From 87ebad74e5d1d7b8c77218caa3199706d01df731 Mon Sep 17 00:00:00 2001
From: Alyssa Rosenzweig <alyssa@collabora.com>
Date: Mon, 26 Jul 2021 12:15:41 -0400
Subject: [PATCH] pan/bi: Refactor constant folding for testability

Signed-off-by: Alyssa Rosenzweig <alyssa@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/12026>
---
 src/panfrost/bifrost/bi_opt_constant_fold.c | 29 +++++++++------------
 src/panfrost/bifrost/compiler.h             |  4 ++-
 2 files changed, 16 insertions(+), 17 deletions(-)

diff --git a/src/panfrost/bifrost/bi_opt_constant_fold.c b/src/panfrost/bifrost/bi_opt_constant_fold.c
index e1c048fc0ed..bf4cae2e5ae 100644
--- a/src/panfrost/bifrost/bi_opt_constant_fold.c
+++ b/src/panfrost/bifrost/bi_opt_constant_fold.c
@@ -28,12 +28,24 @@
  * adding a new pattern here, check why you need it and whether we can avoid
  * generating the constant BIR at all. */
 
-static uint32_t
+uint32_t
 bi_fold_constant(bi_instr *I, bool *unsupported)
 {
+        /* We can only fold instructions where all sources are constant */
+        bi_foreach_src(I, s) {
+                enum bi_index_type type = I->src[s].type;
+
+                if (!(type == BI_INDEX_NULL || type == BI_INDEX_CONSTANT)) {
+                        *unsupported = true;
+                        return 0;
+                }
+        }
+
+        /* Grab the sources */
         uint32_t a = bi_apply_swizzle(I->src[0].value, I->src[0].swizzle);
         uint32_t b = bi_apply_swizzle(I->src[1].value, I->src[1].swizzle);
 
+        /* Evaluate the instruction */
         switch (I->op) {
         case BI_OPCODE_SWZ_V2I16:
                 return a;
@@ -47,25 +59,10 @@ bi_fold_constant(bi_instr *I, bool *unsupported)
         }
 }
 
-static bool
-bi_all_srcs_const(bi_instr *I)
-{
-        bi_foreach_src(I, s) {
-                enum bi_index_type type = I->src[s].type;
-
-                if (!(type == BI_INDEX_NULL || type == BI_INDEX_CONSTANT))
-                        return false;
-        }
-
-        return true;
-}
-
 void
 bi_opt_constant_fold(bi_context *ctx)
 {
         bi_foreach_instr_global_safe(ctx, ins) {
-                if (!bi_all_srcs_const(ins)) continue;
-
                 bool unsupported = false;
                 uint32_t replace = bi_fold_constant(ins, &unsupported);
                 if (unsupported) continue;
diff --git a/src/panfrost/bifrost/compiler.h b/src/panfrost/bifrost/compiler.h
index b469a067697..0858a358c35 100644
--- a/src/panfrost/bifrost/compiler.h
+++ b/src/panfrost/bifrost/compiler.h
@@ -889,13 +889,15 @@ void bi_opt_mod_prop_backward(bi_context *ctx);
 void bi_opt_dead_code_eliminate(bi_context *ctx);
 void bi_opt_dce_post_ra(bi_context *ctx);
 void bi_opt_push_ubo(bi_context *ctx);
-void bi_opt_constant_fold(bi_context *ctx);
 void bi_lower_swizzle(bi_context *ctx);
 void bi_lower_fau(bi_context *ctx);
 void bi_schedule(bi_context *ctx);
 void bi_assign_scoreboard(bi_context *ctx);
 void bi_register_allocate(bi_context *ctx);
 
+uint32_t bi_fold_constant(bi_instr *I, bool *unsupported);
+void bi_opt_constant_fold(bi_context *ctx);
+
 /* Test suite */
 int bi_test_scheduler(void);
 int bi_test_packing(void);