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llvm-mirror/docs
Rafael Espindola 5c8926deed Prevent alias from pointing to weak aliases.
This adds back r204781.

Original message:

Aliases are just another name for a position in a file. As such, the
regular symbol resolutions are not applied. For example, given

define void @my_func() {
  ret void
}
@my_alias = alias weak void ()* @my_func
@my_alias2 = alias void ()* @my_alias

We produce without this patch:

        .weak   my_alias
my_alias = my_func
        .globl  my_alias2
my_alias2 = my_alias

That is, in the resulting ELF file my_alias, my_func and my_alias are
just 3 names pointing to offset 0 of .text. That is *not* the
semantics of IR linking. For example, linking in a

@my_alias = alias void ()* @other_func

would require the strong my_alias to override the weak one and
my_alias2 would end up pointing to other_func.

There is no way to represent that with aliases being just another
name, so the best solution seems to be to just disallow it, converting
a miscompile into an error.

llvm-svn: 204934
2014-03-27 15:26:56 +00:00
..
_static
_templates
_themes/llvm-theme
CommandGuide
HistoricalNotes
TableGen
tutorial
AliasAnalysis.rst
Atomics.rst
BitCodeFormat.rst
BranchWeightMetadata.rst
Bugpoint.rst
CMake.rst
CMakeLists.txt
CodeGenerator.rst
CodingStandards.rst
CommandLine.rst
CompilerWriterInfo.rst
conf.py
DebuggingJITedCode.rst
DeveloperPolicy.rst
doxygen.cfg.in
doxygen.css
doxygen.footer
doxygen.header
doxygen.intro
Dummy.html
ExceptionHandling.rst
ExtendedIntegerResults.txt
ExtendingLLVM.rst
Extensions.rst
FAQ.rst
GarbageCollection.rst
gcc-loops.png
GetElementPtr.rst
GettingStarted.rst
GettingStartedVS.rst
GoldPlugin.rst
HowToAddABuilder.rst
HowToBuildOnARM.rst
HowToCrossCompileLLVM.rst
HowToReleaseLLVM.rst
HowToSetUpLLVMStyleRTTI.rst
HowToSubmitABug.rst
HowToUseAttributes.rst
HowToUseInstrMappings.rst
InAlloca.rst
index.rst
LangRef.rst
Lexicon.rst
LinkTimeOptimization.rst
linpack-pc.png
LLVMBuild.rst
LLVMBuild.txt
make.bat
Makefile
Makefile.sphinx
MakefileGuide.rst
MarkedUpDisassembly.rst
MCJIT-creation.png
MCJIT-dyld-load.png
MCJIT-engine-builder.png
MCJIT-load-object.png
MCJIT-load.png
MCJIT-resolve-relocations.png
MCJITDesignAndImplementation.rst
NVPTXUsage.rst
Packaging.rst
Passes.rst
Phabricator.rst
ProgrammersManual.rst
Projects.rst
re_format.7
README.txt
ReleaseNotes.rst
ReleaseProcess.rst
SegmentedStacks.rst
SourceLevelDebugging.rst
SphinxQuickstartTemplate.rst
StackMaps.rst
SystemLibrary.rst
TableGenFundamentals.rst
TestingGuide.rst
TestSuiteMakefileGuide.rst
Vectorizers.rst
WritingAnLLVMBackend.rst
WritingAnLLVMPass.rst
yaml2obj.rst
YamlIO.rst

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