path: root/contrib/restricted/wavm/Lib/LLVMJIT/EmitModule.cpp

#include <stdint.h>
#include <vector>
#include "EmitFunctionContext.h"
#include "EmitModuleContext.h"
#include "LLVMJITPrivate.h"
#include "WAVM/IR/Module.h"
#include "WAVM/IR/Types.h"
#include "WAVM/Inline/BasicTypes.h"
#include "WAVM/Inline/Timing.h"

PUSH_DISABLE_WARNINGS_FOR_LLVM_HEADERS
#include <llvm/ADT/Twine.h>
#include <llvm/BinaryFormat/Dwarf.h>
#include <llvm/IR/Constants.h>
#include <llvm/IR/DIBuilder.h>
#include <llvm/IR/DebugInfoMetadata.h>
#include <llvm/IR/DerivedTypes.h>
#include <llvm/IR/Function.h>
#include <llvm/IR/GlobalValue.h>
#include <llvm/IR/GlobalVariable.h>
#include <llvm/IR/Metadata.h>
#include <llvm/IR/Module.h>
#include <llvm/IR/Type.h>
POP_DISABLE_WARNINGS_FOR_LLVM_HEADERS

namespace llvm {
	class Constant;
}

using namespace WAVM;
using namespace WAVM::IR;
using namespace WAVM::LLVMJIT;
using namespace WAVM::Runtime;

EmitModuleContext::EmitModuleContext(const IR::Module& inIRModule,
									 LLVMContext& inLLVMContext,
									 llvm::Module* inLLVMModule,
									 llvm::TargetMachine* inTargetMachine)
: irModule(inIRModule)
, llvmContext(inLLVMContext)
, llvmModule(inLLVMModule)
, targetMachine(inTargetMachine)
, defaultTableOffset(nullptr)
, diBuilder(*inLLVMModule)
{
	targetArch = targetMachine->getTargetTriple().getArch();
	useWindowsSEH = targetMachine->getTargetTriple().getOS() == llvm::Triple::Win32;

#if LLVM_VERSION_MAJOR >= 7
	const U32 numPointerBytes = targetMachine->getProgramPointerSize();
#else
	const U32 numPointerBytes = targetMachine->getPointerSize();
#endif
	iptrAlignment = numPointerBytes;
	iptrType = getIptrType(llvmContext, numPointerBytes);
	switch(iptrAlignment)
	{
	case 4: iptrValueType = ValueType::i32; break;
	case 8: iptrValueType = ValueType::i64; break;
	default: Errors::fatalf("Unexpected pointer size: %u bytes", numPointerBytes);
	};

	diModuleScope = diBuilder.createFile("unknown", "unknown");
#if LLVM_VERSION_MAJOR >= 9
	diCompileUnit
		= diBuilder.createCompileUnit(0xffff,
									  diModuleScope,
									  "WAVM",
									  true,
									  "",
									  0,
									  llvm::StringRef(),
									  llvm::DICompileUnit::DebugEmissionKind::LineTablesOnly,
									  0,
									  true,
									  false,
									  llvm::DICompileUnit::DebugNameTableKind::None,
									  false);
#else
	diCompileUnit = diBuilder.createCompileUnit(0xffff, diModuleScope, "WAVM", true, "", 0);
#endif

	diValueTypes[(Uptr)ValueType::any] = nullptr;
	diValueTypes[(Uptr)ValueType::i32]
		= diBuilder.createBasicType("i32", 32, llvm::dwarf::DW_ATE_signed);
	diValueTypes[(Uptr)ValueType::i64]
		= diBuilder.createBasicType("i64", 64, llvm::dwarf::DW_ATE_signed);
	diValueTypes[(Uptr)ValueType::f32]
		= diBuilder.createBasicType("f32", 32, llvm::dwarf::DW_ATE_float);
	diValueTypes[(Uptr)ValueType::f64]
		= diBuilder.createBasicType("f64", 64, llvm::dwarf::DW_ATE_float);
	diValueTypes[(Uptr)ValueType::v128]
		= diBuilder.createBasicType("v128", 128, llvm::dwarf::DW_ATE_signed);
	diValueTypes[(Uptr)ValueType::externref]
		= diBuilder.createBasicType("externref", 8, llvm::dwarf::DW_ATE_address);
	diValueTypes[(Uptr)ValueType::funcref]
		= diBuilder.createBasicType("funcref", 8, llvm::dwarf::DW_ATE_address);

	auto zeroAsMetadata = llvm::ConstantAsMetadata::get(emitLiteral(llvmContext, I32(0)));
	auto i32MaxAsMetadata = llvm::ConstantAsMetadata::get(emitLiteral(llvmContext, I32(INT32_MAX)));
	likelyFalseBranchWeights = llvm::MDTuple::getDistinct(
		llvmContext,
		{llvm::MDString::get(llvmContext, "branch_weights"), zeroAsMetadata, i32MaxAsMetadata});
	likelyTrueBranchWeights = llvm::MDTuple::getDistinct(
		llvmContext,
		{llvm::MDString::get(llvmContext, "branch_weights"), i32MaxAsMetadata, zeroAsMetadata});

