summaryrefslogtreecommitdiff
path: root/lib/Target/Mips/MCTargetDesc/MipsELFObjectWriter.cpp
diff options
context:
space:
mode:
Diffstat (limited to 'lib/Target/Mips/MCTargetDesc/MipsELFObjectWriter.cpp')
-rw-r--r--lib/Target/Mips/MCTargetDesc/MipsELFObjectWriter.cpp614
1 files changed, 413 insertions, 201 deletions
diff --git a/lib/Target/Mips/MCTargetDesc/MipsELFObjectWriter.cpp b/lib/Target/Mips/MCTargetDesc/MipsELFObjectWriter.cpp
index 5b9f02b89be5d..cdad7ce1b73a5 100644
--- a/lib/Target/Mips/MCTargetDesc/MipsELFObjectWriter.cpp
+++ b/lib/Target/Mips/MCTargetDesc/MipsELFObjectWriter.cpp
@@ -7,8 +7,11 @@
//
//===----------------------------------------------------------------------===//
+#include <algorithm>
+#include <list>
#include "MCTargetDesc/MipsBaseInfo.h"
#include "MCTargetDesc/MipsFixupKinds.h"
+#include "MCTargetDesc/MipsMCExpr.h"
#include "MCTargetDesc/MipsMCTargetDesc.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/MC/MCAssembler.h"
@@ -17,42 +20,190 @@
#include "llvm/MC/MCSection.h"
#include "llvm/MC/MCSymbolELF.h"
#include "llvm/MC/MCValue.h"
+#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
-#include <list>
+
+#define DEBUG_TYPE "mips-elf-object-writer"
using namespace llvm;
namespace {
-// A helper structure based on ELFRelocationEntry, used for sorting entries in
-// the relocation table.
+/// Holds additional information needed by the relocation ordering algorithm.
struct MipsRelocationEntry {
- MipsRelocationEntry(const ELFRelocationEntry &R)
- : R(R), SortOffset(R.Offset), HasMatchingHi(false) {}
- const ELFRelocationEntry R;
- // SortOffset equals R.Offset except for the *HI16 relocations, for which it
- // will be set based on the R.Offset of the matching *LO16 relocation.
- int64_t SortOffset;
- // True when this is a *LO16 relocation chosen as a match for a *HI16
- // relocation.
- bool HasMatchingHi;
+ const ELFRelocationEntry R; ///< The relocation.
+ bool Matched; ///< Is this relocation part of a match.
+
+ MipsRelocationEntry(const ELFRelocationEntry &R) : R(R), Matched(false) {}
+
+ void print(raw_ostream &Out) const {
+ R.print(Out);
+ Out << ", Matched=" << Matched;
+ }
+};
+
+#ifndef NDEBUG
+raw_ostream &operator<<(raw_ostream &OS, const MipsRelocationEntry &RHS) {
+ RHS.print(OS);
+ return OS;
+}
+#endif
+
+class MipsELFObjectWriter : public MCELFObjectTargetWriter {
+public:
+ MipsELFObjectWriter(bool _is64Bit, uint8_t OSABI, bool _isN64,
+ bool IsLittleEndian);
+
+ ~MipsELFObjectWriter() override;
+
+ unsigned getRelocType(MCContext &Ctx, const MCValue &Target,
+ const MCFixup &Fixup, bool IsPCRel) const override;
+ bool needsRelocateWithSymbol(const MCSymbol &Sym,
+ unsigned Type) const override;
+ virtual void sortRelocs(const MCAssembler &Asm,
+ std::vector<ELFRelocationEntry> &Relocs) override;
+};
+
+/// Copy elements in the range [First, Last) to d1 when the predicate is true or
+/// d2 when the predicate is false. This is essentially both std::copy_if and
+/// std::remove_copy_if combined into a single pass.
+template <class InputIt, class OutputIt1, class OutputIt2, class UnaryPredicate>
+std::pair<OutputIt1, OutputIt2> copy_if_else(InputIt First, InputIt Last,
+ OutputIt1 d1, OutputIt2 d2,
+ UnaryPredicate Predicate) {
+ for (InputIt I = First; I != Last; ++I) {
+ if (Predicate(*I)) {
+ *d1 = *I;
+ d1++;
+ } else {
+ *d2 = *I;
+ d2++;
+ }
+ }
+
+ return std::make_pair(d1, d2);
+}
+
+/// The possible results of the Predicate function used by find_best.
