RegScavenging: Add scavengeRegisterBackwards()
This is a variant of scavengeRegister() that works for
enterBasicBlockEnd()/backward(). The benefit of the backward mode is
that it is not affected by incomplete kill flags.
This patch also changes
PrologEpilogInserter::doScavengeFrameVirtualRegs() to use the register
scavenger in backwards mode.
Differential Revision: http://reviews.llvm.org/D21885
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@276044 91177308-0d34-0410-b5e6-96231b3b80d8
11 files changed