LiveVariables::VarInfo contains an AliveBlocks BitVector, which has as many
entries as there are basic blocks in the function. LiveVariables::getVarInfo
creates a VarInfo struct for every register in the function, leading to
quadratic space use. This patch changes the BitVector to a SparseBitVector,
which doesn't help the worst-case memory use but does reduce the actual use in
very long functions with short-lived variables.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@72426 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/PHIElimination.cpp b/lib/CodeGen/PHIElimination.cpp
index 2eacb08..c5c76fc 100644
--- a/lib/CodeGen/PHIElimination.cpp
+++ b/lib/CodeGen/PHIElimination.cpp
@@ -334,8 +334,7 @@
// Is it alive in this successor?
unsigned SuccIdx = SuccMBB->getNumber();
- if (SuccIdx < InRegVI.AliveBlocks.size() &&
- InRegVI.AliveBlocks[SuccIdx]) {
+ if (InRegVI.AliveBlocks.test(SuccIdx)) {
ValueIsLive = true;
break;
}
@@ -407,8 +406,7 @@
// This vreg no longer lives all of the way through opBlock.
unsigned opBlockNum = opBlock.getNumber();
- if (opBlockNum < InRegVI.AliveBlocks.size())
- InRegVI.AliveBlocks[opBlockNum] = false;
+ InRegVI.AliveBlocks.reset(opBlockNum);
}
}