pan/bi: Lower swizzles

Signed-off-by: Alyssa Rosenzweig <alyssa@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/10065>

src/panfrost/Makefile.sources

@@ -4,6 +4,7 @@ bifrost_FILES := \
         bifrost/bifrost_compile.h \
         bifrost/bi_layout.c \
         bifrost/bi_liveness.c \
+        bifrost/bi_lower_swizzle.c \
         bifrost/bi_schedule.c \
         bifrost/bi_scoreboard.c \
         bifrost/bi_pack.c \

src/panfrost/bifrost/bi_lower_swizzle.c

@@ -0,0 +1,85 @@
+/*
+ * Copyright (C) 2020 Collabora Ltd.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#include "compiler.h"
+#include "bi_builder.h"
+
+/* Not all 8-bit and 16-bit instructions support all swizzles on all sources.
+ * These passes, intended to run after NIR->BIR but before scheduling/RA, lower
+ * away swizzles that cannot be represented. In the future, we should try to
+ * recombine swizzles where we can as an optimization.
+ */
+
+static void
+bi_lower_swizzle_16(bi_context *ctx, bi_instr *ins, unsigned src)
+{
+        /* TODO: Use the opcode table and be a lot more methodical about this... */
+        switch (ins->op) {
+        case BI_OPCODE_CSEL_V2F16:
+        case BI_OPCODE_CSEL_V2I16:
+        case BI_OPCODE_CSEL_V2S16:
+        case BI_OPCODE_CSEL_V2U16:
+            break;
+        case BI_OPCODE_IADD_V2S16:
+        case BI_OPCODE_IADD_V2U16:
+        case BI_OPCODE_ISUB_V2S16:
+        case BI_OPCODE_ISUB_V2U16:
+            if (src == 0 && ins->src[src].swizzle != BI_SWIZZLE_H10)
+                    break;
+            else
+                    return;
+        case BI_OPCODE_LSHIFT_AND_V2I16:
+        case BI_OPCODE_LSHIFT_OR_V2I16:
+        case BI_OPCODE_LSHIFT_XOR_V2I16:
+        case BI_OPCODE_RSHIFT_AND_V2I16:
+        case BI_OPCODE_RSHIFT_OR_V2I16:
+        case BI_OPCODE_RSHIFT_XOR_V2I16:
+            if (src == 2)
+                    return;
+            else
+                    break;
+        default:
+            return;
+        }
+
+        /* Identity is ok (TODO: what about replicate only?) */
+        if (ins->src[src].swizzle == BI_SWIZZLE_H01)
+                return;
+
+        /* Lower it away */
+        bi_builder b = bi_init_builder(ctx, bi_before_instr(ins));
+        ins->src[src] = bi_replace_index(ins->src[src],
+                        bi_swz_v2i16(&b, ins->src[src]));
+        ins->src[src].swizzle = BI_SWIZZLE_H01;
+}
+
+void
+bi_lower_swizzle(bi_context *ctx)
+{
+        bi_foreach_instr_global_safe(ctx, ins) {
+                bi_foreach_src(ins, s) {
+                        if (!bi_is_null(ins->src[s]))
+                                bi_lower_swizzle_16(ctx, ins, s);
+                }
+        }
+}

src/panfrost/bifrost/bifrost_compile.c

@@ -3084,6 +3084,8 @@ bifrost_compile_shader_nir(nir_shader *nir,
                 bi_lower_branch(block);
         }
 
+        bi_lower_swizzle(ctx);
+
         if (bifrost_debug & BIFROST_DBG_SHADERS && !skip_internal)
                 bi_print_shader(ctx, stdout);
         bi_schedule(ctx);

src/panfrost/bifrost/compiler.h

@@ -753,6 +753,7 @@ void bi_print_shader(bi_context *ctx, FILE *fp);
 void bi_opt_copy_prop(bi_context *ctx);
 void bi_opt_dead_code_eliminate(bi_context *ctx, bool soft);
 void bi_opt_push_ubo(bi_context *ctx);
+void bi_lower_swizzle(bi_context *ctx);
 void bi_schedule(bi_context *ctx);
 void bi_assign_scoreboard(bi_context *ctx);
 void bi_register_allocate(bi_context *ctx);

src/panfrost/bifrost/meson.build

@@ -22,6 +22,7 @@
 libpanfrost_bifrost_files = files(
   'bi_layout.c',
   'bi_liveness.c',
+  'bi_lower_swizzle.c',
   'bi_print.c',
   'bi_opt_copy_prop.c',
   'bi_opt_dce.c',