From 223af79274c4062e977e2fcd36fe8dbf3a582ae1 Mon Sep 17 00:00:00 2001
From: Rhys Perry <pendingchaos02@gmail.com>
Date: Wed, 25 Feb 2026 13:05:35 +0000
Subject: [PATCH] aco: perform dce for blocks skipped for process_block()
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We might need to DCE users of dead instructions removed by
process_block().

Signed-off-by: Rhys Perry <pendingchaos02@gmail.com>
Fixes: 9e8ba10447f0 ("aco/vn: remove dead instructions early")
Reviewed-by: Daniel Schürmann <daniel@schuermann.dev>
(cherry picked from commit 17b18496f6bd0e3a425b9ff09b6cf843de787b31)

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/40359>
---
 .pick_status.json                            |  2 +-
 src/amd/compiler/aco_opt_value_numbering.cpp | 21 ++++++++++++++++++--
 2 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/.pick_status.json b/.pick_status.json
index ed59eba0199..bd00c0b978a 100644
--- a/.pick_status.json
+++ b/.pick_status.json
@@ -4374,7 +4374,7 @@
         "description": "aco: perform dce for blocks skipped for process_block()",
         "nominated": true,
         "nomination_type": 2,
-        "resolution": 0,
+        "resolution": 1,
         "main_sha": null,
         "because_sha": "9e8ba10447f08ee757f6a4719ff23960a2b18c6b",
         "notes": null
diff --git a/src/amd/compiler/aco_opt_value_numbering.cpp b/src/amd/compiler/aco_opt_value_numbering.cpp
index dfd8c1e3891..9f867e2e0af 100644
--- a/src/amd/compiler/aco_opt_value_numbering.cpp
+++ b/src/amd/compiler/aco_opt_value_numbering.cpp
@@ -427,6 +427,21 @@ process_block(vn_ctx& ctx, Block& block)
    block.instructions = std::move(new_instructions);
 }
 
+void
+dce_instructions(vn_ctx& ctx, Block& block)
+{
+   std::vector<aco_ptr<Instruction>> new_instructions;
+   new_instructions.reserve(block.instructions.size());
+
+   for (aco_ptr<Instruction>& instr : block.instructions) {
+      if (is_dead(ctx.uses, instr.get()))
+         continue;
+      new_instructions.emplace_back(std::move(instr));
+   }
+
+   block.instructions = std::move(new_instructions);
+}
+
 void
 rename_phi_operands(Block& block, aco::unordered_map<uint32_t, Temp>& renames)
 {
@@ -467,10 +482,12 @@ value_numbering(Program* program)
       if (block.logical_idom == (int)block.index)
          ctx.expr_values.clear();
 
-      if (block.logical_idom != -1)
+      if (block.logical_idom != -1) {
          process_block(ctx, block);
-      else
+      } else {
+         dce_instructions(ctx, block);
          rename_phi_operands(block, ctx.renames);
+      }
 
       /* increment exec_id when entering nested control flow */
       if (block.kind & block_kind_branch || block.kind & block_kind_loop_preheader ||