AutoDiff: Add #_hasSymbol SILGen tests for @differentiable and @derivative(of:) functions.

Author: tshortli

test/AutoDiff/SILGen/has_symbol.swift

@@ -0,0 +1,46 @@
+// RUN: %empty-directory(%t)
+// RUN: split-file %s %t
+// RUN: %target-swift-frontend -emit-module -emit-module-path %t/Library.swiftmodule -parse-as-library %t/Library.swift -enable-library-evolution
+// RUN: %target-swift-frontend -emit-silgen %t/Client.swift -I %t -module-name test | %FileCheck %t/Client.swift
+
+// REQUIRES: VENDOR=apple
+
+//--- Library.swift
+
+import _Differentiation
+
+@differentiable(reverse)
+public func foo(_ x: Float) -> Float { x }
+
+@derivative(of: foo)
+public func bar(_ x: Float) -> (value: Float, pullback: (Float) -> Float) {
+  fatalError()
+}
+
+//--- Client.swift
+
+@_weakLinked import Library
+
+// CHECK: sil hidden [ossa] @$s4test0A15GlobalFunctionsyyF : $@convention(thin) () -> ()
+func testGlobalFunctions() {
+  // CHECK: [[QUERY:%[0-9]+]] = function_ref @$s7Library3fooyS2fFTwS : $@convention(thin) () -> Builtin.Int1
+  // CHECK: [[RES:%[0-9]+]] = apply [[QUERY]]() : $@convention(thin) () -> Builtin.Int1
+  // CHECK: cond_br [[RES]], bb{{[0-9]+}}, bb{{[0-9]+}}
+  if #_hasSymbol(foo(_:)) {}
+
+  // CHECK: [[QUERY:%[0-9]+]] = function_ref @$s7Library3barySf5value_S2fc8pullbacktSfFTwS : $@convention(thin) () -> Builtin.Int1
+  // CHECK: [[RES:%[0-9]+]] = apply [[QUERY]]() : $@convention(thin) () -> Builtin.Int1
+  // CHECK: cond_br [[RES]], bb{{[0-9]+}}, bb{{[0-9]+}}
+  if #_hasSymbol(bar(_:)) {}
+}
+
+// --- foo(_:) ---
+// CHECK: sil @$s7Library3fooyS2fF : $@convention(thin) (Float) -> Float
+// CHECK: sil @$s7Library3fooyS2fFTJfSpSr : $@convention(thin) (Float) -> (Float, @owned @callee_guaranteed (Float) -> Float)
+// CHECK: sil @$s7Library3fooyS2fFTJrSpSr : $@convention(thin) (Float) -> (Float, @owned @callee_guaranteed (Float) -> Float)
+// FIXME: missing reverse-mode differentiability witness for foo(_:)
+
+// --- bar(_:) ---
+// CHECK: sil hidden_external @$s7Library3barySf5value_S2fc8pullbacktSfFTwS : $@convention(thin) () -> Builtin.Int1
+// CHECK: sil @$s7Library3barySf5value_S2fc8pullbacktSfF : $@convention(thin) (Float) -> (Float, @owned @callee_guaranteed (Float) -> Float)
+// FIXME: missing reverse-mode differentiability witness for foo(_:)