Make DataLayout Non-Optional in the Module

Summary:
DataLayout keeps the string used for its creation.

As a side effect it is no longer needed in the Module.
This is "almost" NFC, the string is no longer
canonicalized, you can't rely on two "equals" DataLayout
having the same string returned by getStringRepresentation().

Get rid of DataLayoutPass: the DataLayout is in the Module

The DataLayout is "per-module", let's enforce this by not
duplicating it more than necessary.
One more step toward non-optionality of the DataLayout in the
module.

Make DataLayout Non-Optional in the Module

Module->getDataLayout() will never returns nullptr anymore.

Reviewers: echristo

Subscribers: resistor, llvm-commits, jholewinski

Differential Revision: http://reviews.llvm.org/D7992

From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 231270
diff --git a/llvm/lib/Analysis/LibCallAliasAnalysis.cpp b/llvm/lib/Analysis/LibCallAliasAnalysis.cpp
index 016f8c5..f6025e3 100644
--- a/llvm/lib/Analysis/LibCallAliasAnalysis.cpp
+++ b/llvm/lib/Analysis/LibCallAliasAnalysis.cpp
@@ -36,7 +36,11 @@
   AU.setPreservesAll();                         // Does not transform code
 }
 
-
+bool LibCallAliasAnalysis::runOnFunction(Function &F) {
+  // set up super class
+  InitializeAliasAnalysis(this, &F.getParent()->getDataLayout());
+  return false;
+}
 
 /// AnalyzeLibCallDetails - Given a call to a function with the specified
 /// LibCallFunctionInfo, see if we can improve the mod/ref footprint of the call