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comparison lib/CodeGen/AsmPrinter/ErlangGCPrinter.cpp @ 0:95c75e76d11b LLVM3.4

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LLVM 3.4
author Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
date Thu, 12 Dec 2013 13:56:28 +0900
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children 54457678186b
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-1:000000000000 0:95c75e76d11b
1 //===-- ErlangGCPrinter.cpp - Erlang/OTP frametable emitter -----*- C++ -*-===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file implements the compiler plugin that is used in order to emit
11 // garbage collection information in a convenient layout for parsing and
12 // loading in the Erlang/OTP runtime.
13 //
14 //===----------------------------------------------------------------------===//
15
16 #include "llvm/CodeGen/AsmPrinter.h"
17 #include "llvm/CodeGen/GCs.h"
18 #include "llvm/CodeGen/GCMetadataPrinter.h"
19 #include "llvm/IR/DataLayout.h"
20 #include "llvm/IR/Function.h"
21 #include "llvm/IR/Instruction.h"
22 #include "llvm/IR/IntrinsicInst.h"
23 #include "llvm/IR/Metadata.h"
24 #include "llvm/MC/MCAsmInfo.h"
25 #include "llvm/MC/MCContext.h"
26 #include "llvm/MC/MCSectionELF.h"
27 #include "llvm/MC/MCStreamer.h"
28 #include "llvm/MC/MCSymbol.h"
29 #include "llvm/Target/TargetLoweringObjectFile.h"
30 #include "llvm/Target/TargetMachine.h"
31
32 using namespace llvm;
33
34 namespace {
35
36 class ErlangGCPrinter : public GCMetadataPrinter {
37 public:
38 void beginAssembly(AsmPrinter &AP);
39 void finishAssembly(AsmPrinter &AP);
40 };
41
42 }
43
44 static GCMetadataPrinterRegistry::Add<ErlangGCPrinter>
45 X("erlang", "erlang-compatible garbage collector");
46
47 void llvm::linkErlangGCPrinter() { }
48
49 void ErlangGCPrinter::beginAssembly(AsmPrinter &AP) { }
50
51 void ErlangGCPrinter::finishAssembly(AsmPrinter &AP) {
52 MCStreamer &OS = AP.OutStreamer;
53 unsigned IntPtrSize = AP.TM.getDataLayout()->getPointerSize();
54
55 // Put this in a custom .note section.
56 AP.OutStreamer.SwitchSection(AP.getObjFileLowering().getContext()
57 .getELFSection(".note.gc", ELF::SHT_PROGBITS, 0,
58 SectionKind::getDataRel()));
59
60 // For each function...
61 for (iterator FI = begin(), FE = end(); FI != FE; ++FI) {
62 GCFunctionInfo &MD = **FI;
63
64 /** A compact GC layout. Emit this data structure:
65 *
66 * struct {
67 * int16_t PointCount;
68 * void *SafePointAddress[PointCount];
69 * int16_t StackFrameSize; (in words)
70 * int16_t StackArity;
71 * int16_t LiveCount;
72 * int16_t LiveOffsets[LiveCount];
73 * } __gcmap_<FUNCTIONNAME>;
74 **/
75
76 // Align to address width.
77 AP.EmitAlignment(IntPtrSize == 4 ? 2 : 3);
78
79 // Emit PointCount.
80 OS.AddComment("safe point count");
81 AP.EmitInt16(MD.size());
82
83 // And each safe point...
84 for (GCFunctionInfo::iterator PI = MD.begin(), PE = MD.end(); PI != PE;
85 ++PI) {
86 // Emit the address of the safe point.
87 OS.AddComment("safe point address");
88 MCSymbol *Label = PI->Label;
89 AP.EmitLabelPlusOffset(Label/*Hi*/, 0/*Offset*/, 4/*Size*/);
90 }
91
92 // Stack information never change in safe points! Only print info from the
93 // first call-site.
94 GCFunctionInfo::iterator PI = MD.begin();
95
96 // Emit the stack frame size.
97 OS.AddComment("stack frame size (in words)");
98 AP.EmitInt16(MD.getFrameSize() / IntPtrSize);
99
100 // Emit stack arity, i.e. the number of stacked arguments.
101 unsigned RegisteredArgs = IntPtrSize == 4 ? 5 : 6;
102 unsigned StackArity = MD.getFunction().arg_size() > RegisteredArgs ?
103 MD.getFunction().arg_size() - RegisteredArgs : 0;
104 OS.AddComment("stack arity");
105 AP.EmitInt16(StackArity);
106
107 // Emit the number of live roots in the function.
108 OS.AddComment("live root count");
109 AP.EmitInt16(MD.live_size(PI));
110
111 // And for each live root...
112 for (GCFunctionInfo::live_iterator LI = MD.live_begin(PI),
113 LE = MD.live_end(PI);
114 LI != LE; ++LI) {
115 // Emit live root's offset within the stack frame.
116 OS.AddComment("stack index (offset / wordsize)");
117 AP.EmitInt16(LI->StackOffset / IntPtrSize);
118 }
119 }
120 }