The scalar VS backend has never handled float[] and vec2[] outputs
correctly (my original code was broken). Outputs need to be padded
out to vec4 slots.
In fs_visitor::nir_setup_outputs(), we tried to process each vec4 slot
by looping from 0 to ALIGN(type_size_scalar(type), 4) / 4. However,
this is wrong: type_size_scalar() for a float[2] would return 2, or
for vec2[2] it would return 4. This looked like a single slot, even
though in reality each array element would be stored in separate vec4
slots.
Because of this bug, outputs[] and output_components[] would not get
initialized for the second element's VARYING_SLOT, which meant
emit_urb_writes() would skip writing them. Nothing used those values,
and dead code elimination threw a party.
The new type_size_4x() function pads array elements correctly, but
still counts in scalar components, generating correct indices in
store_output intrinsics.
Not observed to fix any Piglit or dEQP tests, but does fix various
tcs-input Piglit tests on a branch that implements tessellation shaders.
Cc: mesa-sta...@lists.freedesktop.org
Signed-off-by: Kenneth Graunke <kenn...@whitecape.org>
---
src/mesa/drivers/dri/i965/brw_fs_nir.cpp | 2 +-
src/mesa/drivers/dri/i965/brw_nir.c | 3 ++-
2 files changed, 3 insertions(+), 2 deletions(-)
diff --git a/src/mesa/drivers/dri/i965/brw_fs_nir.cpp
b/src/mesa/drivers/dri/i965/brw_fs_nir.cpp
index 0e044d0..a290656 100644
--- a/src/mesa/drivers/dri/i965/brw_fs_nir.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs_nir.cpp
@@ -93,7 +93,7 @@ fs_visitor::nir_setup_outputs()
switch (stage) {
case MESA_SHADER_VERTEX:
- for (unsigned int i = 0; i < ALIGN(type_size_scalar(var->type), 4) /
4; i++) {
+ for (int i = 0; i < type_size_4x(var->type) / 4; i++) {
int output = var->data.location + i;
this->outputs[output] = offset(reg, bld, 4 * i);
this->output_components[output] = vector_elements;
diff --git a/src/mesa/drivers/dri/i965/brw_nir.c
b/src/mesa/drivers/dri/i965/brw_nir.c
index 1b4dace..c7f94a6 100644
--- a/src/mesa/drivers/dri/i965/brw_nir.c
+++ b/src/mesa/drivers/dri/i965/brw_nir.c
@@ -117,7 +117,8 @@ brw_nir_lower_outputs(nir_shader *nir, bool is_scalar)
case MESA_SHADER_GEOMETRY:
if (is_scalar) {
nir_assign_var_locations(&nir->outputs, &nir->num_outputs,
- type_size_scalar);
+ type_size_4x);
+ nir_lower_io(nir, nir_var_shader_out, type_size_4x);
} else {
nir_foreach_variable(var, &nir->outputs)
var->data.driver_location = var->data.location;
--
2.6.1
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