Mesa (master): tgsi_exec: Fix NaN behavior of saturate

[GitLab Mirror]

Module: Mesa
Branch: master
Commit: d1c0f62b4296799014a0a7ad09b8baae8961c974
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=d1c0f62b4296799014a0a7ad09b8baae8961c974

Author: Ian Romanick <ian.d.romanick at intel.com>
Date:   Thu Apr 22 17:41:57 2021 -0700

tgsi_exec: Fix NaN behavior of saturate

Modern shader APIs, like DX10 and GLSL 1.30, want saturate or
clamp(..., 0.0, 1.0) to "cleanse" NaN.  If the source is NaN, the
result should be zero.

There are many cases where TGSI is generate from NIR, and many
optimizations in NIR expect this behavior.  Not meeting these
expectations can lead to unexpected results.

Reviewed-by: Eric Anholt <eric at anholt.net>
Fixes: 56c30bf17b9 ("tgsi: Saturate modifier obeys ExecMask. Implement NVIDIA [-1;+1] saturate mode.")
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/10419>

---

 src/gallium/auxiliary/tgsi/tgsi_exec.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/gallium/auxiliary/tgsi/tgsi_exec.c b/src/gallium/auxiliary/tgsi/tgsi_exec.c
index 008d8c0f4bb..b4c6f60f888 100644
--- a/src/gallium/auxiliary/tgsi/tgsi_exec.c
+++ b/src/gallium/auxiliary/tgsi/tgsi_exec.c
@@ -1938,7 +1938,7 @@ store_dest(struct tgsi_exec_machine *mach,
    else {
       for (i = 0; i < TGSI_QUAD_SIZE; i++)
          if (execmask & (1 << i)) {
-            if (chan->f[i] < 0.0f)
+            if (chan->f[i] < 0.0f || isnan(chan->f[i]))
                dst->f[i] = 0.0f;
             else if (chan->f[i] > 1.0f)
                dst->f[i] = 1.0f;
@@ -3621,7 +3621,7 @@ store_double_channel(struct tgsi_exec_machine *mach,
    else {
       for (i = 0; i < TGSI_QUAD_SIZE; i++)
          if (execmask & (1 << i)) {
-            if (chan->d[i] < 0.0)
+            if (chan->d[i] < 0.0 || isnan(chan->d[i]))
                temp.d[i] = 0.0;
             else if (chan->d[i] > 1.0)
                temp.d[i] = 1.0;