From: Dan Gohman <gohman@apple.com>
Date: Mon, 16 Aug 2010 16:57:24 +0000 (+0000)
Subject: To create a copy of a SmallVector with an element removed from the
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=1895991a084d5d45d091a24542ad111946738e70;p=oota-llvm.git

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 714065234f8..6eb07938894 100644
--- 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);