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clang-p2996/lld/ELF/Mips.cpp
Simon Atanasyan 9e0297b8bc [ELF][MIPS] N32 ABI support 
In short the patch introduces support for linking object file conform
MIPS N32 ABI [1]. This ABI is similar to N64 ABI but uses 32-bit
pointer size.

The most non-trivial requirement of this ABI is one more relocation
packing format. N64 ABI puts multiple relocation type into the single
relocation record. The N32 ABI uses series of successive relocations
with the same offset for this purpose. In this patch, new function
`mergeMipsN32RelTypes` handle this case and "convert" N32 relocation to
the N64 relocation so the rest of the code keep unchanged.

For now, linker does not support series of relocations applied to sections
without SHF_ALLOC bit. Probably later I will add the support or insert
some sort of assert into the `relocateNonAlloc` routine to catch this
case.

[1] ftp://www.linux-mips.org/pub/linux/mips/doc/ABI/MIPS-N32-ABI-Handbook.pdf

Differential revision: https://reviews.llvm.org/D26298

llvm-svn: 286052
2016-11-05 22:58:01 +00:00

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//===- Mips.cpp ----------------------------------------------------------===//
//
// The LLVM Linker
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===---------------------------------------------------------------------===//
//
// This file contains a helper function for the Writer.
//
//===---------------------------------------------------------------------===//
#include "Error.h"
#include "InputFiles.h"
#include "SymbolTable.h"
#include "Writer.h"
#include "llvm/Object/ELF.h"
#include "llvm/Support/ELF.h"
#include "llvm/Support/MipsABIFlags.h"
using namespace llvm;
using namespace llvm::object;
using namespace llvm::ELF;
using namespace lld;
using namespace lld::elf;
namespace {
struct ArchTreeEdge {
uint32_t Child;
uint32_t Parent;
};
struct FileFlags {
StringRef Filename;
uint32_t Flags;
};
}
static StringRef getAbiName(uint32_t Flags) {
switch (Flags) {
case 0:
return "n64";
case EF_MIPS_ABI2:
return "n32";
case EF_MIPS_ABI_O32:
return "o32";
case EF_MIPS_ABI_O64:
return "o64";
case EF_MIPS_ABI_EABI32:
return "eabi32";
case EF_MIPS_ABI_EABI64:
return "eabi64";
default:
return "unknown";
}
}
static StringRef getNanName(bool IsNan2008) {
return IsNan2008 ? "2008" : "legacy";
}
static StringRef getFpName(bool IsFp64) { return IsFp64 ? "64" : "32"; }
static void checkFlags(ArrayRef<FileFlags> Files) {
uint32_t ABI = Files[0].Flags & (EF_MIPS_ABI | EF_MIPS_ABI2);
bool Nan = Files[0].Flags & EF_MIPS_NAN2008;
bool Fp = Files[0].Flags & EF_MIPS_FP64;
for (const FileFlags &F : Files.slice(1)) {
uint32_t ABI2 = F.Flags & (EF_MIPS_ABI | EF_MIPS_ABI2);
if (ABI != ABI2)
error("target ABI '" + getAbiName(ABI) + "' is incompatible with '" +
getAbiName(ABI2) + "': " + F.Filename);
bool Nan2 = F.Flags & EF_MIPS_NAN2008;
if (Nan != Nan2)
error("target -mnan=" + getNanName(Nan) + " is incompatible with -mnan=" +
getNanName(Nan2) + ": " + F.Filename);
bool Fp2 = F.Flags & EF_MIPS_FP64;
if (Fp != Fp2)
error("target -mfp" + getFpName(Fp) + " is incompatible with -mfp" +
getFpName(Fp2) + ": " + F.Filename);
}
}
static uint32_t getMiscFlags(ArrayRef<FileFlags> Files) {
uint32_t Ret = 0;
for (const FileFlags &F : Files)
Ret |= F.Flags &
(EF_MIPS_ABI | EF_MIPS_ABI2 | EF_MIPS_ARCH_ASE | EF_MIPS_NOREORDER |
EF_MIPS_MICROMIPS | EF_MIPS_NAN2008 | EF_MIPS_32BITMODE);
return Ret;
}
static uint32_t getPicFlags(ArrayRef<FileFlags> Files) {
// Check PIC/non-PIC compatibility.
