1 files changed, 364 insertions, 0 deletions
diff --git a/clang/lib/AST/Interp/Program.cpp b/clang/lib/AST/Interp/Program.cpp
new file mode 100644
index 000000000000..fcbab0ea8172
--- /dev/null
+++ b/clang/lib/AST/Interp/Program.cpp
@@ -0,0 +1,364 @@
+//===--- Program.cpp - Bytecode for the constexpr VM ------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "Program.h"
+#include "ByteCodeStmtGen.h"
+#include "Context.h"
+#include "Function.h"
+#include "Opcode.h"
+#include "PrimType.h"
+#include "clang/AST/Decl.h"
+#include "clang/AST/DeclCXX.h"
+
+using namespace clang;
+using namespace clang::interp;
+
+unsigned Program::createGlobalString(const StringLiteral *S) {
+  const size_t CharWidth = S->getCharByteWidth();
+  const size_t BitWidth = CharWidth * Ctx.getCharBit();
+
+  PrimType CharType;
+  switch (CharWidth) {
+  case 1:
+    CharType = PT_Sint8;
+    break;
+  case 2:
+    CharType = PT_Uint16;
+    break;
+  case 4:
+    CharType = PT_Uint32;
+    break;
+  default:
+    llvm_unreachable("unsupported character width");
+  }
+
+  // Create a descriptor for the string.
+  Descriptor *Desc = allocateDescriptor(S, CharType, S->getLength() + 1,
+                                        /*isConst=*/true,
+                                        /*isTemporary=*/false,
+                                        /*isMutable=*/false);
+
+  // Allocate storage for the string.
+  // The byte length does not include the null terminator.
+  unsigned I = Globals.size();
+  unsigned Sz = Desc->getAllocSize();
+  auto *G = new (Allocator, Sz) Global(Desc, /*isStatic=*/true,
+                                       /*isExtern=*/false);
+  Globals.push_back(G);
+
+  // Construct the string in storage.
+  const Pointer Ptr(G->block());
+  for (unsigned I = 0, N = S->getLength(); I <= N; ++I) {
+    Pointer Field = Ptr.atIndex(I).narrow();
+    const uint32_t CodePoint = I == N ? 0 : S->getCodeUnit(I);
+    switch (CharType) {
+      case PT_Sint8: {
+        using T = PrimConv<PT_Sint8>::T;
+        Field.deref<T>() = T::from(CodePoint, BitWidth);
+        break;
+      }
+      case PT_Uint16: {
+        using T = PrimConv<PT_Uint16>::T;
+        Field.deref<T>() = T::from(CodePoint, BitWidth);
+        break;
+      }
+      case PT_Uint32: {
+        using T = PrimConv<PT_Uint32>::T;
+        Field.deref<T>() = T::from(CodePoint, BitWidth);
+        break;
+      }
+      default:
+        llvm_unreachable("unsupported character type");
+    }
+  }
+  return I;
+}
+
+Pointer Program::getPtrGlobal(unsigned Idx) {
+  assert(Idx < Globals.size());
+  return Pointer(Globals[Idx]->block());
+}
+
+llvm::Optional<unsigned> Program::getGlobal(const ValueDecl *VD) {
+  auto It = GlobalIndices.find(VD);
+  if (It != GlobalIndices.end())
+    return It->second;
+
+  // Find any previous declarations which were aleady evaluated.
+  llvm::Optional<unsigned> Index;
+  for (const Decl *P = VD; P; P = P->getPreviousDecl()) {
+    auto It = GlobalIndices.find(P);
+    if (It != GlobalIndices.end()) {
+      Index = It->second;
+      break;
+    }
+  }
+
+  // Map the decl to the existing index.
+  if (Index) {
+    GlobalIndices[VD] = *Index;
+    return {};
+  }
+
+  return Index;
+}
+
+llvm::Optional<unsigned> Program::getOrCreateGlobal(const ValueDecl *VD) {
+  if (auto Idx = getGlobal(VD))
+    return Idx;
+
+  if (auto Idx = createGlobal(VD)) {
+    GlobalIndices[VD] = *Idx;
+    return Idx;
+  }
+  return {};
+}
+
+llvm::Optional<unsigned> Program::getOrCreateDummy(const ParmVarDecl *PD) {
+  auto &ASTCtx = Ctx.getASTContext();
+
+  // Create a pointer to an incomplete array of the specified elements.
+  QualType ElemTy = PD->getType()->castAs<PointerType>()->getPointeeType();
+  QualType Ty = ASTCtx.getIncompleteArrayType(ElemTy, ArrayType::Normal, 0);
+
+  // Dedup blocks since they are immutable and pointers cannot be compared.
