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, 17 insertions, 10 deletions

diff --git a/llvm/lib/Transforms/Scalar/LoopInterchange.cpp b/llvm/lib/Transforms/Scalar/LoopInterchange.cpp
index 6026a90..4295235 100644
--- a/llvm/lib/Transforms/Scalar/LoopInterchange.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopInterchange.cpp
@@ -331,9 +331,9 @@ static PHINode *getInductionVariable(Loop *L, ScalarEvolution *SE) {
 class LoopInterchangeLegality {
 public:
   LoopInterchangeLegality(Loop *Outer, Loop *Inner, ScalarEvolution *SE,
-                          LoopInterchange *Pass)
-      : OuterLoop(Outer), InnerLoop(Inner), SE(SE), CurrentPass(Pass),
-        InnerLoopHasReduction(false) {}
+                          LoopInfo *LI, DominatorTree *DT, bool PreserveLCSSA)
+      : OuterLoop(Outer), InnerLoop(Inner), SE(SE), LI(LI), DT(DT),
+        PreserveLCSSA(PreserveLCSSA), InnerLoopHasReduction(false) {}
 
   /// Check if the loops can be interchanged.
   bool canInterchangeLoops(unsigned InnerLoopId, unsigned OuterLoopId,
@@ -357,9 +357,10 @@ private:
   Loop *OuterLoop;
   Loop *InnerLoop;
 
-  /// Scev analysis.
   ScalarEvolution *SE;
-  LoopInterchange *CurrentPass;
+  LoopInfo *LI;
+  DominatorTree *DT;
+  bool PreserveLCSSA;
 
   bool InnerLoopHasReduction;
 };
@@ -390,7 +391,7 @@ class LoopInterchangeTransform {
 public:
   LoopInterchangeTransform(Loop *Outer, Loop *Inner, ScalarEvolution *SE,
                            LoopInfo *LI, DominatorTree *DT,
-                           LoopInterchange *Pass, BasicBlock *LoopNestExit,
+                           BasicBlock *LoopNestExit,
                            bool InnerLoopContainsReductions)
       : OuterLoop(Outer), InnerLoop(Inner), SE(SE), LI(LI), DT(DT),
         LoopExit(LoopNestExit),
@@ -431,6 +432,7 @@ struct LoopInterchange : public FunctionPass {
   LoopInfo *LI;
   DependenceAnalysis *DA;
   DominatorTree *DT;
+  bool PreserveLCSSA;
   LoopInterchange()
       : FunctionPass(ID), SE(nullptr), LI(nullptr), DA(nullptr), DT(nullptr) {
     initializeLoopInterchangePass(*PassRegistry::getPassRegistry());
@@ -452,6 +454,8 @@ struct LoopInterchange : public FunctionPass {
     DA = &getAnalysis<DependenceAnalysis>();
     auto *DTWP = getAnalysisIfAvailable<DominatorTreeWrapperPass>();
     DT = DTWP ? &DTWP->getDomTree() : nullptr;
+    PreserveLCSSA = mustPreserveAnalysisID(LCSSAID);
+
     // Build up a worklist of loop pairs to analyze.
     SmallVector<LoopVector, 8> Worklist;
 
@@ -574,7 +578,8 @@ struct LoopInterchange : public FunctionPass {
     Loop *InnerLoop = LoopList[InnerLoopId];
     Loop *OuterLoop = LoopList[OuterLoopId];
 
-    LoopInterchangeLegality LIL(OuterLoop, InnerLoop, SE, this);
+    LoopInterchangeLegality LIL(OuterLoop, InnerLoop, SE, LI, DT,
+                                PreserveLCSSA);
     if (!LIL.canInterchangeLoops(InnerLoopId, OuterLoopId, DependencyMatrix)) {
       DEBUG(dbgs() << "Not interchanging Loops. Cannot prove legality\n");
       return false;
@@ -586,7 +591,7 @@ struct LoopInterchange : public FunctionPass {
       return false;
     }
 
-    LoopInterchangeTransform LIT(OuterLoop, InnerLoop, SE, LI, DT, this,
+    LoopInterchangeTransform LIT(OuterLoop, InnerLoop, SE, LI, DT,
                                  LoopNestExit, LIL.hasInnerLoopReduction());
     LIT.transform();
     DEBUG(dbgs() << "Loops interchanged\n");
@@ -867,12 +872,14 @@ bool LoopInterchangeLegality::canInterchangeLoops(unsigned InnerLoopId,
   if (!OuterLoopPreHeader || OuterLoopPreHeader == OuterLoop->getHeader() ||
       isa<PHINode>(OuterLoopPreHeader->begin()) ||
       !OuterLoopPreHeader->getUniquePredecessor()) {
-    OuterLoopPreHeader = InsertPreheaderForLoop(OuterLoop, CurrentPass);
+    OuterLoopPreHeader =
+        InsertPreheaderForLoop(OuterLoop, DT, LI, PreserveLCSSA);
   }
 
   if (!InnerLoopPreHeader || InnerLoopPreHeader == InnerLoop->getHeader() ||
       InnerLoopPreHeader == OuterLoop->getHeader()) {
-    InnerLoopPreHeader = InsertPreheaderForLoop(InnerLoop, CurrentPass);
+    InnerLoopPreHeader =
+        InsertPreheaderForLoop(InnerLoop, DT, LI, PreserveLCSSA);
   }
 
   // TODO: The loops could not be interchanged due to current limitations in the