Commit 191172e5 authored by Dimitry Andric's avatar Dimitry Andric
Browse files

Merging r257645: 

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r257645 | dim | 2016-01-13 19:29:46 +0100 (Wed, 13 Jan 2016) | 22 lines

Avoid undefined behavior in LinkAllPasses.h

The LinkAllPasses.h file is included in several main programs, to force
a large number of passes to be linked in.  However, the ForcePassLinking
constructor uses undefined behavior, since it calls member functions on
`nullptr`, e.g.:

      ((llvm::Function*)nullptr)->viewCFGOnly();
      llvm::RGPassManager RGM;
      ((llvm::RegionPass*)nullptr)->runOnRegion((llvm::Region*)nullptr, RGM);

When the optimization level is -O2 or higher, the code below the first
nullptr dereference is optimized away, and replaced by `ud2` (on x86).

Therefore, the calls after that first dereference are never emitted.  In
my case, I noticed there was no call to `llvm::sys::RunningOnValgrind()`!

Replace instances of dereferencing `nullptr` with either objects on the
stack, or regular function calls.

Differential Revision: http://reviews.llvm.org/D15996

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llvm-svn: 257660
parent 0247e865

llvm/include/llvm/LinkAllPasses.h

+8 −6
Original line number Diff line number Diff line
@@ -160,9 +160,11 @@ namespace { 
      (void) llvm::createPostOrderFunctionAttrsPass();

      (void) llvm::createReversePostOrderFunctionAttrsPass();

      (void) llvm::createMergeFunctionsPass();

      (void) llvm::createPrintModulePass(*(llvm::raw_ostream*)nullptr);

      (void) llvm::createPrintFunctionPass(*(llvm::raw_ostream*)nullptr);

      (void) llvm::createPrintBasicBlockPass(*(llvm::raw_ostream*)nullptr);

      std::string buf;

      llvm::raw_string_ostream os(buf);

      (void) llvm::createPrintModulePass(os);

      (void) llvm::createPrintFunctionPass(os);

      (void) llvm::createPrintBasicBlockPass(os);

      (void) llvm::createModuleDebugInfoPrinterPass();

      (void) llvm::createPartialInliningPass();

      (void) llvm::createLintPass();
@@ -186,10 +188,10 @@ namespace { 


      (void)new llvm::IntervalPartition();

      (void)new llvm::ScalarEvolutionWrapperPass();

      ((llvm::Function*)nullptr)->viewCFGOnly();

      llvm::Function::Create(nullptr, llvm::GlobalValue::ExternalLinkage)->viewCFGOnly();

      llvm::RGPassManager RGM;

      ((llvm::RegionPass*)nullptr)->runOnRegion((llvm::Region*)nullptr, RGM);

      llvm::AliasSetTracker X(*(llvm::AliasAnalysis*)nullptr);

      llvm::AliasAnalysis AA;

      llvm::AliasSetTracker X(AA);

      X.add(nullptr, 0, llvm::AAMDNodes()); // for -print-alias-sets

      (void) llvm::AreStatisticsEnabled();

      (void) llvm::sys::RunningOnValgrind();