CSE simple binary expressions when they are inserted. This makes LSR produce
less huge code that needs to be cleaned up by sdisel.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@35959 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/ScalarEvolutionExpander.cpp b/lib/Analysis/ScalarEvolutionExpander.cpp
index a50d572..a9b88c1 100644
--- a/lib/Analysis/ScalarEvolutionExpander.cpp
+++ b/lib/Analysis/ScalarEvolutionExpander.cpp
@@ -68,6 +68,25 @@
return CastInst::create(opcode, V, Ty, V->getName(), IP);
}
+/// InsertBinop - Insert the specified binary operator, doing a small amount
+/// of work to avoid inserting an obviously redundant operation.
+Value *SCEVExpander::InsertBinop(Instruction::BinaryOps Opcode, Value *LHS,
+ Value *RHS, Instruction *InsertPt) {
+ // Do a quick scan to see if we have this binop nearby. If so, reuse it.
+ unsigned ScanLimit = 6;
+ for (BasicBlock::iterator IP = InsertPt, E = InsertPt->getParent()->begin();
+ ScanLimit; --IP, --ScanLimit) {
+ if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(IP))
+ if (BinOp->getOpcode() == Opcode && BinOp->getOperand(0) == LHS &&
+ BinOp->getOperand(1) == RHS)
+ return BinOp;
+ if (IP == E) break;
+ }
+
+ // If we don't have
+ return BinaryOperator::create(Opcode, LHS, RHS, "tmp.", InsertPt);
+}
+
Value *SCEVExpander::visitMulExpr(SCEVMulExpr *S) {
const Type *Ty = S->getType();
int FirstOp = 0; // Set if we should emit a subtract.
@@ -80,11 +99,12 @@
// Emit a bunch of multiply instructions
for (; i >= FirstOp; --i)
- V = BinaryOperator::createMul(V, expandInTy(S->getOperand(i), Ty),
- "tmp.", InsertPt);
+ V = InsertBinop(Instruction::Mul, V, expandInTy(S->getOperand(i), Ty),
+ InsertPt);
// -1 * ... ---> 0 - ...
if (FirstOp == 1)
- V = BinaryOperator::createNeg(V, "tmp.", InsertPt);
+ V = InsertBinop(Instruction::Sub, Constant::getNullValue(V->getType()), V,
+ InsertPt);
return V;
}
@@ -103,7 +123,7 @@
Value *Rest = expandInTy(SCEVAddRecExpr::get(NewOps, L), Ty);
// FIXME: look for an existing add to use.
- return BinaryOperator::createAdd(Rest, Start, "tmp.", InsertPt);
+ return InsertBinop(Instruction::Add, Rest, Start, InsertPt);
}
// {0,+,1} --> Insert a canonical induction variable into the loop!
@@ -164,7 +184,7 @@
}
}
- return BinaryOperator::createMul(I, F, "tmp.", MulInsertPt);
+ return InsertBinop(Instruction::Mul, I, F, MulInsertPt);
}
// If this is a chain of recurrences, turn it into a closed form, using the