	fpRoundingModeMetadata = llvm::MetadataAsValue::get(
		llvmContext, llvm::MDString::get(llvmContext, "round.tonearest"));
	fpExceptionMetadata = llvm::MetadataAsValue::get(
		llvmContext, llvm::MDString::get(llvmContext, "fpexcept.strict"));
}

static llvm::Constant* createImportedConstant(llvm::Module& llvmModule, llvm::Twine externalName)
{
	return new llvm::GlobalVariable(llvmModule,
									llvm::Type::getInt8Ty(llvmModule.getContext()),
									false,
									llvm::GlobalVariable::ExternalLinkage,
									nullptr,
									externalName);
}

void LLVMJIT::emitModule(const IR::Module& irModule,
						 LLVMContext& llvmContext,
						 llvm::Module& outLLVMModule,
						 llvm::TargetMachine* targetMachine)
{
	Timing::Timer emitTimer;
	EmitModuleContext moduleContext(irModule, llvmContext, &outLLVMModule, targetMachine);

	// Set the module data layout for the target machine.
	outLLVMModule.setDataLayout(targetMachine->createDataLayout());

	// Create an external reference to the appropriate exception personality function.
	auto personalityFunction = llvm::Function::Create(
		llvm::FunctionType::get(llvmContext.i32Type, {}, false),
		llvm::GlobalValue::LinkageTypes::ExternalLinkage,
		moduleContext.useWindowsSEH ? "__CxxFrameHandler3" : "__gxx_personality_v0",
		&outLLVMModule);

	// Create LLVM external globals corresponding to the encoded function types for the module's
	// indexed function types.
	for(Uptr typeIndex = 0; typeIndex < irModule.types.size(); ++typeIndex)
	{
		moduleContext.typeIds.push_back(llvm::ConstantExpr::getPtrToInt(
			createImportedConstant(outLLVMModule, getExternalName("typeId", typeIndex)),
			moduleContext.iptrType));
	}

	// Create LLVM external globals corresponding to offsets to table base pointers in
	// CompartmentRuntimeData for the module's declared table objects.
	for(Uptr tableIndex = 0; tableIndex < irModule.tables.size(); ++tableIndex)
	{
		moduleContext.tableOffsets.push_back(llvm::ConstantExpr::getPtrToInt(
			createImportedConstant(outLLVMModule, getExternalName("tableOffset", tableIndex)),
			moduleContext.iptrType));
	}
	if(moduleContext.tableOffsets.size())
	{ moduleContext.defaultTableOffset = moduleContext.tableOffsets[0]; }

	// Create LLVM external globals corresponding to offsets to memory base pointers in
	// CompartmentRuntimeData for the module's declared memory objects.
	for(Uptr memoryIndex = 0; memoryIndex < irModule.memories.size(); ++memoryIndex)
	{
		moduleContext.memoryOffsets.push_back(llvm::ConstantExpr::getPtrToInt(
			createImportedConstant(outLLVMModule, getExternalName("memoryOffset", memoryIndex)),
			moduleContext.iptrType));
	}

	// Create LLVM external globals for the module's globals.
	for(Uptr globalIndex = 0; globalIndex < irModule.globals.size(); ++globalIndex)
	{
		moduleContext.globals.push_back(
			createImportedConstant(outLLVMModule, getExternalName("global", globalIndex)));
	}

	// Create LLVM external globals corresponding to pointers to ExceptionTypes for the
	// module's declared exception types.
	for(Uptr exceptionTypeIndex = 0; exceptionTypeIndex < irModule.exceptionTypes.size();
		++exceptionTypeIndex)
	{
		llvm::Constant* biasedExceptionTypeIdAsPointer = createImportedConstant(
			outLLVMModule, getExternalName("biasedExceptionTypeId", exceptionTypeIndex));
		llvm::Constant* biasedExceptionTypeId = llvm::ConstantExpr::getPtrToInt(
			biasedExceptionTypeIdAsPointer, moduleContext.iptrType);
		llvm::Constant* exceptionTypeId = llvm::ConstantExpr::getSub(
			biasedExceptionTypeId, emitLiteralIptr(1, moduleContext.iptrType));
		moduleContext.exceptionTypeIds.push_back(exceptionTypeId);
	}

	// Create a LLVM external global that will point to the Instance.
	llvm::Constant* biasedInstanceIdAsPointer
		= createImportedConstant(outLLVMModule, "biasedInstanceId");
	llvm::Constant* biasedInstanceId
		= llvm::ConstantExpr::getPtrToInt(biasedInstanceIdAsPointer, moduleContext.iptrType);
	moduleContext.instanceId
		= llvm::ConstantExpr::getSub(biasedInstanceId, emitLiteralIptr(1, moduleContext.iptrType));

