Speculatively revert r112433.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@112608 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp
index 5204cf5ffcf14268fb211bd32258177c62675457..121c6e2a3270a35761b0f562a0921af677eb09ae 100644 (file)
--- a/lib/Analysis/ScalarEvolution.cpp
+++ b/lib/Analysis/ScalarEvolution.cpp
@@ -1886,30 +1886,27 @@ const SCEV *ScalarEvolution::getMulExpr(SmallVectorImpl<const SCEV *> &Ops,
     // there are multiple AddRec's with the same loop induction variable being
     // multiplied together.  If so, we can fold them.
     for (unsigned OtherIdx = Idx+1;
-         OtherIdx < Ops.size() && isa<SCEVAddRecExpr>(Ops[OtherIdx]);
-         ++OtherIdx)
-      if (AddRecLoop == cast<SCEVAddRecExpr>(Ops[OtherIdx])->getLoop()) {
-        // F * G, where F = {A,+,B}<L> and G = {C,+,D}<L>  -->
-        // {A*C,+,F*D + G*B + B*D}<L>
-        for (; OtherIdx != Ops.size() && isa<SCEVAddRecExpr>(Ops[OtherIdx]);
-             ++OtherIdx)
-          if (const SCEVAddRecExpr *OtherAddRec =
-                dyn_cast<SCEVAddRecExpr>(Ops[OtherIdx]))
-            if (OtherAddRec->getLoop() == AddRecLoop) {
-              const SCEVAddRecExpr *F = AddRec, *G = OtherAddRec;
-              const SCEV *NewStart = getMulExpr(F->getStart(), G->getStart());
-              const SCEV *B = F->getStepRecurrence(*this);
-              const SCEV *D = G->getStepRecurrence(*this);
-              const SCEV *NewStep = getAddExpr(getMulExpr(F, D),
-                                               getMulExpr(G, B),
-                                               getMulExpr(B, D));
-              const SCEV *NewAddRec = getAddRecExpr(NewStart, NewStep,
-                                                    F->getLoop());
-              if (Ops.size() == 2) return NewAddRec;
-              Ops[Idx] = AddRec = cast<SCEVAddRecExpr>(NewAddRec);
-              Ops.erase(Ops.begin() + OtherIdx); --OtherIdx;
-            }
-        return getMulExpr(Ops);
+         OtherIdx < Ops.size() && isa<SCEVAddRecExpr>(Ops[OtherIdx]);++OtherIdx)
+      if (OtherIdx != Idx) {
+        const SCEVAddRecExpr *OtherAddRec = cast<SCEVAddRecExpr>(Ops[OtherIdx]);
+        if (AddRecLoop == OtherAddRec->getLoop()) {
+          // F * G  -->  {A,+,B} * {C,+,D}  -->  {A*C,+,F*D + G*B + B*D}
+          const SCEVAddRecExpr *F = AddRec, *G = OtherAddRec;
+          const SCEV *NewStart = getMulExpr(F->getStart(), G->getStart());
+          const SCEV *B = F->getStepRecurrence(*this);
+          const SCEV *D = G->getStepRecurrence(*this);
+          const SCEV *NewStep = getAddExpr(getMulExpr(F, D),
+                                           getMulExpr(G, B),
+                                           getMulExpr(B, D));
+          const SCEV *NewAddRec = getAddRecExpr(NewStart, NewStep,
+                                                F->getLoop());
+          if (Ops.size() == 2) return NewAddRec;
+
+          Ops.erase(Ops.begin()+Idx);
+          Ops.erase(Ops.begin()+OtherIdx-1);
+          Ops.push_back(NewAddRec);
+          return getMulExpr(Ops);
+        }
       }
 
     // Otherwise couldn't fold anything into this recurrence.  Move onto the