[llvm] [TableGen] New tblgen Pattern bit to disable GISel pattern imports (PR #88382)

[Matt Arsenault via llvm-commits]

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@@ -4378,7 +4378,8 @@ void CodeGenDAGPatterns::ParsePatterns() {
       FindPatternInputsAndOutputs(Pattern, Pattern.getTree(j), InstInputs,
                                   InstResults, InstImpResults);
 
-    ParseOnePattern(CurPattern, Pattern, Result, InstImpResults);
+    ParseOnePattern(CurPattern, Pattern, Result, InstImpResults,
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arsenm wrote:

Can you just skip everything here if it's ignored? This currently defers it to as late as possible, and still forces you through all the rest of the machinery 

https://github.com/llvm/llvm-project/pull/88382