[OpaqueValues] Initial support for AD.

Just enough to build _Differentiation.

Author: nate-chandler

lib/SILGen/SILGenBuiltin.cpp

@@ -1201,7 +1201,8 @@ static ManagedValue emitBuiltinAutoDiffApplyDerivativeFunction(
   assert(derivativeFn->getType().isTrivial(SGF.F));
 
   // Do the apply for the indirect result case.
-  if (derivativeFnType->hasIndirectFormalResults()) {
+  if (derivativeFnType->hasIndirectFormalResults() &&
+      SGF.SGM.M.useLoweredAddresses()) {
     auto indResBuffer = SGF.getBufferForExprResult(
         loc, derivativeFnType->getAllResultsInterfaceType(), C);
     SmallVector<SILValue, 3> applyArgs;

lib/SILGen/SILGenPoly.cpp

@@ -3496,7 +3496,86 @@ ManagedValue SILGenFunction::getThunkedAutoDiffLinearMap(
 
   SILFunctionConventions fromConv(fromType, getModule());
   SILFunctionConventions toConv(toType, getModule());
-  assert(toConv.useLoweredAddresses());
+  if (!toConv.useLoweredAddresses()) {
+    SmallVector<ManagedValue, 4> thunkArguments;
+    for (auto *indRes : thunkIndirectResults)
+      thunkArguments.push_back(ManagedValue::forLValue(indRes));
+    thunkArguments.append(params.begin(), params.end());
+    SmallVector<SILParameterInfo, 4> toParameters(
+        toConv.getParameters().begin(), toConv.getParameters().end());
+    SmallVector<SILResultInfo, 4> toResults(toConv.getResults().begin(),
+                                            toConv.getResults().end());
+    // Handle self reordering.
+    // - For pullbacks: reorder result infos.
+    // - For differentials: reorder parameter infos and arguments.
+    auto numIndirectResults = thunkIndirectResults.size();
+    if (reorderSelf && linearMapKind == AutoDiffLinearMapKind::Pullback &&
+        toResults.size() > 1) {
+      std::rotate(toResults.begin(), toResults.end() - 1, toResults.end());
+    }
+    if (reorderSelf && linearMapKind == AutoDiffLinearMapKind::Differential &&
+        thunkArguments.size() > 1) {
+      // Before: [arg1, arg2, ..., arg_self, df]
+      //  After: [arg_self, arg1, arg2, ..., df]
+      std::rotate(thunkArguments.begin() + numIndirectResults,
+                  thunkArguments.end() - 2, thunkArguments.end() - 1);
+      // Before: [arg1, arg2, ..., arg_self]
+      //  After: [arg_self, arg1, arg2, ...]
+      std::rotate(toParameters.begin(), toParameters.end() - 1,
+                  toParameters.end());
+    }
+
+    // Correctness assertions.
+#ifndef NDEBUG
+    assert(toType->getNumParameters() == fromType->getNumParameters());
+    for (unsigned paramIdx : range(toType->getNumParameters())) {
+      auto fromParam = fromConv.getParameters()[paramIdx];
+      auto toParam = toParameters[paramIdx];
+      assert(fromParam.getInterfaceType() == toParam.getInterfaceType());
+    }
+    assert(fromType->getNumResults() == toType->getNumResults());
+    for (unsigned resIdx : range(toType->getNumResults())) {
+      auto fromRes = fromConv.getResults()[resIdx];
+      auto toRes = toResults[resIdx];
+      assert(fromRes.getInterfaceType() == toRes.getInterfaceType());
+    }
+#endif // NDEBUG
+
+    auto *linearMapArg = thunk->getArguments().back();
+    SmallVector<SILValue, 4> arguments;
+    for (unsigned paramIdx : range(toType->getNumParameters())) {
+      arguments.push_back(thunkArguments[paramIdx].getValue());
+    }
+    auto *apply =
+        thunkSGF.B.createApply(loc, linearMapArg, SubstitutionMap(), arguments);
+
+    // Get return elements.
+    SmallVector<SILValue, 4> results;
+    extractAllElements(apply, loc, thunkSGF.B, results);
+
+    // Handle self reordering.
+    // For pullbacks: rotate direct results if self is direct.
+    if (reorderSelf && linearMapKind == AutoDiffLinearMapKind::Pullback) {
+      auto fromSelfResult = fromConv.getResults().front();
+      auto toSelfResult = toConv.getResults().back();
+      assert(fromSelfResult.getInterfaceType() ==
+             toSelfResult.getInterfaceType());
+      // Before: [dir_res_self, dir_res1, dir_res2, ...]
+      //  After: [dir_res1, dir_res2, ..., dir_res_self]
+      if (results.size() > 1) {
+        std::rotate(results.begin(), results.begin() + 1, results.end());
+      }
+    }
+    auto retVal = joinElements(results, thunkSGF.B, loc);
+
+    // Emit cleanups.
+    thunkSGF.Cleanups.emitCleanupsForReturn(CleanupLocation(loc), NotForUnwind);
+
+    // Create return.
+    thunkSGF.B.createReturn(loc, retVal);
+
+    return getThunkedResult();
+  }
 
   SmallVector<ManagedValue, 4> thunkArguments;
   for (auto *indRes : thunkIndirectResults)
@@ -3833,7 +3912,10 @@ SILFunction *SILGenModule::getOrCreateCustomDerivativeThunk(
   };
 
   if (!reorderSelf && linearMapFnType == targetLinearMapFnType) {
-    createReturn(apply);
+    SmallVector<SILValue, 8> results;
+    extractAllElements(apply, loc, thunkSGF.B, results);
+    auto result = joinElements(results, thunkSGF.B, apply.getLoc());
+    createReturn(result);
     return thunk;
   }