Avoid allocating a value of zero in a register if the initial formula
inputs happen to negate each other.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@100828 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/LoopStrengthReduce.cpp b/lib/Transforms/Scalar/LoopStrengthReduce.cpp
index e50b13d..4669b60 100644
--- a/lib/Transforms/Scalar/LoopStrengthReduce.cpp
+++ b/lib/Transforms/Scalar/LoopStrengthReduce.cpp
@@ -262,11 +262,15 @@
SmallVector<const SCEV *, 4> Bad;
DoInitialMatch(S, L, Good, Bad, SE, DT);
if (!Good.empty()) {
- BaseRegs.push_back(SE.getAddExpr(Good));
+ const SCEV *Sum = SE.getAddExpr(Good);
+ if (!Sum->isZero())
+ BaseRegs.push_back(Sum);
AM.HasBaseReg = true;
}
if (!Bad.empty()) {
- BaseRegs.push_back(SE.getAddExpr(Bad));
+ const SCEV *Sum = SE.getAddExpr(Bad);
+ if (!Sum->isZero())
+ BaseRegs.push_back(Sum);
AM.HasBaseReg = true;
}
}