cf893baf02
Some function types are special to us, so add an enum and determinte the function kind once when creating the function, instead of looking at the Decl every time we need the information.
377 lines
12 KiB
C++
377 lines
12 KiB
C++
//===--- ByteCodeEmitter.cpp - Instruction emitter for the VM ---*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "ByteCodeEmitter.h"
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#include "Context.h"
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#include "Floating.h"
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#include "IntegralAP.h"
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#include "Opcode.h"
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#include "Program.h"
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#include "clang/AST/ASTLambda.h"
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#include "clang/AST/Attr.h"
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#include "clang/AST/DeclCXX.h"
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#include <type_traits>
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using namespace clang;
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using namespace clang::interp;
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Function *ByteCodeEmitter::compileFunc(const FunctionDecl *FuncDecl) {
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// Manually created functions that haven't been assigned proper
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// parameters yet.
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if (!FuncDecl->param_empty() && !FuncDecl->param_begin())
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return nullptr;
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bool IsLambdaStaticInvoker = false;
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if (const auto *MD = dyn_cast<CXXMethodDecl>(FuncDecl);
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MD && MD->isLambdaStaticInvoker()) {
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// For a lambda static invoker, we might have to pick a specialized
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// version if the lambda is generic. In that case, the picked function
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// will *NOT* be a static invoker anymore. However, it will still
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// be a non-static member function, this (usually) requiring an
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// instance pointer. We suppress that later in this function.
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IsLambdaStaticInvoker = true;
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const CXXRecordDecl *ClosureClass = MD->getParent();
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assert(ClosureClass->captures_begin() == ClosureClass->captures_end());
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if (ClosureClass->isGenericLambda()) {
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const CXXMethodDecl *LambdaCallOp = ClosureClass->getLambdaCallOperator();
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assert(MD->isFunctionTemplateSpecialization() &&
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"A generic lambda's static-invoker function must be a "
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"template specialization");
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const TemplateArgumentList *TAL = MD->getTemplateSpecializationArgs();
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FunctionTemplateDecl *CallOpTemplate =
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LambdaCallOp->getDescribedFunctionTemplate();
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void *InsertPos = nullptr;
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const FunctionDecl *CorrespondingCallOpSpecialization =
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CallOpTemplate->findSpecialization(TAL->asArray(), InsertPos);
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assert(CorrespondingCallOpSpecialization);
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FuncDecl = cast<CXXMethodDecl>(CorrespondingCallOpSpecialization);
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}
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}
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// Set up argument indices.
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unsigned ParamOffset = 0;
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SmallVector<PrimType, 8> ParamTypes;
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SmallVector<unsigned, 8> ParamOffsets;
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llvm::DenseMap<unsigned, Function::ParamDescriptor> ParamDescriptors;
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// If the return is not a primitive, a pointer to the storage where the
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// value is initialized in is passed as the first argument. See 'RVO'
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// elsewhere in the code.
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QualType Ty = FuncDecl->getReturnType();
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bool HasRVO = false;
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if (!Ty->isVoidType() && !Ctx.classify(Ty)) {
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HasRVO = true;
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ParamTypes.push_back(PT_Ptr);
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ParamOffsets.push_back(ParamOffset);
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ParamOffset += align(primSize(PT_Ptr));
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}
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// If the function decl is a member decl, the next parameter is
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// the 'this' pointer. This parameter is pop()ed from the
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// InterpStack when calling the function.
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bool HasThisPointer = false;
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if (const auto *MD = dyn_cast<CXXMethodDecl>(FuncDecl)) {
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if (!IsLambdaStaticInvoker) {
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HasThisPointer = MD->isInstance();
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if (MD->isImplicitObjectMemberFunction()) {
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ParamTypes.push_back(PT_Ptr);
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ParamOffsets.push_back(ParamOffset);
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ParamOffset += align(primSize(PT_Ptr));
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}
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}
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// Set up lambda capture to closure record field mapping.
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if (isLambdaCallOperator(MD)) {
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// The parent record needs to be complete, we need to know about all
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// the lambda captures.
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if (!MD->getParent()->isCompleteDefinition())
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return nullptr;
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const Record *R = P.getOrCreateRecord(MD->getParent());
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llvm::DenseMap<const ValueDecl *, FieldDecl *> LC;
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FieldDecl *LTC;
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MD->getParent()->getCaptureFields(LC, LTC);
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for (auto Cap : LC) {
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// Static lambdas cannot have any captures. If this one does,
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// it has already been diagnosed and we can only ignore it.
