nir: add support for gather offsets

Values inside the offsets parameter of textureGatherOffsets are required to be
constants in the range of [GL_MIN_PROGRAM_TEXTURE_GATHER_OFFSET,
GL_MAX_PROGRAM_TEXTURE_GATHER_OFFSET].

As this range is never outside [-32, 31] for all existing drivers inside mesa,
we can simply store the offsets as a int8_t[4][2] array inside nir_tex_instr.

Right now only Nvidia hardware supports this in hardware, so we can turn this
on inside Nouveau for the NIR path as it is already enabled with the TGSI one.

v2: use memcpy instead of for loops
    add missing bits to nir_instr_set
    don't show offsets if they are all 0
v3: default offsets aren't all 0
v4: rename offsets -> tg4_offsets
    rename nir_tex_instr_has_explicit_offsets -> nir_tex_instr_has_explicit_tg4_offsets

Signed-off-by: Karol Herbst <[email protected]>

8 files changed, 66 insertions, 7 deletions

diff --git a/src/compiler/glsl/glsl_to_nir.cpp b/src/compiler/glsl/glsl_to_nir.cpp
index 9084803adf1..6a1a0b5f113 100644
--- a/src/compiler/glsl/glsl_to_nir.cpp
+++ b/src/compiler/glsl/glsl_to_nir.cpp
@@ -2378,7 +2378,8 @@ nir_visitor::visit(ir_texture *ir)
       num_srcs++;
    if (ir->shadow_comparator != NULL)
       num_srcs++;
-   if (ir->offset != NULL)
+   /* offsets are constants we store inside nir_tex_intrs.offsets */
+   if (ir->offset != NULL && !ir->offset->type->is_array())
       num_srcs++;
 
    /* Add one for the texture deref */
@@ -2439,13 +2440,25 @@ nir_visitor::visit(ir_texture *ir)
    }
 
    if (ir->offset != NULL) {
-      /* we don't support multiple offsets yet */
-      assert(ir->offset->type->is_vector() || ir->offset->type->is_scalar());
+      if (ir->offset->type->is_array()) {
+         for (int i = 0; i < ir->offset->type->array_size(); i++) {
+            const ir_constant *c =
+               ir->offset->as_constant()->get_array_element(i);
+
+            for (unsigned j = 0; j < 2; ++j) {
+               int val = c->get_int_component(j);
+               assert(val <= 31 && val >= -32);
+               instr->tg4_offsets[i][j] = val;
+            }
+         }
+      } else {
+         assert(ir->offset->type->is_vector() || ir->offset->type->is_scalar());
 
-      instr->src[src_number].src =
-         nir_src_for_ssa(evaluate_rvalue(ir->offset));
-      instr->src[src_number].src_type = nir_tex_src_offset;
-      src_number++;
+         instr->src[src_number].src =
+            nir_src_for_ssa(evaluate_rvalue(ir->offset));
+         instr->src[src_number].src_type = nir_tex_src_offset;
+         src_number++;
+      }
    }
 
    switch (ir->op) {
diff --git a/src/compiler/nir/nir.c b/src/compiler/nir/nir.c
index 4a7c757db3a..0daafc4936d 100644
--- a/src/compiler/nir/nir.c
+++ b/src/compiler/nir/nir.c
@@ -531,6 +531,14 @@ nir_call_instr_create(nir_shader *shader, nir_function *callee)
    return instr;
 }
 
+static int8_t default_tg4_offsets[4][2] =
+{
+   { 0, 1 },
+   { 1, 1 },
+   { 1, 0 },
+   { 0, 0 },
+};
+
 nir_tex_instr *
 nir_tex_instr_create(nir_shader *shader, unsigned num_srcs)
 {
@@ -547,6 +555,7 @@ nir_tex_instr_create(nir_shader *shader, unsigned num_srcs)
    instr->texture_index = 0;
    instr->texture_array_size = 0;
    instr->sampler_index = 0;
+   memcpy(instr->tg4_offsets, default_tg4_offsets, sizeof(instr->tg4_offsets));
 
    return instr;
 }
@@ -589,6 +598,15 @@ nir_tex_instr_remove_src(nir_tex_instr *tex, unsigned src_idx)
    tex->num_srcs--;
 }
 
+bool
+nir_tex_instr_has_explicit_tg4_offsets(nir_tex_instr *tex)
+{
+   if (tex->op != nir_texop_tg4)
+      return false;
+   return memcmp(tex->tg4_offsets, default_tg4_offsets,
+                 sizeof(tex->tg4_offsets)) != 0;
+}
+
 nir_phi_instr *
 nir_phi_instr_create(nir_shader *shader)
 {
diff --git a/src/compiler/nir/nir.h b/src/compiler/nir/nir.h
index f9c2adb83e5..2c1caf2687a 100644
--- a/src/compiler/nir/nir.h
+++ b/src/compiler/nir/nir.h
@@ -1482,6 +1482,9 @@ typedef struct {
    /* gather component selector */
    unsigned component : 2;
 
+   /* gather offsets */
+   int8_t tg4_offsets[4][2];
+
    /** The texture index
     *
     * If this texture instruction has a nir_tex_src_texture_offset source,
@@ -1699,6 +1702,8 @@ void nir_tex_instr_add_src(nir_tex_instr *tex,
 
 void nir_tex_instr_remove_src(nir_tex_instr *tex, unsigned src_idx);
 
