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llvm-project/llvm/lib/ExecutionEngine/Interpreter/ExternalFunctions.cpp
Chandler Carruth 2946cd7010 Update the file headers across all of the LLVM projects in the monorepo 
to reflect the new license.

We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.

Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.

llvm-svn: 351636
2019-01-19 08:50:56 +00:00

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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/UniqueLock.h"
#include "llvm/Support/raw_ostream.h"
#include <cassert>
#include <cmath>
#include <csignal>
#include <cstdint>
#include <cstdio>
#include <cstring>
#include <map>
#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;
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(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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