[PATCH] D131618: [WIP][Do NOT review] LLD related changes for -ffat-lto-objects support

[Paul Kirth via Phabricator via cfe-commits]

paulkirth added a comment.

I think the test strategy here needs to be:

- Format checking

-. llvm generates the correct object file sections when configured for fatlto

1. clang generates fatlto objects correctly (i.e. correctly sets up the codegen pipeline in llvm)



================
Comment at: clang/lib/Driver/ToolChains/Clang.cpp:7120-7122
+  if (IsUsingLTO && LTOMode == LTOK_Full &&
+      Args.getLastArg(options::OPT_ffat_lto_objects))
+    CmdArgs.push_back("-ffat-lto-objects");
----------------
Do we always do this under `-flto=full`, now? Doesn't that just essentially disable full LTO, since you set it to 'thin' when compiling for fat objects?


================
Comment at: clang/test/CodeGen/embed-lto-fatlto.c:4-5
+//
+// CHECK: !{{[0-9]+}} = !{i32 1, !"ThinLTO", i32 0}
+// CHECK: !{{[0-9]+}} = !{i32 1, !"EnableSplitLTOUnit", i32 1}
+
----------------
What property are you trying to check here? that the full LTO mode is replaced with thin?


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Comment at: lld/test/ELF/fatlto/fatlto.test:28-30
+; RUN: obj2yaml %tfoo-fatLTO > %tfoo-fatLTO.yaml
+; RUN: obj2yaml %tfoo-LTO > %tfoo-LTO.yaml
+; RUN: diff %tfoo-fatLTO.yaml %tfoo-LTO.yaml
----------------
Can this test fail given how you generate the linker's inputs and what you're comparing? 

So, does the diff fail if you don't pass the `-fat-lto-objects` flag on Line 13? 


Repository:
  rG LLVM Github Monorepo

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https://reviews.llvm.org/D131618