Fix atomic ordering accessor

Use the derived ==.  Providing our own causes a
cyclic dependency on the ordering -> LLVM map
which causes crashes on recursive initial accesses
to the dictionary.

Author: CodaFi

Sources/LLVM/IRBuilder.swift

@@ -200,10 +200,8 @@ public enum AtomicOrdering: Comparable {
     .sequentiallyConsistent: LLVMAtomicOrderingSequentiallyConsistent,
   ]
 
-  public static func ==(lhs: AtomicOrdering, rhs: AtomicOrdering) -> Bool {
-    return lhs.llvm == rhs.llvm
-  }
-
+  /// Returns whether the left atomic ordering is strictly weaker than the
+  /// right atomic order.
   public static func <(lhs: AtomicOrdering, rhs: AtomicOrdering) -> Bool {
     return lhs.llvm.rawValue < rhs.llvm.rawValue
   }

Tests/LLVMTests/IRBuilderSpec.swift

@@ -223,6 +223,12 @@ class IRBuilderSpec : XCTestCase {
       // CONTROLFLOW-NEXT: store i64 1, i64* %var
       builder.buildStore(IntType.int64.constant(1), to: variable)
 
+      // CONTROLFLOW-NEXT: store volatile i64 1, i64* %var
+      builder.buildStore(IntType.int64.constant(1), to: variable, volatile: true)
+
+      // CONTROLFLOW-NEXT: store atomic i64 1, i64* %var
+      builder.buildStore(IntType.int64.constant(1), to: variable, ordering: .sequentiallyConsistent)
+
       // CONTROLFLOW-NEXT: %0 = load i64, i64* %var
       let load = builder.buildLoad(variable)