6502/llvm-6502
1
0
Fork 0
mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2025-06-21 18:24:23 +00:00
Code Issues Projects Releases Wiki Activity

Add r224985 back with a fix.

Browse Source 
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.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225048 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Rafael Espindola
2014-12-31 17:19:34 +00:00
parent f5943bd9a9
commit 8093abb745
19 changed files with 302 additions and 246 deletions
Download Patch File Download Diff File Expand all files Collapse all files

16
lib/MC/MCAssembler.cpp
View File

@ -425,6 +425,16 @@ bool MCAssembler::isThumbFunc(const MCSymbol *Symbol) const {
return true;
}
void MCAssembler::addLocalUsedInReloc(const MCSymbol &Sym) {
assert(Sym.isTemporary());
LocalsUsedInReloc.insert(&Sym);
}
bool MCAssembler::isLocalUsedInReloc(const MCSymbol &Sym) const {
assert(Sym.isTemporary());
return LocalsUsedInReloc.count(&Sym);
}
bool MCAssembler::isSymbolLinkerVisible(const MCSymbol &Symbol) const {
// Non-temporary labels should always be visible to the linker.
if (!Symbol.isTemporary())
@ -434,8 +444,10 @@ bool MCAssembler::isSymbolLinkerVisible(const MCSymbol &Symbol) const {
if (!Symbol.isInSection())
return false;
// Otherwise, check if the section requires symbols even for temporary labels.
return getBackend().doesSectionRequireSymbols(Symbol.getSection());
if (isLocalUsedInReloc(Symbol))
return true;
return false;
}
const MCSymbolData *MCAssembler::getAtom(const MCSymbolData *SD) const {