This ordering allows nested if-conversion without using a work list, and
it makes it possible to update the dominator tree on the fly as well.

Any erased basic blocks will always be dominated by the current
post-order position, so the domtree can be pruned without invalidating
the iterator.

llvm-svn: 160025

llvm-svn: 159800

from IfConversion.cc), and fix some spelling and grammar in the surrounding
prose.

llvm-svn: 159699

This pass performs if-conversion on SSA form machine code by
speculatively executing both sides of the branch and using a cmov
instruction to select the result. This can help lower the number of
branch mispredictions on architectures like x86 that don't have
predicable instructions.

The current implementation is very aggressive, and causes regressions on
mosts tests. It needs good heuristics that have yet to be implemented.

llvm-svn: 159694