panfrost: Add support for TXS instructions

This patch adds support for nir_texop_txs instructions which are needed
to support the OpenGL textureSize() function. This is also needed to
support RECT texture sampling which is currently lowered to 2D sampling +
a TXS() instruction by the nir_lower_tex() helper.

Changes in v2:
* Split options for the 1st and 2nd tex lowering passes

Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>

3 files changed, 60 insertions, 2 deletions

diff --git a/src/gallium/drivers/panfrost/midgard/midgard_compile.c b/src/gallium/drivers/panfrost/midgard/midgard_compile.c
index 2d2d69a98ac..602530fad89 100644
--- a/src/gallium/drivers/panfrost/midgard/midgard_compile.c
+++ b/src/gallium/drivers/panfrost/midgard/midgard_compile.c
@@ -313,6 +313,7 @@ static int sysval_for_instr(compiler_context *ctx, nir_instr *instr,
 {
         nir_intrinsic_instr *intr;
         nir_dest *dst = NULL;
+        nir_tex_instr *tex;
         int sysval = -1;
 
         switch (instr->type) {
@@ -321,6 +322,18 @@ static int sysval_for_instr(compiler_context *ctx, nir_instr *instr,
                 sysval = midgard_nir_sysval_for_intrinsic(intr);
                 dst = &intr->dest;
                 break;
+        case nir_instr_type_tex:
+                tex = nir_instr_as_tex(instr);
+                if (tex->op != nir_texop_txs)
+                        break;
+
+                sysval = PAN_SYSVAL(TEXTURE_SIZE,
+				    PAN_TXS_SYSVAL_ID(tex->texture_index,
+					              nir_tex_instr_dest_size(tex) -
+						      (tex->is_array ? 1 : 0),
+						      tex->is_array));
+                dst  = &tex->dest;
+                break;
         default:
                 break;
         }
@@ -411,12 +424,17 @@ optimise_nir(nir_shader *nir)
         NIR_PASS(progress, nir, midgard_nir_lower_fdot2);
         NIR_PASS(progress, nir, nir_lower_idiv);
 
-        nir_lower_tex_options lower_tex_options = {
+        nir_lower_tex_options lower_tex_1st_pass_options = {
                 .lower_rect = true,
                 .lower_txp = ~0
         };
 
-        NIR_PASS(progress, nir, nir_lower_tex, &lower_tex_options);
+        nir_lower_tex_options lower_tex_2nd_pass_options = {
+                .lower_txs_lod = true,
+	};
+
+        NIR_PASS(progress, nir, nir_lower_tex, &lower_tex_1st_pass_options);
+        NIR_PASS(progress, nir, nir_lower_tex, &lower_tex_2nd_pass_options);
 
         do {
                 progress = false;
@@ -1523,6 +1541,9 @@ emit_tex(compiler_context *ctx, nir_tex_instr *instr)
         case nir_texop_txl:
                 emit_texop_native(ctx, instr, TEXTURE_OP_LOD);
                 break;
+        case nir_texop_txs:
+                emit_sysval_read(ctx, &instr->instr);
+                break;
         default:
 		unreachable("Unhanlded texture op");
         }
diff --git a/src/gallium/drivers/panfrost/midgard/midgard_compile.h b/src/gallium/drivers/panfrost/midgard/midgard_compile.h
index f20d7bafe1e..44c3533b6de 100644
--- a/src/gallium/drivers/panfrost/midgard/midgard_compile.h
+++ b/src/gallium/drivers/panfrost/midgard/midgard_compile.h
@@ -44,8 +44,16 @@
 enum {
         PAN_SYSVAL_VIEWPORT_SCALE = 1,
         PAN_SYSVAL_VIEWPORT_OFFSET = 2,
+        PAN_SYSVAL_TEXTURE_SIZE = 3,
 } pan_sysval;
 
+#define PAN_TXS_SYSVAL_ID(texidx, dim, is_array)          \
+	((texidx) | ((dim) << 7) | ((is_array) ? (1 << 9) : 0))
+
+#define PAN_SYSVAL_ID_TO_TXS_TEX_IDX(id)        ((id) & 0x7f)
+#define PAN_SYSVAL_ID_TO_TXS_DIM(id)            (((id) >> 7) & 0x3)
+#define PAN_SYSVAL_ID_TO_TXS_IS_ARRAY(id)       !!((id) & (1 << 9))
+
 typedef struct {
         int work_register_count;
         int uniform_count;
diff --git a/src/gallium/drivers/panfrost/pan_context.c b/src/gallium/drivers/panfrost/pan_context.c
index 6af10496c91..ed19fa17645 100644
--- a/src/gallium/drivers/panfrost/pan_context.c
+++ b/src/gallium/drivers/panfrost/pan_context.c
@@ -1036,6 +1036,31 @@ static void panfrost_upload_viewport_offset_sysval(struct panfrost_context *ctx,
         uniform->f[2] = vp->translate[2];
 }
 
+static void panfrost_upload_txs_sysval(struct panfrost_context *ctx,
+                                       enum pipe_shader_type st,
+                                       unsigned int sysvalid,
+                                       struct sysval_uniform *uniform)
+{
+        unsigned texidx = PAN_SYSVAL_ID_TO_TXS_TEX_IDX(sysvalid);
+        unsigned dim = PAN_SYSVAL_ID_TO_TXS_DIM(sysvalid);
+        bool is_array = PAN_SYSVAL_ID_TO_TXS_IS_ARRAY(sysvalid);
+        struct pipe_sampler_view *tex = &ctx->sampler_views[st][texidx]->base;
+
+        assert(dim);
+        uniform->i[0] = u_minify(tex->texture->width0, tex->u.tex.first_level);
+
+        if (dim > 1)
+                uniform->i[1] = u_minify(tex->texture->height0,
+                                         tex->u.tex.first_level);
+
+        if (dim > 2)
+                uniform->i[2] = u_minify(tex->texture->depth0,
+                                         tex->u.tex.first_level);
+
+        if (is_array)
+                uniform->i[dim] = tex->texture->array_size;
+}
+
 static void panfrost_upload_sysvals(struct panfrost_context *ctx, void *buf,
                                     struct panfrost_shader_state *ss,
                                     enum pipe_shader_type st)
@@ -1052,6 +1077,10 @@ static void panfrost_upload_sysvals(struct panfrost_context *ctx, void *buf,
                 case PAN_SYSVAL_VIEWPORT_OFFSET:
                         panfrost_upload_viewport_offset_sysval(ctx, &uniforms[i]);
                         break;
+                case PAN_SYSVAL_TEXTURE_SIZE:
+                        panfrost_upload_txs_sysval(ctx, st, PAN_SYSVAL_ID(sysval),
+                                                   &uniforms[i]);
+                        break;
                 default:
                         assert(0);
                 }