llvm-6502/lib/CodeGen/AsmPrinter/ErlangGCPrinter.cpp
Rafael Espindola 9936b80df5 Compute the ELF SectionKind from the flags.
Any code creating an MCSectionELF knows ELF and already provides the flags.

SectionKind is an abstraction used by common code that uses a plain
MCSection.

Use the flags to compute the SectionKind. This removes a lot of
guessing and boilerplate from the MCSectionELF construction.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@227476 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-29 17:33:21 +00:00

124 lines
4.2 KiB
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//===-- ErlangGCPrinter.cpp - Erlang/OTP frametable emitter -----*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the compiler plugin that is used in order to emit
// garbage collection information in a convenient layout for parsing and
// loading in the Erlang/OTP runtime.
//
//===----------------------------------------------------------------------===//
#include "llvm/CodeGen/AsmPrinter.h"
#include "llvm/CodeGen/GCMetadataPrinter.h"
#include "llvm/CodeGen/GCs.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/Instruction.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/Metadata.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCSectionELF.h"
#include "llvm/MC/MCStreamer.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/Target/TargetLoweringObjectFile.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetSubtargetInfo.h"
using namespace llvm;
namespace {
class ErlangGCPrinter : public GCMetadataPrinter {
public:
void finishAssembly(Module &M, GCModuleInfo &Info, AsmPrinter &AP) override;
};
}
static GCMetadataPrinterRegistry::Add<ErlangGCPrinter>
X("erlang", "erlang-compatible garbage collector");
void llvm::linkErlangGCPrinter() {}
void ErlangGCPrinter::finishAssembly(Module &M, GCModuleInfo &Info,
AsmPrinter &AP) {
MCStreamer &OS = AP.OutStreamer;
unsigned IntPtrSize = AP.TM.getDataLayout()->getPointerSize();
// Put this in a custom .note section.
AP.OutStreamer.SwitchSection(
AP.getObjFileLowering().getContext().getELFSection(".note.gc",
ELF::SHT_PROGBITS, 0));
// For each function...
for (GCModuleInfo::FuncInfoVec::iterator FI = Info.funcinfo_begin(),
IE = Info.funcinfo_end();
FI != IE; ++FI) {
GCFunctionInfo &MD = **FI;
if (MD.getStrategy().getName() != getStrategy().getName())
// this function is managed by some other GC
continue;
/** A compact GC layout. Emit this data structure:
*
* struct {
* int16_t PointCount;
* void *SafePointAddress[PointCount];
* int16_t StackFrameSize; (in words)
* int16_t StackArity;
* int16_t LiveCount;
* int16_t LiveOffsets[LiveCount];
* } __gcmap_<FUNCTIONNAME>;
**/
// Align to address width.
AP.EmitAlignment(IntPtrSize == 4 ? 2 : 3);
// Emit PointCount.
OS.AddComment("safe point count");
AP.EmitInt16(MD.size());
// And each safe point...
for (GCFunctionInfo::iterator PI = MD.begin(), PE = MD.end(); PI != PE;
++PI) {
// Emit the address of the safe point.
OS.AddComment("safe point address");
MCSymbol *Label = PI->Label;
AP.EmitLabelPlusOffset(Label /*Hi*/, 0 /*Offset*/, 4 /*Size*/);
}
// Stack information never change in safe points! Only print info from the
// first call-site.
GCFunctionInfo::iterator PI = MD.begin();
// Emit the stack frame size.
OS.AddComment("stack frame size (in words)");
AP.EmitInt16(MD.getFrameSize() / IntPtrSize);
// Emit stack arity, i.e. the number of stacked arguments.
unsigned RegisteredArgs = IntPtrSize == 4 ? 5 : 6;
unsigned StackArity = MD.getFunction().arg_size() > RegisteredArgs
? MD.getFunction().arg_size() - RegisteredArgs
: 0;
OS.AddComment("stack arity");
AP.EmitInt16(StackArity);
// Emit the number of live roots in the function.
OS.AddComment("live root count");
AP.EmitInt16(MD.live_size(PI));
// And for each live root...
for (GCFunctionInfo::live_iterator LI = MD.live_begin(PI),
LE = MD.live_end(PI);
LI != LE; ++LI) {
// Emit live root's offset within the stack frame.
OS.AddComment("stack index (offset / wordsize)");
AP.EmitInt16(LI->StackOffset / IntPtrSize);
}
}
}