+enum FindBestPredicateResult {
+ FindBest_NoMatch = 0, ///< The current element is not a match.
+ FindBest_Match, ///< The current element is a match but better ones are
+ /// possible.
+ FindBest_PerfectMatch, ///< The current element is an unbeatable match.
};
- class MipsELFObjectWriter : public MCELFObjectTargetWriter {
- public:
- MipsELFObjectWriter(bool _is64Bit, uint8_t OSABI,
- bool _isN64, bool IsLittleEndian);
+/// Find the best match in the range [First, Last).
+///
+/// An element matches when Predicate(X) returns FindBest_Match or
+/// FindBest_PerfectMatch. A value of FindBest_PerfectMatch also terminates
+/// the search. BetterThan(A, B) is a comparator that returns true when A is a
+/// better match than B. The return value is the position of the best match.
+///
+/// This is similar to std::find_if but finds the best of multiple possible
+/// matches.
+template <class InputIt, class UnaryPredicate, class Comparator>
+InputIt find_best(InputIt First, InputIt Last, UnaryPredicate Predicate,
+ Comparator BetterThan) {
+ InputIt Best = Last;
+
+ for (InputIt I = First; I != Last; ++I) {
+ unsigned Matched = Predicate(*I);
+ if (Matched != FindBest_NoMatch) {
+ DEBUG(dbgs() << std::distance(First, I) << " is a match (";
+ I->print(dbgs()); dbgs() << ")\n");
+ if (Best == Last || BetterThan(*I, *Best)) {
+ DEBUG(dbgs() << ".. and it beats the last one\n");
+ Best = I;
+ }
+ }
+ if (Matched == FindBest_PerfectMatch) {
+ DEBUG(dbgs() << ".. and it is unbeatable\n");
+ break;
+ }
+ }
+
+ return Best;
+}
+
+/// Determine the low relocation that matches the given relocation.
+/// If the relocation does not need a low relocation then the return value
+/// is ELF::R_MIPS_NONE.
+///
+/// The relocations that need a matching low part are
+/// R_(MIPS|MICROMIPS|MIPS16)_HI16 for all symbols and
+/// R_(MIPS|MICROMIPS|MIPS16)_GOT16 for local symbols only.
+static unsigned getMatchingLoType(const ELFRelocationEntry &Reloc) {
+ unsigned Type = Reloc.Type;
+ if (Type == ELF::R_MIPS_HI16)
+ return ELF::R_MIPS_LO16;
+ if (Type == ELF::R_MICROMIPS_HI16)
+ return ELF::R_MICROMIPS_LO16;
+ if (Type == ELF::R_MIPS16_HI16)
+ return ELF::R_MIPS16_LO16;
+
+ if (Reloc.OriginalSymbol->getBinding() != ELF::STB_LOCAL)
+ return ELF::R_MIPS_NONE;
+
+ if (Type == ELF::R_MIPS_GOT16)
+ return ELF::R_MIPS_LO16;
+ if (Type == ELF::R_MICROMIPS_GOT16)
+ return ELF::R_MICROMIPS_LO16;
+ if (Type == ELF::R_MIPS16_GOT16)
+ return ELF::R_MIPS16_LO16;
+
+ return ELF::R_MIPS_NONE;
+}
- ~MipsELFObjectWriter() override;
+/// Determine whether a relocation (X) matches the one given in R.
+///
+/// A relocation matches if:
+/// - It's type matches that of a corresponding low part. This is provided in
+/// MatchingType for efficiency.
+/// - It's based on the same symbol.
+/// - It's offset of greater or equal to that of the one given in R.
+/// It should be noted that this rule assumes the programmer does not use
+/// offsets that exceed the alignment of the symbol. The carry-bit will be
+/// incorrect if this is not true.
+///
+/// A matching relocation is unbeatable if:
+/// - It is not already involved in a match.
+/// - It's offset is exactly that of the one given in R.
