Allow changing the data layout and target triple

Author: CodaFi

Sources/LLVM/Module.swift

@@ -80,11 +80,32 @@ public final class Module: CustomStringConvertible {
     self.dataLayout = TargetData(llvm: LLVMGetModuleDataLayout(llvm))
   }
 
+  /// Obtain the target triple for this module.
+  var targetTriple: String {
+    get {
+      guard let id = LLVMGetTarget(llvm) else { return "" }
+      return String(cString: id)
+    }
+    set { LLVMSetTarget(llvm, newValue) }
+  }
+
   /// Returns the context associated with this module.
   public let context: Context
 
   /// Obtain the data layout for this module.
-  public var dataLayout: TargetData
+  public var dataLayout: TargetData {
+    get { return TargetData(llvm: LLVMGetModuleDataLayout(llvm)) }
+    set { LLVMSetModuleDataLayout(llvm, newValue.llvm) }
+  }
+
+  /// Returns a string describing the data layout associated with this module.
+  public var dataLayoutString: String {
+    get {
+      guard let id = LLVMGetDataLayoutStr(llvm) else { return "" }
+      return String(cString: id)
+    }
+    set { LLVMSetDataLayout(llvm, newValue) }
+  }
 
   /// The identifier of this module.
   public var name: String {

Tests/LLVMTests/UnitSpec.swift

@@ -77,12 +77,73 @@ class UnitSpec : XCTestCase {
     ])
   }
 
+  func testStructLayoutOnMachine() {
+    let mod = Module(name: "StructLayout")
+    let aarch64 = try! TargetMachine(triple: "aarch64--", cpu: "", features: "",
+                                     optLevel: .none, relocMode: .default, codeModel: .default)
+    mod.dataLayout = aarch64.dataLayout
+    XCTAssertEqual(mod.dataLayoutString, "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128")
+
+    let packedStruct = StructType(elementTypes: [
+      IntType.int1,
+      IntType.int8,
+      IntType.int1,
+      PointerType(pointee: IntType.int8),
+    ], isPacked: true, in: Context.global)
+    let unpackedStruct = StructType(elementTypes: [
+      IntType.int1,
+      IntType.int8,
+      IntType.int1,
+      PointerType(pointee: IntType.int8),
+    ], isPacked: false, in: Context.global)
+
+    let packedLayout64 = mod.dataLayout.layout(of: packedStruct)
+    XCTAssertEqual(packedLayout64.alignment, Alignment.one)
+    XCTAssertEqual(packedLayout64.size, Size(11))
+    XCTAssertEqual(packedLayout64.elementCount, 4)
+    XCTAssertFalse(packedLayout64.isPadded)
+    XCTAssertEqual(packedLayout64.memberOffsets, [
+      Size(0), Size(1), Size(2), Size(3),
+    ])
+    let unpackedLayout64 = mod.dataLayout.layout(of: unpackedStruct)
+    XCTAssertEqual(unpackedLayout64.alignment, Alignment(8))
+    XCTAssertEqual(unpackedLayout64.size, Size(16))
+    XCTAssertEqual(unpackedLayout64.elementCount, 4)
+    XCTAssertTrue(unpackedLayout64.isPadded)
+    XCTAssertEqual(unpackedLayout64.memberOffsets, [
+      Size(0), Size(1), Size(2), Size(8),
+    ])
+
+    let aarch32 = try! TargetMachine(triple: "arm--", cpu: "", features: "",
+                                     optLevel: .none, relocMode: .default, codeModel: .default)
+    mod.dataLayout = aarch32.dataLayout
+    XCTAssertEqual(mod.dataLayoutString, "e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64")
+
+    let packedLayout32 = mod.dataLayout.layout(of: packedStruct)
+    XCTAssertEqual(packedLayout32.alignment, Alignment.one)
+    XCTAssertEqual(packedLayout32.size, Size(7))
+    XCTAssertEqual(packedLayout32.elementCount, 4)
+    XCTAssertFalse(packedLayout32.isPadded)
+    XCTAssertEqual(packedLayout32.memberOffsets, [
+      Size(0), Size(1), Size(2), Size(3),
+    ])
+    let unpackedLayout32 = mod.dataLayout.layout(of: unpackedStruct)
+    XCTAssertEqual(unpackedLayout32.alignment, Alignment(4))
+    XCTAssertEqual(unpackedLayout32.size, Size(8))
+    XCTAssertEqual(unpackedLayout32.elementCount, 4)
+    XCTAssertTrue(unpackedLayout32.isPadded)
+    XCTAssertEqual(unpackedLayout32.memberOffsets, [
+      Size(0), Size(1), Size(2), Size(4),
+    ])
+  }
+
 
   #if !os(macOS)
   static var allTests = testCase([
     ("testAlign", testAlign),
     ("testEmptyStructLayout", testEmptyStructLayout),
     ("testStructLayout", testStructLayout),
+    ("testStructLayoutOnMachine", testStructLayoutOnMachine),
   ])
   #endif
 }