[lld] r264790 - [LTO] Teach LTO about @llvm.used global.

[Davide Italiano via llvm-commits]

On Tue, Mar 29, 2016 at 4:59 PM, Rui Ueyama <ruiu at google.com> wrote:
> LGTM
>

Committed thusly (r264809).


> On Tue, Mar 29, 2016 at 4:47 PM, Davide Italiano <davide at freebsd.org> wrote:
>>
>> On Tue, Mar 29, 2016 at 2:59 PM, Rui Ueyama <ruiu at google.com> wrote:
>> > On Tue, Mar 29, 2016 at 2:46 PM, Davide Italiano via llvm-commits
>> > <llvm-commits at lists.llvm.org> wrote:
>> >>
>> >> Author: davide
>> >> Date: Tue Mar 29 16:46:35 2016
>> >> New Revision: 264790
>> >>
>> >> URL: http://llvm.org/viewvc/llvm-project?rev=264790&view=rev
>> >> Log:
>> >> [LTO] Teach LTO about @llvm.used global.
>> >>
>> >> If a symbol appears in @llvm.used, the linker is forced to treat
>> >> the symbol as there's a reference to it.
>> >>
>> >> Added:
>> >>     lld/trunk/test/ELF/lto/internalize-llvmused.ll
>> >> Modified:
>> >>     lld/trunk/ELF/LTO.cpp
>> >>
>> >> Modified: lld/trunk/ELF/LTO.cpp
>> >> URL:
>> >>
>> >> http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/LTO.cpp?rev=264790&r1=264789&r2=264790&view=diff
>> >>
>> >>
>> >> ==============================================================================
>> >> --- lld/trunk/ELF/LTO.cpp (original)
>> >> +++ lld/trunk/ELF/LTO.cpp Tue Mar 29 16:46:35 2016
>> >> @@ -21,6 +21,7 @@
>> >>  #include "llvm/Support/TargetRegistry.h"
>> >>  #include "llvm/Target/TargetMachine.h"
>> >>  #include "llvm/Transforms/IPO.h"
>> >> +#include "llvm/Transforms/Utils/ModuleUtils.h"
>> >>  #include "llvm/Transforms/IPO/PassManagerBuilder.h"
>> >>
>> >>  using namespace llvm;
>> >> @@ -76,6 +77,10 @@ void BitcodeCompiler::add(BitcodeFile &F
>> >>    unsigned BodyIndex = 0;
>> >>    ArrayRef<SymbolBody *> Bodies = F.getSymbols();
>> >>
>> >> +  Module &M = Obj->getModule();
>> >> +  SmallPtrSet<GlobalValue *, 8> Used;
>> >> +  collectUsedGlobalVariables(M, Used, /* CompilerUsed */ false);
>> >
>> >
>> > Please add a comment.
>> >
>>
>> Does the following look good to you?
>>
>> diff --git a/ELF/LTO.cpp b/ELF/LTO.cpp
>> index 63fb6e3..b1d5d60 100644
>> --- a/ELF/LTO.cpp
>> +++ b/ELF/LTO.cpp
>> @@ -78,6 +78,10 @@ void BitcodeCompiler::add(BitcodeFile &F) {
>>    ArrayRef<SymbolBody *> Bodies = F.getSymbols();
>>
>>    Module &M = Obj->getModule();
>> +
>> +  // If a symbol appears in @llvm.used, the linker is required
>> +  // to treat the symbol as there is a reference to the symbol
>> +  // that it cannot see. Therefore, we can't internalize.
>>    SmallPtrSet<GlobalValue *, 8> Used;
>>    collectUsedGlobalVariables(M, Used, /* CompilerUsed */ false);
>>
>>
>>
>> --
>> Davide
>>
>> "There are no solved problems; there are only problems that are more
>> or less solved" -- Henri Poincare
>
>



-- 
Davide

"There are no solved problems; there are only problems that are more
or less solved" -- Henri Poincare