[IR] Add hasNPredecessors, hasNPredecessorsOrMore to BasicBlock
Add methods to BasicBlock which make it easier to efficiently check
whether a block has N (or more) predecessors.
This can be more efficient than using pred_size(), which is a linear
time operation.
We might consider adding similar methods for successors. I haven't done
so in this patch because succ_size() is already O(1).
With this patch applied, I measured a 0.065% compile-time reduction in
user time for running `opt -O3` on the sqlite3 amalgamation (30 trials).
The change in mergeStoreIntoSuccessor alone saves 45 million linked list
iterations in a stage2 Release build of llc.
See llvm.org/PR39702 for a harder but more general way of achieving
similar results.
Differential Revision: https://reviews.llvm.org/D54686
llvm-svn: 347256
diff --git a/llvm/lib/Transforms/IPO/PartialInlining.cpp b/llvm/lib/Transforms/IPO/PartialInlining.cpp
index a96342b..00ad0d8 100644
--- a/llvm/lib/Transforms/IPO/PartialInlining.cpp
+++ b/llvm/lib/Transforms/IPO/PartialInlining.cpp
@@ -403,7 +403,7 @@
auto IsSingleEntry = [](SmallVectorImpl<BasicBlock *> &BlockList) {
BasicBlock *Dom = BlockList.front();
- return BlockList.size() > 1 && pred_size(Dom) == 1;
+ return BlockList.size() > 1 && Dom->hasNPredecessors(1);
};
auto IsSingleExit =