+static FindBestPredicateResult isMatchingReloc(const MipsRelocationEntry &X,
+ const ELFRelocationEntry &R,
+ unsigned MatchingType) {
+ if (X.R.Type == MatchingType && X.R.OriginalSymbol == R.OriginalSymbol) {
+ if (!X.Matched &&
+ X.R.OriginalAddend == R.OriginalAddend)
+ return FindBest_PerfectMatch;
+ else if (X.R.OriginalAddend >= R.OriginalAddend)
+ return FindBest_Match;
+ }
+ return FindBest_NoMatch;
+}
- unsigned GetRelocType(const MCValue &Target, const MCFixup &Fixup,
- bool IsPCRel) const override;
- bool needsRelocateWithSymbol(const MCSymbol &Sym,
- unsigned Type) const override;
- virtual void sortRelocs(const MCAssembler &Asm,
- std::vector<ELFRelocationEntry> &Relocs) override;
- };
+/// Determine whether Candidate or PreviousBest is the better match.
+/// The return value is true if Candidate is the better match.
+///
+/// A matching relocation is a better match if:
+/// - It has a smaller addend.
+/// - It is not already involved in a match.
+static bool compareMatchingRelocs(const MipsRelocationEntry &Candidate,
+ const MipsRelocationEntry &PreviousBest) {
+ if (Candidate.R.OriginalAddend != PreviousBest.R.OriginalAddend)
+ return Candidate.R.OriginalAddend < PreviousBest.R.OriginalAddend;
+ return PreviousBest.Matched && !Candidate.Matched;
}
+#ifndef NDEBUG
+/// Print all the relocations.
+template <class Container>
+static void dumpRelocs(const char *Prefix, const Container &Relocs) {
+ for (const auto &R : Relocs)
+ dbgs() << Prefix << R << "\n";
+}
+#endif
+
+} // end anonymous namespace
+
MipsELFObjectWriter::MipsELFObjectWriter(bool _is64Bit, uint8_t OSABI,
bool _isN64, bool IsLittleEndian)
: MCELFObjectTargetWriter(_is64Bit, OSABI, ELF::EM_MIPS,
@@ -61,7 +212,8 @@ MipsELFObjectWriter::MipsELFObjectWriter(bool _is64Bit, uint8_t OSABI,
MipsELFObjectWriter::~MipsELFObjectWriter() {}
-unsigned MipsELFObjectWriter::GetRelocType(const MCValue &Target,
+unsigned MipsELFObjectWriter::getRelocType(MCContext &Ctx,
+ const MCValue &Target,
const MCFixup &Fixup,
bool IsPCRel) const {
// Determine the type of the relocation.
@@ -89,6 +241,14 @@ unsigned MipsELFObjectWriter::GetRelocType(const MCValue &Target,
return ELF::R_MICROMIPS_PC10_S1;
case Mips::fixup_MICROMIPS_PC16_S1:
return ELF::R_MICROMIPS_PC16_S1;
+ case Mips::fixup_MICROMIPS_PC26_S1:
+ return ELF::R_MICROMIPS_PC26_S1;
+ case Mips::fixup_MICROMIPS_PC19_S2:
+ return ELF::R_MICROMIPS_PC19_S2;
+ case Mips::fixup_MICROMIPS_PC18_S3:
+ return ELF::R_MICROMIPS_PC18_S3;
+ case Mips::fixup_MICROMIPS_PC21_S1:
+ return ELF::R_MICROMIPS_PC21_S1;
case Mips::fixup_MIPS_PC19_S2:
return ELF::R_MIPS_PC19_S2;
case Mips::fixup_MIPS_PC18_S3:
@@ -125,8 +285,7 @@ unsigned MipsELFObjectWriter::GetRelocType(const MCValue &Target,
return ELF::R_MIPS_26;
case Mips::fixup_Mips_CALL16:
return ELF::R_MIPS_CALL16;
- case Mips::fixup_Mips_GOT_Global:
- case Mips::fixup_Mips_GOT_Local:
+ case Mips::fixup_Mips_GOT:
return ELF::R_MIPS_GOT16;
case Mips::fixup_Mips_HI16:
return ELF::R_MIPS_HI16;
@@ -211,213 +370,266 @@ unsigned MipsELFObjectWriter::GetRelocType(const MCValue &Target,
llvm_unreachable("invalid fixup kind!");
}
-// Sort entries by SortOffset in descending order.
-// When there are more *HI16 relocs paired with one *LO16 reloc, the 2nd rule
-// sorts them in ascending order of R.Offset.
