[GVNHoist] computeInsertionPoints() miscalculates IDF
Fix for https://bugs.llvm.org/show_bug.cgi?id=38912.
In GVNHoist::computeInsertionPoints() we iterate over the Value
Numbers and calculate the Iterated Dominance Frontiers without
clearing the IDFBlocks vector first. IDFBlocks ends up accumulating
an insane number of basic blocks, which bloats the compilation time
of SemaChecking.cpp with ubsan enabled.
Differential Revision: https://reviews.llvm.org/D51980
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@342055
91177308-0d34-0410-b5e6-
96231b3b80d8
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