mirror of
https://github.com/RPCS3/llvm-mirror.git
synced 2024-11-25 20:23:11 +01:00
8057a16e18
N_FUNC_COLD is a new MachO symbol attribute. It's a hint to the linker
to order a symbol towards the end of its section, to improve locality.
Example:
```
void a1() {}
__attribute__((cold)) void a2() {}
void a3() {}
int main() {
a1();
a2();
a3();
return 0;
}
```
A linker that supports N_FUNC_COLD will order _a2 to the end of the text
section. From `nm -njU` output, we see:
```
_a1
_a3
_main
_a2
```
Differential Revision: https://reviews.llvm.org/D57190
llvm-svn: 352227
141 lines
4.2 KiB
C++
141 lines
4.2 KiB
C++
//===- MCSymbolMachO.h - ---------------------------------------*- C++ -*-===//
|
|
//
|
|
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
|
|
// See https://llvm.org/LICENSE.txt for license information.
|
|
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
#ifndef LLVM_MC_MCSYMBOLMACHO_H
|
|
#define LLVM_MC_MCSYMBOLMACHO_H
|
|
|
|
#include "llvm/ADT/Twine.h"
|
|
#include "llvm/MC/MCSymbol.h"
|
|
|
|
namespace llvm {
|
|
class MCSymbolMachO : public MCSymbol {
|
|
/// We store the value for the 'desc' symbol field in the
|
|
/// lowest 16 bits of the implementation defined flags.
|
|
enum MachOSymbolFlags : uint16_t { // See <mach-o/nlist.h>.
|
|
SF_DescFlagsMask = 0xFFFF,
|
|
|
|
// Reference type flags.
|
|
SF_ReferenceTypeMask = 0x0007,
|
|
SF_ReferenceTypeUndefinedNonLazy = 0x0000,
|
|
SF_ReferenceTypeUndefinedLazy = 0x0001,
|
|
SF_ReferenceTypeDefined = 0x0002,
|
|
SF_ReferenceTypePrivateDefined = 0x0003,
|
|
SF_ReferenceTypePrivateUndefinedNonLazy = 0x0004,
|
|
SF_ReferenceTypePrivateUndefinedLazy = 0x0005,
|
|
|
|
// Other 'desc' flags.
|
|
SF_ThumbFunc = 0x0008,
|
|
SF_NoDeadStrip = 0x0020,
|
|
SF_WeakReference = 0x0040,
|
|
SF_WeakDefinition = 0x0080,
|
|
SF_SymbolResolver = 0x0100,
|
|
SF_AltEntry = 0x0200,
|
|
SF_Cold = 0x0400,
|
|
|
|
// Common alignment
|
|
SF_CommonAlignmentMask = 0xF0FF,
|
|
SF_CommonAlignmentShift = 8
|
|
};
|
|
|
|
public:
|
|
MCSymbolMachO(const StringMapEntry<bool> *Name, bool isTemporary)
|
|
: MCSymbol(SymbolKindMachO, Name, isTemporary) {}
|
|
|
|
// Reference type methods.
|
|
|
|
void clearReferenceType() const {
|
|
modifyFlags(0, SF_ReferenceTypeMask);
|
|
}
|
|
|
|
void setReferenceTypeUndefinedLazy(bool Value) const {
|
|
modifyFlags(Value ? SF_ReferenceTypeUndefinedLazy : 0,
|
|
SF_ReferenceTypeUndefinedLazy);
|
|
}
|
|
|
|
// Other 'desc' methods.
|
|
|
|
void setThumbFunc() const {
|
|
modifyFlags(SF_ThumbFunc, SF_ThumbFunc);
|
|
}
|
|
|
|
bool isNoDeadStrip() const {
|
|
return getFlags() & SF_NoDeadStrip;
|
|
}
|
|
void setNoDeadStrip() const {
|
|
modifyFlags(SF_NoDeadStrip, SF_NoDeadStrip);
|
|
}
|
|
|
|
bool isWeakReference() const {
|
|
return getFlags() & SF_WeakReference;
|
|
}
|
|
void setWeakReference() const {
|
|
modifyFlags(SF_WeakReference, SF_WeakReference);
|
|
}
|
|
|
|
bool isWeakDefinition() const {
|
|
return getFlags() & SF_WeakDefinition;
|
|
}
|
|
void setWeakDefinition() const {
|
|
modifyFlags(SF_WeakDefinition, SF_WeakDefinition);
|
|
}
|
|
|
|
bool isSymbolResolver() const {
|
|
return getFlags() & SF_SymbolResolver;
|
|
}
|
|
void setSymbolResolver() const {
|
|
modifyFlags(SF_SymbolResolver, SF_SymbolResolver);
|
|
}
|
|
|
|
void setAltEntry() const {
|
|
modifyFlags(SF_AltEntry, SF_AltEntry);
|
|
}
|
|
|
|
bool isAltEntry() const {
|
|
return getFlags() & SF_AltEntry;
|
|
}
|
|
|
|
void setCold() const { modifyFlags(SF_Cold, SF_Cold); }
|
|
|
|
bool isCold() const { return getFlags() & SF_Cold; }
|
|
|
|
void setDesc(unsigned Value) const {
|
|
assert(Value == (Value & SF_DescFlagsMask) &&
|
|
"Invalid .desc value!");
|
|
setFlags(Value & SF_DescFlagsMask);
|
|
}
|
|
|
|
/// Get the encoded value of the flags as they will be emitted in to
|
|
/// the MachO binary
|
|
uint16_t getEncodedFlags(bool EncodeAsAltEntry) const {
|
|
uint16_t Flags = getFlags();
|
|
|
|
// Common alignment is packed into the 'desc' bits.
|
|
if (isCommon()) {
|
|
if (unsigned Align = getCommonAlignment()) {
|
|
unsigned Log2Size = Log2_32(Align);
|
|
assert((1U << Log2Size) == Align && "Invalid 'common' alignment!");
|
|
if (Log2Size > 15)
|
|
report_fatal_error("invalid 'common' alignment '" +
|
|
Twine(Align) + "' for '" + getName() + "'",
|
|
false);
|
|
Flags = (Flags & SF_CommonAlignmentMask) |
|
|
(Log2Size << SF_CommonAlignmentShift);
|
|
}
|
|
}
|
|
|
|
if (EncodeAsAltEntry)
|
|
Flags |= SF_AltEntry;
|
|
|
|
return Flags;
|
|
}
|
|
|
|
static bool classof(const MCSymbol *S) { return S->isMachO(); }
|
|
};
|
|
}
|
|
|
|
#endif
|