AMDGPU: Add implicit def of SCC to kill and indirect pseudos
Summary:
Kill instructions sometimes do use SCC in unusual circumstances, when
v_cmpx cannot be used due to the operands that are involved.
Additionally, even if SCC was never defined by the expansion, kill pseudos
could previously occur between an s_cmp and an s_cbranch_scc, which breaks
the SCC liveness tracking when the pseudo is expanded to split the basic
block. While it would be possible to explicitly mark the SCC as live-in for
the successor basic block, it's simpler to just mark the pseudo as using SCC,
so that such a sequence is never emitted by instruction selection in the
first place.
A similar issue affects indirect source/dest pseudos in principle, although
I haven't been able to come up with a test case where it actually matters
(this affects instruction selection, so a MIR test can't be used).
Fixes: dEQP-GLES3.functional.shaders.discard.dynamic_loop_always
Change-Id: Ica8d82ecff1a763b892a1112cf1b06c948863a4f
Reviewers: arsenm, rampitec
Subscribers: kzhuravl, wdng, yaxunl, dstuttard, tpr, t-tye, llvm-commits
Differential Revision: https://reviews.llvm.org/D47761
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@335223 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed