[sanitizers] Disable target-specific lowering of string functions.

CodeGen has hooks that allow targets to emit specialized code instead
of calls to memcmp, memchr, strcpy, stpcpy, strcmp, strlen, strnlen.
When ASan/MSan/TSan/ESan is in use, this sidesteps its interceptors, resulting
in uninstrumented memory accesses.  To avoid that, make these sanitizers
mark the calls as nobuiltin.

Differential Revision: http://reviews.llvm.org/D19781

llvm-svn: 273083

1 files changed, 26 insertions, 0 deletions

diff --git a/llvm/lib/Transforms/Utils/Local.cpp b/llvm/lib/Transforms/Utils/Local.cpp
index a0dd5d1..4f8935d 100644
--- a/llvm/lib/Transforms/Utils/Local.cpp
+++ b/llvm/lib/Transforms/Utils/Local.cpp
@@ -1942,3 +1942,29 @@ bool llvm::recognizeBSwapOrBitReverseIdiom(
   InsertedInsts.push_back(CallInst::Create(F, Res->Provider, "rev", I));
   return true;
 }
+
+// CodeGen has special handling for some string functions that may replace
+// them with target-specific intrinsics.  Since that'd skip our interceptors
+// in ASan/MSan/TSan/DFSan, and thus make us miss some memory accesses,
+// we mark affected calls as NoBuiltin, which will disable optimization
+// in CodeGen.
+void llvm::maybeMarkSanitizerLibraryCallNoBuiltin(CallInst *CI,
+                                          const TargetLibraryInfo *TLI) {
+  Function *F = CI->getCalledFunction();
+  LibFunc::Func Func;
+  if (!F || F->hasLocalLinkage() || !F->hasName() ||
+      !TLI->getLibFunc(F->getName(), Func))
+    return;
+  switch (Func) {
+    default: break;
+    case LibFunc::memcmp:
+    case LibFunc::memchr:
+    case LibFunc::strcpy:
+    case LibFunc::stpcpy:
+    case LibFunc::strcmp:
+    case LibFunc::strlen:
+    case LibFunc::strnlen:
+      CI->addAttribute(AttributeSet::FunctionIndex, Attribute::NoBuiltin);
+      break;
+  }
+}