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if (MD->isStatic())
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return nullptr;
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unsigned Offset = R->getField(Cap.second)->Offset;
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this->LambdaCaptures[Cap.first] = {
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Offset, Cap.second->getType()->isReferenceType()};
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}
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if (LTC) {
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QualType CaptureType = R->getField(LTC)->Decl->getType();
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this->LambdaThisCapture = {R->getField(LTC)->Offset,
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CaptureType->isReferenceType() ||
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CaptureType->isPointerType()};
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}
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}
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}
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// Assign descriptors to all parameters.
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// Composite objects are lowered to pointers.
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for (const ParmVarDecl *PD : FuncDecl->parameters()) {
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std::optional<PrimType> T = Ctx.classify(PD->getType());
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PrimType PT = T.value_or(PT_Ptr);
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Descriptor *Desc = P.createDescriptor(PD, PT);
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ParamDescriptors.insert({ParamOffset, {PT, Desc}});
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Params.insert({PD, {ParamOffset, T != std::nullopt}});
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ParamOffsets.push_back(ParamOffset);
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ParamOffset += align(primSize(PT));
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ParamTypes.push_back(PT);
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}
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// Create a handle over the emitted code.
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Function *Func = P.getFunction(FuncDecl);
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if (!Func) {
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Func = P.createFunction(FuncDecl, ParamOffset, std::move(ParamTypes),
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std::move(ParamDescriptors),
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std::move(ParamOffsets), HasThisPointer, HasRVO);
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}
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assert(Func);
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// For not-yet-defined functions, we only create a Function instance and
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// compile their body later.
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if (!FuncDecl->isDefined() ||
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(FuncDecl->willHaveBody() && !FuncDecl->hasBody())) {
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Func->setDefined(false);
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return Func;
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}
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Func->setDefined(true);
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// Lambda static invokers are a special case that we emit custom code for.
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bool IsEligibleForCompilation = false;
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if (const auto *MD = dyn_cast<CXXMethodDecl>(FuncDecl))
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IsEligibleForCompilation = MD->isLambdaStaticInvoker();
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if (!IsEligibleForCompilation)
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IsEligibleForCompilation =
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FuncDecl->isConstexpr() || FuncDecl->hasAttr<MSConstexprAttr>();
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// Compile the function body.
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if (!IsEligibleForCompilation || !visitFunc(FuncDecl)) {
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Func->setIsFullyCompiled(true);
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return Func;
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}
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// Create scopes from descriptors.
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llvm::SmallVector<Scope, 2> Scopes;
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for (auto &DS : Descriptors) {
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Scopes.emplace_back(std::move(DS));
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}
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// Set the function's code.
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Func->setCode(NextLocalOffset, std::move(Code), std::move(SrcMap),
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std::move(Scopes), FuncDecl->hasBody());
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Func->setIsFullyCompiled(true);
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return Func;
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}
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/// Compile an ObjC block, i.e. ^(){}, that thing.
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///
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/// FIXME: We do not support calling the block though, so we create a function
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/// here but do not compile any code for it.
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Function *ByteCodeEmitter::compileObjCBlock(const BlockExpr *BE) {
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const BlockDecl *BD = BE->getBlockDecl();
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// Set up argument indices.
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unsigned ParamOffset = 0;
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SmallVector<PrimType, 8> ParamTypes;
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SmallVector<unsigned, 8> ParamOffsets;
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llvm::DenseMap<unsigned, Function::ParamDescriptor> ParamDescriptors;
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// Assign descriptors to all parameters.
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// Composite objects are lowered to pointers.
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for (const ParmVarDecl *PD : BD->parameters()) {
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std::optional<PrimType> T = Ctx.classify(PD->getType());
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PrimType PT = T.value_or(PT_Ptr);
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Descriptor *Desc = P.createDescriptor(PD, PT);
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ParamDescriptors.insert({ParamOffset, {PT, Desc}});
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Params.insert({PD, {ParamOffset, T != std::nullopt}});
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ParamOffsets.push_back(ParamOffset);
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ParamOffset += align(primSize(PT));
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ParamTypes.push_back(PT);
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}
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if (BD->hasCaptures())
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return nullptr;
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// Create a handle over the emitted code.
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Function *Func =
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P.createFunction(BE, ParamOffset, std::move(ParamTypes),
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std::move(ParamDescriptors), std::move(ParamOffsets),
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/*HasThisPointer=*/false, /*HasRVO=*/false);
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assert(Func);
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Func->setDefined(true);
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// We don't compile the BlockDecl code at all right now.
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Func->setIsFullyCompiled(true);
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return Func;
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}
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Scope::Local ByteCodeEmitter::createLocal(Descriptor *D) {
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NextLocalOffset += sizeof(Block);
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unsigned Location = NextLocalOffset;
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NextLocalOffset += align(D->getAllocSize());
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return {Location, D};
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}
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void ByteCodeEmitter::emitLabel(LabelTy Label) {
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const size_t Target = Code.size();
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LabelOffsets.insert({Label, Target});
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if (auto It = LabelRelocs.find(Label); It != LabelRelocs.end()) {
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for (unsigned Reloc : It->second) {
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using namespace llvm::support;
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// Rewrite the operand of all jumps to this label.
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void *Location = Code.data() + Reloc - align(sizeof(int32_t));
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assert(aligned(Location));
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const int32_t Offset = Target - static_cast<int64_t>(Reloc);
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endian::write<int32_t, llvm::endianness::native>(Location, Offset);
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}
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LabelRelocs.erase(It);
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}
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}
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int32_t ByteCodeEmitter::getOffset(LabelTy Label) {
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// Compute the PC offset which the jump is relative to.
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const int64_t Position =
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Code.size() + align(sizeof(Opcode)) + align(sizeof(int32_t));
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assert(aligned(Position));
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// If target is known, compute jump offset.
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if (auto It = LabelOffsets.find(Label); It != LabelOffsets.end())
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return It->second - Position;
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// Otherwise, record relocation and return dummy offset.
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LabelRelocs[Label].push_back(Position);
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return 0ull;
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}
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/// Helper to write bytecode and bail out if 32-bit offsets become invalid.
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/// Pointers will be automatically marshalled as 32-bit IDs.
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template <typename T>
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static void emit(Program &P, std::vector<std::byte> &Code, const T &Val,
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bool &Success) {
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size_t Size;
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if constexpr (std::is_pointer_v<T>)
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Size = sizeof(uint32_t);
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else
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Size = sizeof(T);
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if (Code.size() + Size > std::numeric_limits<unsigned>::max()) {
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Success = false;
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return;
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}
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// Access must be aligned!
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size_t ValPos = align(Code.size());
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Size = align(Size);
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assert(aligned(ValPos + Size));
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Code.resize(ValPos + Size);
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if constexpr (!std::is_pointer_v<T>) {
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new (Code.data() + ValPos) T(Val);
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} else {
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uint32_t ID = P.getOrCreateNativePointer(Val);
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new (Code.data() + ValPos) uint32_t(ID);
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}
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}
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/// Emits a serializable value. These usually (potentially) contain
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/// heap-allocated memory and aren't trivially copyable.
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template <typename T>
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static void emitSerialized(std::vector<std::byte> &Code, const T &Val,
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bool &Success) {
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size_t Size = Val.bytesToSerialize();
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if (Code.size() + Size > std::numeric_limits<unsigned>::max()) {
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Success = false;
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return;
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}
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// Access must be aligned!
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size_t ValPos = align(Code.size());
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Size = align(Size);
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assert(aligned(ValPos + Size));
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Code.resize(ValPos + Size);
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Val.serialize(Code.data() + ValPos);
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}
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template <>
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void emit(Program &P, std::vector<std::byte> &Code, const Floating &Val,
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bool &Success) {
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emitSerialized(Code, Val, Success);
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}
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template <>
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void emit(Program &P, std::vector<std::byte> &Code,
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const IntegralAP<false> &Val, bool &Success) {
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emitSerialized(Code, Val, Success);
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}
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template <>
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void emit(Program &P, std::vector<std::byte> &Code, const IntegralAP<true> &Val,
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bool &Success) {
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emitSerialized(Code, Val, Success);
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}
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template <>
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void emit(Program &P, std::vector<std::byte> &Code, const FixedPoint &Val,
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bool &Success) {
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emitSerialized(Code, Val, Success);
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}
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template <typename... Tys>
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bool ByteCodeEmitter::emitOp(Opcode Op, const Tys &...Args,
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const SourceInfo &SI) {
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bool Success = true;
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// The opcode is followed by arguments. The source info is
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// attached to the address after the opcode.
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emit(P, Code, Op, Success);
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if (SI)
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SrcMap.emplace_back(Code.size(), SI);
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(..., emit(P, Code, Args, Success));
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return Success;
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}
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bool ByteCodeEmitter::jumpTrue(const LabelTy &Label) {
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return emitJt(getOffset(Label), SourceInfo{});
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}
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bool ByteCodeEmitter::jumpFalse(const LabelTy &Label) {
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return emitJf(getOffset(Label), SourceInfo{});
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}
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bool ByteCodeEmitter::jump(const LabelTy &Label) {
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return emitJmp(getOffset(Label), SourceInfo{});
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}
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bool ByteCodeEmitter::fallthrough(const LabelTy &Label) {
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emitLabel(Label);
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return true;
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}
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//===----------------------------------------------------------------------===//
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// Opcode emitters
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//===----------------------------------------------------------------------===//
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#define GET_LINK_IMPL
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#include "Opcodes.inc"
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#undef GET_LINK_IMPL
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