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llvm-project/llvm/lib/ExecutionEngine/Interpreter/ExternalFunctions.cpp

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//===-- ExternalFunctions.cpp - Implement External Functions --------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// This file contains both code to deal with invoking "external" functions, but
// also contains code that implements "exported" external functions.
//
// There are currently two mechanisms for handling external functions in the
// Interpreter. The first is to implement lle_* wrapper functions that are
// specific to well-known library functions which manually translate the
// arguments from GenericValues and make the call. If such a wrapper does
// not exist, and libffi is available, then the Interpreter will attempt to
// invoke the function using libffi, after finding its address.
//
//===----------------------------------------------------------------------===//
#include "Interpreter.h"
#include "llvm/ADT/APInt.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/Config/config.h" // Detect libffi
#include "llvm/ExecutionEngine/GenericValue.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/Type.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/DynamicLibrary.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/ManagedStatic.h"
#include "llvm/Support/Mutex.h"
#include "llvm/Support/raw_ostream.h"
#include <cassert>
#include <cmath>
#include <csignal>
#include <cstdint>
#include <cstdio>
#include <cstring>
#include <map>
#include <mutex>
#include <string>
#include <utility>
#include <vector>
#ifdef HAVE_FFI_CALL
#ifdef HAVE_FFI_H
#include <ffi.h>
#define USE_LIBFFI
#elif HAVE_FFI_FFI_H
#include <ffi/ffi.h>
#define USE_LIBFFI
#endif
#endif
using namespace llvm;
static ManagedStatic<sys::Mutex> FunctionsLock;
typedef GenericValue (*ExFunc)(FunctionType *, ArrayRef<GenericValue>);
static ManagedStatic<std::map<const Function *, ExFunc> > ExportedFunctions;
static ManagedStatic<std::map<std::string, ExFunc> > FuncNames;
#ifdef USE_LIBFFI
typedef void (*RawFunc)();
static ManagedStatic<std::map<const Function *, RawFunc> > RawFunctions;
#endif
static Interpreter *TheInterpreter;
static char getTypeID(Type *Ty) {
switch (Ty->getTypeID()) {
case Type::VoidTyID: return 'V';
case Type::IntegerTyID:
switch (cast<IntegerType>(Ty)->getBitWidth()) {
case 1: return 'o';
case 8: return 'B';
case 16: return 'S';
case 32: return 'I';
case 64: return 'L';
default: return 'N';
}
case Type::FloatTyID: return 'F';
case Type::DoubleTyID: return 'D';
case Type::PointerTyID: return 'P';
case Type::FunctionTyID:return 'M';
case Type::StructTyID: return 'T';
case Type::ArrayTyID: return 'A';
default: return 'U';
}
}
// Try to find address of external function given a Function object.
// Please note, that interpreter doesn't know how to assemble a
// real call in general case (this is JIT job), that's why it assumes,
// that all external functions has the same (and pretty "general") signature.
// The typical example of such functions are "lle_X_" ones.
static ExFunc lookupFunction(const Function *F) {
// Function not found, look it up... start by figuring out what the
// composite function name should be.
std::string ExtName = "lle_";
FunctionType *FT = F->getFunctionType();
ExtName += getTypeID(FT->getReturnType());
for (Type *T : FT->params())
ExtName += getTypeID(T);
ExtName += ("_" + F->getName()).str();
sys::ScopedLock Writer(*FunctionsLock);
ExFunc FnPtr = (*FuncNames)[ExtName];
if (!FnPtr)
FnPtr = (*FuncNames)[("lle_X_" + F->getName()).str()];
if (!FnPtr) // Try calling a generic function... if it exists...