	// Create a LLVM external global that will be a bias applied to all references in a table.
	moduleContext.tableReferenceBias = llvm::ConstantExpr::getPtrToInt(
		createImportedConstant(outLLVMModule, "tableReferenceBias"), moduleContext.iptrType);

#if LLVM_VERSION_MAJOR < 10
	// Create a LLVM external global that will be a constant Iptr 1 that is opaque to the optimizer.
	moduleContext.unoptimizableOne = llvm::ConstantExpr::getPtrToInt(
		createImportedConstant(outLLVMModule, "unoptimizableOne"), moduleContext.iptrType);
#endif

	// Create a LLVM external global that will point to the std::type_info for Runtime::Exception.
	if(moduleContext.useWindowsSEH)
	{
		// The Windows type_info is referenced by the exception handling tables with a 32-bit
		// image-relative offset, so we have to create a copy of it in the image.
		const char* typeMangledName = ".PEAUException@Runtime@WAVM@@";
		llvm::Type* typeDescriptorTypeElements[3]
			= {llvmContext.i8PtrType->getPointerTo(),
			   llvmContext.i8PtrType,
			   llvm::ArrayType::get(llvmContext.i8Type, strlen(typeMangledName) + 1)};
		llvm::StructType* typeDescriptorType = llvm::StructType::create(typeDescriptorTypeElements);
		llvm::Constant* typeDescriptorElements[3]
			= {llvm::ConstantPointerNull::get(llvmContext.i8PtrType->getPointerTo()),
			   llvm::ConstantPointerNull::get(llvmContext.i8PtrType),
			   llvm::ConstantDataArray::getString(llvmContext, typeMangledName, true)};
		llvm::Constant* typeDescriptor
			= llvm::ConstantStruct::get(typeDescriptorType, typeDescriptorElements);
		llvm::GlobalVariable* typeDescriptorVariable
			= new llvm::GlobalVariable(*moduleContext.llvmModule,
									   typeDescriptorType,
									   false,
									   llvm::GlobalVariable::LinkOnceODRLinkage,
									   typeDescriptor,
									   "??_R0PEAUException@Runtime@WAVM@@@8");
		typeDescriptorVariable->setComdat(
			moduleContext.llvmModule->getOrInsertComdat("??_R0PEAUException@Runtime@WAVM@@@8"));
		moduleContext.runtimeExceptionTypeInfo = typeDescriptorVariable;
	}
	else
	{
		moduleContext.runtimeExceptionTypeInfo = llvm::ConstantExpr::getPointerCast(
			createImportedConstant(*moduleContext.llvmModule, "runtimeExceptionTypeInfo"),
			llvmContext.i8PtrType);
	}

	// Create the LLVM functions.
	moduleContext.functions.resize(irModule.functions.size());
	for(Uptr functionIndex = 0; functionIndex < irModule.functions.size(); ++functionIndex)
	{
		FunctionType functionType = irModule.types[irModule.functions.getType(functionIndex).index];

		llvm::Function* function = llvm::Function::Create(
			asLLVMType(llvmContext, functionType),
			llvm::Function::ExternalLinkage,
			functionIndex >= irModule.functions.imports.size()
				? getExternalName("functionDef", functionIndex - irModule.functions.imports.size())
				: getExternalName("functionImport", functionIndex),
			&outLLVMModule);
		function->setCallingConv(asLLVMCallingConv(functionType.callingConvention()));
		moduleContext.functions[functionIndex] = function;
	}

	// Compile each function in the module.
	for(Uptr functionDefIndex = 0; functionDefIndex < irModule.functions.defs.size();
		++functionDefIndex)
	{
		const FunctionDef& functionDef = irModule.functions.defs[functionDefIndex];
		llvm::Function* function
			= moduleContext.functions[irModule.functions.imports.size() + functionDefIndex];

		function->setPersonalityFn(personalityFunction);

		llvm::Constant* functionDefMutableData = createImportedConstant(
			outLLVMModule, getExternalName("functionDefMutableDatas", functionDefIndex));
		llvm::Constant* functionDefMutableDataAsIptr
			= llvm::ConstantExpr::getPtrToInt(functionDefMutableData, moduleContext.iptrType);

		setRuntimeFunctionPrefix(llvmContext,
								 moduleContext.iptrType,
								 function,
								 functionDefMutableDataAsIptr,
								 moduleContext.instanceId,
								 moduleContext.typeIds[functionDef.type.index]);
		setFunctionAttributes(targetMachine, function);

		EmitFunctionContext(llvmContext, moduleContext, irModule, functionDef, function).emit();
	}

	// Finalize the debug info.
	moduleContext.diBuilder.finalize();

	Timing::logRatePerSecond("Emitted LLVM IR", emitTimer, (F64)outLLVMModule.size(), "functions");
}