DataLayout is mandatory, update the API to reflect it with references.

Summary:
Now that the DataLayout is a mandatory part of the module, let's start
cleaning the codebase. This patch is a first attempt at doing that.

This patch is not exactly NFC as for instance some places were passing
a nullptr instead of the DataLayout, possibly just because there was a
default value on the DataLayout argument to many functions in the API.
Even though it is not purely NFC, there is no change in the
validation.

I turned as many pointer to DataLayout to references, this helped
figuring out all the places where a nullptr could come up.

I had initially a local version of this patch broken into over 30
independant, commits but some later commit were cleaning the API and
touching part of the code modified in the previous commits, so it
seemed cleaner without the intermediate state.

Test Plan:

Reviewers: echristo

Subscribers: llvm-commits

From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 231740
diff --git a/llvm/lib/Transforms/Utils/Local.cpp b/llvm/lib/Transforms/Utils/Local.cpp
index 4830568..5a1fb1d 100644
--- a/llvm/lib/Transforms/Utils/Local.cpp
+++ b/llvm/lib/Transforms/Utils/Local.cpp
@@ -417,7 +417,7 @@
 ///
 /// This returns true if it changed the code, note that it can delete
 /// instructions in other blocks as well in this block.
-bool llvm::SimplifyInstructionsInBlock(BasicBlock *BB, const DataLayout *TD,
+bool llvm::SimplifyInstructionsInBlock(BasicBlock *BB,
                                        const TargetLibraryInfo *TLI) {
   bool MadeChange = false;
 
@@ -434,7 +434,7 @@
     Instruction *Inst = BI++;
 
     WeakVH BIHandle(BI);
-    if (recursivelySimplifyInstruction(Inst, TD, TLI)) {
+    if (recursivelySimplifyInstruction(Inst, TLI)) {
       MadeChange = true;
       if (BIHandle != BI)
         BI = BB->begin();
@@ -464,8 +464,7 @@
 ///
 /// .. and delete the predecessor corresponding to the '1', this will attempt to
 /// recursively fold the and to 0.
-void llvm::RemovePredecessorAndSimplify(BasicBlock *BB, BasicBlock *Pred,
-                                        DataLayout *TD) {
+void llvm::RemovePredecessorAndSimplify(BasicBlock *BB, BasicBlock *Pred) {
   // This only adjusts blocks with PHI nodes.
   if (!isa<PHINode>(BB->begin()))
     return;
@@ -480,7 +479,7 @@
     PhiIt = &*++BasicBlock::iterator(cast<Instruction>(PhiIt));
     Value *OldPhiIt = PhiIt;
 
-    if (!recursivelySimplifyInstruction(PN, TD))
+    if (!recursivelySimplifyInstruction(PN))
       continue;
 
     // If recursive simplification ended up deleting the next PHI node we would
@@ -900,13 +899,14 @@
 /// their preferred alignment from the beginning.
 ///
 static unsigned enforceKnownAlignment(Value *V, unsigned Align,
-                                      unsigned PrefAlign, const DataLayout *TD) {
+                                      unsigned PrefAlign,
+                                      const DataLayout &DL) {
   V = V->stripPointerCasts();
 
   if (AllocaInst *AI = dyn_cast<AllocaInst>(V)) {
     // If the preferred alignment is greater than the natural stack alignment
     // then don't round up. This avoids dynamic stack realignment.
-    if (TD && TD->exceedsNaturalStackAlignment(PrefAlign))
+    if (DL.exceedsNaturalStackAlignment(PrefAlign))
       return Align;
     // If there is a requested alignment and if this is an alloca, round up.
     if (AI->getAlignment() >= PrefAlign)
@@ -945,13 +945,13 @@
 /// and it is more than the alignment of the ultimate object, see if we can
 /// increase the alignment of the ultimate object, making this check succeed.
 unsigned llvm::getOrEnforceKnownAlignment(Value *V, unsigned PrefAlign,
-                                          const DataLayout *DL,
-                                          AssumptionCache *AC,
+                                          const DataLayout &DL,
                                           const Instruction *CxtI,
+                                          AssumptionCache *AC,
                                           const DominatorTree *DT) {
   assert(V->getType()->isPointerTy() &&
          "getOrEnforceKnownAlignment expects a pointer!");
-  unsigned BitWidth = DL ? DL->getPointerTypeSizeInBits(V->getType()) : 64;
+  unsigned BitWidth = DL.getPointerTypeSizeInBits(V->getType());
 
   APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
   computeKnownBits(V, KnownZero, KnownOne, DL, 0, AC, CxtI, DT);