[llvm] [AArch64][GlobalISel] Add pre-legalizer combines for AVGFLOOR and AVGCEIL (PR #192866)

[David Green via llvm-commits]

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@@ -2300,6 +2300,70 @@ def overflow_combines: GICombineGroup<[
   match_subo_no_overflow
 ]>;
 
+
+def avgfloor_u_match : GICombineRule<
+  (defs root:$dst, build_fn_matchinfo:$matchinfo),
+  (match (G_ZEXT $ext1, $x),
+         (G_ZEXT $ext2, $y),
+         (G_ADD $sum, $ext1, $ext2),
+         (G_LSHR $dst, $sum, 1):$mi,
+         [{ return Helper.matchAVG(*${mi}, MRI, /*IsSigned=*/false, /*IsCeil=*/false); }]),
+  (apply [{ Helper.applyAVG(B, *${mi}, ${x}.getReg(), ${y}.getReg(), /*IsSigned=*/false, /*IsCeil=*/false); }])
+>;
+
+def avgfloor_s_match : GICombineRule<
+  (defs root:$dst, build_fn_matchinfo:$matchinfo),
+  (match (G_SEXT $ext1, $x),
+         (G_SEXT $ext2, $y),
+         (G_ADD $sum, $ext1, $ext2),
+         (G_ASHR $dst, $sum, 1):$mi,
+         [{ return Helper.matchAVG(*${mi}, MRI, /*IsSigned=*/true, /*IsCeil=*/false); }]),
+  (apply [{ Helper.applyAVG(B, *${mi}, ${x}.getReg(), ${y}.getReg(), /*IsSigned=*/true, /*IsCeil=*/false); }])
+>;
+
+def avgceil_sum : GICombinePatFrag<
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davemgreen wrote:

This one isn't used any more?

https://github.com/llvm/llvm-project/pull/192866