1 //===-- OcamlGCPrinter.cpp - Ocaml frametable emitter ---------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements printing the assembly code for an Ocaml frametable.
12 //===----------------------------------------------------------------------===//
14 #include "llvm/CodeGen/GCs.h"
15 #include "llvm/ADT/SmallString.h"
16 #include "llvm/CodeGen/AsmPrinter.h"
17 #include "llvm/CodeGen/GCMetadataPrinter.h"
18 #include "llvm/IR/DataLayout.h"
19 #include "llvm/IR/Mangler.h"
20 #include "llvm/IR/Module.h"
21 #include "llvm/MC/MCAsmInfo.h"
22 #include "llvm/MC/MCContext.h"
23 #include "llvm/MC/MCStreamer.h"
24 #include "llvm/MC/MCSymbol.h"
25 #include "llvm/Support/ErrorHandling.h"
26 #include "llvm/Support/FormattedStream.h"
27 #include "llvm/Target/TargetLoweringObjectFile.h"
28 #include "llvm/Target/TargetMachine.h"
29 #include "llvm/Target/TargetSubtargetInfo.h"
35 class OcamlGCMetadataPrinter : public GCMetadataPrinter {
37 void beginAssembly(Module &M, GCModuleInfo &Info, AsmPrinter &AP) override;
38 void finishAssembly(Module &M, GCModuleInfo &Info, AsmPrinter &AP) override;
42 static GCMetadataPrinterRegistry::Add<OcamlGCMetadataPrinter>
43 Y("ocaml", "ocaml 3.10-compatible collector");
45 void llvm::linkOcamlGCPrinter() {}
47 static void EmitCamlGlobal(const Module &M, AsmPrinter &AP, const char *Id) {
48 const std::string &MId = M.getModuleIdentifier();
52 size_t Letter = SymName.size();
53 SymName.append(MId.begin(), std::find(MId.begin(), MId.end(), '.'));
57 // Capitalize the first letter of the module name.
58 SymName[Letter] = toupper(SymName[Letter]);
60 SmallString<128> TmpStr;
61 Mangler::getNameWithPrefix(TmpStr, SymName, M.getDataLayout());
63 MCSymbol *Sym = AP.OutContext.getOrCreateSymbol(TmpStr);
65 AP.OutStreamer->EmitSymbolAttribute(Sym, MCSA_Global);
66 AP.OutStreamer->EmitLabel(Sym);
69 void OcamlGCMetadataPrinter::beginAssembly(Module &M, GCModuleInfo &Info,
71 AP.OutStreamer->SwitchSection(AP.getObjFileLowering().getTextSection());
72 EmitCamlGlobal(M, AP, "code_begin");
74 AP.OutStreamer->SwitchSection(AP.getObjFileLowering().getDataSection());
75 EmitCamlGlobal(M, AP, "data_begin");
78 /// emitAssembly - Print the frametable. The ocaml frametable format is thus:
80 /// extern "C" struct align(sizeof(intptr_t)) {
81 /// uint16_t NumDescriptors;
82 /// struct align(sizeof(intptr_t)) {
83 /// void *ReturnAddress;
84 /// uint16_t FrameSize;
85 /// uint16_t NumLiveOffsets;
86 /// uint16_t LiveOffsets[NumLiveOffsets];
87 /// } Descriptors[NumDescriptors];
88 /// } caml${module}__frametable;
90 /// Note that this precludes programs from stack frames larger than 64K
91 /// (FrameSize and LiveOffsets would overflow). FrameTablePrinter will abort if
92 /// either condition is detected in a function which uses the GC.
94 void OcamlGCMetadataPrinter::finishAssembly(Module &M, GCModuleInfo &Info,
96 unsigned IntPtrSize = M.getDataLayout().getPointerSize();
98 AP.OutStreamer->SwitchSection(AP.getObjFileLowering().getTextSection());
99 EmitCamlGlobal(M, AP, "code_end");
101 AP.OutStreamer->SwitchSection(AP.getObjFileLowering().getDataSection());
102 EmitCamlGlobal(M, AP, "data_end");
104 // FIXME: Why does ocaml emit this??
105 AP.OutStreamer->EmitIntValue(0, IntPtrSize);
107 AP.OutStreamer->SwitchSection(AP.getObjFileLowering().getDataSection());
108 EmitCamlGlobal(M, AP, "frametable");
110 int NumDescriptors = 0;
111 for (GCModuleInfo::FuncInfoVec::iterator I = Info.funcinfo_begin(),
112 IE = Info.funcinfo_end();
114 GCFunctionInfo &FI = **I;
115 if (FI.getStrategy().getName() != getStrategy().getName())
116 // this function is managed by some other GC
118 for (GCFunctionInfo::iterator J = FI.begin(), JE = FI.end(); J != JE; ++J) {
123 if (NumDescriptors >= 1 << 16) {
125 report_fatal_error(" Too much descriptor for ocaml GC");
127 AP.EmitInt16(NumDescriptors);
128 AP.EmitAlignment(IntPtrSize == 4 ? 2 : 3);
130 for (GCModuleInfo::FuncInfoVec::iterator I = Info.funcinfo_begin(),
131 IE = Info.funcinfo_end();
133 GCFunctionInfo &FI = **I;
134 if (FI.getStrategy().getName() != getStrategy().getName())
135 // this function is managed by some other GC
138 uint64_t FrameSize = FI.getFrameSize();
139 if (FrameSize >= 1 << 16) {
141 report_fatal_error("Function '" + FI.getFunction().getName() +
142 "' is too large for the ocaml GC! "
144 Twine(FrameSize) + ">= 65536.\n"
146 Twine(uintptr_t(&FI)) + ")");
149 AP.OutStreamer->AddComment("live roots for " +
150 Twine(FI.getFunction().getName()));
151 AP.OutStreamer->AddBlankLine();
153 for (GCFunctionInfo::iterator J = FI.begin(), JE = FI.end(); J != JE; ++J) {
154 size_t LiveCount = FI.live_size(J);
155 if (LiveCount >= 1 << 16) {
157 report_fatal_error("Function '" + FI.getFunction().getName() +
158 "' is too large for the ocaml GC! "
160 Twine(LiveCount) + " >= 65536.");
163 AP.OutStreamer->EmitSymbolValue(J->Label, IntPtrSize);
164 AP.EmitInt16(FrameSize);
165 AP.EmitInt16(LiveCount);
167 for (GCFunctionInfo::live_iterator K = FI.live_begin(J),
170 if (K->StackOffset >= 1 << 16) {
173 "GC root stack offset is outside of fixed stack frame and out "
174 "of range for ocaml GC!");
176 AP.EmitInt16(K->StackOffset);
179 AP.EmitAlignment(IntPtrSize == 4 ? 2 : 3);