[llvm] [GlobalISel] Combine [S,U]SUBO (PR #116489)

[Thorsten Schütt via llvm-commits]

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@@ -1385,6 +1385,12 @@ def match_addos : GICombineRule<
         [{ return Helper.matchAddOverflow(*${root}, ${matchinfo}); }]),
   (apply [{ Helper.applyBuildFn(*${root}, ${matchinfo}); }])>;
 
+def match_subo_no_overflow : GICombineRule<
+  (defs root:$root, build_fn_matchinfo:$matchinfo),
+  (match (wip_match_opcode G_SSUBO, G_USUBO):$root,
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tschuett wrote:

Firstly, it was copy-pasted from `match_addos` above. Secondly, I believe we can match only one tree/graph per match. I can split it into two combines if you want.

https://github.com/llvm/llvm-project/pull/116489