Move replaceCongruentIVs into SCEVExapander and bias toward "expanded"

IVs.

Indvars previously chose randomly between congruent IVs. Now it will
bias the decision toward IVs that SCEVExpander likes to create. This
was not done to fix any problem, it's just a welcome side effect of
factoring code.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@141633 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 22 insertions, 1 deletions

diff --git a/include/llvm/Analysis/ScalarEvolutionExpander.h b/include/llvm/Analysis/ScalarEvolutionExpander.h
index f7bab30836..1080580c96 100644
--- a/include/llvm/Analysis/ScalarEvolutionExpander.h
+++ b/include/llvm/Analysis/ScalarEvolutionExpander.h
@@ -72,6 +72,10 @@ namespace llvm {
     typedef IRBuilder<true, TargetFolder> BuilderType;
     BuilderType Builder;
 
+#ifndef NDEBUG
+    const char *DebugType;
+#endif
+
     friend struct SCEVVisitor<SCEVExpander, Value*>;
 
   public:
@@ -79,7 +83,15 @@ namespace llvm {
     explicit SCEVExpander(ScalarEvolution &se, const char *name)
       : SE(se), IVName(name), IVIncInsertLoop(0), IVIncInsertPos(0),
         CanonicalMode(true), LSRMode(false),
-        Builder(se.getContext(), TargetFolder(se.TD)) {}
+        Builder(se.getContext(), TargetFolder(se.TD)) {
+#ifndef NDEBUG
+      DebugType = "";
+#endif
+    }
+
+#ifndef NDEBUG
+    void setDebugType(const char* s) { DebugType = s; }
+#endif
 
     /// clear - Erase the contents of the InsertedExpressions map so that users
     /// trying to expand the same expression into multiple BasicBlocks or
@@ -96,6 +108,15 @@ namespace llvm {
     /// starts at zero and steps by one on each iteration.
     PHINode *getOrInsertCanonicalInductionVariable(const Loop *L, Type *Ty);
 
+    /// hoistStep - Utility for hoisting an IV increment.
+    static bool hoistStep(Instruction *IncV, Instruction *InsertPos,
+                          const DominatorTree *DT);
+
+    /// replaceCongruentIVs - replace congruent phis with their most canonical
+    /// representative. Return the number of phis eliminated.
+    unsigned replaceCongruentIVs(Loop *L, const DominatorTree *DT,
+                                 SmallVectorImpl<WeakVH> &DeadInsts);
+
     /// expandCodeFor - Insert code to directly compute the specified SCEV
     /// expression into the program.  The inserted code is inserted into the
     /// specified block.