-static int cmpRelMips(const MipsRelocationEntry *AP,
- const MipsRelocationEntry *BP) {
- const MipsRelocationEntry &A = *AP;
- const MipsRelocationEntry &B = *BP;
- if (A.SortOffset != B.SortOffset)
- return B.SortOffset - A.SortOffset;
- if (A.R.Offset != B.R.Offset)
- return A.R.Offset - B.R.Offset;
- if (B.R.Type != A.R.Type)
- return B.R.Type - A.R.Type;
- //llvm_unreachable("ELFRelocs might be unstable!");
- return 0;
-}
-
-// For the given Reloc.Type, return the matching relocation type, as in the
-// table below.
-static unsigned getMatchingLoType(const MCAssembler &Asm,
- const ELFRelocationEntry &Reloc) {
- unsigned Type = Reloc.Type;
- if (Type == ELF::R_MIPS_HI16)
- return ELF::R_MIPS_LO16;
- if (Type == ELF::R_MICROMIPS_HI16)
- return ELF::R_MICROMIPS_LO16;
- if (Type == ELF::R_MIPS16_HI16)
- return ELF::R_MIPS16_LO16;
-
- if (Reloc.Symbol->getBinding() != ELF::STB_LOCAL)
- return ELF::R_MIPS_NONE;
-
- if (Type == ELF::R_MIPS_GOT16)
- return ELF::R_MIPS_LO16;
- if (Type == ELF::R_MICROMIPS_GOT16)
- return ELF::R_MICROMIPS_LO16;
- if (Type == ELF::R_MIPS16_GOT16)
- return ELF::R_MIPS16_LO16;
-
- return ELF::R_MIPS_NONE;
-}
-
-// Return true if First needs a matching *LO16, its matching *LO16 type equals
-// Second's type and both relocations are against the same symbol.
-static bool areMatchingHiAndLo(const MCAssembler &Asm,
- const ELFRelocationEntry &First,
- const ELFRelocationEntry &Second) {
- return getMatchingLoType(Asm, First) != ELF::R_MIPS_NONE &&
- getMatchingLoType(Asm, First) == Second.Type &&
- First.Symbol && First.Symbol == Second.Symbol;
-}
-
-// Return true if MipsRelocs[Index] is a *LO16 preceded by a matching *HI16.
-static bool
-isPrecededByMatchingHi(const MCAssembler &Asm, uint32_t Index,
- std::vector<MipsRelocationEntry> &MipsRelocs) {
- return Index < MipsRelocs.size() - 1 &&
- areMatchingHiAndLo(Asm, MipsRelocs[Index + 1].R, MipsRelocs[Index].R);
-}
-
-// Return true if MipsRelocs[Index] is a *LO16 not preceded by a matching *HI16
-// and not chosen by a *HI16 as a match.
-static bool isFreeLo(const MCAssembler &Asm, uint32_t Index,
- std::vector<MipsRelocationEntry> &MipsRelocs) {
- return Index < MipsRelocs.size() && !MipsRelocs[Index].HasMatchingHi &&
- !isPrecededByMatchingHi(Asm, Index, MipsRelocs);
-}
-
-// Lo is chosen as a match for Hi, set their fields accordingly.
-// Mips instructions have fixed length of at least two bytes (two for
-// micromips/mips16, four for mips32/64), so we can set HI's SortOffset to
-// matching LO's Offset minus one to simplify the sorting function.
-static void setMatch(MipsRelocationEntry &Hi, MipsRelocationEntry &Lo) {
- Lo.HasMatchingHi = true;
- Hi.SortOffset = Lo.R.Offset - 1;
-}
-
-// We sort relocation table entries by offset, except for one additional rule
-// required by MIPS ABI: every *HI16 relocation must be immediately followed by
-// the corresponding *LO16 relocation. We also support a GNU extension that
-// allows more *HI16s paired with one *LO16.
-//
-// *HI16 relocations and their matching *LO16 are:
-//
-// +---------------------------------------------+-------------------+
-// | *HI16 | matching *LO16 |
-// |---------------------------------------------+-------------------|
-// | R_MIPS_HI16, local R_MIPS_GOT16 | R_MIPS_LO16 |
-// | R_MICROMIPS_HI16, local R_MICROMIPS_GOT16 | R_MICROMIPS_LO16 |
-// | R_MIPS16_HI16, local R_MIPS16_GOT16 | R_MIPS16_LO16 |
-// +---------------------------------------------+-------------------+
-//
-// (local R_*_GOT16 meaning R_*_GOT16 against the local symbol.)