FnPtr = (ExFunc)(intptr_t)sys::DynamicLibrary::SearchForAddressOfSymbol(
("lle_X_" + F->getName()).str());
if (FnPtr)
ExportedFunctions->insert(std::make_pair(F, FnPtr)); // Cache for later
return FnPtr;
}
#ifdef USE_LIBFFI
static ffi_type *ffiTypeFor(Type *Ty) {
switch (Ty->getTypeID()) {
case Type::VoidTyID: return &ffi_type_void;
case Type::IntegerTyID:
switch (cast<IntegerType>(Ty)->getBitWidth()) {
case 8: return &ffi_type_sint8;
case 16: return &ffi_type_sint16;
case 32: return &ffi_type_sint32;
case 64: return &ffi_type_sint64;
}
case Type::FloatTyID: return &ffi_type_float;
case Type::DoubleTyID: return &ffi_type_double;
case Type::PointerTyID: return &ffi_type_pointer;
default: break;
}
// TODO: Support other types such as StructTyID, ArrayTyID, OpaqueTyID, etc.
report_fatal_error("Type could not be mapped for use with libffi.");
return NULL;
}
static void *ffiValueFor(Type *Ty, const GenericValue &AV,
void *ArgDataPtr) {
switch (Ty->getTypeID()) {
case Type::IntegerTyID:
switch (cast<IntegerType>(Ty)->getBitWidth()) {
case 8: {
int8_t *I8Ptr = (int8_t *) ArgDataPtr;
*I8Ptr = (int8_t) AV.IntVal.getZExtValue();
return ArgDataPtr;
}
case 16: {
int16_t *I16Ptr = (int16_t *) ArgDataPtr;
*I16Ptr = (int16_t) AV.IntVal.getZExtValue();
return ArgDataPtr;
}
case 32: {
int32_t *I32Ptr = (int32_t *) ArgDataPtr;
*I32Ptr = (int32_t) AV.IntVal.getZExtValue();
return ArgDataPtr;
}
case 64: {
int64_t *I64Ptr = (int64_t *) ArgDataPtr;
*I64Ptr = (int64_t) AV.IntVal.getZExtValue();
return ArgDataPtr;
}
}
case Type::FloatTyID: {
float *FloatPtr = (float *) ArgDataPtr;
*FloatPtr = AV.FloatVal;
return ArgDataPtr;
}
case Type::DoubleTyID: {
double *DoublePtr = (double *) ArgDataPtr;
*DoublePtr = AV.DoubleVal;
return ArgDataPtr;
}
case Type::PointerTyID: {
void **PtrPtr = (void **) ArgDataPtr;
*PtrPtr = GVTOP(AV);
return ArgDataPtr;
}
default: break;
}
// TODO: Support other types such as StructTyID, ArrayTyID, OpaqueTyID, etc.
report_fatal_error("Type value could not be mapped for use with libffi.");
return NULL;
}
static bool ffiInvoke(RawFunc Fn, Function *F, ArrayRef<GenericValue> ArgVals,
const DataLayout &TD, GenericValue &Result) {
ffi_cif cif;
FunctionType *FTy = F->getFunctionType();
const unsigned NumArgs = F->arg_size();
// TODO: We don't have type information about the remaining arguments, because
// this information is never passed into ExecutionEngine::runFunction().
