Fix a quadratic algorithm in MachineBranchProbabilityInfo.
The getSumForBlock function was quadratic in the number of successors
because getSuccWeight would perform a linear search for an already known
iterator.
This patch was originally committed as r161460, but reverted again
because of assertion failures. Now that duplicate Machine CFG edges have
been eliminated, this works properly.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@162233 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/MachineBasicBlock.cpp b/lib/CodeGen/MachineBasicBlock.cpp
index fa6b450..cf13dbd 100644
--- a/lib/CodeGen/MachineBasicBlock.cpp
+++ b/lib/CodeGen/MachineBasicBlock.cpp
@@ -942,12 +942,11 @@
/// getSuccWeight - Return weight of the edge from this block to MBB.
///
-uint32_t MachineBasicBlock::getSuccWeight(const MachineBasicBlock *succ) const {
+uint32_t MachineBasicBlock::getSuccWeight(const_succ_iterator Succ) const {
if (Weights.empty())
return 0;
- const_succ_iterator I = std::find(Successors.begin(), Successors.end(), succ);
- return *getWeightIterator(I);
+ return *getWeightIterator(Succ);
}
/// getWeightIterator - Return wight iterator corresonding to the I successor