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-rw-r--r--lib/AST/Interp/ByteCodeEmitter.cpp175
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diff --git a/lib/AST/Interp/ByteCodeEmitter.cpp b/lib/AST/Interp/ByteCodeEmitter.cpp
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+//===--- ByteCodeEmitter.cpp - Instruction emitter for the 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 "ByteCodeEmitter.h"
+#include "Context.h"
+#include "Opcode.h"
+#include "Program.h"
+#include "clang/AST/DeclCXX.h"
+
+using namespace clang;
+using namespace clang::interp;
+
+using APSInt = llvm::APSInt;
+using Error = llvm::Error;
+
+Expected<Function *> ByteCodeEmitter::compileFunc(const FunctionDecl *F) {
+ // Do not try to compile undefined functions.
+ if (!F->isDefined(F) || (!F->hasBody() && F->willHaveBody()))
+ return nullptr;
+
+ // Set up argument indices.
+ unsigned ParamOffset = 0;
+ SmallVector<PrimType, 8> ParamTypes;
+ llvm::DenseMap<unsigned, Function::ParamDescriptor> ParamDescriptors;
+
+ // If the return is not a primitive, a pointer to the storage where the value
+ // is initialized in is passed as the first argument.
+ QualType Ty = F->getReturnType();
+ if (!Ty->isVoidType() && !Ctx.classify(Ty)) {
+ ParamTypes.push_back(PT_Ptr);
+ ParamOffset += align(primSize(PT_Ptr));
+ }
+
+ // Assign descriptors to all parameters.
+ // Composite objects are lowered to pointers.
+ for (const ParmVarDecl *PD : F->parameters()) {
+ PrimType Ty;
+ if (llvm::Optional<PrimType> T = Ctx.classify(PD->getType())) {
+ Ty = *T;
+ } else {
+ Ty = PT_Ptr;
+ }
+
+ Descriptor *Desc = P.createDescriptor(PD, Ty);
+ ParamDescriptors.insert({ParamOffset, {Ty, Desc}});
+ Params.insert({PD, ParamOffset});
+ ParamOffset += align(primSize(Ty));
+ ParamTypes.push_back(Ty);
+ }
+
+ // Create a handle over the emitted code.
+ Function *Func = P.createFunction(F, ParamOffset, std::move(ParamTypes),
+ std::move(ParamDescriptors));
+ // Compile the function body.
+ if (!F->isConstexpr() || !visitFunc(F)) {
+ // Return a dummy function if compilation failed.
+ if (BailLocation)
+ return llvm::make_error<ByteCodeGenError>(*BailLocation);
+ else
+ return Func;
+ } else {
+ // Create scopes from descriptors.
+ llvm::SmallVector<Scope, 2> Scopes;
+ for (auto &DS : Descriptors) {
+ Scopes.emplace_back(std::move(DS));
+ }
+
+ // Set the function's code.
+ Func->setCode(NextLocalOffset, std::move(Code), std::move(SrcMap),
+ std::move(Scopes));
+ return Func;
+ }
+}
+
+Scope::Local ByteCodeEmitter::createLocal(Descriptor *D) {
+ NextLocalOffset += sizeof(Block);
+ unsigned Location = NextLocalOffset;
+ NextLocalOffset += align(D->getAllocSize());
+ return {Location, D};
+}
+
+void ByteCodeEmitter::emitLabel(LabelTy Label) {
+ const size_t Target = Code.size();
+ LabelOffsets.insert({Label, Target});
+ auto It = LabelRelocs.find(Label);
+ if (It != LabelRelocs.end()) {
+ for (unsigned Reloc : It->second) {
+ using namespace llvm::support;
+
+ /// Rewrite the operand of all jumps to this label.
+ void *Location = Code.data() + Reloc - sizeof(int32_t);
+ const int32_t Offset = Target - static_cast<int64_t>(Reloc);
+ endian::write<int32_t, endianness::native, 1>(Location, Offset);
+ }
+ LabelRelocs.erase(It);
+ }
+}
+
+int32_t ByteCodeEmitter::getOffset(LabelTy Label) {
+ // Compute the PC offset which the jump is relative to.
+ const int64_t Position = Code.size() + sizeof(Opcode) + sizeof(int32_t);
+
+ // If target is known, compute jump offset.
+ auto It = LabelOffsets.find(Label);
+ if (It != LabelOffsets.end()) {
+ return It->second - Position;
+ }
+
+ // Otherwise, record relocation and return dummy offset.
+ LabelRelocs[Label].push_back(Position);
+ return 0ull;
+}
+
+bool ByteCodeEmitter::bail(const SourceLocation &Loc) {
+ if (!BailLocation)
+ BailLocation = Loc;
+ return false;
+}
+
+template <typename... Tys>
+bool ByteCodeEmitter::emitOp(Opcode Op, const Tys &... Args, const SourceInfo &SI) {
+ bool Success = true;
+
+ /// Helper to write bytecode and bail out if 32-bit offsets become invalid.
+ auto emit = [this, &Success](const char *Data, size_t Size) {
+ if (Code.size() + Size > std::numeric_limits<unsigned>::max()) {
+ Success = false;
+ return;
+ }
+ Code.insert(Code.end(), Data, Data + Size);
+ };
+
+ /// The opcode is followed by arguments. The source info is
+ /// attached to the address after the opcode.
+ emit(reinterpret_cast<const char *>(&Op), sizeof(Opcode));
+ if (SI)
+ SrcMap.emplace_back(Code.size(), SI);
+
+ /// The initializer list forces the expression to be evaluated
+ /// for each argument in the variadic template, in order.
+ (void)std::initializer_list<int>{
+ (emit(reinterpret_cast<const char *>(&Args), sizeof(Args)), 0)...};
+
+ return Success;
+}
+
+bool ByteCodeEmitter::jumpTrue(const LabelTy &Label) {
+ return emitJt(getOffset(Label), SourceInfo{});
+}
+
+bool ByteCodeEmitter::jumpFalse(const LabelTy &Label) {
+ return emitJf(getOffset(Label), SourceInfo{});
+}
+
+bool ByteCodeEmitter::jump(const LabelTy &Label) {
+ return emitJmp(getOffset(Label), SourceInfo{});
+}
+
+bool ByteCodeEmitter::fallthrough(const LabelTy &Label) {
+ emitLabel(Label);
+ return true;
+}
+
+//===----------------------------------------------------------------------===//
+// Opcode emitters
+//===----------------------------------------------------------------------===//
+
+#define GET_LINK_IMPL
+#include "Opcodes.inc"
+#undef GET_LINK_IMPL