bool IsPic = Files[0].Flags & (EF_MIPS_PIC | EF_MIPS_CPIC);
for (const FileFlags &F : Files.slice(1)) {
bool IsPic2 = F.Flags & (EF_MIPS_PIC | EF_MIPS_CPIC);
if (IsPic && !IsPic2)
warn("linking abicalls code with non-abicalls file: " + F.Filename);
if (!IsPic && IsPic2)
warn("linking non-abicalls code with abicalls file: " + F.Filename);
}
// Compute the result PIC/non-PIC flag.
uint32_t Ret = Files[0].Flags & (EF_MIPS_PIC | EF_MIPS_CPIC);
for (const FileFlags &F : Files.slice(1))
Ret &= F.Flags & (EF_MIPS_PIC | EF_MIPS_CPIC);
// PIC code is inherently CPIC and may not set CPIC flag explicitly.
if (Ret & EF_MIPS_PIC)
Ret |= EF_MIPS_CPIC;
return Ret;
}
static ArchTreeEdge ArchTree[] = {
// MIPS32R6 and MIPS64R6 are not compatible with other extensions
// MIPS64R2 extensions.
{EF_MIPS_ARCH_64R2 | EF_MIPS_MACH_OCTEON3, EF_MIPS_ARCH_64R2},
{EF_MIPS_ARCH_64R2 | EF_MIPS_MACH_OCTEON2, EF_MIPS_ARCH_64R2},
{EF_MIPS_ARCH_64R2 | EF_MIPS_MACH_OCTEON, EF_MIPS_ARCH_64R2},
{EF_MIPS_ARCH_64R2 | EF_MIPS_MACH_LS3A, EF_MIPS_ARCH_64R2},
// MIPS64 extensions.
{EF_MIPS_ARCH_64 | EF_MIPS_MACH_SB1, EF_MIPS_ARCH_64},
{EF_MIPS_ARCH_64 | EF_MIPS_MACH_XLR, EF_MIPS_ARCH_64},
{EF_MIPS_ARCH_64R2, EF_MIPS_ARCH_64},
// MIPS V extensions.
{EF_MIPS_ARCH_64, EF_MIPS_ARCH_5},
// R5000 extensions.
{EF_MIPS_ARCH_4 | EF_MIPS_MACH_5500, EF_MIPS_ARCH_4 | EF_MIPS_MACH_5400},
// MIPS IV extensions.
{EF_MIPS_ARCH_4 | EF_MIPS_MACH_5400, EF_MIPS_ARCH_4},
{EF_MIPS_ARCH_4 | EF_MIPS_MACH_9000, EF_MIPS_ARCH_4},
{EF_MIPS_ARCH_5, EF_MIPS_ARCH_4},
// VR4100 extensions.
{EF_MIPS_ARCH_3 | EF_MIPS_MACH_4111, EF_MIPS_ARCH_3 | EF_MIPS_MACH_4100},
{EF_MIPS_ARCH_3 | EF_MIPS_MACH_4120, EF_MIPS_ARCH_3 | EF_MIPS_MACH_4100},
// MIPS III extensions.
{EF_MIPS_ARCH_3 | EF_MIPS_MACH_4010, EF_MIPS_ARCH_3},
{EF_MIPS_ARCH_3 | EF_MIPS_MACH_4100, EF_MIPS_ARCH_3},
{EF_MIPS_ARCH_3 | EF_MIPS_MACH_4650, EF_MIPS_ARCH_3},
{EF_MIPS_ARCH_3 | EF_MIPS_MACH_5900, EF_MIPS_ARCH_3},
{EF_MIPS_ARCH_3 | EF_MIPS_MACH_LS2E, EF_MIPS_ARCH_3},
{EF_MIPS_ARCH_3 | EF_MIPS_MACH_LS2F, EF_MIPS_ARCH_3},
{EF_MIPS_ARCH_4, EF_MIPS_ARCH_3},
// MIPS32 extensions.
