[llvm] [RFC][GlobalISel] Use Builders in MatchTable (PR #65955)

[via llvm-commits]

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@@ -1239,8 +1258,11 @@ bool GIMatchTableExecutor::executeMatchTable(
       DEBUG_WITH_TYPE(TgtExecutor::getName(),
                       dbgs() << CurrentIdx << ": GIR_EraseFromParent(MIs["
                              << InsnID << "])\n");
-      if (Observer)
-        Observer->erasingInstr(*MI);
+      // If we're erasing the insertion point, ensure we don't leave a dangling
+      // pointer in the builder.
+      if (Builder.getInsertPt() == MI)
+        Builder.setInsertPt(*MI->getParent(), ++MI->getIterator());
+      Observer.erasingInstr(*MI);
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qcolombet wrote:

I believe this fixes a problem that is independent from this PR.

Could you commit that part separately (and with a test if possible)?

https://github.com/llvm/llvm-project/pull/65955