The "dead" markings allow existing target-independent optimizations,
like MachineSink, to trigger more frequently. The CPSR defs would have
eventually been marked dead by LiveVariables, so this only affects
optimizations before regalloc.
The ARMBaseInstrInfo.cpp change is fixing a bug which is only visible
with this change: the transform adds a use to an otherwise dead def
of CPSR. This is covered by existing regression tests.
thumb2-tbh.ll breaks for Thumb1 due to MachineLICM changing the
generated code; I'll fix it in D53452.
Differential Revision: https://reviews.llvm.org/D53453
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@345420 91177308-0d34-0410-b5e6-96231b3b80d8
There's a missed optimization for immediates: we can save two
instructions by using adds instead of movs+mvns+cmp.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@335002 91177308-0d34-0410-b5e6-96231b3b80d8
This patch combines some cases of ARMISD::CMOV for integers that arise in comparisons of the form
a != b ? x : 0
a == b ? 0 : x
and that currently (e.g. in Thumb1) are emitted as branches.
Differential Revision: https://reviews.llvm.org/D34515
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@325323 91177308-0d34-0410-b5e6-96231b3b80d8
We turned off the CMN instruction because it had semantics which we weren't
getting correct. If we are comparing with an immediate, then it's okay to use
the CMN instruction.
<rdar://problem/7569620>
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@158302 91177308-0d34-0410-b5e6-96231b3b80d8
Eli Friedman