = 0; i < MAX_LIGHTS; i++) {
-      if (p->state->unit[i].light_enabled)
+      if (p->state->unit[i].light_enabled &&
+          (!p->state->unit[i].light_spotcutoff_is_180 ||
+           (p->state->unit[i].light_attenuated &&
+            !p->state->unit[i].light_eyepos3_is_zero)))
          register_param3(p, STATE_LIGHT, i, STATE_ATTENUATION);
    }