From 0ffacf22e61e2a993190396c3ef233ea1560bae1 Mon Sep 17 00:00:00 2001
From: nmzik <Nmzik@mail.ru>
Date: Sat, 15 Aug 2026 08:48:20 +0200
Subject: [PATCH] graphics: accept phi-mediated SRT cycles

---
 .../shader/recompiler/ir/passes/SrtWalker.cpp | 13 +++++++++--
 tests/ResourceTrackingTests.cpp               | 23 +++++++++++++++++++
 2 files changed, 34 insertions(+), 2 deletions(-)

diff --git a/src/graphics/shader/recompiler/ir/passes/SrtWalker.cpp b/src/graphics/shader/recompiler/ir/passes/SrtWalker.cpp
index 51d5eb10f..8ffd61bba 100644
--- a/src/graphics/shader/recompiler/ir/passes/SrtWalker.cpp
+++ b/src/graphics/shader/recompiler/ir/passes/SrtWalker.cpp
@@ -308,8 +308,17 @@ private:
 		if (inst == nullptr) {
 			return Fail(use_pc, error, "invalid typed planning value");
 		}
-		if (std::ranges::find(m_visiting, inst) != m_visiting.end()) {
-			return inst->GetOpcode() == ValueOpcode::Phi;
+		const auto cycle = std::ranges::find(m_visiting, inst);
+		if (cycle != m_visiting.end()) {
+			const auto contains_phi = std::any_of(cycle, m_visiting.end(), [](const Inst* value) {
+				return value->GetOpcode() == ValueOpcode::Phi;
+			});
+			if (contains_phi) {
+				return true;
+			}
+			return Fail(use_pc, error,
+			            fmt::format("cyclic typed planning value {} without a phi",
+			                        ValueOpcodeName(inst->GetOpcode())));
 		}
 		if (std::ranges::find(m_visited, inst) != m_visited.end()) {
 			return true;
diff --git a/tests/ResourceTrackingTests.cpp b/tests/ResourceTrackingTests.cpp
index 1ef021e75..e0da7f013 100644
--- a/tests/ResourceTrackingTests.cpp
+++ b/tests/ResourceTrackingTests.cpp
@@ -447,6 +447,28 @@ void TestPhiValidation() {
         "control-dependent descriptor phi was not rejected transactionally");
 }
 
+void TestLoopCycleEnteredThroughRuntimeValue() {
+  Fixture fixture;
+  auto *entry = fixture.block;
+  auto *loop = fixture.AddBlock();
+  const auto initial = fixture.UserData(0);
+  entry->AddBranch(loop);
+  loop->AddBranch(loop);
+  auto &phi = loop->AppendNewInst(ValueOpcode::Phi, {},
+                                  static_cast<uint64_t>(Type::U32));
+  const auto carried = fixture.Emit(
+      ValueOpcode::BitwiseAnd32, {Value(&phi), Value(0xffffffffu)}, 0, loop);
+  phi.AddPhiOperand(entry, initial);
+  phi.AddPhiOperand(loop, carried);
+  fixture.Emit(ValueOpcode::GetBufferResource,
+               {carried, Value(0u), Value(0u), Value(0u)},
+               MemoryFlags{0, 12}, loop);
+
+  std::string error;
+  Check(BuildSrtPlan(fixture.program, &error),
+        "SRT planning rejected a valid loop entered through a runtime value");
+}
+
 void TestInvariantLoopPhi() {
   Fixture fixture;
   auto *entry = fixture.block;
@@ -610,6 +632,7 @@ int main() {
     Run("SRT runtime", TestSrtFlatteningAndRuntimeMemoization);
     Run("dynamic SRT", TestDynamicSrtReadRemainsExplicit);
     Run("phi validation", TestPhiValidation);
+    Run("runtime-rooted loop", TestLoopCycleEnteredThroughRuntimeValue);
     Run("invariant loop phi", TestInvariantLoopPhi);
     Run("address materialization", TestAddressMaterializationAndSpecialization);
     Run("shader info and bindings", TestShaderInfoAndBindingLayout);