[RegAllocGreedy] Record missed hint for late recoloring.
In https://reviews.llvm.org/D25347, Geoff noticed that we still have
useless copy that we can eliminate after register allocation. At the
time the allocation is chosen for those copies, they are not useless
but, because of changes in the surrounding code, later on they might
become useless.
The Greedy allocator already has a mechanism to deal with such cases
with a late recoloring. However, we missed to record the some of the
missed hints.
This commit fixes that.
llvm-svn: 287070
diff --git a/llvm/lib/CodeGen/RegAllocGreedy.cpp b/llvm/lib/CodeGen/RegAllocGreedy.cpp
index 9a0fc66..4a381e0 100644
--- a/llvm/lib/CodeGen/RegAllocGreedy.cpp
+++ b/llvm/lib/CodeGen/RegAllocGreedy.cpp
@@ -646,6 +646,9 @@
evictInterference(VirtReg, Hint, NewVRegs);
return Hint;
}
+ // Record the missed hint, we may be able to recover
+ // at the end if the surrounding allocation changed.
+ SetOfBrokenHints.insert(&VirtReg);
}
// Try to evict interference from a cheaper alternative.