To create a copy of a SmallVector with an element removed from the

middle, copy the elements in two groups, rather than copying all the
elements and then doing an erase on the middle of the result. These
are SmallVectors, so we shouldn't expect to hit dynamic allocation
in the common case.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@111151 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp
index 714065234f88ba7185ae11138ac037c3fa390b71..6eb0793889451a71cc4cbe583dbaf66380bf8eff 100644 (file)
--- a/lib/Analysis/ScalarEvolution.cpp
+++ b/lib/Analysis/ScalarEvolution.cpp
@@ -1530,8 +1530,9 @@ const SCEV *ScalarEvolution::getAddExpr(SmallVectorImpl<const SCEV *> &Ops,
           if (Mul->getNumOperands() != 2) {
             // If the multiply has more than two operands, we must get the
             // Y*Z term.
-            SmallVector<const SCEV *, 4> MulOps(Mul->op_begin(), Mul->op_end());
-            MulOps.erase(MulOps.begin()+MulOp);
+            SmallVector<const SCEV *, 4> MulOps(Mul->op_begin(),
+                                                Mul->op_begin()+MulOp);
+            MulOps.append(Mul->op_begin()+MulOp+1, Mul->op_end());
             InnerMul = getMulExpr(MulOps);
           }
           const SCEV *One = getConstant(Ty, 1);
@@ -1564,15 +1565,15 @@ const SCEV *ScalarEvolution::getAddExpr(SmallVectorImpl<const SCEV *> &Ops,
             const SCEV *InnerMul1 = Mul->getOperand(MulOp == 0);
             if (Mul->getNumOperands() != 2) {
               SmallVector<const SCEV *, 4> MulOps(Mul->op_begin(),
-                                                  Mul->op_end());
-              MulOps.erase(MulOps.begin()+MulOp);
+                                                  Mul->op_begin()+MulOp);
+              MulOps.append(Mul->op_begin()+MulOp+1, Mul->op_end());
               InnerMul1 = getMulExpr(MulOps);
             }
             const SCEV *InnerMul2 = OtherMul->getOperand(OMulOp == 0);
             if (OtherMul->getNumOperands() != 2) {
               SmallVector<const SCEV *, 4> MulOps(OtherMul->op_begin(),
-                                                  OtherMul->op_end());
-              MulOps.erase(MulOps.begin()+OMulOp);
+                                                  OtherMul->op_begin()+OMulOp);
+              MulOps.append(OtherMul->op_begin()+OMulOp+1, OtherMul->op_end());
               InnerMul2 = getMulExpr(MulOps);
             }
             const SCEV *InnerMulSum = getAddExpr(InnerMul1,InnerMul2);