-//
-// To handle *HI16 and *LO16 relocations, the linker needs a combined addend
-// ("AHL") calculated from both *HI16 ("AHI") and *LO16 ("ALO") relocations:
-// AHL = (AHI << 16) + (short)ALO;
-//
-// We are reusing gnu as sorting algorithm so we are emitting the relocation
-// table sorted the same way as gnu as would sort it, for easier comparison of
-// the generated .o files.
-//
-// The logic is:
-// search the table (starting from the highest offset and going back to zero)
-// for all *HI16 relocations that don't have a matching *LO16.
-// For every such HI, find a matching LO with highest offset that isn't already
-// matched with another HI. If there are no free LOs, match it with the first
-// found (starting from lowest offset).
-// When there are more HIs matched with one LO, sort them in descending order by
-// offset.
-//
-// In other words, when searching for a matching LO:
-// - don't look for a 'better' match for the HIs that are already followed by a
-// matching LO;
-// - prefer LOs without a pair;
-// - prefer LOs with higher offset;
-
-static int cmpRel(const ELFRelocationEntry *AP, const ELFRelocationEntry *BP) {
- const ELFRelocationEntry &A = *AP;
- const ELFRelocationEntry &B = *BP;
- if (A.Offset != B.Offset)
- return B.Offset - A.Offset;
- if (B.Type != A.Type)
- return A.Type - B.Type;
- return 0;
-}
-
+/// Sort relocation table entries by offset except where another order is
+/// required by the MIPS ABI.
+///
+/// MIPS has a few relocations that have an AHL component in the expression used
+/// to evaluate them. This AHL component is an addend with the same number of
+/// bits as a symbol value but not all of our ABI's are able to supply a
+/// sufficiently sized addend in a single relocation.
+///
+/// The O32 ABI for example, uses REL relocations which store the addend in the
+/// section data. All the relocations with AHL components affect 16-bit fields
+/// so the addend for a single relocation is limited to 16-bit. This ABI
+/// resolves the limitation by linking relocations (e.g. R_MIPS_HI16 and
+/// R_MIPS_LO16) and distributing the addend between the linked relocations. The
+/// ABI mandates that such relocations must be next to each other in a
+/// particular order (e.g. R_MIPS_HI16 must be immediately followed by a
+/// matching R_MIPS_LO16) but the rule is less strict in practice.
+///
+/// The de facto standard is lenient in the following ways:
+/// - 'Immediately following' does not refer to the next relocation entry but
+/// the next matching relocation.
+/// - There may be multiple high parts relocations for one low part relocation.
+/// - There may be multiple low part relocations for one high part relocation.
+/// - The AHL addend in each part does not have to be exactly equal as long as
+/// the difference does not affect the carry bit from bit 15 into 16. This is
+/// to allow, for example, the use of %lo(foo) and %lo(foo+4) when loading
+/// both halves of a long long.
+///
+/// See getMatchingLoType() for a description of which high part relocations
+/// match which low part relocations. One particular thing to note is that
+/// R_MIPS_GOT16 and similar only have AHL addends if they refer to local
+/// symbols.
+///
+/// It should also be noted that this function is not affected by whether
+/// the symbol was kept or rewritten into a section-relative equivalent. We
+/// always match using the expressions from the source.
void MipsELFObjectWriter::sortRelocs(const MCAssembler &Asm,
std::vector<ELFRelocationEntry> &Relocs) {
if (Relocs.size() < 2)
return;
- // Sorts entries by Offset in descending order.
- array_pod_sort(Relocs.begin(), Relocs.end(), cmpRel);
-
- // Init MipsRelocs from Relocs.
- std::vector<MipsRelocationEntry> MipsRelocs;
- for (unsigned I = 0, E = Relocs.size(); I != E; ++I)
- MipsRelocs.push_back(MipsRelocationEntry(Relocs[I]));
-
- // Find a matching LO for all HIs that need it.
- for (int32_t I = 0, E = MipsRelocs.size(); I != E; ++I) {
- if (getMatchingLoType(Asm, MipsRelocs[I].R) == ELF::R_MIPS_NONE ||
- (I > 0 && isPrecededByMatchingHi(Asm, I - 1, MipsRelocs)))
- continue;
-
- int32_t MatchedLoIndex = -1;
-
- // Search the list in the ascending order of Offset.
