From: Dan Gohman <gohman@apple.com>
Date: Sun, 29 Aug 2010 15:10:06 +0000 (+0000)
Subject: Batch up subtracts along with adds, when analyzing long chains of
X-Git-Url: http://plrg.eecs.uci.edu/git/?a=commitdiff_plain;h=b8fc62bc58d945a4e820ee3676c17793e8770b3a;p=oota-llvm.git

Batch up subtracts along with adds, when analyzing long chains of
operations.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@112432 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp
index 863f8a65409..121c6e2a327 100644
--- a/lib/Analysis/ScalarEvolution.cpp
+++ b/lib/Analysis/ScalarEvolution.cpp
@@ -3332,11 +3332,16 @@ const SCEV *ScalarEvolution::createSCEV(Value *V) {
     // LLVM IR canonical form means we need only traverse the left operands.
     SmallVector<const SCEV *, 4> AddOps;
     AddOps.push_back(getSCEV(U->getOperand(1)));
-    for (Value *Op = U->getOperand(0);
-         Op->getValueID() == Instruction::Add + Value::InstructionVal;
-         Op = U->getOperand(0)) {
+    for (Value *Op = U->getOperand(0); ; Op = U->getOperand(0)) {
+      unsigned Opcode = Op->getValueID() - Value::InstructionVal;
+      if (Opcode != Instruction::Add && Opcode != Instruction::Sub)
+        break;
       U = cast<Operator>(Op);
-      AddOps.push_back(getSCEV(U->getOperand(1)));
+      const SCEV *Op1 = getSCEV(U->getOperand(1));
+      if (Opcode == Instruction::Sub)
+        AddOps.push_back(getNegativeSCEV(Op1));
+      else
+        AddOps.push_back(Op1);
     }
     AddOps.push_back(getSCEV(U->getOperand(0)));
     return getAddExpr(AddOps);