[AutoDiff] Fix differentiation transform crashers in library evolution mode. (#34704)

AD-generated data structures (linear map structs and branching trace enums) do not need to be resilient data structures. These decls ade missing a `@frozen` attribute.

Resolves rdar://71319547.

Author: rxwei

lib/SILOptimizer/Differentiation/LinearMapInfo.cpp

@@ -138,6 +138,8 @@ LinearMapInfo::createBranchingTraceDecl(SILBasicBlock *originalBB,
   // Note: must mark enum as implicit to satisfy assertion in
   // `Parser::parseDeclListDelayed`.
   branchingTraceDecl->setImplicit();
+  // Branching trace enums shall not be resilient.
+  branchingTraceDecl->getAttrs().add(new (astCtx) FrozenAttr(/*implicit*/ true));
   if (genericSig)
     branchingTraceDecl->setGenericSignature(genericSig);
   computeAccessLevel(branchingTraceDecl, original->getEffectiveSymbolLinkage());
@@ -201,6 +203,8 @@ LinearMapInfo::createLinearMapStruct(SILBasicBlock *originalBB,
   // Note: must mark struct as implicit to satisfy assertion in
   // `Parser::parseDeclListDelayed`.
   linearMapStruct->setImplicit();
+  // Linear map structs shall not be resilient.
+  linearMapStruct->getAttrs().add(new (astCtx) FrozenAttr(/*implicit*/ true));
   if (genericSig)
     linearMapStruct->setGenericSignature(genericSig);
   computeAccessLevel(linearMapStruct, original->getEffectiveSymbolLinkage());

test/AutoDiff/compiler_crashers_fixed/rdar71191415-nested-differentiation-of-extension-method-optimized.swift

@@ -5,29 +5,29 @@
 import _Differentiation
 
 protocol P {
-    @differentiable
-    func req(_ input: Float) -> Float
+  @differentiable
+  func req(_ input: Float) -> Float
 }
 
 extension P {
-    @differentiable
-    func foo(_ input: Float) -> Float {
-        return req(input)
-    }
+  @differentiable
+  func foo(_ input: Float) -> Float {
+    return req(input)
+  }
 }
 
 struct Dummy: P {
-    @differentiable
-    func req(_ input: Float) -> Float {
-        input
-    }
+  @differentiable
+  func req(_ input: Float) -> Float {
+    input
+  }
 }
 
 struct DummyComposition: P {
-    var layer = Dummy()
+  var layer = Dummy()
 
-    @differentiable
-    func req(_ input: Float) -> Float {
-        layer.foo(input)
-    }
+  @differentiable
+  func req(_ input: Float) -> Float {
+    layer.foo(input)
+  }
 }

test/AutoDiff/compiler_crashers_fixed/rdar71319547-generated-decls-shall-not-be-resilient.swift

@@ -0,0 +1,39 @@
+// RUN: %target-build-swift -enable-library-evolution %s
+// RUN: %target-build-swift -O -enable-library-evolution %s
+// RUN: %target-build-swift -O -g -enable-library-evolution %s
+
+// rdar://71319547
+
+import _Differentiation
+
+
+// Assertion failed: (mainPullbackStruct->getType() == pbStructLoweredType), function run, file swift/lib/SILOptimizer/Differentiation/PullbackCloner.cpp, line 1899.
+// Stack dump:
+// 1.	Swift version 5.3-dev (LLVM 618cb952e0f199a, Swift d74c261f098665c)
+// 2.	While evaluating request ExecuteSILPipelineRequest(Run pipelines { Mandatory Diagnostic Passes + Enabling Optimization Passes } on SIL for main.main)
+// 3.	While running pass #17 SILModuleTransform "Differentiation".
+// 4.	While processing // differentiability witness for foo(_:)
+// sil_differentiability_witness [serialized] [parameters 0] [results 0] @$s4main3fooyS2fF : $@convention(thin) (Float) -> Float {
+// }
+@differentiable(wrt: x)
+public func i_have_a_pullback_struct(_ x: Float) -> Float {
+  return x
+}
+
+
+// Assertion failed: (v->getType().isObject()), function operator(), file swift/lib/SIL/Utils/ValueUtils.cpp, line 22.
+// Stack dump:
+// 1.	Swift version 5.3-dev (LLVM 618cb952e0f199a, Swift d74c261f098665c)
+// 2.	While evaluating request ExecuteSILPipelineRequest(Run pipelines { Mandatory Diagnostic Passes + Enabling Optimization Passes } on SIL for main.main)
+// 3.	While running pass #24 SILModuleTransform "Differentiation".
+// 4.	While processing // differentiability witness for i_have_a_branching_trace_enum(_:)
+// sil_differentiability_witness [serialized] [parameters 0] [results 0] @$s4main29i_have_a_branching_trace_enumyS2fF : $@convention(thin) (Float) -> Float {
+// }
+@differentiable(wrt: x)
+public func i_have_a_branching_trace_enum(_ x: Float) -> Float {
+  if true {
+    return x
+  } else {
+    return x.squareRoot()
+  }
+}