[llvm] r178156 - Specutively revert r178130.

[Michael Gottesman]

Specifically:

http://lab.llvm.org:8013/builders/clang-x86_64-darwin11-Rlto/builds/131

On Mar 27, 2013, at 10:54 AM, Bill Wendling <isanbard at gmail.com> wrote:

> Author: void
> Date: Wed Mar 27 12:54:41 2013
> New Revision: 178156
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=178156&view=rev
> Log:
> Specutively revert r178130.
> 
> This may be causing a failure on some buildbots:
> 
> Referencing function in another module!
>  tail call fastcc void @_ZL11EvaluateOpstPtRj(i16 zeroext %17, i16* %Vals, i32* %NumVals), !dbg !219
> Referencing function in another module!
>  tail call fastcc void @_ZL11EvaluateOpstPtRj(i16 zeroext %19, i16* %Vals, i32* %NumVals), !dbg !221
> Broken module found, compilation aborted!
> Stack dump:
> 0.    Running pass 'Function Pass Manager' on module 'ld-temp.o'.
> 1.    Running pass 'Module Verifier' on function '@_ZL11EvaluateOpstPtRj'
> clang: error: unable to execute command: Illegal instruction: 4
> clang: error: linker command failed due to signal (use -v to see invocation)
> 
> <rdar://problem/13516485>
> 
> Modified:
>    llvm/trunk/lib/Linker/LinkModules.cpp
> 
> Modified: llvm/trunk/lib/Linker/LinkModules.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Linker/LinkModules.cpp?rev=178156&r1=178155&r2=178156&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Linker/LinkModules.cpp (original)
> +++ llvm/trunk/lib/Linker/LinkModules.cpp Wed Mar 27 12:54:41 2013
> @@ -370,16 +370,11 @@ namespace {
> 
>     unsigned Mode; // Mode to treat source module.
> 
> -    struct LazyLinkEntry {
> -      Function *Fn;
> -      llvm::SmallPtrSet<User*, 4> Uses;
> -    };
> -
>     // Set of items not to link in from source.
>     SmallPtrSet<const Value*, 16> DoNotLinkFromSource;
> 
>     // Vector of functions to lazily link in.
> -    std::vector<LazyLinkEntry> LazilyLinkFunctions;
> +    std::vector<Function*> LazilyLinkFunctions;
> 
>   public:
>     std::string ErrorMsg;
> @@ -806,18 +801,6 @@ bool ModuleLinker::linkFunctionProto(Fun
>     }
>   }
> 
> -  // If the function is to be lazily linked, don't create it just yet.
> -  // Instead, remember its current set of uses to diff against later.
> -  if (!DGV && (SF->hasLocalLinkage() || SF->hasLinkOnceLinkage() ||
> -               SF->hasAvailableExternallyLinkage())) {
> -    LazyLinkEntry LLE;
> -    LLE.Fn = SF;
> -    LLE.Uses.insert(SF->use_begin(), SF->use_end());
> -    LazilyLinkFunctions.push_back(LLE);
> -    DoNotLinkFromSource.insert(SF);
> -    return false;
> -  }
> -
>   // If there is no linkage to be performed or we are linking from the source,
>   // bring SF over.
>   Function *NewDF = Function::Create(TypeMap.get(SF->getFunctionType()),
> @@ -830,6 +813,13 @@ bool ModuleLinker::linkFunctionProto(Fun
>     // Any uses of DF need to change to NewDF, with cast.
>     DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDF, DGV->getType()));
>     DGV->eraseFromParent();
> +  } else {
> +    // Internal, LO_ODR, or LO linkage - stick in set to ignore and lazily link.
> +    if (SF->hasLocalLinkage() || SF->hasLinkOnceLinkage() ||
> +        SF->hasAvailableExternallyLinkage()) {
> +      DoNotLinkFromSource.insert(SF);
> +      LazilyLinkFunctions.push_back(SF);
> +    }
>   }
> 
>   ValueMap[SF] = NewDF;
> @@ -1246,33 +1236,16 @@ bool ModuleLinker::run() {
>   do {
>     LinkedInAnyFunctions = false;
> 
> -    for(std::vector<LazyLinkEntry>::iterator I = LazilyLinkFunctions.begin(),
> -        E = LazilyLinkFunctions.end(); I != E; ++I) {      
> -      Function *SF = I->Fn;
> -      if (!SF)
> +    for(std::vector<Function*>::iterator I = LazilyLinkFunctions.begin(),
> +        E = LazilyLinkFunctions.end(); I != E; ++I) {
> +      if (!*I)
>         continue;
> 
> -      // If the number of uses of this function is the same as it was at the
> -      // start of the link, it is not used in this link.
> -      if (SF->getNumUses() != I->Uses.size()) {
> -        Function *DF = Function::Create(TypeMap.get(SF->getFunctionType()),
> -                                        SF->getLinkage(), SF->getName(), DstM);
> -        copyGVAttributes(DF, SF);
> -
> -        // Now, copy over any uses of SF that were from DstM to DF.
> -        for (Function::use_iterator UI = SF->use_begin(), UE = SF->use_end();
> -             UI != UE;) {
> -          if (I->Uses.count(*UI) == 0) {
> -            Use &U = UI.getUse();
> -            // Increment UI before performing the set to ensure the iterator
> -            // remains valid.
> -            ++UI;
> -            U.set(DF);
> -          } else {
> -            ++UI;
> -          }
> -        }
> -
> +      Function *SF = *I;
> +      Function *DF = cast<Function>(ValueMap[SF]);
> +      
> +      if (!DF->use_empty()) {
> +        
>         // Materialize if necessary.
>         if (SF->isDeclaration()) {
>           if (!SF->isMaterializable())
> @@ -1286,7 +1259,7 @@ bool ModuleLinker::run() {
>         SF->Dematerialize();
> 
>         // "Remove" from vector by setting the element to 0.
> -        I->Fn = 0;
> +        *I = 0;
> 
>         // Set flag to indicate we may have more functions to lazily link in
>         // since we linked in a function.
> @@ -1295,6 +1268,18 @@ bool ModuleLinker::run() {
>     }
>   } while (LinkedInAnyFunctions);
> 
> +  // Remove any prototypes of functions that were not actually linked in.
> +  for(std::vector<Function*>::iterator I = LazilyLinkFunctions.begin(),
> +      E = LazilyLinkFunctions.end(); I != E; ++I) {
> +    if (!*I)
> +      continue;
> +    
> +    Function *SF = *I;
> +    Function *DF = cast<Function>(ValueMap[SF]);
> +    if (DF->use_empty())
> +      DF->eraseFromParent();
> +  }
> +  
>   // Now that all of the types from the source are used, resolve any structs
>   // copied over to the dest that didn't exist there.
>   TypeMap.linkDefinedTypeBodies();
> 
> 
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