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Teach LTOModule to emit linker flags for dllexported symbols, plus interface cleanup.

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This change unifies how LTOModule and the backend obtain linker flags
for globals: via a new TargetLoweringObjectFile member function named
emitLinkerFlagsForGlobal. A new function LTOModule::getLinkerOpts() returns
the list of linker flags as a single concatenated string.

This change affects the C libLTO API: the function lto_module_get_*deplibs now
exposes an empty list, and lto_module_get_*linkeropts exposes a single element
which combines the contents of all observed flags. libLTO should never have
tried to parse the linker flags; it is the linker's job to do so. Because
linkers will need to be able to parse flags in regular object files, it
makes little sense for libLTO to have a redundant mechanism for doing so.

The new API is compatible with the old one. It is valid for a user to specify
multiple linker flags in a single pragma directive like this:

 #pragma comment(linker, "/defaultlib:foo /defaultlib:bar")

The previous implementation would not have exposed
either flag via lto_module_get_*deplibs (as the test in
TargetLoweringObjectFileCOFF::getDepLibFromLinkerOpt was case sensitive)
and would have exposed "/defaultlib:foo /defaultlib:bar" as a single flag via
lto_module_get_*linkeropts. This may have been a bug in the implementation,
but it does give us a chance to fix the interface.

Differential Revision: http://reviews.llvm.org/D10548

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@241010 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Peter Collingbourne
2015-06-29 22:04:09 +00:00
parent b370959788
commit a6367d9136
11 changed files with 155 additions and 197 deletions
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51
lib/CodeGen/TargetLoweringObjectFileImpl.cpp
View File

@@ -440,16 +440,6 @@ TargetLoweringObjectFileMachO::TargetLoweringObjectFileMachO()
SupportIndirectSymViaGOTPCRel = true;
}
/// getDepLibFromLinkerOpt - Extract the dependent library name from a linker
/// option string. Returns StringRef() if the option does not specify a library.
StringRef TargetLoweringObjectFileMachO::
getDepLibFromLinkerOpt(StringRef LinkerOption) const {
const char *LibCmd = "-l";
if (LinkerOption.startswith(LibCmd))
return LinkerOption.substr(strlen(LibCmd));
return StringRef();
}
/// emitModuleFlags - Perform code emission for module flags.
void TargetLoweringObjectFileMachO::
emitModuleFlags(MCStreamer &Streamer,
@@ -990,14 +980,6 @@ MCSection *TargetLoweringObjectFileCOFF::getSectionForJumpTable(
COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE);
}
StringRef TargetLoweringObjectFileCOFF::
getDepLibFromLinkerOpt(StringRef LinkerOption) const {
const char *LibCmd = "/DEFAULTLIB:";
if (LinkerOption.startswith(LibCmd))
return LinkerOption.substr(strlen(LibCmd));
return StringRef();
}
void TargetLoweringObjectFileCOFF::
emitModuleFlags(MCStreamer &Streamer,
ArrayRef<Module::ModuleFlagEntry> ModuleFlags,
@@ -1045,3 +1027,36 @@ MCSection *TargetLoweringObjectFileCOFF::getStaticDtorSection(
return getContext().getAssociativeCOFFSection(
cast<MCSectionCOFF>(StaticDtorSection), KeySym);
}
void TargetLoweringObjectFileCOFF::emitLinkerFlagsForGlobal(
raw_ostream &OS, const GlobalValue *GV, const Mangler &Mang) const {
if (!GV->hasDLLExportStorageClass() || GV->isDeclaration())
return;
const Triple &TT = getTargetTriple();
if (TT.isKnownWindowsMSVCEnvironment())
OS << " /EXPORT:";
else
OS << " -export:";
if (TT.isWindowsGNUEnvironment() || TT.isWindowsCygwinEnvironment()) {
std::string Flag;
raw_string_ostream FlagOS(Flag);
Mang.getNameWithPrefix(FlagOS, GV, false);
FlagOS.flush();
if (Flag[0] == DL->getGlobalPrefix())
OS << Flag.substr(1);
else
OS << Flag;
} else {
Mang.getNameWithPrefix(OS, GV, false);
}
if (!GV->getValueType()->isFunctionTy()) {
if (TT.isKnownWindowsMSVCEnvironment())
OS << ",DATA";
else
OS << ",data";
}
}