[asan] set a hard limit on the number of instructions instrumented pear each BB. This is (hopefully temporary) workaround for PR13225

llvm-svn: 159344

1 files changed, 12 insertions, 0 deletions

diff --git a/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp b/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
index 375a2ae7b0a..f80c8c4fa60 100644
--- a/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
@@ -82,6 +82,14 @@ static cl::opt<bool> ClInstrumentWrites("asan-instrument-writes",
 static cl::opt<bool> ClInstrumentAtomics("asan-instrument-atomics",
        cl::desc("instrument atomic instructions (rmw, cmpxchg)"),
        cl::Hidden, cl::init(true));
+// This flags limits the number of instructions to be instrumented
+// in any given BB. Normally, this should be set to unlimited (INT_MAX),
+// but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary
+// set it to 10000.
+static cl::opt<int> ClMaxInsnsToInstrumentPerBB("asan-max-ins-per-bb",
+       cl::init(10000),
+       cl::desc("maximal number of instructions to instrument in any given BB"),
+       cl::Hidden);
 // This flag may need to be replaced with -f[no]asan-stack.
 static cl::opt<bool> ClStack("asan-stack",
        cl::desc("Handle stack memory"), cl::Hidden, cl::init(true));
@@ -689,6 +697,7 @@ bool AddressSanitizer::handleFunction(Module &M, Function &F) {
   for (Function::iterator FI = F.begin(), FE = F.end();
        FI != FE; ++FI) {
     TempsToInstrument.clear();
+    int NumInsnsPerBB = 0;
     for (BasicBlock::iterator BI = FI->begin(), BE = FI->end();
          BI != BE; ++BI) {
       if (LooksLikeCodeInBug11395(BI)) return false;
@@ -710,6 +719,9 @@ bool AddressSanitizer::handleFunction(Module &M, Function &F) {
         continue;
       }
       ToInstrument.push_back(BI);
+      NumInsnsPerBB++;
+      if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB)
+        break;
     }
   }