llvm/lib/CodeGen/AsmPrinter/ErlangGCPrinter.cpp
David Blaikie e3a9b4ce3a Fix a bunch more layering of CodeGen headers that are in Target
All these headers already depend on CodeGen headers so moving them into
CodeGen fixes the layering (since CodeGen depends on Target, not the
other way around).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@318490 91177308-0d34-0410-b5e6-96231b3b80d8
2017-11-17 01:07:10 +00:00

123 lines
4.1 KiB
C++

//===- ErlangGCPrinter.cpp - Erlang/OTP 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 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/BinaryFormat/ELF.h"
#include "llvm/CodeGen/AsmPrinter.h"
#include "llvm/CodeGen/GCMetadata.h"
#include "llvm/CodeGen/GCMetadataPrinter.h"
#include "llvm/CodeGen/GCStrategy.h"
#include "llvm/CodeGen/GCs.h"
#include "llvm/CodeGen/TargetLoweringObjectFile.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/Module.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCSectionELF.h"
#include "llvm/MC/MCStreamer.h"
#include "llvm/MC/MCSymbol.h"
using namespace llvm;
namespace {
class ErlangGCPrinter : public GCMetadataPrinter {
public:
void finishAssembly(Module &M, GCModuleInfo &Info, AsmPrinter &AP) override;
};
} // end anonymous namespace
static GCMetadataPrinterRegistry::Add<ErlangGCPrinter>
X("erlang", "erlang-compatible garbage collector");
void ErlangGCPrinter::finishAssembly(Module &M, GCModuleInfo &Info,
AsmPrinter &AP) {
MCStreamer &OS = *AP.OutStreamer;
unsigned IntPtrSize = M.getDataLayout().getPointerSize();
// Put this in a custom .note section.
OS.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);
}
}
}
void llvm::linkErlangGCPrinter() {}