if (ArgVals.size() > NumArgs && F->isVarArg()) {
report_fatal_error("Calling external var arg function '" + F->getName()
+ "' is not supported by the Interpreter.");
}
unsigned ArgBytes = 0;
std::vector<ffi_type*> args(NumArgs);
for (Function::const_arg_iterator A = F->arg_begin(), E = F->arg_end();
A != E; ++A) {
const unsigned ArgNo = A->getArgNo();
Type *ArgTy = FTy->getParamType(ArgNo);
args[ArgNo] = ffiTypeFor(ArgTy);
ArgBytes += TD.getTypeStoreSize(ArgTy);
}
SmallVector<uint8_t, 128> ArgData;
ArgData.resize(ArgBytes);
uint8_t *ArgDataPtr = ArgData.data();
SmallVector<void*, 16> values(NumArgs);
for (Function::const_arg_iterator A = F->arg_begin(), E = F->arg_end();
A != E; ++A) {
const unsigned ArgNo = A->getArgNo();
Type *ArgTy = FTy->getParamType(ArgNo);
values[ArgNo] = ffiValueFor(ArgTy, ArgVals[ArgNo], ArgDataPtr);
ArgDataPtr += TD.getTypeStoreSize(ArgTy);
}
Type *RetTy = FTy->getReturnType();
ffi_type *rtype = ffiTypeFor(RetTy);
if (ffi_prep_cif(&cif, FFI_DEFAULT_ABI, NumArgs, rtype, args.data()) ==
FFI_OK) {
SmallVector<uint8_t, 128> ret;
if (RetTy->getTypeID() != Type::VoidTyID)
ret.resize(TD.getTypeStoreSize(RetTy));
ffi_call(&cif, Fn, ret.data(), values.data());
switch (RetTy->getTypeID()) {
case Type::IntegerTyID:
switch (cast<IntegerType>(RetTy)->getBitWidth()) {
case 8: Result.IntVal = APInt(8 , *(int8_t *) ret.data()); break;
case 16: Result.IntVal = APInt(16, *(int16_t*) ret.data()); break;
case 32: Result.IntVal = APInt(32, *(int32_t*) ret.data()); break;
case 64: Result.IntVal = APInt(64, *(int64_t*) ret.data()); break;
}
break;
case Type::FloatTyID: Result.FloatVal = *(float *) ret.data(); break;
case Type::DoubleTyID: Result.DoubleVal = *(double*) ret.data(); break;
case Type::PointerTyID: Result.PointerVal = *(void **) ret.data(); break;
default: break;
}
return true;
}
return false;
}
#endif // USE_LIBFFI
GenericValue Interpreter::callExternalFunction(Function *F,
ArrayRef<GenericValue> ArgVals) {
TheInterpreter = this;
std::unique_lock<sys::Mutex> Guard(*FunctionsLock);
// Do a lookup to see if the function is in our cache... this should just be a
// deferred annotation!
std::map<const Function *, ExFunc>::iterator FI = ExportedFunctions->find(F);
if (ExFunc Fn = (FI == ExportedFunctions->end()) ? lookupFunction(F)
: FI->second) {
Guard.unlock();
return Fn(F->getFunctionType(), ArgVals);
}
#ifdef USE_LIBFFI
std::map<const Function *, RawFunc>::iterator RF = RawFunctions->find(F);
RawFunc RawFn;
if (RF == RawFunctions->end()) {
RawFn = (RawFunc)(intptr_t)
sys::DynamicLibrary::SearchForAddressOfSymbol(std::string(F->getName()));
if (!RawFn)
RawFn = (RawFunc)(intptr_t)getPointerToGlobalIfAvailable(F);
if (RawFn != 0)
RawFunctions->insert(std::make_pair(F, RawFn)); // Cache for later
} else {
RawFn = RF->second;
}
Guard.unlock();
GenericValue Result;
if (RawFn != 0 && ffiInvoke(RawFn, F, ArgVals, getDataLayout(), Result))
return Result;
#endif // USE_LIBFFI
if (F->getName() == "__main")
errs() << "Tried to execute an unknown external function: "
<< *F->getType() << " __main\n";
else
report_fatal_error("Tried to execute an unknown external function: " +
F->getName());
#ifndef USE_LIBFFI
errs() << "Recompiling LLVM with --enable-libffi might help.\n";
#endif
return GenericValue();
}
//===----------------------------------------------------------------------===//
// Functions "exported" to the running application...
//
// void atexit(Function*)
static GenericValue lle_X_atexit(FunctionType *FT,
ArrayRef<GenericValue> Args) {
assert(Args.size() == 1);
TheInterpreter->addAtExitHandler((Function*)GVTOP(Args[0]));
GenericValue GV;
GV.IntVal = 0;
return GV;
}
// void exit(int)
static GenericValue lle_X_exit(FunctionType *FT, ArrayRef<GenericValue> Args) {
TheInterpreter->exitCalled(Args[0]);
return GenericValue();
}
// void abort(void)
static GenericValue lle_X_abort(FunctionType *FT, ArrayRef<GenericValue> Args) {
//FIXME: should we report or raise here?
