[Mesa-dev] [PATCH] svga: allow non-contiguous VS input declarations

[Charmaine Lee]

Reviewed-by: Charmaine Lee <charmainel at vmware.com>
________________________________________
From: Brian Paul <brianp at vmware.com>
Sent: Thursday, February 18, 2016 12:30 PM
To: mesa-dev at lists.freedesktop.org
Cc: Charmaine Lee
Subject: [PATCH] svga: allow non-contiguous VS input declarations

This fixes a glDrawPixels regression since b63fe0552b5f.  The new
quad-drawing utility code uses 3 vertex attributes (xyz, rgba, st).
For glDrawPixels path we don't use the rgba attribute so there's a
gap in the TGSI VS input declarations (INPUT[0] = pos, INPUT[2] =
texcoord).  The TGSI->VGPU10 translations code did not handle this
correctly.  I missed this because my VM was configured for HWv11
while testing.

Another way to fix this would be to change the tgsi_scan.c code so
that the tgsi_shader_info::num_inputs (and num_outputs) included
the unused inputs/outputs.  These counts would then actually be
"max input register index + 1" rather than "number of used inputs".
But that change could impact all drivers so put it off for now.

No regressions found with piglit or typical GL apps.

v2: also update alloc_system_value_index() to use info.file_max[]
---
 src/gallium/drivers/svga/svga_tgsi_vgpu10.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/gallium/drivers/svga/svga_tgsi_vgpu10.c b/src/gallium/drivers/svga/svga_tgsi_vgpu10.c
index 1223e44..0c5afeb 100644
--- a/src/gallium/drivers/svga/svga_tgsi_vgpu10.c
+++ b/src/gallium/drivers/svga/svga_tgsi_vgpu10.c
@@ -1782,7 +1782,7 @@ alloc_immediate_int4(struct svga_shader_emitter_v10 *emit,
 static unsigned
 alloc_system_value_index(struct svga_shader_emitter_v10 *emit, unsigned index)
 {
-   const unsigned n = emit->info.num_inputs + index;
+   const unsigned n = emit->info.file_max[TGSI_FILE_INPUT] + 1 + index;
    assert(index < Elements(emit->system_value_indexes));
    emit->system_value_indexes[index] = n;
    return n;
@@ -2446,7 +2446,7 @@ emit_input_declarations(struct svga_shader_emitter_v10 *emit)
    else {
       assert(emit->unit == PIPE_SHADER_VERTEX);

-      for (i = 0; i < emit->info.num_inputs; i++) {
+      for (i = 0; i < emit->info.file_max[TGSI_FILE_INPUT] + 1; i++) {
          unsigned usage_mask = emit->info.input_usage_mask[i];
          unsigned index = i;

--
1.9.1