[llvm] [GlobalISel] Migrate remaining generic wip_match_opcode combines to MIR-pattern. (PR #222851)

[Yaxun Liu via llvm-commits]

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@@ -619,15 +655,26 @@ def select_constant_cmp_true : GICombineRule<
   (apply (GIReplaceReg $dst, $tval))
 >;
 
-def select_constant_cmp_general: GICombineRule<
-  (defs root:$root, unsigned_matchinfo:$matchinfo),
+def select_constant_cmp_general_false: GICombineRule<
+  (defs root:$dst),
   (match (G_SELECT $dst, $cond, $tval, $fval):$root,
-    [{ return Helper.matchConstantSelectCmp(*${root}, ${matchinfo}); }]),
-  (apply [{ Helper.replaceSingleDefInstWithOperand(*${root}, ${matchinfo}); }])
->;
+    [{
+      auto C = isConstantOrConstantSplatVector(${cond}.getReg(), MRI);
+      return C && C->isZero();
+    }]),
+  (apply (COPY $dst, $fval))>;
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yxsamliu wrote:

The old combine replaced the destination directly. Could these two rules use `GIReplaceReg` instead of creating a `COPY`, like the nearby constant-select rules?

https://github.com/llvm/llvm-project/pull/222851