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//===-- OcamlGCPrinter.cpp - Ocaml frametable emitter ---------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements printing the assembly code for an Ocaml frametable.
//
//===----------------------------------------------------------------------===//
#include "llvm/CodeGen/GCs.h"
#include "llvm/CodeGen/AsmPrinter.h"
#include "llvm/CodeGen/GCMetadataPrinter.h"
#include "llvm/Module.h"
#include "llvm/MC/MCStreamer.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Target/TargetLoweringObjectFile.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/FormattedStream.h"
using namespace llvm;
namespace {
class OcamlGCMetadataPrinter : public GCMetadataPrinter {
public:
void beginAssembly(raw_ostream &OS, AsmPrinter &AP,
const MCAsmInfo &MAI);
void finishAssembly(raw_ostream &OS, AsmPrinter &AP,
const MCAsmInfo &MAI);
};
}
static GCMetadataPrinterRegistry::Add<OcamlGCMetadataPrinter>
Y("ocaml", "ocaml 3.10-compatible collector");
void llvm::linkOcamlGCPrinter() { }
static void EmitCamlGlobal(const Module &M, raw_ostream &OS, AsmPrinter &AP,
const MCAsmInfo &MAI, const char *Id) {
const std::string &MId = M.getModuleIdentifier();
std::string Mangled;
Mangled += MAI.getGlobalPrefix();
Mangled += "caml";
size_t Letter = Mangled.size();
Mangled.append(MId.begin(), std::find(MId.begin(), MId.end(), '.'));
Mangled += "__";
Mangled += Id;
// Capitalize the first letter of the module name.
Mangled[Letter] = toupper(Mangled[Letter]);
if (const char *GlobalDirective = MAI.getGlobalDirective())
OS << GlobalDirective << Mangled << "\n";
OS << Mangled << ":\n";
}
void OcamlGCMetadataPrinter::beginAssembly(raw_ostream &OS, AsmPrinter &AP,
const MCAsmInfo &MAI) {
AP.OutStreamer.SwitchSection(AP.getObjFileLowering().getTextSection());
EmitCamlGlobal(getModule(), OS, AP, MAI, "code_begin");
AP.OutStreamer.SwitchSection(AP.getObjFileLowering().getDataSection());
EmitCamlGlobal(getModule(), OS, AP, MAI, "data_begin");
}
/// emitAssembly - Print the frametable. The ocaml frametable format is thus:
///
/// extern "C" struct align(sizeof(intptr_t)) {
/// uint16_t NumDescriptors;
/// struct align(sizeof(intptr_t)) {
/// void *ReturnAddress;
/// uint16_t FrameSize;
/// uint16_t NumLiveOffsets;
/// uint16_t LiveOffsets[NumLiveOffsets];
/// } Descriptors[NumDescriptors];
/// } caml${module}__frametable;
///
/// Note that this precludes programs from stack frames larger than 64K
/// (FrameSize and LiveOffsets would overflow). FrameTablePrinter will abort if
/// either condition is detected in a function which uses the GC.
///
void OcamlGCMetadataPrinter::finishAssembly(raw_ostream &OS, AsmPrinter &AP,
const MCAsmInfo &MAI) {
const char *AddressDirective;
int AddressAlignLog;
if (AP.TM.getTargetData()->getPointerSize() == sizeof(int32_t)) {
AddressDirective = MAI.getData32bitsDirective();
AddressAlignLog = 2;
} else {
AddressDirective = MAI.getData64bitsDirective();
AddressAlignLog = 3;
}
AP.OutStreamer.SwitchSection(AP.getObjFileLowering().getTextSection());
EmitCamlGlobal(getModule(), OS, AP, MAI, "code_end");
AP.OutStreamer.SwitchSection(AP.getObjFileLowering().getDataSection());
EmitCamlGlobal(getModule(), OS, AP, MAI, "data_end");
OS << AddressDirective << 0 << '\n'; // FIXME: Why does ocaml emit this??
AP.OutStreamer.SwitchSection(AP.getObjFileLowering().getDataSection());
EmitCamlGlobal(getModule(), OS, AP, MAI, "frametable");
for (iterator I = begin(), IE = end(); I != IE; ++I) {
GCFunctionInfo &FI = **I;
uint64_t FrameSize = FI.getFrameSize();
if (FrameSize >= 1<<16) {
std::string msg;
raw_string_ostream Msg(msg);
Msg << "Function '" << FI.getFunction().getName()
<< "' is too large for the ocaml GC! "
<< "Frame size " << FrameSize << " >= 65536.\n";
Msg << "(" << uintptr_t(&FI) << ")";
llvm_report_error(Msg.str()); // Very rude!
}
OS << "\t" << MAI.getCommentString() << " live roots for "
<< FI.getFunction().getName() << "\n";
for (GCFunctionInfo::iterator J = FI.begin(), JE = FI.end(); J != JE; ++J) {
size_t LiveCount = FI.live_size(J);
if (LiveCount >= 1<<16) {
std::string msg;
raw_string_ostream Msg(msg);
Msg << "Function '" << FI.getFunction().getName()
<< "' is too large for the ocaml GC! "
<< "Live root count " << LiveCount << " >= 65536.";
llvm_report_error(Msg.str()); // Very rude!
}
OS << AddressDirective
<< MAI.getPrivateGlobalPrefix() << "label" << J->Num << '\n';
AP.EmitInt16(FrameSize);
AP.EmitInt16(LiveCount);
for (GCFunctionInfo::live_iterator K = FI.live_begin(J),
KE = FI.live_end(J); K != KE; ++K) {
assert(K->StackOffset < 1<<16 &&
"GC root stack offset is outside of fixed stack frame and out "
"of range for ocaml GC!");
AP.EmitInt32(K->StackOffset);
}
AP.EmitAlignment(AddressAlignLog);
}
}
}
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