Integrate the readonly/readnone logic more deeply

into alias analysis.  This meant updating the API
which now has versions of the getModRefBehavior,
doesNotAccessMemory and onlyReadsMemory methods
which take a callsite parameter.  These should be
used unless the callsite is not known, since in
general they can do a better job than the versions
that take a function.  Also, users should no longer
call the version of getModRefBehavior that takes
both a function and a callsite.  To reduce the
chance of misuse it is now protected.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@44487 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/Scalar/ADCE.cpp

@@ -198,8 +198,7 @@ bool ADCE::doADCE() {
     for (BasicBlock::iterator II = BB->begin(), EI = BB->end(); II != EI; ) {
       Instruction *I = II++;
       if (CallInst *CI = dyn_cast<CallInst>(I)) {
-        Function *F = CI->getCalledFunction();
-        if (F && AA.onlyReadsMemory(F)) {
+        if (AA.onlyReadsMemory(CI)) {
           if (CI->use_empty()) {
             BB->getInstList().erase(CI);
             ++NumCallRemoved;