Summary: How we copying the CRRC to GRC is using a single MFOCRF to copy the contents of CR field n (CR bits 4×n+32:4×n+35) into bits 4×n+32:4×n+35 of register GRC. That’s not correct because we expect the value of destination register equals to source so we have to put the the contents of CR field in the lowest 4 bits. This patch adds a RLWINM after MFOCRF to achieve that.
The problem came up when adding builtins for xvtdivdp, xvtdivsp, xvtsqrtdp, xvtsqrtsp, as posted in D88278. We need to move the outputs (in CR register) to GRC. However outputs of these instructions may not in a fixed CR# register, so we can’t directly add a rotation instruction in the .td patterns, but need to wait until the CR register is determined. Then we confirmed this should be a bug in POST-RA PSEUDO PASS.
Reviewed By: nemanjai, shchenz
Differential Revision: https://reviews.llvm.org/D88274
Summary:
This is exposed by our internal testing.
The reduced testcase will assert with "Impossible reg-to-reg copy"
We can't use COPY to do 32-bit to 64-bit conversion.
Reviewers: kbarton, hfinkel, nemanjai
Reviewed By: hfinkel
Subscribers: hiraditya, MaskRay, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D64499
llvm-svn: 366255
Esme-Yi