{EF_MIPS_ARCH_32R2, EF_MIPS_ARCH_32},
// MIPS II extensions.
{EF_MIPS_ARCH_3, EF_MIPS_ARCH_2},
{EF_MIPS_ARCH_32, EF_MIPS_ARCH_2},
// MIPS I extensions.
{EF_MIPS_ARCH_1 | EF_MIPS_MACH_3900, EF_MIPS_ARCH_1},
{EF_MIPS_ARCH_2, EF_MIPS_ARCH_1},
};
static bool isArchMatched(uint32_t New, uint32_t Res) {
if (New == Res)
return true;
if (New == EF_MIPS_ARCH_32 && isArchMatched(EF_MIPS_ARCH_64, Res))
return true;
if (New == EF_MIPS_ARCH_32R2 && isArchMatched(EF_MIPS_ARCH_64R2, Res))
return true;
for (const auto &Edge : ArchTree) {
if (Res == Edge.Child) {
Res = Edge.Parent;
if (Res == New)
return true;
}
}
return false;
}
static StringRef getMachName(uint32_t Flags) {
switch (Flags & EF_MIPS_MACH) {
case EF_MIPS_MACH_NONE:
return "";
case EF_MIPS_MACH_3900:
return "r3900";
case EF_MIPS_MACH_4010:
return "r4010";
case EF_MIPS_MACH_4100:
return "r4100";
case EF_MIPS_MACH_4650:
return "r4650";
case EF_MIPS_MACH_4120:
return "r4120";
case EF_MIPS_MACH_4111:
return "r4111";
case EF_MIPS_MACH_5400:
return "vr5400";
case EF_MIPS_MACH_5900:
return "vr5900";
case EF_MIPS_MACH_5500:
return "vr5500";
case EF_MIPS_MACH_9000:
return "rm9000";
case EF_MIPS_MACH_LS2E:
return "loongson2e";
case EF_MIPS_MACH_LS2F:
return "loongson2f";
case EF_MIPS_MACH_LS3A:
return "loongson3a";
case EF_MIPS_MACH_OCTEON:
return "octeon";
case EF_MIPS_MACH_OCTEON2:
return "octeon2";
case EF_MIPS_MACH_OCTEON3:
return "octeon3";
case EF_MIPS_MACH_SB1:
return "sb1";
case EF_MIPS_MACH_XLR:
return "xlr";
default:
return "unknown machine";
}
}
static StringRef getArchName(uint32_t Flags) {
StringRef S = getMachName(Flags);
if (!S.empty())
return S;
switch (Flags & EF_MIPS_ARCH) {
case EF_MIPS_ARCH_1:
return "mips1";
case EF_MIPS_ARCH_2:
return "mips2";
case EF_MIPS_ARCH_3:
return "mips3";
case EF_MIPS_ARCH_4:
return "mips4";
case EF_MIPS_ARCH_5:
return "mips5";
case EF_MIPS_ARCH_32:
return "mips32";
case EF_MIPS_ARCH_64:
return "mips64";
case EF_MIPS_ARCH_32R2:
return "mips32r2";
case EF_MIPS_ARCH_64R2:
return "mips64r2";
case EF_MIPS_ARCH_32R6:
return "mips32r6";
case EF_MIPS_ARCH_64R6:
return "mips64r6";
default:
return "unknown arch";
}
}
// There are (arguably too) many MIPS ISAs out there. Their relationships
// can be represented as a forest. If all input files have ISAs which
// reachable by repeated proceeding from the single child to the parent,
// these input files are compatible. In that case we need to return "highest"
// ISA. If there are incompatible input files, we show an error.
// For example, mips1 is a "parent" of mips2 and such files are compatible.