+  auto It = DummyParams.find(PD);
+  if (It != DummyParams.end())
+    return It->second;
+
+  if (auto Idx = createGlobal(PD, Ty, /*isStatic=*/true, /*isExtern=*/true)) {
+    DummyParams[PD] = *Idx;
+    return Idx;
+  }
+  return {};
+}
+
+llvm::Optional<unsigned> Program::createGlobal(const ValueDecl *VD) {
+  bool IsStatic, IsExtern;
+  if (auto *Var = dyn_cast<VarDecl>(VD)) {
+    IsStatic = !Var->hasLocalStorage();
+    IsExtern = !Var->getAnyInitializer();
+  } else {
+    IsStatic = false;
+    IsExtern = true;
+  }
+  if (auto Idx = createGlobal(VD, VD->getType(), IsStatic, IsExtern)) {
+    for (const Decl *P = VD; P; P = P->getPreviousDecl())
+      GlobalIndices[P] = *Idx;
+    return *Idx;
+  }
+  return {};
+}
+
+llvm::Optional<unsigned> Program::createGlobal(const Expr *E) {
+  return createGlobal(E, E->getType(), /*isStatic=*/true, /*isExtern=*/false);
+}
+
+llvm::Optional<unsigned> Program::createGlobal(const DeclTy &D, QualType Ty,
+                                               bool IsStatic, bool IsExtern) {
+  // Create a descriptor for the global.
+  Descriptor *Desc;
+  const bool IsConst = Ty.isConstQualified();
+  const bool IsTemporary = D.dyn_cast<const Expr *>();
+  if (auto T = Ctx.classify(Ty)) {
+    Desc = createDescriptor(D, *T, IsConst, IsTemporary);
+  } else {
+    Desc = createDescriptor(D, Ty.getTypePtr(), IsConst, IsTemporary);
+  }
+  if (!Desc)
+    return {};
+
+  // Allocate a block for storage.
+  unsigned I = Globals.size();
+
+  auto *G = new (Allocator, Desc->getAllocSize())
+      Global(getCurrentDecl(), Desc, IsStatic, IsExtern);
+  G->block()->invokeCtor();
+
+  Globals.push_back(G);
+
+  return I;
+}
+
+Function *Program::getFunction(const FunctionDecl *F) {
+  F = F->getDefinition();
+  auto It = Funcs.find(F);
+  return It == Funcs.end() ? nullptr : It->second.get();
+}
+
+llvm::Expected<Function *> Program::getOrCreateFunction(const FunctionDecl *F) {
+  if (Function *Func = getFunction(F)) {
+    return Func;
+  }
+
+  // Try to compile the function if it wasn't compiled yet.
+  if (const FunctionDecl *FD = F->getDefinition())
+    return ByteCodeStmtGen<ByteCodeEmitter>(Ctx, *this).compileFunc(FD);
+
+  // A relocation which traps if not resolved.
+  return nullptr;
+}
+
+Record *Program::getOrCreateRecord(const RecordDecl *RD) {
+  // Use the actual definition as a key.
+  RD = RD->getDefinition();
+  if (!RD)
+    return nullptr;
+
+  // Deduplicate records.
+  auto It = Records.find(RD);
+  if (It != Records.end()) {
+    return It->second;
+  }
+
+  // Number of bytes required by fields and base classes.
+  unsigned Size = 0;
+  // Number of bytes required by virtual base.
+  unsigned VirtSize = 0;
+
+  // Helper to get a base descriptor.
+  auto GetBaseDesc = [this](const RecordDecl *BD, Record *BR) -> Descriptor * {
+    if (!BR)
+      return nullptr;
+    return allocateDescriptor(BD, BR, /*isConst=*/false,
+                              /*isTemporary=*/false,
+                              /*isMutable=*/false);
+  };
+
+  // Reserve space for base classes.
+  Record::BaseList Bases;
+  Record::VirtualBaseList VirtBases;
+  if (auto *CD = dyn_cast<CXXRecordDecl>(RD)) {
+    for (const CXXBaseSpecifier &Spec : CD->bases()) {
+      if (Spec.isVirtual())
+        continue;
+
+      const RecordDecl *BD = Spec.getType()->castAs<RecordType>()->getDecl();
+      Record *BR = getOrCreateRecord(BD);
+      if (Descriptor *Desc = GetBaseDesc(BD, BR)) {
+        Size += align(sizeof(InlineDescriptor));
+        Bases.push_back({BD, Size, Desc, BR});
+        Size += align(BR->getSize());
+        continue;
+      }
+      return nullptr;
+    }
+
+    for (const CXXBaseSpecifier &Spec : CD->vbases()) {
+      const RecordDecl *BD = Spec.getType()->castAs<RecordType>()->getDecl();
+      Record *BR = getOrCreateRecord(BD);
+
+      if (Descriptor *Desc = GetBaseDesc(BD, BR)) {
+        VirtSize += align(sizeof(InlineDescriptor));
+        VirtBases.push_back({BD, VirtSize, Desc, BR});
+        VirtSize += align(BR->getSize());
+        continue;
+      }
+      return nullptr;
+    }
+  }
+
+  // Reserve space for fields.
