Only generate AcqRel SafeHeap load methods when --relaxed-atomics is

enabled

Author: stevenfontanella

src/passes/SafeHeap.cpp

@@ -243,9 +243,15 @@ struct SafeHeap : public Pass {
             if (align > bytes) {
               continue;
             }
-            for (auto memoryOrder : {MemoryOrder::Unordered,
-                                     MemoryOrder::AcqRel,
-                                     MemoryOrder::SeqCst}) {
+
+            std::vector<MemoryOrder> memoryOrders(
+              features.hasRelaxedAtomics()
+                ? std::initializer_list<MemoryOrder>{MemoryOrder::Unordered,
+                                                     MemoryOrder::AcqRel,
+                                                     MemoryOrder::SeqCst}
+                : std::initializer_list<MemoryOrder>{MemoryOrder::Unordered,
+                                                     MemoryOrder::SeqCst});
+            for (MemoryOrder memoryOrder : memoryOrders) {
               load.order = memoryOrder;
               if (load.isAtomic() &&
                   !isPossibleAtomicOperation(
@@ -424,8 +430,9 @@ struct SafeHeap : public Pass {
                               bool is64,
                               Name memory) {
     bool lowMemUnused = getPassOptions().lowMemoryUnused;
-    auto upperOp = is64 ? lowMemUnused ? LtUInt64 : EqInt64
-                        : lowMemUnused ? LtUInt32 : EqInt32;
+    auto upperOp = is64           ? lowMemUnused ? LtUInt64 : EqInt64
+                   : lowMemUnused ? LtUInt32
+                                  : EqInt32;
     auto upperBound = lowMemUnused ? PassOptions::LowMemoryBound : 0;
     Expression* brkLocation;
     if (sbrk.is()) {