Make one getAddExpr call when analyzing a+b+c+d+e+... instead of one
for each add instruction. Ditto for Mul.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@111136 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp
index 47ec304..8c9b72f 100644
--- a/lib/Analysis/ScalarEvolution.cpp
+++ b/lib/Analysis/ScalarEvolution.cpp
@@ -3244,12 +3244,37 @@
Operator *U = cast<Operator>(V);
switch (Opcode) {
- case Instruction::Add:
- return getAddExpr(getSCEV(U->getOperand(0)),
- getSCEV(U->getOperand(1)));
- case Instruction::Mul:
- return getMulExpr(getSCEV(U->getOperand(0)),
- getSCEV(U->getOperand(1)));
+ case Instruction::Add: {
+ // The simple thing to do would be to just call getSCEV on both operands
+ // and call getAddExpr with the result. However if we're looking at a
+ // bunch of things all added together, this can be quite inefficient,
+ // because it leads to N-1 getAddExpr calls for N ultimate operands.
+ // Instead, gather up all the operands and make a single getAddExpr call.
+ // 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)) {
+ U = cast<Operator>(Op);
+ AddOps.push_back(getSCEV(U->getOperand(1)));
+ }
+ AddOps.push_back(getSCEV(U->getOperand(0)));
+ return getAddExpr(AddOps);
+ }
+ case Instruction::Mul: {
+ // See the Add code above.
+ SmallVector<const SCEV *, 4> MulOps;
+ MulOps.push_back(getSCEV(U->getOperand(1)));
+ for (Value *Op = U->getOperand(0);
+ Op->getValueID() == Instruction::Mul + Value::InstructionVal;
+ Op = U->getOperand(0)) {
+ U = cast<Operator>(Op);
+ MulOps.push_back(getSCEV(U->getOperand(1)));
+ }
+ MulOps.push_back(getSCEV(U->getOperand(0)));
+ return getMulExpr(MulOps);
+ }
case Instruction::UDiv:
return getUDivExpr(getSCEV(U->getOperand(0)),
getSCEV(U->getOperand(1)));