From b53b4573c3f0571253672e44ce7d6310d9f987bf Mon Sep 17 00:00:00 2001
From: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Date: Thu, 25 Apr 2019 03:18:34 +0000
Subject: [PATCH] panfrost/midgard: Extend copy propagation pass

This extends copy propagation to respect output modifiers for ALU
instructions, as well as potentially fixing some bugs related to looping
(all dEQP loop tests pass).

Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
---
 .../panfrost/midgard/midgard_compile.c        | 56 ++++++++++++++++---
 1 file changed, 48 insertions(+), 8 deletions(-)

diff --git a/src/gallium/drivers/panfrost/midgard/midgard_compile.c b/src/gallium/drivers/panfrost/midgard/midgard_compile.c
index 5f62225de17..5b5a44013a2 100644
--- a/src/gallium/drivers/panfrost/midgard/midgard_compile.c
+++ b/src/gallium/drivers/panfrost/midgard/midgard_compile.c
@@ -3123,6 +3123,36 @@ midgard_opt_dead_code_eliminate(compiler_context *ctx, midgard_block *block)
         return progress;
 }
 
+/* Combines the two outmods if possible. Returns whether the combination was
+ * successful */
+
+static bool
+midgard_combine_outmod(midgard_outmod *main, midgard_outmod overlay)
+{
+        if (overlay == midgard_outmod_none)
+                return true;
+
+        if (*main == overlay)
+                return true;
+
+        if (*main == midgard_outmod_none) {
+                *main = overlay;
+                return true;
+        }
+
+        if (*main == midgard_outmod_pos && overlay == midgard_outmod_sat) {
+                *main = midgard_outmod_sat;
+                return true;
+        }
+
+        if (overlay == midgard_outmod_pos && *main == midgard_outmod_sat) {
+                *main = midgard_outmod_sat;
+                return true;
+        }
+
+        return false;
+}
+
 static bool
 midgard_opt_copy_prop(compiler_context *ctx, midgard_block *block)
 {
@@ -3139,8 +3169,12 @@ midgard_opt_copy_prop(compiler_context *ctx, midgard_block *block)
 
                 if (to >= SSA_FIXED_MINIMUM) continue;
                 if (from >= SSA_FIXED_MINIMUM) continue;
+                if (to >= ctx->func->impl->ssa_alloc) continue;
+                if (from >= ctx->func->impl->ssa_alloc) continue;
 
-                /* Also, if the move has side effects, we're helpless */
+                /* Also, if the move has source side effects, we're not sure
+                 * what to do. Destination side effects we can handle, though.
+                 */
 
                 midgard_vector_alu_src src =
                         vector_alu_from_unsigned(ins->alu.src2);
@@ -3149,17 +3183,23 @@ midgard_opt_copy_prop(compiler_context *ctx, midgard_block *block)
 
                 if (mir_nontrivial_mod(src, is_int, mask)) continue;
 
-                mir_foreach_instr_in_block_from(block, v, mir_next_op(ins)) {
-                        if (v->ssa_args.src0 == to) {
-                                v->ssa_args.src0 = from;
-                                progress = true;
-                        }
+                mir_foreach_instr_in_block_from_rev(block, v, mir_prev_op(ins)) {
+                        if (v->ssa_args.dest == from) {
+                                if (v->type == TAG_ALU_4) {
+                                        midgard_outmod final = v->alu.outmod;
 
-                        if (v->ssa_args.src1 == to && !v->ssa_args.inline_constant) {
-                                v->ssa_args.src1 = from;
+                                        if (!midgard_combine_outmod(&final, ins->alu.outmod))
+                                                continue;
+
+                                        v->alu.outmod = final;
+                                }
+
+                                v->ssa_args.dest = to;
                                 progress = true;
                         }
                 }
+
+                mir_remove_instruction(ins);
         }
 
         return progress;
-- 
2.30.2