[sancov] specifying sanitizer coverage dependencies.

[aizatsky]

Summary

These dependencies would be used in the future to reduce the number
of instrumented blocks(http://reviews.llvm.org/rL262103)

This is submitted as a separate CL because of previous problems with
ARM.

[aizatsky]

This should be a trivial change. But because it broke ARM build before I will submit it first thing tomorrow morning and will monitor ARM builds through the day.

[kcc]

LGTM

lib/Transforms/Instrumentation/SanitizerCoverage.cpp

 // it only tells if a given function (block) was ever executed. No counters.
 // But for many use cases this is what we need and the added slowdown small.
 //
 //===----------------------------------------------------------------------===//
 
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/Analysis/EHPersonalities.h"
+#include "llvm/Analysis/PostDominators.h"
 #include "llvm/IR/CFG.h"
 #include "llvm/IR/CallSite.h"
 #include "llvm/IR/DataLayout.h"
 #include "llvm/IR/DebugInfo.h"
 #include "llvm/IR/Dominators.h"
 #include "llvm/IR/Function.h"
 #include "llvm/IR/IRBuilder.h"
 #include "llvm/IR/InlineAsm.h"
SanitizerCoverageModule(
       : ModulePass(ID), Options(OverrideFromCL(Options)) {}
   bool runOnModule(Module &M) override;
   bool runOnFunction(Function &F);
   static char ID;  // Pass identification, replacement for typeid
   const char *getPassName() const override {
     return "SanitizerCoverageModule";
   }
 
- private:
+  void getAnalysisUsage(AnalysisUsage &AU) const override {
+    AU.addRequired<DominatorTreeWrapperPass>();
+    AU.addRequired<PostDominatorTreeWrapperPass>();
+  }
+
   void InjectCoverageForIndirectCalls(Function &F,
                                       ArrayRef<Instruction *> IndirCalls);
   void InjectTraceForCmp(Function &F, ArrayRef<Instruction *> CmpTraceTargets);
   void InjectTraceForSwitch(Function &F,
                             ArrayRef<Instruction *> SwitchTraceTargets);
   bool InjectCoverage(Function &F, ArrayRef<BasicBlock *> AllBlocks);
   void SetNoSanitizeMetadata(Instruction *I);
   void InjectCoverageAtBlock(Function &F, BasicBlock &BB, bool UseCalls);