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Fix PR18743.

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The IR
@foo = private constant i32 42

is valid, but before this patch we would produce an invalid MachO from it. It
was invalid because it would use an L label in a section where the liker needs
the labels in order to atomize it.

One way of fixing it would be to just reject this IR in the backend, but that
would not be very front end friendly.

What this patch does is use an 'l' prefix in sections that we know the linker
requires symbols for atomizing them. This allows frontends to just use
private and not worry about which sections they go to or how the linker handles
them.

One small issue with this strategy is that now a symbol name depends on the
section, which is not available before codegen. This is not a problem in
practice. The reason is that it only happens with private linkage, which will
be ignored by the non codegen users (llvm-nm and llvm-ar).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@201608 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Rafael Espindola
2014-02-18 22:24:57 +00:00
parent 1836fe5651
commit 6880f0e19f
30 changed files with 333 additions and 156 deletions
Download Patch File Download Diff File Expand all files Collapse all files

33
lib/Target/TargetLoweringObjectFile.cpp
View File

@@ -28,6 +28,7 @@
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetLowering.h"
#include "llvm/Target/TargetOptions.h"
using namespace llvm;
@@ -99,30 +100,22 @@ static bool IsNullTerminatedString(const Constant *C) {
return false;
}
/// Return the MCSymbol for the specified global value. This
/// symbol is the main label that is the address of the global.
MCSymbol *TargetLoweringObjectFile::getSymbol(const GlobalValue *GV,
Mangler &M) const {
SmallString<60> NameStr;
M.getNameWithPrefix(NameStr, GV);
return Ctx->GetOrCreateSymbol(NameStr.str());
}
MCSymbol *TargetLoweringObjectFile::getSymbolWithGlobalValueBase(
const GlobalValue *GV, StringRef Suffix, Mangler &M) const {
const GlobalValue *GV, StringRef Suffix, Mangler &Mang,
const TargetMachine &TM) const {
assert(!Suffix.empty());
SmallString<60> NameStr;
NameStr += DL->getPrivateGlobalPrefix();
M.getNameWithPrefix(NameStr, GV);
TM.getTargetLowering()->getNameWithPrefix(NameStr, GV, Mang);
NameStr.append(Suffix.begin(), Suffix.end());
return Ctx->GetOrCreateSymbol(NameStr.str());
}
MCSymbol *TargetLoweringObjectFile::
getCFIPersonalitySymbol(const GlobalValue *GV, Mangler &Mang,
MachineModuleInfo *MMI) const {
return getSymbol(GV, Mang);
MCSymbol *TargetLoweringObjectFile::getCFIPersonalitySymbol(
const GlobalValue *GV, Mangler &Mang, const TargetMachine &TM,
MachineModuleInfo *MMI) const {
return TM.getTargetLowering()->getSymbol(GV, Mang);
}
void TargetLoweringObjectFile::emitPersonalityValue(MCStreamer &Streamer,
@@ -275,6 +268,10 @@ SectionForGlobal(const GlobalValue *GV, SectionKind Kind, Mangler &Mang,
return SelectSectionForGlobal(GV, Kind, Mang, TM);
}
bool TargetLoweringObjectFile::isSectionAtomizableBySymbols(
const MCSection &Section) const {
return false;
}
// Lame default implementation. Calculate the section name for global.
const MCSection *
@@ -312,9 +309,11 @@ TargetLoweringObjectFile::getSectionForConstant(SectionKind Kind) const {
/// handling information.
const MCExpr *TargetLoweringObjectFile::getTTypeGlobalReference(
const GlobalValue *GV, unsigned Encoding, Mangler &Mang,
MachineModuleInfo *MMI, MCStreamer &Streamer) const {
const TargetMachine &TM, MachineModuleInfo *MMI,
MCStreamer &Streamer) const {
const MCSymbolRefExpr *Ref =
MCSymbolRefExpr::Create(getSymbol(GV, Mang), getContext());
MCSymbolRefExpr::Create(TM.getTargetLowering()->getSymbol(GV, Mang),
getContext());
return getTTypeReference(Ref, Encoding, Streamer);
}