- for (int32_t J = MipsRelocs.size() - 1, N = -1; J != N; --J) {
- // check for a match
- if (areMatchingHiAndLo(Asm, MipsRelocs[I].R, MipsRelocs[J].R) &&
- (MatchedLoIndex == -1 || // first match
- // or we already have a match,
- // but this one is with higher offset and it's free
- (MatchedLoIndex > J && isFreeLo(Asm, J, MipsRelocs))))
- MatchedLoIndex = J;
- }
-
- if (MatchedLoIndex != -1)
- // We have a match.
- setMatch(MipsRelocs[I], MipsRelocs[MatchedLoIndex]);
+ // Sort relocations by the address they are applied to.
+ std::sort(Relocs.begin(), Relocs.end(),
+ [](const ELFRelocationEntry &A, const ELFRelocationEntry &B) {
+ return A.Offset < B.Offset;
+ });
+
+ std::list<MipsRelocationEntry> Sorted;
+ std::list<ELFRelocationEntry> Remainder;
+
+ DEBUG(dumpRelocs("R: ", Relocs));
+
+ // Separate the movable relocations (AHL relocations using the high bits) from
+ // the immobile relocations (everything else). This does not preserve high/low
+ // matches that already existed in the input.
+ copy_if_else(Relocs.begin(), Relocs.end(), std::back_inserter(Remainder),
+ std::back_inserter(Sorted), [](const ELFRelocationEntry &Reloc) {
+ return getMatchingLoType(Reloc) != ELF::R_MIPS_NONE;
+ });
+
+ for (auto &R : Remainder) {
+ DEBUG(dbgs() << "Matching: " << R << "\n");
+
+ unsigned MatchingType = getMatchingLoType(R);
+ assert(MatchingType != ELF::R_MIPS_NONE &&
+ "Wrong list for reloc that doesn't need a match");
+
+ // Find the best matching relocation for the current high part.
+ // See isMatchingReloc for a description of a matching relocation and
+ // compareMatchingRelocs for a description of what 'best' means.
+ auto InsertionPoint =
+ find_best(Sorted.begin(), Sorted.end(),
+ [&R, &MatchingType](const MipsRelocationEntry &X) {
+ return isMatchingReloc(X, R, MatchingType);
+ },
+ compareMatchingRelocs);
+
+ // If we matched then insert the high part in front of the match and mark
+ // both relocations as being involved in a match. We only mark the high
+ // part for cosmetic reasons in the debug output.
+ //
+ // If we failed to find a match then the high part is orphaned. This is not
+ // permitted since the relocation cannot be evaluated without knowing the
+ // carry-in. We can sometimes handle this using a matching low part that is
+ // already used in a match but we already cover that case in
+ // isMatchingReloc and compareMatchingRelocs. For the remaining cases we
+ // should insert the high part at the end of the list. This will cause the
+ // linker to fail but the alternative is to cause the linker to bind the
+ // high part to a semi-matching low part and silently calculate the wrong
+ // value. Unfortunately we have no means to warn the user that we did this
+ // so leave it up to the linker to complain about it.
+ if (InsertionPoint != Sorted.end())
+ InsertionPoint->Matched = true;
+ Sorted.insert(InsertionPoint, R)->Matched = true;
}
- // SortOffsets are calculated, call the sorting function.
- array_pod_sort(MipsRelocs.begin(), MipsRelocs.end(), cmpRelMips);
+ DEBUG(dumpRelocs("S: ", Sorted));
+
+ assert(Relocs.size() == Sorted.size() && "Some relocs were not consumed");
- // Copy sorted MipsRelocs back to Relocs.
- for (unsigned I = 0, E = MipsRelocs.size(); I != E; ++I)
- Relocs[I] = MipsRelocs[I].R;
+ // Overwrite the original vector with the sorted elements. The caller expects
+ // them in reverse order.
+ unsigned CopyTo = 0;
+ for (const auto &R : reverse(Sorted))
+ Relocs[CopyTo++] = R.R;
}
bool MipsELFObjectWriter::needsRelocateWithSymbol(const MCSymbol &Sym,
unsigned Type) const {
- // FIXME: This is extremely conservative. This really needs to use a
- // whitelist with a clear explanation for why each realocation needs to
- // point to the symbol, not to the section.