//report_fatal_error("Interpreted program raised SIGABRT");
raise (SIGABRT);
return GenericValue();
}
// int sprintf(char *, const char *, ...) - a very rough implementation to make
// output useful.
static GenericValue lle_X_sprintf(FunctionType *FT,
ArrayRef<GenericValue> Args) {
char *OutputBuffer = (char *)GVTOP(Args[0]);
const char *FmtStr = (const char *)GVTOP(Args[1]);
unsigned ArgNo = 2;
// printf should return # chars printed. This is completely incorrect, but
// close enough for now.
GenericValue GV;
GV.IntVal = APInt(32, strlen(FmtStr));
while (true) {
switch (*FmtStr) {
case 0: return GV; // Null terminator...
default: // Normal nonspecial character
sprintf(OutputBuffer++, "%c", *FmtStr++);
break;
case '\\': { // Handle escape codes
sprintf(OutputBuffer, "%c%c", *FmtStr, *(FmtStr+1));
FmtStr += 2; OutputBuffer += 2;
break;
}
case '%': { // Handle format specifiers
char FmtBuf[100] = "", Buffer[1000] = "";
char *FB = FmtBuf;
*FB++ = *FmtStr++;
char Last = *FB++ = *FmtStr++;
unsigned HowLong = 0;
while (Last != 'c' && Last != 'd' && Last != 'i' && Last != 'u' &&
Last != 'o' && Last != 'x' && Last != 'X' && Last != 'e' &&
Last != 'E' && Last != 'g' && Last != 'G' && Last != 'f' &&
Last != 'p' && Last != 's' && Last != '%') {
if (Last == 'l' || Last == 'L') HowLong++; // Keep track of l's
Last = *FB++ = *FmtStr++;
}
*FB = 0;
switch (Last) {
case '%':
memcpy(Buffer, "%", 2); break;
case 'c':
sprintf(Buffer, FmtBuf, uint32_t(Args[ArgNo++].IntVal.getZExtValue()));
break;
case 'd': case 'i':
case 'u': case 'o':
case 'x': case 'X':
if (HowLong >= 1) {
if (HowLong == 1 &&
TheInterpreter->getDataLayout().getPointerSizeInBits() == 64 &&
sizeof(long) < sizeof(int64_t)) {
// Make sure we use %lld with a 64 bit argument because we might be
// compiling LLI on a 32 bit compiler.
unsigned Size = strlen(FmtBuf);
FmtBuf[Size] = FmtBuf[Size-1];
FmtBuf[Size+1] = 0;
FmtBuf[Size-1] = 'l';
}
sprintf(Buffer, FmtBuf, Args[ArgNo++].IntVal.getZExtValue());
} else
sprintf(Buffer, FmtBuf,uint32_t(Args[ArgNo++].IntVal.getZExtValue()));
break;
case 'e': case 'E': case 'g': case 'G': case 'f':
sprintf(Buffer, FmtBuf, Args[ArgNo++].DoubleVal); break;
case 'p':
sprintf(Buffer, FmtBuf, (void*)GVTOP(Args[ArgNo++])); break;
case 's':
sprintf(Buffer, FmtBuf, (char*)GVTOP(Args[ArgNo++])); break;
default:
errs() << "<unknown printf code '" << *FmtStr << "'!>";
ArgNo++; break;
}
size_t Len = strlen(Buffer);
memcpy(OutputBuffer, Buffer, Len + 1);
OutputBuffer += Len;
}
break;
}
}
return GV;
}
// int printf(const char *, ...) - a very rough implementation to make output
// useful.
