Add r224985 back with a fix.

The issues was that AArch64 has additional restrictions on when local
relocations can be used. We have to take those into consideration when
deciding to put a L symbol in the symbol table or not.

Original message:

Remove doesSectionRequireSymbols.

In an assembly expression like

bar:
.long L0 + 1

the intended semantics is that bar will contain a pointer one byte past L0.

In sections that are merged by content (strings, 4 byte constants, etc), a
single position in the section doesn't give the linker enough information.
For example, it would not be able to tell a relocation must point to the
end of a string, since that would look just like the start of the next.

The solution used in ELF to use relocation with symbols if there is a non-zero
addend.

In MachO before this patch we would just keep all symbols in some sections.

This would miss some cases (only cstrings on x86_64 were implemented) and was
inefficient since most relocations have an addend of 0 and can be represented
without the symbol.

This patch implements the non-zero addend logic for MachO too.

llvm-svn: 225048

1 files changed, 4 insertions, 8 deletions

diff --git a/llvm/lib/MC/WinCOFFObjectWriter.cpp b/llvm/lib/MC/WinCOFFObjectWriter.cpp
index 2180b42bcb5..2cb247a7a90 100644
--- a/llvm/lib/MC/WinCOFFObjectWriter.cpp
+++ b/llvm/lib/MC/WinCOFFObjectWriter.cpp
@@ -175,7 +175,7 @@ public:
                                               const MCFragment &FB, bool InSet,
                                               bool IsPCRel) const override;
 
-  void RecordRelocation(const MCAssembler &Asm, const MCAsmLayout &Layout,
+  void RecordRelocation(MCAssembler &Asm, const MCAsmLayout &Layout,
                         const MCFragment *Fragment, const MCFixup &Fixup,
                         MCValue Target, bool &IsPCRel,
                         uint64_t &FixedValue) override;
@@ -661,13 +661,9 @@ bool WinCOFFObjectWriter::IsSymbolRefDifferenceFullyResolvedImpl(
                                                                 InSet, IsPCRel);
 }
 
-void WinCOFFObjectWriter::RecordRelocation(const MCAssembler &Asm,
-                                           const MCAsmLayout &Layout,
-                                           const MCFragment *Fragment,
-                                           const MCFixup &Fixup,
-                                           MCValue Target,
-                                           bool &IsPCRel,
-                                           uint64_t &FixedValue) {
+void WinCOFFObjectWriter::RecordRelocation(
+    MCAssembler &Asm, const MCAsmLayout &Layout, const MCFragment *Fragment,
+    const MCFixup &Fixup, MCValue Target, bool &IsPCRel, uint64_t &FixedValue) {
   assert(Target.getSymA() && "Relocation must reference a symbol!");
 
   const MCSymbol &Symbol = Target.getSymA()->getSymbol();