Fix function multiversioning dispatcher link error with LTO

We forgot to apply DECL_EXTERNAL to __init_cpu_features_resolver decl. When
building with LTO, the linker cannot find the
__init_cpu_features_resolver.lto_priv* symbol, causing the link error.

This patch gets this fixed by adding DECL_EXTERNAL to the decl. To avoid used
but never defined warning for this symbol, we also mark TREE_PUBLIC to the decl.
We should also mark the decl having hidden visibility. And fix the attribute in
the same way for __aarch64_cpu_features identifier.

Minimal steps to reproduce the bug:

echo '__attribute__((target_clones("default", "aes"))) void func1() { }' > 1.c
echo '__attribute__((target_clones("default", "aes"))) void func2() { }' > 2.c
echo 'void func1();void func2();int main(){func1();func2();return 0;}' > main.c
gcc -flto -c 1.c 2.c
gcc -flto main.c 1.o 2.o

Fixes: 0cfde688e213 ("[aarch64] Add function multiversioning support")
Signed-off-by: Yangyu Chen <cyy@cyyself.name>
gcc/ChangeLog:

	* config/aarch64/aarch64.cc (dispatch_function_versions): Adding
	DECL_EXTERNAL, TREE_PUBLIC and hidden DECL_VISIBILITY to
	__init_cpu_features_resolver and __aarch64_cpu_features.

diff --git a/gcc/config/aarch64/aarch64.cc b/gcc/config/aarch64/aarch64.cc
index df170d875f60c7d32cedbf81f9d7674e8e1e36ca..0fa7927d821ade7bc9dc648ec10827fd436b734e 100644 (file)
--- a/gcc/config/aarch64/aarch64.cc
+++ b/gcc/config/aarch64/aarch64.cc
@@ -20463,6 +20463,10 @@ dispatch_function_versions (tree dispatch_decl,
   tree init_fn_id = get_identifier ("__init_cpu_features_resolver");
   tree init_fn_decl = build_decl (UNKNOWN_LOCATION, FUNCTION_DECL,
                                  init_fn_id, init_fn_type);
+  DECL_EXTERNAL (init_fn_decl) = 1;
+  TREE_PUBLIC (init_fn_decl) = 1;
+  DECL_VISIBILITY (init_fn_decl) = VISIBILITY_HIDDEN;
+  DECL_VISIBILITY_SPECIFIED (init_fn_decl) = 1;
   tree arg1 = DECL_ARGUMENTS (dispatch_decl);
   tree arg2 = TREE_CHAIN (arg1);
   ifunc_cpu_init_stmt = gimple_build_call (init_fn_decl, 2, arg1, arg2);
@@ -20482,6 +20486,9 @@ dispatch_function_versions (tree dispatch_decl,
                                get_identifier ("__aarch64_cpu_features"),
                                global_type);
   DECL_EXTERNAL (global_var) = 1;
+  TREE_PUBLIC (global_var) = 1;
+  DECL_VISIBILITY (global_var) = VISIBILITY_HIDDEN;
+  DECL_VISIBILITY_SPECIFIED (global_var) = 1;
   tree mask_var = create_tmp_var (long_long_unsigned_type_node);
 
   tree component_expr = build3 (COMPONENT_REF, long_long_unsigned_type_node,