Mesa (master): nir: Fix interaction of GL_CLAMP lowering with texture offsets.

[Eric Anholt]

Module: Mesa
Branch: master
Commit: b08b6289943b225b6451e6c8ce331a8c11bd0c7f
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=b08b6289943b225b6451e6c8ce331a8c11bd0c7f

Author: Eric Anholt <eric at anholt.net>
Date:   Tue Nov 21 13:42:08 2017 -0800

nir: Fix interaction of GL_CLAMP lowering with texture offsets.

We want the clamping of the coordinate to apply after the offset, so we
need to do math to lower the offset out of the instruction.  Fixes texwrap
offset cases for GL_CLAMP with GL_NEAREST on vc5.

Note: I moved the get_texture_size() verbatim, so that it was defined
before use.

Reviewed-by: Ian Romanick <ian.d.romanick at intel.com>

---

 src/compiler/nir/nir_lower_tex.c | 75 ++++++++++++++++++++++------------------
 1 file changed, 42 insertions(+), 33 deletions(-)

diff --git a/src/compiler/nir/nir_lower_tex.c b/src/compiler/nir/nir_lower_tex.c
index a50cb52d54..bd603cc228 100644
--- a/src/compiler/nir/nir_lower_tex.c
+++ b/src/compiler/nir/nir_lower_tex.c
@@ -101,6 +101,36 @@ project_src(nir_builder *b, nir_tex_instr *tex)
    nir_tex_instr_remove_src(tex, proj_index);
 }
 
+static nir_ssa_def *
+get_texture_size(nir_builder *b, nir_tex_instr *tex)
+{
+   b->cursor = nir_before_instr(&tex->instr);
+
+   nir_tex_instr *txs;
+
+   txs = nir_tex_instr_create(b->shader, 1);
+   txs->op = nir_texop_txs;
+   txs->sampler_dim = tex->sampler_dim;
+   txs->is_array = tex->is_array;
+   txs->is_shadow = tex->is_shadow;
+   txs->is_new_style_shadow = tex->is_new_style_shadow;
+   txs->texture_index = tex->texture_index;
+   txs->texture = nir_deref_var_clone(tex->texture, txs);
+   txs->sampler_index = tex->sampler_index;
+   txs->sampler = nir_deref_var_clone(tex->sampler, txs);
+   txs->dest_type = nir_type_int;
+
+   /* only single src, the lod: */
+   txs->src[0].src = nir_src_for_ssa(nir_imm_int(b, 0));
+   txs->src[0].src_type = nir_tex_src_lod;
+
+   nir_ssa_dest_init(&txs->instr, &txs->dest,
+                     nir_tex_instr_dest_size(txs), 32, NULL);
+   nir_builder_instr_insert(b, &txs->instr);
+
+   return nir_i2f32(b, &txs->dest.ssa);
+}
+
 static bool
 lower_offset(nir_builder *b, nir_tex_instr *tex)
 {
@@ -120,8 +150,17 @@ lower_offset(nir_builder *b, nir_tex_instr *tex)
 
    nir_ssa_def *offset_coord;
    if (nir_tex_instr_src_type(tex, coord_index) == nir_type_float) {
-      assert(tex->sampler_dim == GLSL_SAMPLER_DIM_RECT);
-      offset_coord = nir_fadd(b, coord, nir_i2f32(b, offset));
+      if (tex->sampler_dim == GLSL_SAMPLER_DIM_RECT) {
+         offset_coord = nir_fadd(b, coord, nir_i2f32(b, offset));
+      } else {
+         nir_ssa_def *txs = get_texture_size(b, tex);
+         nir_ssa_def *scale = nir_frcp(b, txs);
+
+         offset_coord = nir_fadd(b, coord,
+                                 nir_fmul(b,
+                                          nir_i2f32(b, offset),
+                                          scale));
+      }
    } else {
       offset_coord = nir_iadd(b, coord, offset);
    }
@@ -148,37 +187,6 @@ lower_offset(nir_builder *b, nir_tex_instr *tex)
    return true;
 }
 
-
-static nir_ssa_def *
-get_texture_size(nir_builder *b, nir_tex_instr *tex)
-{
-   b->cursor = nir_before_instr(&tex->instr);
-
-   nir_tex_instr *txs;
-
-   txs = nir_tex_instr_create(b->shader, 1);
-   txs->op = nir_texop_txs;
-   txs->sampler_dim = tex->sampler_dim;
-   txs->is_array = tex->is_array;
-   txs->is_shadow = tex->is_shadow;
-   txs->is_new_style_shadow = tex->is_new_style_shadow;
-   txs->texture_index = tex->texture_index;
-   txs->texture = nir_deref_var_clone(tex->texture, txs);
-   txs->sampler_index = tex->sampler_index;
-   txs->sampler = nir_deref_var_clone(tex->sampler, txs);
-   txs->dest_type = nir_type_int;
-
-   /* only single src, the lod: */
-   txs->src[0].src = nir_src_for_ssa(nir_imm_int(b, 0));
-   txs->src[0].src_type = nir_tex_src_lod;
-
-   nir_ssa_dest_init(&txs->instr, &txs->dest,
-                     nir_tex_instr_dest_size(txs), 32, NULL);
-   nir_builder_instr_insert(b, &txs->instr);
-
-   return nir_i2f32(b, &txs->dest.ssa);
-}
-
 static void
 lower_rect(nir_builder *b, nir_tex_instr *tex)
 {
@@ -749,6 +757,7 @@ nir_lower_tex_block(nir_block *block, nir_builder *b,
       }
 
       if ((tex->op == nir_texop_txf && options->lower_txf_offset) ||
+          (sat_mask && nir_tex_instr_src_index(tex, nir_tex_src_coord) >= 0) ||
           (tex->sampler_dim == GLSL_SAMPLER_DIM_RECT &&
            options->lower_rect_offset)) {
          progress = lower_offset(b, tex) || progress;