Mesa (master): ffvertex: Don't try to read output registers in fog calculation

[Ian Romanick]

Module: Mesa
Branch: master
Commit: df80ffa4aaf18433d8e3e97b7cb86426a1e8654b
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=df80ffa4aaf18433d8e3e97b7cb86426a1e8654b

Author: Ian Romanick <ian.d.romanick at intel.com>
Date:   Fri Jun 16 19:02:48 2017 -0700

ffvertex: Don't try to read output registers in fog calculation

Gallium drivers use _mesa_remove_output_reads() via st_program to lower
output reads away.  It seems better to just generate the right thing in
the first place.

Signed-off-by: Ian Romanick <ian.d.romanick at intel.com>
Reviewed-by: Kenneth Graunke <kenneth at whitecape.org>

---

 src/mesa/main/ffvertex_prog.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/src/mesa/main/ffvertex_prog.c b/src/mesa/main/ffvertex_prog.c
index 1c755592bd..dfb494bd8c 100644
--- a/src/mesa/main/ffvertex_prog.c
+++ b/src/mesa/main/ffvertex_prog.c
@@ -1297,12 +1297,14 @@ static void build_fog( struct tnl_program *p )
    struct ureg input;
 
    switch (p->state->fog_distance_mode) {
-   case FDM_EYE_RADIAL: /* Z = sqrt(Xe*Xe + Ye*Ye + Ze*Ze) */
+   case FDM_EYE_RADIAL: { /* Z = sqrt(Xe*Xe + Ye*Ye + Ze*Ze) */
+      struct ureg tmp = get_temp(p);
       input = get_eye_position(p);
-      emit_op2(p, OPCODE_DP3, fog, WRITEMASK_X, input, input);
-      emit_op1(p, OPCODE_RSQ, fog, WRITEMASK_X, fog);
-      emit_op1(p, OPCODE_RCP, fog, WRITEMASK_X, fog);
+      emit_op2(p, OPCODE_DP3, tmp, WRITEMASK_X, input, input);
+      emit_op1(p, OPCODE_RSQ, tmp, WRITEMASK_X, tmp);
+      emit_op1(p, OPCODE_RCP, fog, WRITEMASK_X, tmp);
       break;
+   }
    case FDM_EYE_PLANE: /* Z = Ze */
       input = get_eye_position_z(p);
       emit_op1(p, OPCODE_MOV, fog, WRITEMASK_X, input);