tccgen: handle __attribute((alias("target")))

3 files changed, 27 insertions, 1 deletions

diff --git a/tcc.h b/tcc.h
index 5f8b145..6d37860 100644
--- a/tcc.h
+++ b/tcc.h
@@ -285,6 +285,7 @@ typedef struct AttributeDef {
       resize	    : 1,
       fill          : 10;
     struct Section *section;
+    int alias_target;    /* token */
 } AttributeDef;
 
 /* gr: wrappers for casting sym->r for other purposes */
diff --git a/tccgen.c b/tccgen.c
index 22d58ec..da970fd 100644
--- a/tccgen.c
+++ b/tccgen.c
@@ -2472,6 +2472,16 @@ static void parse_attribute(AttributeDef *ad)
             next();
             skip(')');
             break;
+        case TOK_ALIAS1:
+        case TOK_ALIAS2:
+            skip('(');
+            if (tok != TOK_STR)
+                expect("alias(\"target\")");
+            ad->alias_target = /* save string as token, for later */
+              tok_alloc((char*)tokc.cstr->data, tokc.cstr->size-1)->tok;
+            next();
+            skip(')');
+            break;
         case TOK_ALIGNED1:
         case TOK_ALIGNED2:
             if (tok == '(') {
@@ -5578,7 +5588,20 @@ ST_FUNC void decl(int l)
                         /* NOTE: as GCC, uninitialized global static
                            arrays of null size are considered as
                            extern */
-                        external_sym(v, &type, r, asm_label);
+                        sym = external_sym(v, &type, r, asm_label);
+
+                        if (ad.alias_target) {
+                            Section tsec;
+                            Elf32_Sym *esym;
+                            Sym *alias_target;
+
+                            alias_target = sym_find(ad.alias_target);
+                            if (!alias_target || !alias_target->c)
+                                error("unsupported forward __alias__ attribute");
+                            esym = &((Elf32_Sym *)symtab_section->data)[alias_target->c];
+                            tsec.sh_num = esym->st_shndx;
+                            put_extern_sym2(sym, &tsec, esym->st_value, esym->st_size, 0);
+                        }
                     } else {
                         type.t |= (btype.t & VT_STATIC); /* Retain "static". */
                         if (type.t & VT_STATIC)
diff --git a/tcctok.h b/tcctok.h
index ec14c1a..aabbd05 100644
--- a/tcctok.h
+++ b/tcctok.h
@@ -100,6 +100,8 @@
      DEF(TOK_PACKED2, "__packed__")
      DEF(TOK_WEAK1, "weak")
      DEF(TOK_WEAK2, "__weak__")
+     DEF(TOK_ALIAS1, "alias")
+     DEF(TOK_ALIAS2, "__alias__")
      DEF(TOK_UNUSED1, "unused")
      DEF(TOK_UNUSED2, "__unused__")
      DEF(TOK_CDECL1, "cdecl")