[llvm-branch-commits] [llvm] Add SimplifyTypeTests pass. (PR #141327)

[Teresa Johnson via llvm-branch-commits]

================
@@ -2478,3 +2479,76 @@ PreservedAnalyses LowerTypeTestsPass::run(Module &M,
     return PreservedAnalyses::all();
   return PreservedAnalyses::none();
 }
+
+PreservedAnalyses SimplifyTypeTestsPass::run(Module &M,
+                                             ModuleAnalysisManager &AM) {
+  bool Changed = false;
+  // Figure out whether inlining has exposed a constant address to a lowered
+  // type test, and remove the test if so and the address is known to pass the
+  // test. Unfortunately this pass ends up needing to reverse engineer what
+  // LowerTypeTests did; this is currently inherent to the design of ThinLTO
----------------
teresajohnson wrote:

Can you add a more extensive comment with what this is looking for and why? I don't look at lower type test output often so I don't recall offhand what e.g. it would have looked like without inlining vs with.

https://github.com/llvm/llvm-project/pull/141327