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477de3a785
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@177867 91177308-0d34-0410-b5e6-96231b3b80d8
121 lines
3.9 KiB
C++
121 lines
3.9 KiB
C++
//===-- ErlangGCPrinter.cpp - Erlang/OTP frametable emitter -----*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements the compiler plugin that is used in order to emit
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// garbage collection information in a convenient layout for parsing and
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// loading in the Erlang/OTP runtime.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/CodeGen/AsmPrinter.h"
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#include "llvm/CodeGen/GCs.h"
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#include "llvm/CodeGen/GCMetadataPrinter.h"
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#include "llvm/IR/DataLayout.h"
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#include "llvm/IR/Function.h"
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#include "llvm/IR/Instruction.h"
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#include "llvm/IR/IntrinsicInst.h"
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#include "llvm/IR/Metadata.h"
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#include "llvm/MC/MCAsmInfo.h"
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#include "llvm/MC/MCContext.h"
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#include "llvm/MC/MCSectionELF.h"
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#include "llvm/MC/MCStreamer.h"
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#include "llvm/MC/MCSymbol.h"
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#include "llvm/Target/TargetLoweringObjectFile.h"
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#include "llvm/Target/TargetMachine.h"
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using namespace llvm;
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namespace {
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class ErlangGCPrinter : public GCMetadataPrinter {
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public:
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void beginAssembly(AsmPrinter &AP);
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void finishAssembly(AsmPrinter &AP);
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};
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}
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static GCMetadataPrinterRegistry::Add<ErlangGCPrinter>
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X("erlang", "erlang-compatible garbage collector");
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void llvm::linkErlangGCPrinter() { }
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void ErlangGCPrinter::beginAssembly(AsmPrinter &AP) { }
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void ErlangGCPrinter::finishAssembly(AsmPrinter &AP) {
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MCStreamer &OS = AP.OutStreamer;
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unsigned IntPtrSize = AP.TM.getDataLayout()->getPointerSize();
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// Put this in a custom .note section.
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AP.OutStreamer.SwitchSection(AP.getObjFileLowering().getContext()
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.getELFSection(".note.gc", ELF::SHT_PROGBITS, 0,
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SectionKind::getDataRel()));
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// For each function...
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for (iterator FI = begin(), FE = end(); FI != FE; ++FI) {
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GCFunctionInfo &MD = **FI;
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/** A compact GC layout. Emit this data structure:
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*
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* struct {
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* int16_t PointCount;
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* void *SafePointAddress[PointCount];
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* int16_t StackFrameSize; (in words)
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* int16_t StackArity;
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* int16_t LiveCount;
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* int16_t LiveOffsets[LiveCount];
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* } __gcmap_<FUNCTIONNAME>;
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**/
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// Align to address width.
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AP.EmitAlignment(IntPtrSize == 4 ? 2 : 3);
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// Emit PointCount.
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OS.AddComment("safe point count");
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AP.EmitInt16(MD.size());
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// And each safe point...
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for (GCFunctionInfo::iterator PI = MD.begin(), PE = MD.end(); PI != PE;
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++PI) {
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// Emit the address of the safe point.
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OS.AddComment("safe point address");
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MCSymbol *Label = PI->Label;
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AP.EmitLabelPlusOffset(Label/*Hi*/, 0/*Offset*/, 4/*Size*/);
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}
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// Stack information never change in safe points! Only print info from the
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// first call-site.
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GCFunctionInfo::iterator PI = MD.begin();
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// Emit the stack frame size.
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OS.AddComment("stack frame size (in words)");
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AP.EmitInt16(MD.getFrameSize() / IntPtrSize);
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// Emit stack arity, i.e. the number of stacked arguments.
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unsigned RegisteredArgs = IntPtrSize == 4 ? 5 : 6;
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unsigned StackArity = MD.getFunction().arg_size() > RegisteredArgs ?
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MD.getFunction().arg_size() - RegisteredArgs : 0;
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OS.AddComment("stack arity");
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AP.EmitInt16(StackArity);
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// Emit the number of live roots in the function.
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OS.AddComment("live root count");
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AP.EmitInt16(MD.live_size(PI));
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// And for each live root...
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for (GCFunctionInfo::live_iterator LI = MD.live_begin(PI),
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LE = MD.live_end(PI);
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LI != LE; ++LI) {
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// Emit live root's offset within the stack frame.
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OS.AddComment("stack index (offset / wordsize)");
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AP.EmitInt16(LI->StackOffset / IntPtrSize);
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}
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}
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}
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