Feeding isSafeToSpeculativelyExecute its DataLayout pointer

isSafeToSpeculativelyExecute can optionally take a DataLayout pointer. In the
past, this was mainly used to make better decisions regarding divisions known
not to trap, and so was not all that important for users concerned with "cheap"
instructions. However, now it also helps look through bitcasts for
dereferencable loads, and will also be important if/when we add a
dereferencable pointer attribute.

This is some initial work to feed a DataLayout pointer through to callers of
isSafeToSpeculativelyExecute, generally where one was already available.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@212720 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/Utils/LoopSimplify.cpp

@@ -50,6 +50,7 @@
 #include "llvm/Analysis/ScalarEvolution.h"
 #include "llvm/IR/CFG.h"
 #include "llvm/IR/Constants.h"
+#include "llvm/IR/DataLayout.h"
 #include "llvm/IR/Dominators.h"
 #include "llvm/IR/Function.h"
 #include "llvm/IR/Instructions.h"
@@ -473,7 +474,8 @@ static BasicBlock *insertUniqueBackedgeBlock(Loop *L, BasicBlock *Preheader,
 /// explicit if they accepted the analysis directly and then updated it.
 static bool simplifyOneLoop(Loop *L, SmallVectorImpl<Loop *> &Worklist,
                             AliasAnalysis *AA, DominatorTree *DT, LoopInfo *LI,
-                            ScalarEvolution *SE, Pass *PP) {
+                            ScalarEvolution *SE, Pass *PP,
+                            const DataLayout *DL) {
   bool Changed = false;
 ReprocessLoop:
 
@@ -672,7 +674,7 @@ ReprocessLoop:
       // The block has now been cleared of all instructions except for
       // a comparison and a conditional branch. SimplifyCFG may be able
       // to fold it now.
-      if (!FoldBranchToCommonDest(BI)) continue;
+      if (!FoldBranchToCommonDest(BI, DL)) continue;
 
       // Success. The block is now dead, so remove it from the loop,
       // update the dominator tree and delete it.
@@ -709,7 +711,8 @@ ReprocessLoop:
 }
 
 bool llvm::simplifyLoop(Loop *L, DominatorTree *DT, LoopInfo *LI, Pass *PP,
-                        AliasAnalysis *AA, ScalarEvolution *SE) {
+                        AliasAnalysis *AA, ScalarEvolution *SE,
+                        const DataLayout *DL) {
   bool Changed = false;
 
   // Worklist maintains our depth-first queue of loops in this nest to process.
@@ -726,7 +729,8 @@ bool llvm::simplifyLoop(Loop *L, DominatorTree *DT, LoopInfo *LI, Pass *PP,
   }
 
   while (!Worklist.empty())
-    Changed |= simplifyOneLoop(Worklist.pop_back_val(), Worklist, AA, DT, LI, SE, PP);
+    Changed |= simplifyOneLoop(Worklist.pop_back_val(), Worklist, AA, DT, LI,
+                               SE, PP, DL);
 
   return Changed;
 }
@@ -744,6 +748,7 @@ namespace {
     DominatorTree *DT;
     LoopInfo *LI;
     ScalarEvolution *SE;
+    const DataLayout *DL;
 
     bool runOnFunction(Function &F) override;
 
@@ -787,10 +792,12 @@ bool LoopSimplify::runOnFunction(Function &F) {
   LI = &getAnalysis<LoopInfo>();
   DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
   SE = getAnalysisIfAvailable<ScalarEvolution>();
+  DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
+  DL = DLP ? &DLP->getDataLayout() : nullptr;
 
   // Simplify each loop nest in the function.
   for (LoopInfo::iterator I = LI->begin(), E = LI->end(); I != E; ++I)
-    Changed |= simplifyLoop(*I, DT, LI, this, AA, SE);
+    Changed |= simplifyLoop(*I, DT, LI, this, AA, SE, DL);
 
   return Changed;
 }