[PATCH] D103048: [IR] make -stack-alignment= into a module attr

Mon Jun 7 15:48:55 PDT 2021

nickdesaulniers added inline comments.

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Comment at: llvm/test/Linker/stack-alignment.ll:11
+;--- main.ll
+; NONE: error: linking module flags 'override-stack-alignment': IDs have conflicting values
+; CHECK-16: error: linking module flags 'override-stack-alignment': IDs have conflicting values
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tejohnson wrote:
> Will you get this error currently? I thought per comment and behavior of Error that it shouldn't give an error.
the `RUN` line for that check is missing the `:`, so it's not actually run.  I think I'll create the new `ModFlagBehavior` as a child revision to this commit, in which I add the new behavior and upgrade this attribute to use it, adding in this unit test.

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Now that I've had time to play with implementing such a `ModFlagBehavior`; it looks like it's not possible to create a module with such semantics then test it properly with `llvm-link`.  The reason is that `llvm-link` is structured to start with an empty module ("Composite"), then link in the first module specified on the command line, then link in the rest of the modules specified.  So we can't disambiguate between the initial empty module being linked against the initial source file with the MDNode vs 2 full modules where 1 is missing the MD node.  (ie. for two input source files, the main module linking logic is run twice, not once).

See: https://reviews.llvm.org/D103851

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In that case, I just plan to remove this test case then, since it wasn't being `RUN` anyways.

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D103048/new/

https://reviews.llvm.org/D103048