+ // If it's a compound relocation for N64 then we need the relocation if any
+ // sub-relocation needs it.
+ if (!isUInt<8>(Type))
+ return needsRelocateWithSymbol(Sym, Type & 0xff) ||
+ needsRelocateWithSymbol(Sym, (Type >> 8) & 0xff) ||
+ needsRelocateWithSymbol(Sym, (Type >> 16) & 0xff);
+
switch (Type) {
default:
+ errs() << Type << "\n";
+ llvm_unreachable("Unexpected relocation");
return true;
+ // This relocation doesn't affect the section data.
+ case ELF::R_MIPS_NONE:
+ return false;
+
+ // On REL ABI's (e.g. O32), these relocations form pairs. The pairing is done
+ // by the static linker by matching the symbol and offset.
+ // We only see one relocation at a time but it's still safe to relocate with
+ // the section so long as both relocations make the same decision.
+ //
+ // Some older linkers may require the symbol for particular cases. Such cases
+ // are not supported yet but can be added as required.
case ELF::R_MIPS_GOT16:
case ELF::R_MIPS16_GOT16:
case ELF::R_MICROMIPS_GOT16:
- llvm_unreachable("Should have been handled already");
-
- // These relocations might be paired with another relocation. The pairing is
- // done by the static linker by matching the symbol. Since we only see one
- // relocation at a time, we have to force them to relocate with a symbol to
- // avoid ending up with a pair where one points to a section and another
- // points to a symbol.
case ELF::R_MIPS_HI16:
case ELF::R_MIPS16_HI16:
case ELF::R_MICROMIPS_HI16:
case ELF::R_MIPS_LO16:
case ELF::R_MIPS16_LO16:
case ELF::R_MICROMIPS_LO16:
- return true;
+ // FIXME: It should be safe to return false for the STO_MIPS_MICROMIPS but
+ // we neglect to handle the adjustment to the LSB of the addend that
+ // it causes in applyFixup() and similar.
+ if (cast<MCSymbolELF>(Sym).getOther() & ELF::STO_MIPS_MICROMIPS)
+ return true;
+ return false;
+ case ELF::R_MIPS_16:
case ELF::R_MIPS_32:
+ case ELF::R_MIPS_GPREL32:
if (cast<MCSymbolELF>(Sym).getOther() & ELF::STO_MIPS_MICROMIPS)
return true;
- // falltrough
+ // fallthrough
case ELF::R_MIPS_26:
case ELF::R_MIPS_64:
case ELF::R_MIPS_GPREL16:
+ case ELF::R_MIPS_PC16:
+ case ELF::R_MIPS_SUB:
return false;
+
+ // FIXME: Many of these relocations should probably return false but this
+ // hasn't been confirmed to be safe yet.
+ case ELF::R_MIPS_REL32:
+ case ELF::R_MIPS_LITERAL:
+ case ELF::R_MIPS_CALL16:
+ case ELF::R_MIPS_SHIFT5:
+ case ELF::R_MIPS_SHIFT6:
+ case ELF::R_MIPS_GOT_DISP:
+ case ELF::R_MIPS_GOT_PAGE:
+ case ELF::R_MIPS_GOT_OFST:
+ case ELF::R_MIPS_GOT_HI16:
+ case ELF::R_MIPS_GOT_LO16:
+ case ELF::R_MIPS_INSERT_A:
+ case ELF::R_MIPS_INSERT_B:
+ case ELF::R_MIPS_DELETE:
