[PATCH] D139163: Utils: Add utility pass to lower ifuncs

[Duncan P. N. Exon Smith via Phabricator via llvm-commits]

dexonsmith added a subscriber: rjmccall.
dexonsmith added a comment.

In D139163#3991248 <https://reviews.llvm.org/D139163#3991248>, @MoritzS wrote:

> To answer your questions in the comments about what to do about resolvers with arguments: At least glibc always calls ifunc resolvers without any arguments. It just reads the address of the resolver function from the ELF file, casts it to a pointer to a void-returning function with no arguments and calls it.
>
> So, I agree: Resolvers with arguments should not be allowed.

@rjmccall, I'm trying to remember whether Mach-O has an ifunc-like thing that takes an argument.



================
Comment at: llvm/lib/Transforms/Utils/ModuleUtils.cpp:352-361
+    // We don't know what to pass to a resolver function taking arguments
+    //
+    // FIXME: Is this even valid? clang and gcc don't complain but this
+    // probably should be invalid IR. We could just pass through undef.
+    if (!std::empty(ResolvedFunction->getFunctionType()->params())) {
+      LLVM_DEBUG(dbgs() << "Not lowering ifunc resolver function "
+                        << ResolvedFunction->getName() << " with parameters\n");
----------------
This is where ifuncs with arguments are handled. @rjmccall, thoughts on the FIXME?


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https://reviews.llvm.org/D139163