[gcc r12-7357] nvptx: Back-end portion of a fix for PR target/104489.

[Roger Sayle]

https://gcc.gnu.org/g:06770148711226ba243b964451dfa8816d5d23e5

commit r12-7357-g06770148711226ba243b964451dfa8816d5d23e5
Author: Roger Sayle <roger@nextmovesoftware.com>
Date:   Wed Feb 23 07:24:50 2022 +0000

    nvptx: Back-end portion of a fix for PR target/104489.
    
    This one line fix/tweak is the back-end specific change for a fix for
    PR target/104489, that allows the ISA for GCC's nvptx backend to be bumped
    to sm_53.  The machine-independent middle-end pieces were posted here:
    https://gcc.gnu.org/pipermail/gcc-patches/2022-February/590139.html
    
    2022-02-23  Roger Sayle  <roger@nextmovesoftware.com>
    
    gcc/ChangeLog
            PR target/104489
            * config/nvptx/nvptx.md (*movhf_insn): Add subregs_ok attribute.

Diff:
---
 gcc/config/nvptx/nvptx.md | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/gcc/config/nvptx/nvptx.md b/gcc/config/nvptx/nvptx.md
index f6dc817632c..216e89f230a 100644
--- a/gcc/config/nvptx/nvptx.md
+++ b/gcc/config/nvptx/nvptx.md
@@ -288,7 +288,8 @@
   "@
    %.\\tmov.b16\\t%0, %1;
    %.\\tld.b16\\t%0, %1;
-   %.\\tst.b16\\t%0, %1;")
+   %.\\tst.b16\\t%0, %1;"
+  [(set_attr "subregs_ok" "true")])
 
 (define_expand "movhf"
   [(set (match_operand:HF 0 "nonimmediate_operand" "")