[Dominators] PR42041: Skip nullpointer successors

Authored by Szelethus on Jul 3 2019, 4:14 AM.


[Dominators] PR42041: Skip nullpointer successors


In Clang's CFG, we use nullpointers to represent unreachable nodes, for
example, in the included testfile, block B0 is unreachable from block
B1, resulting in a nullpointer dereference somewhere in
llvm::DominatorTreeBase<clang::CFGBlock, false>::recalculate.

This patch fixes this issue by specializing
llvm::DomTreeBuilder::SemiNCAInfo::ChildrenGetter::Get for
clang::CFG to not contain nullpointer successors.

Differential Revision: https://reviews.llvm.org/D62507

llvm-svn: 365026