Mesa (main): etnaviv: add mov for direct depth store output from load input

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Module: Mesa
Branch: main
Commit: b1b6d9e9a1e8cebc8ddb865a667f3d6dbc6d2821
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=b1b6d9e9a1e8cebc8ddb865a667f3d6dbc6d2821

Author: Philipp Zabel <p.zabel at pengutronix.de>
Date:   Wed Sep 15 18:19:02 2021 +0200

etnaviv: add mov for direct depth store output from load input

If the fragment shader writes fragment depth from an ALU instruction,
the register allocator makes sure that the instruction is pointed to the
correct register and write mask (t0.__z_).
If there is no instruction emitted because the source is an input
load intrinsic, or if the source instruction does not support swizzle
and write mask, we have to add a mov instruction for this to work.

Fixes piglit test spec at glsl-1.10@execution at glsl-1.10-fragdepth.

Signed-off-by: Philipp Zabel <p.zabel at pengutronix.de>
Reviewed-by: Christian Gmeiner <christian.gmeiner at gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/12891>

---

 src/gallium/drivers/etnaviv/etnaviv_compiler_nir.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/src/gallium/drivers/etnaviv/etnaviv_compiler_nir.c b/src/gallium/drivers/etnaviv/etnaviv_compiler_nir.c
index 77af20859e2..00ebc250bdd 100644
--- a/src/gallium/drivers/etnaviv/etnaviv_compiler_nir.c
+++ b/src/gallium/drivers/etnaviv/etnaviv_compiler_nir.c
@@ -944,7 +944,7 @@ emit_shader(struct etna_compile *c, unsigned *num_temps, unsigned *num_consts)
       c->const_count = indirect_max;
    }
 
-   /* add mov for any store output using sysval/const  */
+   /* add mov for any store output using sysval/const and for depth stores from intrinsics */
    nir_foreach_block(block, c->impl) {
       nir_foreach_instr_safe(instr, block) {
          if (instr->type != nir_instr_type_intrinsic)
@@ -954,8 +954,13 @@ emit_shader(struct etna_compile *c, unsigned *num_temps, unsigned *num_consts)
 
          switch (intr->intrinsic) {
          case nir_intrinsic_store_deref: {
+            nir_deref_instr *deref = nir_src_as_deref(intr->src[0]);
             nir_src *src = &intr->src[1];
-            if (nir_src_is_const(*src) || is_sysval(src->ssa->parent_instr)) {
+            if (nir_src_is_const(*src) || is_sysval(src->ssa->parent_instr) ||
+                (shader->info.stage == MESA_SHADER_FRAGMENT &&
+                 deref->var->data.location == FRAG_RESULT_DEPTH &&
+                 src->is_ssa &&
+                 src->ssa->parent_instr->type != nir_instr_type_alu)) {
                b.cursor = nir_before_instr(instr);
                nir_instr_rewrite_src(instr, src, nir_src_for_ssa(nir_mov(&b, src->ssa)));
             }