From cd47e5563b1bc6d621bbf56573f9b5ca0150ae03 Mon Sep 17 00:00:00 2001
From: Tyson Jones <tyson.jones.input@gmail.com>
Date: Sun, 16 Aug 2026 23:35:15 -0400
Subject: [PATCH] add AMD bug guard

---
 quest/src/api/qureg.cpp   |  6 ++++++
 quest/src/core/errors.cpp | 11 +++++++++++
 quest/src/core/errors.hpp |  8 ++++++++
 3 files changed, 25 insertions(+)

diff --git a/quest/src/api/qureg.cpp b/quest/src/api/qureg.cpp
index 84bcd2bd0..683ca183d 100644
--- a/quest/src/api/qureg.cpp
+++ b/quest/src/api/qureg.cpp
@@ -168,6 +168,12 @@ Qureg validateAndCreateCustomQureg(int numQubits, int isDensMatr, int useDistrib
     freeAllMemoryIfAnyAllocsFailed(qureg);
     validate_newQuregAllocs(qureg, __func__);
 
+    // TODO / DEBUG:
+    // TEMPORARILY FORBID HIP GPU ACCELERATION OF > 2^32 AMPS PER NODE,
+    // SINCE THIS WILL LEAD TO LATER KERNEL LAUNCH FAILURES; see issue #815
+    if (useGpuAccel && gpu_isHipCompiled() && qureg.numAmpsPerNode >= (1LL << 32))
+        error_quregTooLargeForHipGpuAccel();
+
     // initialise state to |0> or |0><0|
     initZeroState(qureg); 
 
diff --git a/quest/src/core/errors.cpp b/quest/src/core/errors.cpp
index 807cad105..c78f1c727 100644
--- a/quest/src/core/errors.cpp
+++ b/quest/src/core/errors.cpp
@@ -58,6 +58,17 @@ void raiseInternalError(string errorMsg) {
 
 
 
+/*
+ * TEMPORARY / DEBUG ERRORS
+ */
+
+void error_quregTooLargeForHipGpuAccel() {
+
+    raiseInternalError("The created Qureg contains more than 2^32 amplitudes per GPU, which would later trigger a current bug/limitation in QuEST's execution on AMD GPUs. See Github issue #815.");
+}
+
+
+
 /*
  * VALIDATION ERRORS
  */
diff --git a/quest/src/core/errors.hpp b/quest/src/core/errors.hpp
index f91f890b0..7db4e69f5 100644
--- a/quest/src/core/errors.hpp
+++ b/quest/src/core/errors.hpp
@@ -27,6 +27,14 @@ using std::string;
 
 
 
+/*
+ * TEMPORARY / DEBUG ERRORS
+ */
+
+void error_quregTooLargeForHipGpuAccel();
+
+
+
 /*
  * VALIDATION ERRORS
  */