// Output file gets EF_MIPS_ARCH_2 flag. From the other side mips3 and mips32
// are incompatible because nor mips3 is a parent for misp32, nor mips32
// is a parent for mips3.
static uint32_t getArchFlags(ArrayRef<FileFlags> Files) {
uint32_t Ret = Files[0].Flags & (EF_MIPS_ARCH | EF_MIPS_MACH);
for (const FileFlags &F : Files.slice(1)) {
uint32_t New = F.Flags & (EF_MIPS_ARCH | EF_MIPS_MACH);
// Check ISA compatibility.
if (isArchMatched(New, Ret))
continue;
if (!isArchMatched(Ret, New)) {
error("target ISA '" + getArchName(Ret) + "' is incompatible with '" +
getArchName(New) + "': " + F.Filename);
return 0;
}
Ret = New;
}
return Ret;
}
template <class ELFT> uint32_t elf::getMipsEFlags() {
std::vector<FileFlags> V;
for (elf::ObjectFile<ELFT> *F : Symtab<ELFT>::X->getObjectFiles())
V.push_back({F->getName(), F->getObj().getHeader()->e_flags});
if (V.empty())
return 0;
checkFlags(V);
return getMiscFlags(V) | getPicFlags(V) | getArchFlags(V);
}
static int compareMipsFpAbi(uint8_t FpA, uint8_t FpB) {
if (FpA == FpB)
return 0;
if (FpB == Mips::Val_GNU_MIPS_ABI_FP_ANY)
return 1;
if (FpB == Mips::Val_GNU_MIPS_ABI_FP_64A &&
FpA == Mips::Val_GNU_MIPS_ABI_FP_64)
return 1;
if (FpB != Mips::Val_GNU_MIPS_ABI_FP_XX)
return -1;
if (FpA == Mips::Val_GNU_MIPS_ABI_FP_DOUBLE ||
FpA == Mips::Val_GNU_MIPS_ABI_FP_64 ||
FpA == Mips::Val_GNU_MIPS_ABI_FP_64A)
return 1;
return -1;
}
static StringRef getMipsFpAbiName(uint8_t FpAbi) {
switch (FpAbi) {
case Mips::Val_GNU_MIPS_ABI_FP_ANY:
return "any";
case Mips::Val_GNU_MIPS_ABI_FP_DOUBLE:
return "-mdouble-float";
case Mips::Val_GNU_MIPS_ABI_FP_SINGLE:
return "-msingle-float";
case Mips::Val_GNU_MIPS_ABI_FP_SOFT:
return "-msoft-float";
case Mips::Val_GNU_MIPS_ABI_FP_OLD_64:
return "-mips32r2 -mfp64 (old)";
case Mips::Val_GNU_MIPS_ABI_FP_XX:
return "-mfpxx";
case Mips::Val_GNU_MIPS_ABI_FP_64:
return "-mgp32 -mfp64";
case Mips::Val_GNU_MIPS_ABI_FP_64A:
return "-mgp32 -mfp64 -mno-odd-spreg";
default:
return "unknown";
}
}
uint8_t elf::getMipsFpAbiFlag(uint8_t OldFlag, uint8_t NewFlag,
StringRef FileName) {
if (compareMipsFpAbi(NewFlag, OldFlag) >= 0)
return NewFlag;
if (compareMipsFpAbi(OldFlag, NewFlag) < 0)
error("target floating point ABI '" + getMipsFpAbiName(OldFlag) +
"' is incompatible with '" + getMipsFpAbiName(NewFlag) + "': " +
FileName);
return OldFlag;
}
template <class ELFT> static bool isN32Abi(const InputFile *F) {
if (auto *EF = dyn_cast<ELFFileBase<ELFT>>(F))
return EF->getObj().getHeader()->e_flags & EF_MIPS_ABI2;
return false;
}
bool elf::isMipsN32Abi(const InputFile *F) {
switch (Config->EKind) {
case ELF32LEKind:
return isN32Abi<ELF32LE>(F);
case ELF32BEKind:
return isN32Abi<ELF32BE>(F);
case ELF64LEKind:
return isN32Abi<ELF64LE>(F);
case ELF64BEKind:
return isN32Abi<ELF64BE>(F);
default:
llvm_unreachable("unknown Config->EKind");
}
}
template uint32_t elf::getMipsEFlags<ELF32LE>();
template uint32_t elf::getMipsEFlags<ELF32BE>();
template uint32_t elf::getMipsEFlags<ELF64LE>();
template uint32_t elf::getMipsEFlags<ELF64BE>();
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