Mesa (10.3): glsl_to_tgsi: fix the value of gl_FrontFacing with native integers

[Emil Velikov]

Module: Mesa
Branch: 10.3
Commit: 6fa07d1d4842169906155c6de58475fefe780204
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=6fa07d1d4842169906155c6de58475fefe780204

Author: Marek Olšák <marek.olsak at amd.com>
Date:   Thu Oct 16 16:21:54 2014 +0200

glsl_to_tgsi: fix the value of gl_FrontFacing with native integers

We must convert it to boolean from the DX9 float encoding that Gallium
specifies.

Later, we should probably define that FACE should be 0 or ~0 if native
integers are supported.

Cc: 10.2 10.3 <mesa-stable at lists.freedesktop.org>
Reviewed-by: Eric Anholt <eric at anholt.net>
(cherry picked from commit 9ec305ead7750c7f91c79b043584c1997bacd9a7)

---

 src/mesa/state_tracker/st_glsl_to_tgsi.cpp |   14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
index 34f7e9c..57416d1 100644
--- a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
+++ b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
@@ -4818,15 +4818,19 @@ emit_wpos(struct st_context *st,
  * saturating the value to [0,1] does the job.
  */
 static void
-emit_face_var(struct st_translate *t)
+emit_face_var(struct gl_context *ctx, struct st_translate *t)
 {
    struct ureg_program *ureg = t->ureg;
    struct ureg_dst face_temp = ureg_DECL_temporary(ureg);
    struct ureg_src face_input = t->inputs[t->inputMapping[VARYING_SLOT_FACE]];
 
-   /* MOV_SAT face_temp, input[face] */
-   face_temp = ureg_saturate(face_temp);
-   ureg_MOV(ureg, face_temp, face_input);
+   if (ctx->Const.NativeIntegers) {
+      ureg_FSGE(ureg, face_temp, face_input, ureg_imm1f(ureg, 0));
+   }
+   else {
+      /* MOV_SAT face_temp, input[face] */
+      ureg_MOV(ureg, ureg_saturate(face_temp), face_input);
+   }
 
    /* Use face_temp as face input from here on: */
    t->inputs[t->inputMapping[VARYING_SLOT_FACE]] = ureg_src(face_temp);
@@ -4946,7 +4950,7 @@ st_translate_program(
       }
 
       if (proginfo->InputsRead & VARYING_BIT_FACE)
-         emit_face_var(t);
+         emit_face_var(ctx, t);
 
       /*
        * Declare output attributes.