From 83f8c193c980de696f2b593ee7802be75e190003 Mon Sep 17 00:00:00 2001
From: xXPBSXx <20614131+xXPBSXx@users.noreply.github.com>
Date: Sat, 10 Oct 2026 22:26:51 +0200
Subject: [PATCH] fix(shader): treat an image read as a use that only reads
 where its exec is active

An ImageRead carries a trailing exec argument like the buffer loads, but it
was in neither the read-only-where-active list nor the lane-local list, so a
masked select feeding its address was kept.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
---
 core/libs/prx/libSceAgcDriver/tests/MaskedSelect.cpp  | 11 +++++++++--
 .../Optimization/src/MaskedSelectEliminator.cpp       |  1 +
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/core/libs/prx/libSceAgcDriver/tests/MaskedSelect.cpp b/core/libs/prx/libSceAgcDriver/tests/MaskedSelect.cpp
index 56dc21e87b..ecf3a581e4 100644
--- a/core/libs/prx/libSceAgcDriver/tests/MaskedSelect.cpp
+++ b/core/libs/prx/libSceAgcDriver/tests/MaskedSelect.cpp
@@ -636,6 +636,13 @@ int main() {
             case IrOpcode::LoadBufferU32:
                 b.keep(b.select(exec, b.emit(opcode, IrType::U32, {&b.emit(IrOpcode::GetBufferResource, IrType::BufferResource, {}), &written, &b.constant(0u), &b.constant(0u), &active}), old));
                 break;
+            case IrOpcode::ImageRead: {
+                auto& address = b.emit(IrOpcode::MakeImageAddress, IrType::ImageAddress, {&written, &old});
+                auto& image = b.emit(IrOpcode::GetImageResource, IrType::ImageResource, {});
+                auto& read = b.emit(opcode, IrType::U32x4, {&image, &address, &active});
+                b.keep(b.select(exec, b.emit(IrOpcode::CompositeExtractU32x4, IrType::U32, {&read, &b.constant(0u)}), old));
+                break;
+            }
             default:
                 b.emit(opcode, IrType::Void, {&b.emit(IrOpcode::CompositeConstructU32x4, IrType::U32x4, {&written, &old, &old, &old}), &active});
                 break;
@@ -645,11 +652,11 @@ int main() {
     };
 
     passed &= run("a store, load or export whose exec implies the write's exec drops the select", [&] {
-        return guarded(IrOpcode::WriteSharedU32, true, false) && guarded(IrOpcode::LoadBufferU32, true, false) && guarded(IrOpcode::SetAttribute, true, false);
+        return guarded(IrOpcode::WriteSharedU32, true, false) && guarded(IrOpcode::LoadBufferU32, true, false) && guarded(IrOpcode::ImageRead, true, false) && guarded(IrOpcode::SetAttribute, true, false);
     });
 
     passed &= run("a store, load or export under a wider exec keeps the select", [&] {
-        return !guarded(IrOpcode::WriteSharedU32, false, false) && !guarded(IrOpcode::LoadBufferU32, false, false) && !guarded(IrOpcode::SetAttribute, false, false);
+        return !guarded(IrOpcode::WriteSharedU32, false, false) && !guarded(IrOpcode::LoadBufferU32, false, false) && !guarded(IrOpcode::ImageRead, false, false) && !guarded(IrOpcode::SetAttribute, false, false);
     });
 
     passed &= run("a value used as a store's exec keeps the select", [&] {
diff --git a/core/shader/recompiler/Optimization/src/MaskedSelectEliminator.cpp b/core/shader/recompiler/Optimization/src/MaskedSelectEliminator.cpp
index be902084dd..30331f633b 100644
--- a/core/shader/recompiler/Optimization/src/MaskedSelectEliminator.cpp
+++ b/core/shader/recompiler/Optimization/src/MaskedSelectEliminator.cpp
@@ -204,6 +204,7 @@ bool readsOnlyWhereActive(IrOpcode opcode) {
         case IrOpcode::WriteSharedU32x3:
         case IrOpcode::WriteSharedU32x4:
         case IrOpcode::SetAttribute:
+        case IrOpcode::ImageRead:
             return true;
         default:
             return false;