LPM: Stop threading `Pass *` through all of the loop utility APIs. NFC

A large number of loop utility functions take a `Pass *` and reach
into it to find out which analyses to preserve. There are a number of
problems with this:

- The APIs have access to pretty well any Pass state they want, so
  it's hard to tell what they may or may not do.

- Other APIs have copied these and pass around a `Pass *` even though
  they don't even use it. Some of these just hand a nullptr to the API
  since the callers don't even have a pass available.

- Passes in the new pass manager don't work like the current ones, so
  the APIs can't be used as is there.

Instead, we should explicitly thread the analysis results that we
actually care about through these APIs. This is both simpler and more
reusable.

llvm-svn: 255669

1 files changed, 4 insertions, 7 deletions

diff --git a/llvm/lib/Transforms/Utils/FlattenCFG.cpp b/llvm/lib/Transforms/Utils/FlattenCFG.cpp
index cadc5921346..492ae9f69a6 100644
--- a/llvm/lib/Transforms/Utils/FlattenCFG.cpp
+++ b/llvm/lib/Transforms/Utils/FlattenCFG.cpp
@@ -28,12 +28,11 @@ class FlattenCFGOpt {
   AliasAnalysis *AA;
   /// \brief Use parallel-and or parallel-or to generate conditions for
   /// conditional branches.
-  bool FlattenParallelAndOr(BasicBlock *BB, IRBuilder<> &Builder,
-                            Pass *P = nullptr);
+  bool FlattenParallelAndOr(BasicBlock *BB, IRBuilder<> &Builder);
   /// \brief If \param BB is the merge block of an if-region, attempt to merge
   /// the if-region with an adjacent if-region upstream if two if-regions
   /// contain identical instructions.
-  bool MergeIfRegion(BasicBlock *BB, IRBuilder<> &Builder, Pass *P = nullptr);
+  bool MergeIfRegion(BasicBlock *BB, IRBuilder<> &Builder);
   /// \brief Compare a pair of blocks: \p Block1 and \p Block2, which
   /// are from two if-regions whose entry blocks are \p Head1 and \p
   /// Head2.  \returns true if \p Block1 and \p Block2 contain identical
@@ -122,8 +121,7 @@ public:
 ///  its predecessor.  In Case 2, \param BB (BB3) only has conditional branches
 ///  as its predecessors.
 ///
-bool FlattenCFGOpt::FlattenParallelAndOr(BasicBlock *BB, IRBuilder<> &Builder,
-                                         Pass *P) {
+bool FlattenCFGOpt::FlattenParallelAndOr(BasicBlock *BB, IRBuilder<> &Builder) {
   PHINode *PHI = dyn_cast<PHINode>(BB->begin());
   if (PHI)
     return false; // For simplicity, avoid cases containing PHI nodes.
@@ -387,8 +385,7 @@ bool FlattenCFGOpt::CompareIfRegionBlock(BasicBlock *Head1, BasicBlock *Head2,
 /// if (a || b)
 ///   statement;
 ///
-bool FlattenCFGOpt::MergeIfRegion(BasicBlock *BB, IRBuilder<> &Builder,
-                                  Pass *P) {
+bool FlattenCFGOpt::MergeIfRegion(BasicBlock *BB, IRBuilder<> &Builder) {
   BasicBlock *IfTrue2, *IfFalse2;
   Value *IfCond2 = GetIfCondition(BB, IfTrue2, IfFalse2);
   Instruction *CInst2 = dyn_cast_or_null<Instruction>(IfCond2);