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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

llvm-svn: 257645
This commit is contained in:
Dimitry Andric 2016-01-13 18:29:46 +00:00
parent 744959b9c9
commit 972e2c0cfb
1 changed files with 8 additions and 6 deletions
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14
llvm/include/llvm/LinkAllPasses.h
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@ -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();