[PATCH] Implement nonnull-attribute sanitizer

[Richard Smith]

================
Comment at: projects/compiler-rt/lib/ubsan/ubsan_handlers.cc:355
@@ +354,3 @@
+
+static void handleNonnullArg(NonNullArgData *Data, ValueHandle ArgIndex,
+                             ReportOptions Opts) {
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Please consistently use either `NonNull` or `Nonnull`.

================
Comment at: tools/clang/lib/CodeGen/CGCall.cpp:2414-2415
@@ +2413,4 @@
+                                unsigned ParmNum) {
+  if (!CGF.SanOpts->NonnullAttribute || !FD || ParmNum >= FD->getNumParams())
+    return;
+  const NonNullAttr *NNAtt = FD->getAttr<NonNullAttr>();
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What should happen here:

  __attribute__((nonnull)) void f(const char *, ...);
  int main() { void *p = 0; f("%s", p); }

(I have no idea if the attribute applies in this case.)

================
Comment at: tools/clang/lib/CodeGen/CGCall.cpp:2416-2420
@@ +2415,7 @@
+    return;
+  const NonNullAttr *NNAtt = FD->getAttr<NonNullAttr>();
+  auto PVD = FD->getParamDecl(ParmNum);
+  if (!(NNAtt && NNAtt->isNonNull(PVD->getFunctionScopeIndex())) &&
+      !PVD->hasAttr<NonNullAttr>())
+    return;
+  CodeGenFunction::SanitizerScope SanScope(&CGF);
----------------
Can a function have multiple `__attribute__((nonnull(N)))`s on it?

================
Comment at: tools/clang/lib/CodeGen/CGCall.cpp:2422
@@ +2421,3 @@
+  CodeGenFunction::SanitizerScope SanScope(&CGF);
+  assert(RV.isScalar());
+  llvm::Value *V = RV.getScalarVal();
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What guarantees this? I don't see where you're checking that the parameter is of a pointer type.

http://reviews.llvm.org/D5082