From 01d20680e2e6ef9a9de8a1b4ec66cd569f3b7535 Mon Sep 17 00:00:00 2001
From: Georg Lehmann <dadschoorse@gmail.com>
Date: Sun, 22 Jun 2025 15:07:20 +0200
Subject: [PATCH] aco/optimizer: generalize p_create_vector of split vector opt
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Foz-DB Navi48:
Totals from 116 (0.14% of 80251) affected shaders:
MaxWaves: 2965 -> 2972 (+0.24%)
Instrs: 145933 -> 144632 (-0.89%); split: -0.91%, +0.02%
CodeSize: 815968 -> 806512 (-1.16%); split: -1.20%, +0.04%
VGPRs: 7240 -> 7144 (-1.33%); split: -1.66%, +0.33%
Latency: 3065858 -> 3063802 (-0.07%); split: -0.11%, +0.05%
InvThroughput: 745395 -> 743506 (-0.25%); split: -0.26%, +0.01%
VClause: 3702 -> 3694 (-0.22%); split: -0.65%, +0.43%
SClause: 3187 -> 3191 (+0.13%)
Copies: 12716 -> 11804 (-7.17%); split: -7.42%, +0.25%
Branches: 3501 -> 3503 (+0.06%)
PreVGPRs: 5400 -> 5327 (-1.35%); split: -1.41%, +0.06%
VALU: 76455 -> 75492 (-1.26%); split: -1.30%, +0.04%
SALU: 23594 -> 23595 (+0.00%); split: -0.00%, +0.01%
VOPD: 1478 -> 1527 (+3.32%); split: +4.67%, -1.35%

Mostly helps FSR4.

Reviewed-by: Daniel Schürmann <daniel@schuermann.dev>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/35674>
---
 src/amd/compiler/aco_optimizer.cpp | 67 +++++++++++++++++++-----------
 1 file changed, 43 insertions(+), 24 deletions(-)

diff --git a/src/amd/compiler/aco_optimizer.cpp b/src/amd/compiler/aco_optimizer.cpp
index d392b57e527..0a8fa65efae 100644
--- a/src/amd/compiler/aco_optimizer.cpp
+++ b/src/amd/compiler/aco_optimizer.cpp
@@ -1609,37 +1609,56 @@ label_instruction(opt_ctx& ctx, aco_ptr<Instruction>& instr)
          }
       }
 
+      offset = 0;
+      for (unsigned i = 0; i < ops.size(); i++) {
+         if (ops[i].isTemp()) {
+            if (ctx.info[ops[i].tempId()].is_temp() &&
+                ops[i].regClass() == ctx.info[ops[i].tempId()].temp.regClass()) {
+               ops[i].setTemp(ctx.info[ops[i].tempId()].temp);
+            }
+
+            /* If this and the following operands make up all definitions of a `p_split_vector`,
+             * replace them with the operand of the `p_split_vector` instruction.
+             */
+            Instruction* parent = ctx.info[ops[i].tempId()].parent_instr;
+            if (parent->opcode == aco_opcode::p_split_vector &&
+                (offset % 4 == 0 || parent->operands[0].bytes() < 4) &&
+                parent->definitions.size() <= ops.size() - i) {
+               copy_prop = true;
+               for (unsigned j = 0; copy_prop && j < parent->definitions.size(); j++) {
+                  copy_prop &= ops[i + j].isTemp() &&
+                               ops[i + j].getTemp() == parent->definitions[j].getTemp();
+               }
+
+               if (copy_prop) {
+                  ops.erase(ops.begin() + i + 1, ops.begin() + i + parent->definitions.size());
+                  ops[i] = parent->operands[0];
+               }
+            }
+         }
+
+         offset += ops[i].bytes();
+      }
+
       /* combine expanded operands to new vector */
-      if (ops.size() != instr->operands.size()) {
-         assert(ops.size() > instr->operands.size());
+      if (ops.size() <= instr->operands.size()) {
+         while (instr->operands.size() > ops.size())
+            instr->operands.pop_back();
+
+         if (ops.size() == 1) {
+            instr->opcode = aco_opcode::p_parallelcopy;
+            if (ops[0].isTemp())
+               ctx.info[instr->definitions[0].tempId()].set_temp(ops[0].getTemp());
+         }
+      } else {
          Definition def = instr->definitions[0];
          instr.reset(
             create_instruction(aco_opcode::p_create_vector, Format::PSEUDO, ops.size(), 1));
-         for (unsigned i = 0; i < ops.size(); i++) {
-            if (ops[i].isTemp() && ctx.info[ops[i].tempId()].is_temp() &&
-                ops[i].regClass() == ctx.info[ops[i].tempId()].temp.regClass())
-               ops[i].setTemp(ctx.info[ops[i].tempId()].temp);
-            instr->operands[i] = ops[i];
-         }
          instr->definitions[0] = def;
-      } else {
-         for (unsigned i = 0; i < ops.size(); i++) {
-            assert(instr->operands[i] == ops[i]);
-         }
       }
 
-      if (instr->operands.size() == 2 && instr->operands[1].isTemp()) {
-         /* check if this is created from split_vector */
-         ssa_info& info = ctx.info[instr->operands[1].tempId()];
-         if (info.parent_instr->opcode == aco_opcode::p_split_vector) {
-            Instruction* split = info.parent_instr;
-            if (instr->operands[0].isTemp() &&
-                instr->operands[0].getTemp() == split->definitions[0].getTemp() &&
-                instr->operands[1].getTemp() == split->definitions[1].getTemp() &&
-                instr->definitions[0].regClass() == split->operands[0].regClass())
-               ctx.info[instr->definitions[0].tempId()].set_temp(split->operands[0].getTemp());
-         }
-      }
+      for (unsigned i = 0; i < ops.size(); i++)
+         instr->operands[i] = ops[i];
       break;
    }
    case aco_opcode::p_split_vector: {