[PATCH] D52703: Allow ifunc resolvers to accept arguments

[Ed Maste via Phabricator via cfe-commits]

emaste created this revision.
emaste added a reviewer: DmitryPolukhin.
Herald added a reviewer: javed.absar.
Herald added subscribers: kristof.beyls, krytarowski.

When ifunc support was added to Clang (in https://reviews.llvm.org/rC265917) it did not allow resolvers to take function arguments. This was based on GCC's documentation, which states resolvers return a pointer and take no arguments.

However, GCC actually allows it, and glibc (on non-x86 platforms) and FreeBSD (on x86 and arm64) pass CPU identification information as arguments to ifunc resolvers. I believe GCC's documentation is simply incorrect / out-of-date.

We've removed the prohibition in FreeBSD's in-tree Clang: https://svnweb.freebsd.org/changeset/base/339019.


https://reviews.llvm.org/D52703

Files:
  include/clang/Basic/AttrDocs.td
  include/clang/Basic/DiagnosticSemaKinds.td
  lib/CodeGen/CodeGenModule.cpp
  test/Sema/attr-ifunc.c


Index: test/Sema/attr-ifunc.c
===================================================================
--- test/Sema/attr-ifunc.c
+++ test/Sema/attr-ifunc.c
@@ -27,10 +27,6 @@
 void f4() __attribute__((ifunc("f4_ifunc")));
 //expected-error at -1 {{ifunc resolver function must return a pointer}}
 
-void* f5_ifunc(int i) { return 0; }
-void f5() __attribute__((ifunc("f5_ifunc")));
-//expected-error at -1 {{ifunc resolver function must have no parameters}}
-
 #else
 void f1a() __asm("f1");
 void f1a() {}
Index: lib/CodeGen/CodeGenModule.cpp
===================================================================
--- lib/CodeGen/CodeGenModule.cpp
+++ lib/CodeGen/CodeGenModule.cpp
@@ -322,8 +322,6 @@
       assert(FTy);
       if (!FTy->getReturnType()->isPointerTy())
         Diags.Report(Location, diag::err_ifunc_resolver_return);
-      if (FTy->getNumParams())
-        Diags.Report(Location, diag::err_ifunc_resolver_params);
     }
 
     llvm::Constant *Aliasee = Alias->getIndirectSymbol();
Index: include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- include/clang/Basic/DiagnosticSemaKinds.td
+++ include/clang/Basic/DiagnosticSemaKinds.td
@@ -2887,8 +2887,6 @@
   "%select{alias|ifunc}0 definition is part of a cycle">;
 def err_ifunc_resolver_return : Error<
   "ifunc resolver function must return a pointer">;
-def err_ifunc_resolver_params : Error<
-  "ifunc resolver function must have no parameters">;
 def warn_attribute_wrong_decl_type_str : Warning<
   "%0 attribute only applies to %1">, InGroup<IgnoredAttributes>;
 def err_attribute_wrong_decl_type_str : Error<
Index: include/clang/Basic/AttrDocs.td
===================================================================
--- include/clang/Basic/AttrDocs.td
+++ include/clang/Basic/AttrDocs.td
@@ -3366,7 +3366,7 @@
   let Content = [{
 ``__attribute__((ifunc("resolver")))`` is used to mark that the address of a declaration should be resolved at runtime by calling a resolver function.
 
-The symbol name of the resolver function is given in quotes.  A function with this name (after mangling) must be defined in the current translation unit; it may be ``static``.  The resolver function should take no arguments and return a pointer.
+The symbol name of the resolver function is given in quotes.  A function with this name (after mangling) must be defined in the current translation unit; it may be ``static``.  The resolver function should return a pointer.
 
 The ``ifunc`` attribute may only be used on a function declaration.  A function declaration with an ``ifunc`` attribute is considered to be a definition of the declared entity.  The entity must not have weak linkage; for example, in C++, it cannot be applied to a declaration if a definition at that location would be considered inline.
 


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