llvm-project/llvm/lib/CodeGen/AsmPrinter/OcamlGCPrinter.cpp

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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;
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// Capitalize the first letter of the module name.
SymName[Letter] = toupper(SymName[Letter]);
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SmallString<128> TmpStr;
AP.Mang->getNameWithPrefix(TmpStr, SymName);
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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) {
Revert the majority of the next patch in the address space series: r165941: Resubmit the changes to llvm core to update the functions to support different pointer sizes on a per address space basis. Despite this commit log, this change primarily changed stuff outside of VMCore, and those changes do not carry any tests for correctness (or even plausibility), and we have consistently found questionable or flat out incorrect cases in these changes. Most of them are probably correct, but we need to devise a system that makes it more clear when we have handled the address space concerns correctly, and ideally each pass that gets updated would receive an accompanying test case that exercises that pass specificaly w.r.t. alternate address spaces. However, from this commit, I have retained the new C API entry points. Those were an orthogonal change that probably should have been split apart, but they seem entirely good. In several places the changes were very obvious cleanups with no actual multiple address space code added; these I have not reverted when I spotted them. In a few other places there were merge conflicts due to a cleaner solution being implemented later, often not using address spaces at all. In those cases, I've preserved the new code which isn't address space dependent. This is part of my ongoing effort to clean out the partial address space code which carries high risk and low test coverage, and not likely to be finished before the 3.2 release looms closer. Duncan and I would both like to see the above issues addressed before we return to these changes. llvm-svn: 167222
2012-11-01 17:14:31 +08:00
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);
}
}
}