+ case ELF::R_MIPS_HIGHER:
+ case ELF::R_MIPS_HIGHEST:
+ case ELF::R_MIPS_CALL_HI16:
+ case ELF::R_MIPS_CALL_LO16:
+ case ELF::R_MIPS_SCN_DISP:
+ case ELF::R_MIPS_REL16:
+ case ELF::R_MIPS_ADD_IMMEDIATE:
+ case ELF::R_MIPS_PJUMP:
+ case ELF::R_MIPS_RELGOT:
+ case ELF::R_MIPS_JALR:
+ case ELF::R_MIPS_TLS_DTPMOD32:
+ case ELF::R_MIPS_TLS_DTPREL32:
+ case ELF::R_MIPS_TLS_DTPMOD64:
+ case ELF::R_MIPS_TLS_DTPREL64:
+ case ELF::R_MIPS_TLS_GD:
+ case ELF::R_MIPS_TLS_LDM:
+ case ELF::R_MIPS_TLS_DTPREL_HI16:
+ case ELF::R_MIPS_TLS_DTPREL_LO16:
+ case ELF::R_MIPS_TLS_GOTTPREL:
+ case ELF::R_MIPS_TLS_TPREL32:
+ case ELF::R_MIPS_TLS_TPREL64:
+ case ELF::R_MIPS_TLS_TPREL_HI16:
+ case ELF::R_MIPS_TLS_TPREL_LO16:
+ case ELF::R_MIPS_GLOB_DAT:
+ case ELF::R_MIPS_PC21_S2:
+ case ELF::R_MIPS_PC26_S2:
+ case ELF::R_MIPS_PC18_S3:
+ case ELF::R_MIPS_PC19_S2:
+ case ELF::R_MIPS_PCHI16:
+ case ELF::R_MIPS_PCLO16:
+ case ELF::R_MIPS_COPY:
+ case ELF::R_MIPS_JUMP_SLOT:
+ case ELF::R_MIPS_NUM:
+ case ELF::R_MIPS_PC32:
+ case ELF::R_MIPS_EH:
+ case ELF::R_MICROMIPS_26_S1:
+ case ELF::R_MICROMIPS_GPREL16:
+ case ELF::R_MICROMIPS_LITERAL:
+ case ELF::R_MICROMIPS_PC7_S1:
+ case ELF::R_MICROMIPS_PC10_S1:
+ case ELF::R_MICROMIPS_PC16_S1:
+ case ELF::R_MICROMIPS_CALL16:
+ case ELF::R_MICROMIPS_GOT_DISP:
+ case ELF::R_MICROMIPS_GOT_PAGE:
+ case ELF::R_MICROMIPS_GOT_OFST:
+ case ELF::R_MICROMIPS_GOT_HI16:
+ case ELF::R_MICROMIPS_GOT_LO16:
+ case ELF::R_MICROMIPS_SUB:
+ case ELF::R_MICROMIPS_HIGHER:
+ case ELF::R_MICROMIPS_HIGHEST:
+ case ELF::R_MICROMIPS_CALL_HI16:
+ case ELF::R_MICROMIPS_CALL_LO16:
+ case ELF::R_MICROMIPS_SCN_DISP:
+ case ELF::R_MICROMIPS_JALR:
+ case ELF::R_MICROMIPS_HI0_LO16:
+ case ELF::R_MICROMIPS_TLS_GD:
+ case ELF::R_MICROMIPS_TLS_LDM:
+ case ELF::R_MICROMIPS_TLS_DTPREL_HI16:
+ case ELF::R_MICROMIPS_TLS_DTPREL_LO16:
+ case ELF::R_MICROMIPS_TLS_GOTTPREL:
+ case ELF::R_MICROMIPS_TLS_TPREL_HI16:
+ case ELF::R_MICROMIPS_TLS_TPREL_LO16:
+ case ELF::R_MICROMIPS_GPREL7_S2:
+ case ELF::R_MICROMIPS_PC23_S2:
+ case ELF::R_MICROMIPS_PC21_S1:
+ case ELF::R_MICROMIPS_PC26_S1:
+ case ELF::R_MICROMIPS_PC18_S3:
+ case ELF::R_MICROMIPS_PC19_S2:
+ return true;
+
+ // FIXME: Many of these should probably return false but MIPS16 isn't
+ // supported by the integrated assembler.
+ case ELF::R_MIPS16_26:
+ case ELF::R_MIPS16_GPREL:
+ case ELF::R_MIPS16_CALL16:
+ case ELF::R_MIPS16_TLS_GD:
+ case ELF::R_MIPS16_TLS_LDM:
+ case ELF::R_MIPS16_TLS_DTPREL_HI16:
+ case ELF::R_MIPS16_TLS_DTPREL_LO16:
+ case ELF::R_MIPS16_TLS_GOTTPREL:
+ case ELF::R_MIPS16_TLS_TPREL_HI16:
+ case ELF::R_MIPS16_TLS_TPREL_LO16:
+ llvm_unreachable("Unsupported MIPS16 relocation");
+ return true;
}
}