IRGen: Implement emitPackShapeExpression()

Author: slavapestov

lib/IRGen/CMakeLists.txt

@@ -33,6 +33,7 @@ add_swift_host_library(swiftIRGen STATIC
   GenMeta.cpp
   GenObjC.cpp
   GenOpaque.cpp
+  GenPack.cpp
   GenPointerAuth.cpp
   GenPoly.cpp
   GenProto.cpp

lib/IRGen/GenPack.cpp

@@ -0,0 +1,72 @@
+//===--- GenPack.cpp - Swift IR Generation For Variadic Generics ----------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+//
+//  This file implements IR generation for type and value packs in Swift.
+//
+//===----------------------------------------------------------------------===//
+
+#include "swift/AST/Decl.h"
+#include "swift/AST/IRGenOptions.h"
+#include "swift/AST/Types.h"
+#include "swift/SIL/SILModule.h"
+#include "swift/SIL/SILType.h"
+#include "llvm/IR/DerivedTypes.h"
+
+#include "GenType.h"
+#include "IRGenFunction.h"
+#include "IRGenModule.h"
+
+using namespace swift;
+using namespace irgen;
+
+llvm::Value *IRGenFunction::emitPackShapeExpression(CanType type) {
+
+  type = type->getReducedShape()->getCanonicalType();
+
+  auto kind = LocalTypeDataKind::forPackShapeExpression();
+
+  llvm::Value *result = tryGetLocalTypeData(type, kind);
+  if (result != nullptr)
+    return result;
+
+  // If shape(T) == t and shape(U) == u, the shape expression for a pack
+  // {T..., Int, T..., U..., String} becomes 't + t + u + 2'.
+  unsigned scalarElements = 0;
+
+  auto accumulate = [&](llvm::Value *value) {
+    if (result == nullptr) {
+      result = value;
+      return;
+    }
+
+    result = Builder.CreateAdd(result, value);
+  };
+
+  auto packType = cast<PackType>(type);
+  for (auto elt : packType.getElementTypes()) {
+    if (auto expansionType = dyn_cast<PackExpansionType>(elt)) {
+      auto reducedShape = expansionType.getCountType();
+      accumulate(emitPackShapeExpression(reducedShape));
+      continue;
+    }
+
+    ++scalarElements;
+  }
+
+  if (scalarElements > 0) {
+    auto *constant = llvm::ConstantInt::get(IGM.SizeTy, scalarElements);
+    accumulate(constant);
+  }
+
+  setScopedLocalTypeData(type, kind, result);
+  return result;
+}

lib/IRGen/GenProto.cpp

@@ -3364,19 +3364,22 @@ irgen::emitGenericRequirementFromSubstitutions(IRGenFunction &IGF,
   CanType depTy = requirement.getTypeParameter();
   CanType argType = depTy.subst(subs)->getCanonicalType();
 
-  if (requirement.isMetadata()) {
-    auto argMetadata = IGF.emitTypeMetadataRef(argType);
-    return argMetadata;
-  }
+  switch (requirement.getKind()) {
+  case GenericRequirement::Kind::Shape:
+    return IGF.emitPackShapeExpression(argType);
 
-  assert(requirement.isWitnessTable());
+  case GenericRequirement::Kind::Metadata:
+    return IGF.emitTypeMetadataRef(argType);
 
-  auto proto = requirement.getProtocol();
-  auto conformance = subs.lookupConformance(depTy, proto);
-  assert(conformance.getRequirement() == proto);
-  llvm::Value *metadata = nullptr;
-  auto wtable = emitWitnessTableRef(IGF, argType, &metadata, conformance);
-  return wtable;
+  case GenericRequirement::Kind::WitnessTable: {
+    auto proto = requirement.getProtocol();
+    auto conformance = subs.lookupConformance(depTy, proto);
+    assert(conformance.getRequirement() == proto);
+    llvm::Value *metadata = nullptr;
+    auto wtable = emitWitnessTableRef(IGF, argType, &metadata, conformance);
+    return wtable;
+  }
+  }
 }
 
 void GenericTypeRequirements::bindFromBuffer(IRGenFunction &IGF,

lib/IRGen/IRGenFunction.h

@@ -349,6 +349,8 @@ class IRGenFunction {
                                               llvm::Value *&metadataSlot,
                                               ValueWitness index);
 
+  llvm::Value *emitPackShapeExpression(CanType type);
+
   /// Emit a load of a reference to the given Objective-C selector.
   llvm::Value *emitObjCSelectorRefLoad(StringRef selector);