+bool nir_tex_instr_has_explicit_tg4_offsets(nir_tex_instr *tex);
+
 typedef struct {
    nir_instr instr;
 
diff --git a/src/compiler/nir/nir_clone.c b/src/compiler/nir/nir_clone.c
index fa24f8b6028..9594eb8044d 100644
--- a/src/compiler/nir/nir_clone.c
+++ b/src/compiler/nir/nir_clone.c
@@ -394,6 +394,7 @@ clone_tex(clone_state *state, const nir_tex_instr *tex)
    ntex->is_shadow = tex->is_shadow;
    ntex->is_new_style_shadow = tex->is_new_style_shadow;
    ntex->component = tex->component;
+   memcpy(ntex->tg4_offsets, tex->tg4_offsets, sizeof(tex->tg4_offsets));
 
    ntex->texture_index = tex->texture_index;
    ntex->texture_array_size = tex->texture_array_size;
diff --git a/src/compiler/nir/nir_instr_set.c b/src/compiler/nir/nir_instr_set.c
index 8f4e971b89a..d106e9ebcae 100644
--- a/src/compiler/nir/nir_instr_set.c
+++ b/src/compiler/nir/nir_instr_set.c
@@ -200,6 +200,9 @@ hash_tex(uint32_t hash, const nir_tex_instr *instr)
    hash = HASH(hash, instr->is_new_style_shadow);
    unsigned component = instr->component;
    hash = HASH(hash, component);
+   for (unsigned i = 0; i < 4; ++i)
+      for (unsigned j = 0; j < 2; ++j)
+         hash = HASH(hash, instr->tg4_offsets[i][j]);
    hash = HASH(hash, instr->texture_index);
    hash = HASH(hash, instr->texture_array_size);
    hash = HASH(hash, instr->sampler_index);
@@ -403,6 +406,10 @@ nir_instrs_equal(const nir_instr *instr1, const nir_instr *instr2)
          return false;
       }
 
+      if (memcmp(tex1->tg4_offsets, tex2->tg4_offsets,
+                 sizeof(tex1->tg4_offsets)))
+         return false;
+
       return true;
    }
    case nir_instr_type_load_const: {
diff --git a/src/compiler/nir/nir_print.c b/src/compiler/nir/nir_print.c
index 6b270394f9d..8e714e6666b 100644
--- a/src/compiler/nir/nir_print.c
+++ b/src/compiler/nir/nir_print.c
@@ -984,6 +984,14 @@ print_tex_instr(nir_tex_instr *instr, print_state *state)
       fprintf(fp, "%u (gather_component), ", instr->component);
    }
 
+   if (nir_tex_instr_has_explicit_tg4_offsets(instr)) {
+      fprintf(fp, "{ (%i, %i)", instr->tg4_offsets[0][0], instr->tg4_offsets[0][1]);
+      for (unsigned i = 1; i < 4; ++i)
+         fprintf(fp, ", (%i, %i)", instr->tg4_offsets[i][0],
+                 instr->tg4_offsets[i][1]);
+      fprintf(fp, " } (offsets), ");
+   }
+
    if (!has_texture_deref) {
       fprintf(fp, "%u (texture), ", instr->texture_index);
    }
diff --git a/src/compiler/nir/nir_serialize.c b/src/compiler/nir/nir_serialize.c
index 840a1572786..fd8708fbb43 100644
--- a/src/compiler/nir/nir_serialize.c
+++ b/src/compiler/nir/nir_serialize.c
@@ -617,6 +617,7 @@ write_tex(write_ctx *ctx, const nir_tex_instr *tex)
    blob_write_uint32(ctx->blob, tex->texture_index);
    blob_write_uint32(ctx->blob, tex->texture_array_size);
    blob_write_uint32(ctx->blob, tex->sampler_index);
+   blob_write_bytes(ctx->blob, tex->tg4_offsets, sizeof(tex->tg4_offsets));
 
    STATIC_ASSERT(sizeof(union packed_tex_data) == sizeof(uint32_t));
    union packed_tex_data packed = {
@@ -647,6 +648,7 @@ read_tex(read_ctx *ctx)
    tex->texture_index = blob_read_uint32(ctx->blob);
    tex->texture_array_size = blob_read_uint32(ctx->blob);
    tex->sampler_index = blob_read_uint32(ctx->blob);
+   blob_copy_bytes(ctx->blob, tex->tg4_offsets, sizeof(tex->tg4_offsets));
 
    union packed_tex_data packed;
    packed.u32 = blob_read_uint32(ctx->blob);
diff --git a/src/compiler/nir/nir_validate.c b/src/compiler/nir/nir_validate.c
index 3a3c232d370..ef2e2b62783 100644
--- a/src/compiler/nir/nir_validate.c
+++ b/src/compiler/nir/nir_validate.c
@@ -598,6 +598,11 @@ validate_tex_instr(nir_tex_instr *instr, validate_state *state)
                    0, nir_tex_instr_src_size(instr, i));
    }
 
+   if (nir_tex_instr_has_explicit_tg4_offsets(instr)) {
+      validate_assert(state, instr->op == nir_texop_tg4);
+      validate_assert(state, !src_type_seen[nir_tex_src_offset]);
+   }
+
    validate_dest(&instr->dest, state, 0, nir_tex_instr_dest_size(instr));
 }