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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/ADT/SmallString.h"
#include "llvm/CodeGen/AsmPrinter.h"
#include "llvm/CodeGen/GCMetadataPrinter.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/Module.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCStreamer.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/FormattedStream.h"
#include "llvm/Target/Mangler.h"
#include "llvm/Target/TargetLoweringObjectFile.h"
#include "llvm/Target/TargetMachine.h"
#include <cctype>
using namespace llvm;
namespace {
class OcamlGCMetadataPrinter : public GCMetadataPrinter {
public:
void beginAssembly(AsmPrinter &AP);
void finishAssembly(AsmPrinter &AP);
};
}
static GCMetadataPrinterRegistry::Add<OcamlGCMetadataPrinter>
Y("ocaml", "ocaml 3.10-compatible collector");
void llvm::linkOcamlGCPrinter() { }
static void EmitCamlGlobal(const Module &M, AsmPrinter &AP, const char *Id) {
const std::string &MId = M.getModuleIdentifier();
std::string SymName;
SymName += "caml";
size_t Letter = SymName.size();
SymName.append(MId.begin(), std::find(MId.begin(), MId.end(), '.'));
SymName += "__";
SymName += Id;
// Capitalize the first letter of the module name.
SymName[Letter] = toupper(SymName[Letter]);
SmallString<128> TmpStr;
AP.Mang->getNameWithPrefix(TmpStr, SymName);
MCSymbol *Sym = AP.OutContext.GetOrCreateSymbol(TmpStr);
AP.OutStreamer.EmitSymbolAttribute(Sym, MCSA_Global);
AP.OutStreamer.EmitLabel(Sym);
}
void OcamlGCMetadataPrinter::beginAssembly(AsmPrinter &AP) {
AP.OutStreamer.SwitchSection(AP.getObjFileLowering().getTextSection());
EmitCamlGlobal(getModule(), AP, "code_begin");
AP.OutStreamer.SwitchSection(AP.getObjFileLowering().getDataSection());
EmitCamlGlobal(getModule(), AP, "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(AsmPrinter &AP) {
unsigned IntPtrSize = AP.TM.getDataLayout()->getPointerSize();
AP.OutStreamer.SwitchSection(AP.getObjFileLowering().getTextSection());
EmitCamlGlobal(getModule(), AP, "code_end");
AP.OutStreamer.SwitchSection(AP.getObjFileLowering().getDataSection());
EmitCamlGlobal(getModule(), AP, "data_end");
// FIXME: Why does ocaml emit this??
AP.OutStreamer.EmitIntValue(0, IntPtrSize);
AP.OutStreamer.SwitchSection(AP.getObjFileLowering().getDataSection());
EmitCamlGlobal(getModule(), AP, "frametable");
int NumDescriptors = 0;
for (iterator I = begin(), IE = end(); I != IE; ++I) {
GCFunctionInfo &FI = **I;
for (GCFunctionInfo::iterator J = FI.begin(), JE = FI.end(); J != JE; ++J) {
NumDescriptors++;
}
}
if (NumDescriptors >= 1<<16) {
// Very rude!
report_fatal_error(" Too much descriptor for ocaml GC");
}
AP.EmitInt16(NumDescriptors);
AP.EmitAlignment(IntPtrSize == 4 ? 2 : 3);
for (iterator I = begin(), IE = end(); I != IE; ++I) {
GCFunctionInfo &FI = **I;
uint64_t FrameSize = FI.getFrameSize();
if (FrameSize >= 1<<16) {
// Very rude!
report_fatal_error("Function '" + FI.getFunction().getName() +
"' is too large for the ocaml GC! "
"Frame size " + Twine(FrameSize) + ">= 65536.\n"
"(" + Twine(uintptr_t(&FI)) + ")");
}
AP.OutStreamer.AddComment("live roots for " +
Twine(FI.getFunction().getName()));
AP.OutStreamer.AddBlankLine();
for (GCFunctionInfo::iterator J = FI.begin(), JE = FI.end(); J != JE; ++J) {
size_t LiveCount = FI.live_size(J);
if (LiveCount >= 1<<16) {
// Very rude!
report_fatal_error("Function '" + FI.getFunction().getName() +
"' is too large for the ocaml GC! "
"Live root count "+Twine(LiveCount)+" >= 65536.");
}
AP.OutStreamer.EmitSymbolValue(J->Label, IntPtrSize);
AP.EmitInt16(FrameSize);
AP.EmitInt16(LiveCount);
for (GCFunctionInfo::live_iterator K = FI.live_begin(J),
KE = FI.live_end(J); K != KE; ++K) {
if (K->StackOffset >= 1<<16) {
// Very rude!
report_fatal_error(
"GC root stack offset is outside of fixed stack frame and out "
"of range for ocaml GC!");
}
AP.EmitInt16(K->StackOffset);
}
AP.EmitAlignment(IntPtrSize == 4 ? 2 : 3);
}
}
}
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