forked from OSchip/llvm-project
11549e5c46
Summary:
clang (as of 2019-06-12) / gcc (as of 8.2.1) PPC64 may emit a .rela.toc
which references an embedded switch table in a discarded .rodata/.text
section. The .toc and the .rela.toc are incorrectly not placed in the
comdat.
Technically a relocation from outside the group is not allowed by the ELF spec:
> A symbol table entry with STB_LOCAL binding that is defined relative
> to one of a group's sections, and that is contained in a symbol table
> section that is not part of the group, must be discarded if the group
> members are discarded. References to this symbol table entry from
> outside the group are not allowed.
Don't report errors to work around the bug.
This should fix the ppc64le-lld-multistage-test bot while linking llvm-tblgen:
ld.lld: error: relocation refers to a discarded section: .rodata._ZNK4llvm3MVT13getSizeInBitsEv
>>> defined in utils/TableGen/CMakeFiles/llvm-tblgen.dir/CodeGenRegisters.cpp.o
>>> referenced by CodeGenRegisters.cpp
>>> utils/TableGen/CMakeFiles/llvm-tblgen.dir/CodeGenRegisters.cpp.o:(.toc+0x0)
Some other PPC specific sections may have similar problems. We can blacklist more
section names when problems occur.
// A simple program that reproduces the bug.
// Note .rela.toc (outside the group) references a section symbol (STB_LOCAL) in a group.
void puts(const char *);
struct A {
void foo(int a) {
switch (a) {
case 0: puts("0"); break;
case 1: puts("1"); puts("1"); break;
case 2: puts("2"); break;
case 3: puts("3"); puts("4"); break;
case 4: puts("4"); break;
case 5: puts("5"); puts("5"); break;
case 6: puts("6"); break;
}
}
int a;
};
void foo(A x) { x.foo(x.a); }
Reviewers: ruiu, sfertile, espindola
Reviewed By: ruiu
Subscribers: emaste, nemanjai, arichardson, kbarton, jsji, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D63182
llvm-svn: 363126
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||
|---|---|---|
| .. | ||
| Arch | ||
| AArch64ErrataFix.cpp | ||
| AArch64ErrataFix.h | ||
| CMakeLists.txt | ||
| CallGraphSort.cpp | ||
| CallGraphSort.h | ||
| Config.h | ||
| DWARF.cpp | ||
| DWARF.h | ||
| Driver.cpp | ||
| Driver.h | ||
| DriverUtils.cpp | ||
| EhFrame.cpp | ||
| EhFrame.h | ||
| ICF.cpp | ||
| ICF.h | ||
| InputFiles.cpp | ||
| InputFiles.h | ||
| InputSection.cpp | ||
| InputSection.h | ||
| LTO.cpp | ||
| LTO.h | ||
| LinkerScript.cpp | ||
| LinkerScript.h | ||
| MapFile.cpp | ||
| MapFile.h | ||
| MarkLive.cpp | ||
| MarkLive.h | ||
| Options.td | ||
| OutputSections.cpp | ||
| OutputSections.h | ||
| README.md | ||
| Relocations.cpp | ||
| Relocations.h | ||
| ScriptLexer.cpp | ||
| ScriptLexer.h | ||
| ScriptParser.cpp | ||
| ScriptParser.h | ||
| SymbolTable.cpp | ||
| SymbolTable.h | ||
| Symbols.cpp | ||
| Symbols.h | ||
| SyntheticSections.cpp | ||
| SyntheticSections.h | ||
| Target.cpp | ||
| Target.h | ||
| Thunks.cpp | ||
| Thunks.h | ||
| Writer.cpp | ||
| Writer.h | ||
README.md
See docs/NewLLD.rst