+  Record::FieldList Fields;
+  for (const FieldDecl *FD : RD->fields()) {
+    // Reserve space for the field's descriptor and the offset.
+    Size += align(sizeof(InlineDescriptor));
+
+    // Classify the field and add its metadata.
+    QualType FT = FD->getType();
+    const bool IsConst = FT.isConstQualified();
+    const bool IsMutable = FD->isMutable();
+    Descriptor *Desc;
+    if (llvm::Optional<PrimType> T = Ctx.classify(FT)) {
+      Desc = createDescriptor(FD, *T, IsConst, /*isTemporary=*/false,
+                              IsMutable);
+    } else {
+      Desc = createDescriptor(FD, FT.getTypePtr(), IsConst,
+                              /*isTemporary=*/false, IsMutable);
+    }
+    if (!Desc)
+      return nullptr;
+    Fields.push_back({FD, Size, Desc});
+    Size += align(Desc->getAllocSize());
+  }
+
+  Record *R = new (Allocator) Record(RD, std::move(Bases), std::move(Fields),
+                                     std::move(VirtBases), VirtSize, Size);
+  Records.insert({RD, R});
+  return R;
+}
+
+Descriptor *Program::createDescriptor(const DeclTy &D, const Type *Ty,
+                                      bool IsConst, bool IsTemporary,
+                                      bool IsMutable) {
+  // Classes and structures.
+  if (auto *RT = Ty->getAs<RecordType>()) {
+    if (auto *Record = getOrCreateRecord(RT->getDecl()))
+      return allocateDescriptor(D, Record, IsConst, IsTemporary, IsMutable);
+  }
+
+  // Arrays.
+  if (auto ArrayType = Ty->getAsArrayTypeUnsafe()) {
+    QualType ElemTy = ArrayType->getElementType();
+    // Array of well-known bounds.
+    if (auto CAT = dyn_cast<ConstantArrayType>(ArrayType)) {
+      size_t NumElems = CAT->getSize().getZExtValue();
+      if (llvm::Optional<PrimType> T = Ctx.classify(ElemTy)) {
+        // Arrays of primitives.
+        unsigned ElemSize = primSize(*T);
+        if (std::numeric_limits<unsigned>::max() / ElemSize <= NumElems) {
+          return {};
+        }
+        return allocateDescriptor(D, *T, NumElems, IsConst, IsTemporary,
+                                  IsMutable);
+      } else {
+        // Arrays of composites. In this case, the array is a list of pointers,
+        // followed by the actual elements.
+        Descriptor *Desc =
+            createDescriptor(D, ElemTy.getTypePtr(), IsConst, IsTemporary);
+        if (!Desc)
+          return nullptr;
+        InterpSize ElemSize = Desc->getAllocSize() + sizeof(InlineDescriptor);
+        if (std::numeric_limits<unsigned>::max() / ElemSize <= NumElems)
+          return {};
+        return allocateDescriptor(D, Desc, NumElems, IsConst, IsTemporary,
+                                  IsMutable);
+      }
+    }
+
+    // Array of unknown bounds - cannot be accessed and pointer arithmetic
+    // is forbidden on pointers to such objects.
+    if (isa<IncompleteArrayType>(ArrayType)) {
+      if (llvm::Optional<PrimType> T = Ctx.classify(ElemTy)) {
+        return allocateDescriptor(D, *T, IsTemporary,
+                                  Descriptor::UnknownSize{});
+      } else {
+        Descriptor *Desc =
+            createDescriptor(D, ElemTy.getTypePtr(), IsConst, IsTemporary);
+        if (!Desc)
+          return nullptr;
+        return allocateDescriptor(D, Desc, IsTemporary,
+                                  Descriptor::UnknownSize{});
+      }
+    }
+  }
+
+  // Atomic types.
+  if (auto *AT = Ty->getAs<AtomicType>()) {
+    const Type *InnerTy = AT->getValueType().getTypePtr();
+    return createDescriptor(D, InnerTy, IsConst, IsTemporary, IsMutable);
+  }
+
+  // Complex types - represented as arrays of elements.
+  if (auto *CT = Ty->getAs<ComplexType>()) {
+    PrimType ElemTy = *Ctx.classify(CT->getElementType());
+    return allocateDescriptor(D, ElemTy, 2, IsConst, IsTemporary, IsMutable);
+  }
+
+  return nullptr;
+}