From 31f62a6123d46311bed7a54dc10e518bbe4c5f8d Mon Sep 17 00:00:00 2001
From: Georg Lehmann <dadschoorse@gmail.com>
Date: Tue, 8 Oct 2024 20:30:15 +0200
Subject: [PATCH] aco/insert_exec: don't always reset top exec
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This allows to re-use previous temporaries in case exec was restored
from a Temp, rather than having to create a new copy of exec.

Foz-DB Navi31:
Totals from 545 (0.69% of 79395) affected shaders:
Instrs: 216563 -> 215698 (-0.40%)
CodeSize: 1183536 -> 1180076 (-0.29%)
Latency: 1135269 -> 1135294 (+0.00%); split: -0.00%, +0.00%
Copies: 11933 -> 11072 (-7.22%)
SALU: 18990 -> 18129 (-4.53%)

Reviewed-by: Daniel Schürmann <daniel@schuermann.dev>
Reviewed-by: Timur Kristóf <timur.kristof@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/31567>
---
 src/amd/compiler/aco_insert_exec_mask.cpp | 20 +++++++-------------
 1 file changed, 7 insertions(+), 13 deletions(-)

diff --git a/src/amd/compiler/aco_insert_exec_mask.cpp b/src/amd/compiler/aco_insert_exec_mask.cpp
index 26a06c596da..d6815305ce8 100644
--- a/src/amd/compiler/aco_insert_exec_mask.cpp
+++ b/src/amd/compiler/aco_insert_exec_mask.cpp
@@ -110,7 +110,6 @@ transition_to_WQM(exec_ctx& ctx, Builder bld, unsigned idx)
    assert(ctx.info[idx].exec.back().op.size() == bld.lm.size());
    assert(ctx.info[idx].exec.back().op.isTemp());
    bld.copy(Definition(exec, bld.lm), ctx.info[idx].exec.back().op);
-   ctx.info[idx].exec.back().op = Operand(exec, bld.lm);
 }
 
 void
@@ -128,7 +127,6 @@ transition_to_Exact(exec_ctx& ctx, Builder bld, unsigned idx)
       assert(ctx.info[idx].exec.back().op.size() == bld.lm.size());
       assert(ctx.info[idx].exec.back().op.isTemp());
       bld.copy(Definition(exec, bld.lm), ctx.info[idx].exec.back().op);
-      ctx.info[idx].exec.back().op = Operand(exec, bld.lm);
       return;
    }
    /* otherwise, we create an exact mask and push to the stack */
@@ -366,8 +364,6 @@ add_coupling_code(exec_ctx& ctx, Block* block, std::vector<aco_ptr<Instruction>>
       Operand restore = ctx.info[idx].exec.back().op;
       assert(restore.size() == bld.lm.size());
       bld.copy(Definition(exec, bld.lm), restore);
-      if (!restore.isConstant())
-         ctx.info[idx].exec.back().op = Operand(exec, bld.lm);
    }
 
    return i;
@@ -507,6 +503,8 @@ process_instructions(exec_ctx& ctx, Block* block, std::vector<aco_ptr<Instructio
          } else if (nested_cf) {
             /* Save curent exec temporarily. */
             info.exec.back().op = bld.copy(bld.def(bld.lm), Operand(exec, bld.lm));
+         } else {
+            info.exec.back().op = Operand(exec, bld.lm);
          }
 
          /* Remove invocations from global exact mask. */
@@ -606,16 +604,14 @@ add_branch_code(exec_ctx& ctx, Block* block)
 
       if (has_divergent_break) {
          /* save restore exec mask */
-         uint8_t mask = ctx.info[idx].exec.back().type;
-         if (ctx.info[idx].exec.back().op.constantEquals(-1u)) {
-            ctx.info[idx].exec.emplace_back(Operand(exec, bld.lm), mask);
-         } else {
+         if (!ctx.info[idx].exec.back().op.constantEquals(-1u)) {
             bld.reset(bld.instructions, std::prev(bld.instructions->end()));
             Operand restore = bld.copy(bld.def(bld.lm), Operand(exec, bld.lm));
-            ctx.info[idx].exec.emplace(std::prev(ctx.info[idx].exec.end()), restore, mask);
+            ctx.info[idx].exec.back().op = restore;
             bld.reset(bld.instructions);
          }
-         ctx.info[idx].exec.back().type &= (mask_type_wqm | mask_type_exact);
+         uint8_t mask = ctx.info[idx].exec.back().type & (mask_type_wqm | mask_type_exact);
+         ctx.info[idx].exec.emplace_back(Operand(exec, bld.lm), mask);
       }
       unsigned num_exec_masks = ctx.info[idx].exec.size();
 
@@ -638,10 +634,8 @@ add_branch_code(exec_ctx& ctx, Block* block)
          need_parallelcopy = true;
       }
 
-      if (need_parallelcopy) {
+      if (need_parallelcopy)
          bld.copy(Definition(exec, bld.lm), ctx.info[idx].exec.back().op);
-         ctx.info[idx].exec.back().op = Operand(exec, bld.lm);
-      }
       bld.branch(aco_opcode::p_cbranch_nz, bld.def(s2), Operand(exec, bld.lm),
                  block->linear_succs[1], block->linear_succs[0]);
    } else if (block->kind & block_kind_uniform) {