This patch introduces a codegen-only instruction currently named br_unless,
which makes it convenient to implement ReverseBranchCondition and re-enable
the MachineBlockPlacement pass. Then in a late pass, it lowers br_unless
back into br_if.
Differential Revision: http://reviews.llvm.org/D14995
llvm-svn: 254826
If virtual registers are created late, mappings to WebAssembly
registers need to be added explicitly. This patch adds a function
to do so and teaches WebAssemblyPeephole to use it. This fixes
an out-of-bounds access on the WARegs vector.
llvm-svn: 254094
