Mesa (main): freedreno/ir3: Move the texture array coord fixup to nir

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Module: Mesa
Branch: main
Commit: edb0904775b4f7dea29cfb9ba33e3a1568e99e2e
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=edb0904775b4f7dea29cfb9ba33e3a1568e99e2e

Author: Matt Turner <mattst88 at gmail.com>
Date:   Fri Feb 19 20:30:05 2021 +0000

freedreno/ir3: Move the texture array coord fixup to nir

We're going to optimize sampler coordinates to FP16, so we'll need to
add the appropriately typed 0.5. Move this to NIR where that information
is readily available.

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/16616>

---

 src/freedreno/ir3/ir3_compiler_nir.c | 11 ++--------
 src/freedreno/ir3/ir3_nir.c          | 42 ++++++++++++++++++++++++++++++++++++
 2 files changed, 44 insertions(+), 9 deletions(-)

diff --git a/src/freedreno/ir3/ir3_compiler_nir.c b/src/freedreno/ir3/ir3_compiler_nir.c
index 507606b2af4..8afb148437b 100644
--- a/src/freedreno/ir3/ir3_compiler_nir.c
+++ b/src/freedreno/ir3/ir3_compiler_nir.c
@@ -3081,15 +3081,8 @@ emit_tex(struct ir3_context *ctx, nir_tex_instr *tex)
    if (tex->is_shadow && tex->op != nir_texop_lod)
       src0[nsrc0++] = compare;
 
-   if (tex->is_array && tex->op != nir_texop_lod) {
-      struct ir3_instruction *idx = coord[coords];
-
-      /* the array coord for cube arrays needs 0.5 added to it */
-      if (ctx->compiler->array_index_add_half && !is_isam(opc))
-         idx = ir3_ADD_F(b, idx, 0, create_immed(b, fui(0.5)), 0);
-
-      src0[nsrc0++] = idx;
-   }
+   if (tex->is_array && tex->op != nir_texop_lod)
+      src0[nsrc0++] = coord[coords];
 
    if (has_proj) {
       src0[nsrc0++] = proj;
diff --git a/src/freedreno/ir3/ir3_nir.c b/src/freedreno/ir3/ir3_nir.c
index 5bc960dc16b..31077a9cc95 100644
--- a/src/freedreno/ir3/ir3_nir.c
+++ b/src/freedreno/ir3/ir3_nir.c
@@ -264,6 +264,45 @@ ir3_nir_lower_io_to_temporaries(nir_shader *s)
    NIR_PASS_V(s, nir_lower_indirect_derefs, 0, UINT32_MAX);
 }
 
+/**
+ * Inserts an add of 0.5 to floating point array index values in texture coordinates.
+ */
+static bool
+ir3_nir_lower_array_sampler_cb(struct nir_builder *b, nir_instr *instr, void *_data)
+{
+   if (instr->type != nir_instr_type_tex)
+      return false;
+
+   nir_tex_instr *tex = nir_instr_as_tex(instr);
+   if (!tex->is_array || tex->op == nir_texop_lod)
+      return false;
+
+   int coord_idx = nir_tex_instr_src_index(tex, nir_tex_src_coord);
+   if (coord_idx == -1 ||
+       nir_tex_instr_src_type(tex, coord_idx) != nir_type_float)
+      return false;
+
+   b->cursor = nir_before_instr(&tex->instr);
+
+   unsigned ncomp = tex->coord_components;
+   nir_ssa_def *src = nir_ssa_for_src(b, tex->src[coord_idx].src, ncomp);
+
+   assume(ncomp >= 1);
+   nir_ssa_def *ai = nir_channel(b, src, ncomp - 1);
+   ai = nir_fadd(b, ai, nir_imm_floatN_t(b, 0.5, src->bit_size));
+   nir_instr_rewrite_src(&tex->instr, &tex->src[coord_idx].src,
+                         nir_src_for_ssa(nir_vector_insert_imm(b, src, ai, ncomp - 1)));
+   return true;
+}
+
+static bool
+ir3_nir_lower_array_sampler(nir_shader *shader)
+{
+   return nir_shader_instructions_pass(
+      shader, ir3_nir_lower_array_sampler_cb,
+      nir_metadata_block_index | nir_metadata_dominance, NULL);
+}
+
 void
 ir3_finalize_nir(struct ir3_compiler *compiler, nir_shader *s)
 {
@@ -298,6 +337,9 @@ ir3_finalize_nir(struct ir3_compiler *compiler, nir_shader *s)
    OPT_V(s, nir_lower_tex, &tex_options);
    OPT_V(s, nir_lower_load_const_to_scalar);
 
+   if (compiler->array_index_add_half)
+      OPT_V(s, ir3_nir_lower_array_sampler);
+
    ir3_optimize_loop(compiler, s);
 
    /* do idiv lowering after first opt loop to get a chance to propagate