According to the "Gather4 R32G32_FLOAT Bug" internal documentation
page, the R32G32_UINT and R32G32_SINT formats are affected by the
same bug as R32G32_FLOAT. Applying the same workarounds should be
viable - apparently the R32G32_FLOAT_LD format shouldn't corrupt
integer data which is NaN or other sketchy floating point values.
One irritating caveat is that, because it's a FLOAT format, the
alpha channel or any set to SCS_ONE return 0x3f8 (1.0) rather than
integer 1. So we need shader code to whack those channels to 1.
Fixes GL45-CTS.texture_gather.plain-gather-int-cube-rg on Haswell.
Signed-off-by: Kenneth Graunke <kenn...@whitecape.org>
---
src/mesa/drivers/dri/i965/brw_wm.c | 41 ++++++++++++++++++++----
src/mesa/drivers/dri/i965/brw_wm_surface_state.c | 4 ++-
2 files changed, 37 insertions(+), 8 deletions(-)
Technically the brw_wm_surface_state.c hunk is enough to pass this test.
Asking for a dead channel (alpha) or constant value (one) with texture
gather (which only gives you one channel's worth of data) is fairly
pointless, so I don't expect anyone would actually do it...but, I tried
to fix it with the brw_wm.c hunks. Probably needs tests...
diff --git a/src/mesa/drivers/dri/i965/brw_wm.c
b/src/mesa/drivers/dri/i965/brw_wm.c
index b0cd1635521..024e948391e 100644
--- a/src/mesa/drivers/dri/i965/brw_wm.c
+++ b/src/mesa/drivers/dri/i965/brw_wm.c
@@ -353,13 +353,40 @@ brw_populate_sampler_prog_key_data(struct gl_context *ctx,
key->gl_clamp_mask[2] |= 1 << s;
}
- /* gather4's channel select for green from RG32F is broken; requires
- * a shader w/a on IVB; fixable with just SCS on HSW.
- */
- if (brw->gen == 7 && !brw->is_haswell &&
- prog->nir->info->uses_texture_gather) {
- if (img->InternalFormat == GL_RG32F)
- key->gather_channel_quirk_mask |= 1 << s;
+ /* gather4 for RG32* is broken in multiple ways on Gen7. */
+ if (brw->gen == 7 && prog->nir->info->uses_texture_gather) {
+ switch (img->InternalFormat) {
+ case GL_RG32I:
+ case GL_RG32UI: {
+ /* We have to override the format to R32G32_FLOAT_LD.
+ * This means that SCS_ALPHA and SCS_ONE will return 0x3f8
+ * (1.0) rather than integer 1. This needs shader hacks.
+ *
+ * On Ivybridge, we whack W (alpha) to ONE in our key's
+ * swizzle. On Haswell, we look at the original texture
+ * swizzle, and use XYZW with channels overridden to ONE,
+ * leaving normal texture swizzling to SCS.
+ */
+ unsigned src_swizzle =
+ brw->is_haswell ? t->_Swizzle : key->swizzles[s];
+ for (int i = 0; i < 4; i++) {
+ unsigned src_comp = GET_SWZ(src_swizzle, i);
+ if (src_comp == SWIZZLE_ONE || src_comp == SWIZZLE_W) {
+ key->swizzles[i] &= 0x7 << (3 * i);
+ key->swizzles[i] |= SWIZZLE_ONE << (3 * i);
+ }
+ }
+ /* fallthrough */
+ }
+ case GL_RG32F:
+ /* The channel select for green doesn't work - we have to
+ * request blue. Haswell can use SCS for this, but Ivybridge
+ * needs a shader workaround.
+ */
+ if (!brw->is_haswell)
+ key->gather_channel_quirk_mask |= 1 << s;
+ break;
+ }
}
/* Gen6's gather4 is broken for UINT/SINT; we treat them as
diff --git a/src/mesa/drivers/dri/i965/brw_wm_surface_state.c
b/src/mesa/drivers/dri/i965/brw_wm_surface_state.c
index 6c44381be13..7a99aa434bf 100644
--- a/src/mesa/drivers/dri/i965/brw_wm_surface_state.c
+++ b/src/mesa/drivers/dri/i965/brw_wm_surface_state.c
@@ -565,7 +565,9 @@ brw_update_texture_surface(struct gl_context *ctx,
/* Implement gen6 and gen7 gather work-around */
bool need_green_to_blue = false;
if (for_gather) {
- if (brw->gen == 7 && format == BRW_SURFACEFORMAT_R32G32_FLOAT) {
+ if (brw->gen == 7 && (format == BRW_SURFACEFORMAT_R32G32_FLOAT ||
+ format == BRW_SURFACEFORMAT_R32G32_SINT ||
+ format == BRW_SURFACEFORMAT_R32G32_UINT)) {
format = BRW_SURFACEFORMAT_R32G32_FLOAT_LD;
need_green_to_blue = brw->is_haswell;
} else if (brw->gen == 6) {
--
2.11.0
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