[PATCH] D40593: ThinLTOBitcodeWriter: Try harder to discard unused references to the merged module.

[Peter Collingbourne via Phabricator via llvm-commits]

pcc added a comment.

In https://reviews.llvm.org/D40593#941225, @tejohnson wrote:

> LGTM - I assume the modified test fails without the patch?


It in fact passes because I made a mistake in the test. The declaration that appears in the thin module looks like this:

  @"anon$ae77054242d4de6843fe9803b6a8ac9f" = external hidden unnamed_addr constant { [1 x i8*] }

I will adjust the test so that it would match this.

> I can't tell from looking at it whether it anon would have dead constant users.

It would indeed, specifically the constant `getelementptr inbounds ({ [1 x i8*] }, { [1 x i8*] }* @anon, i32 0, i32 0, i32 1` in `@al`'s definition, which is left unreferenced when we drop `@al` from the thin module in `filterModule`.


https://reviews.llvm.org/D40593