[PATCH] D81052: [ELF] Handle -u before input files

[Fangrui Song via Phabricator via llvm-commits]

MaskRay marked an inline comment as done.
MaskRay added inline comments.


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Comment at: lld/ELF/Driver.cpp:1473
 
 // Force Sym to be entered in the output. Used for -u or equivalent.
 static void handleUndefined(Symbol *sym) {
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psmith wrote:
> We now no longer use this function for -u, will be worth updating comment.
All handleUndefined call sites may use addUndefined instead. I'll experiment. Two `--wrap` uses of addUndefined should probably be addUnusedUndefined instead (to fix https://bugs.llvm.org/show_bug.cgi?id=46169 )


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Comment at: lld/ELF/Driver.cpp:1885
 
-  // Handle the `--undefined <sym>` options.
-  for (StringRef arg : config->undefined)
-    if (Symbol *sym = symtab->find(arg))
-      handleUndefined(sym);
+  // Keep bitcode definitions in the symbol table.
+  for (StringRef name : config->undefined)
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psmith wrote:
> IIUC this is to prevent LTO from removing definitions. May be worth saying
> ```
> // Prevent LTO from removing any definition referenced by an undefined.
> ```
Thanks for the suggestion!

The logic was introduced in D38348 .

We seem to consider a bitcode file a variant of an archive (its symbol table does not translate to .symtab in the output, but -u can force it).


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D81052/new/

https://reviews.llvm.org/D81052