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 = AP.TM.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);