static GenericValue lle_X_printf(FunctionType *FT,
ArrayRef<GenericValue> Args) {
char Buffer[10000];
std::vector<GenericValue> NewArgs;
NewArgs.push_back(PTOGV((void*)&Buffer[0]));
NewArgs.insert(NewArgs.end(), Args.begin(), Args.end());
GenericValue GV = lle_X_sprintf(FT, NewArgs);
outs() << Buffer;
return GV;
}
// int sscanf(const char *format, ...);
static GenericValue lle_X_sscanf(FunctionType *FT,
ArrayRef<GenericValue> args) {
assert(args.size() < 10 && "Only handle up to 10 args to sscanf right now!");
char *Args[10];
for (unsigned i = 0; i < args.size(); ++i)
Args[i] = (char*)GVTOP(args[i]);
GenericValue GV;
GV.IntVal = APInt(32, sscanf(Args[0], Args[1], Args[2], Args[3], Args[4],
Args[5], Args[6], Args[7], Args[8], Args[9]));
return GV;
}
// int scanf(const char *format, ...);
static GenericValue lle_X_scanf(FunctionType *FT, ArrayRef<GenericValue> args) {
assert(args.size() < 10 && "Only handle up to 10 args to scanf right now!");
char *Args[10];
for (unsigned i = 0; i < args.size(); ++i)
Args[i] = (char*)GVTOP(args[i]);
GenericValue GV;
GV.IntVal = APInt(32, scanf( Args[0], Args[1], Args[2], Args[3], Args[4],
Args[5], Args[6], Args[7], Args[8], Args[9]));
return GV;
}
// int fprintf(FILE *, const char *, ...) - a very rough implementation to make
// output useful.
static GenericValue lle_X_fprintf(FunctionType *FT,
ArrayRef<GenericValue> Args) {
assert(Args.size() >= 2);
char Buffer[10000];
std::vector<GenericValue> NewArgs;
NewArgs.push_back(PTOGV(Buffer));
NewArgs.insert(NewArgs.end(), Args.begin()+1, Args.end());
GenericValue GV = lle_X_sprintf(FT, NewArgs);
fputs(Buffer, (FILE *) GVTOP(Args[0]));
return GV;
}
static GenericValue lle_X_memset(FunctionType *FT,
ArrayRef<GenericValue> Args) {
int val = (int)Args[1].IntVal.getSExtValue();
size_t len = (size_t)Args[2].IntVal.getZExtValue();
memset((void *)GVTOP(Args[0]), val, len);
// llvm.memset.* returns void, lle_X_* returns GenericValue,
// so here we return GenericValue with IntVal set to zero
GenericValue GV;
GV.IntVal = 0;
return GV;
}
static GenericValue lle_X_memcpy(FunctionType *FT,
ArrayRef<GenericValue> Args) {
memcpy(GVTOP(Args[0]), GVTOP(Args[1]),
(size_t)(Args[2].IntVal.getLimitedValue()));
// llvm.memcpy* returns void, lle_X_* returns GenericValue,
// so here we return GenericValue with IntVal set to zero
GenericValue GV;
GV.IntVal = 0;
return GV;
}
void Interpreter::initializeExternalFunctions() {
sys::ScopedLock Writer(*FunctionsLock);
(*FuncNames)["lle_X_atexit"] = lle_X_atexit;
(*FuncNames)["lle_X_exit"] = lle_X_exit;
(*FuncNames)["lle_X_abort"] = lle_X_abort;
(*FuncNames)["lle_X_printf"] = lle_X_printf;
(*FuncNames)["lle_X_sprintf"] = lle_X_sprintf;
(*FuncNames)["lle_X_sscanf"] = lle_X_sscanf;
(*FuncNames)["lle_X_scanf"] = lle_X_scanf;
(*FuncNames)["lle_X_fprintf"] = lle_X_fprintf;
(*FuncNames)["lle_X_memset"] = lle_X_memset;
(*FuncNames)["lle_X_memcpy"] = lle_X_memcpy;
}
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