From 4d5105c8f1ff1ac4bae592d6c221e5737614bbad Mon Sep 17 00:00:00 2001
From: Joe Soroka <gits@joesoroka.com>
Date: Tue, 1 Feb 2011 00:37:53 -0800
Subject: [PATCH] support weak attribute on variables

---
 libtcc.c        |  2 +-
 tcc.h           |  6 +++---
 tccgen.c        |  7 +++++++
 tests/tcctest.c | 18 ++++++++++++++++++
 4 files changed, 29 insertions(+), 4 deletions(-)

diff --git a/libtcc.c b/libtcc.c
index 483670a9..58a5ca07 100644
--- a/libtcc.c
+++ b/libtcc.c
@@ -429,7 +429,7 @@ ST_FUNC void put_extern_sym2(Sym *sym, Section *section,
     if (sym->type.t & VT_STATIC)
         sym_bind = STB_LOCAL;
     else {
-        if (sym_type == STT_FUNC && sym->type.ref && FUNC_WEAK(sym->type.ref->r))
+        if (sym->type.t & VT_WEAK)
             sym_bind = STB_WEAK;
         else
             sym_bind = STB_GLOBAL;
diff --git a/tcc.h b/tcc.h
index 2cd2043c..b72f4e4e 100644
--- a/tcc.h
+++ b/tcc.h
@@ -293,7 +293,6 @@ typedef struct AttributeDef {
 #define FUNC_ARGS(r) (((AttributeDef*)&(r))->func_args)
 #define FUNC_ALIGN(r) (((AttributeDef*)&(r))->aligned)
 #define FUNC_PACKED(r) (((AttributeDef*)&(r))->packed)
-#define FUNC_WEAK(r) (((AttributeDef*)&(r))->weak)
 #define ATTR_MODE(r)  (((AttributeDef*)&(r))->mode)
 #define INT_ATTR(ad) (*(int*)(ad))
 
@@ -629,11 +628,12 @@ struct TCCState {
 #define VT_INLINE  0x00000400  /* inline definition */
 #define VT_IMPORT  0x00004000  /* win32: extern data imported from dll */
 #define VT_EXPORT  0x00008000  /* win32: data exported from dll */
+#define VT_WEAK    0x00010000  /* win32: data exported from dll */
 
-#define VT_STRUCT_SHIFT 16   /* shift for bitfield shift values */
+#define VT_STRUCT_SHIFT 17   /* shift for bitfield shift values */
 
 /* type mask (except storage) */
-#define VT_STORAGE (VT_EXTERN | VT_STATIC | VT_TYPEDEF | VT_INLINE | VT_IMPORT | VT_EXPORT)
+#define VT_STORAGE (VT_EXTERN | VT_STATIC | VT_TYPEDEF | VT_INLINE | VT_IMPORT | VT_EXPORT | VT_WEAK)
 #define VT_TYPE    (~(VT_STORAGE))
 
 /* token values */
diff --git a/tccgen.c b/tccgen.c
index 3c6adbc4..2d7e4aec 100644
--- a/tccgen.c
+++ b/tccgen.c
@@ -2922,6 +2922,9 @@ static int parse_btype(CType *type, AttributeDef *ad)
         case TOK_ATTRIBUTE1:
         case TOK_ATTRIBUTE2:
             parse_attribute(ad);
+            if (ad->weak) {
+                t |= VT_WEAK;
+            }
             if (ad->mode) {
                 u = ad->mode -1;
                 t = (t & ~VT_BTYPE) | u;
@@ -3189,6 +3192,10 @@ static void type_decl(CType *type, AttributeDef *ad, int *v, int td)
     post_type(type, ad);
     if (tok == TOK_ATTRIBUTE1 || tok == TOK_ATTRIBUTE2)
         parse_attribute(ad);
+    
+    if (ad->weak)
+        type->t |= VT_WEAK;
+
     if (!type1.t)
         return;
     /* append type at the end of type1 */
diff --git a/tests/tcctest.c b/tests/tcctest.c
index 14ad1e64..8c2b2a25 100644
--- a/tests/tcctest.c
+++ b/tests/tcctest.c
@@ -82,6 +82,7 @@ void local_label_test(void);
 void statement_expr_test(void);
 void asm_test(void);
 void builtin_test(void);
+void weak_test(void);
 
 int fib(int n);
 void num(int n);
@@ -537,6 +538,7 @@ int main(int argc, char **argv)
     local_label_test();
     asm_test();
     builtin_test();
+    weak_test();
     return 0; 
 }
 
@@ -2227,6 +2229,22 @@ void builtin_test(void)
 }
 
 
+extern int __attribute__((weak)) weak_f1(void);
+extern int __attribute__((weak)) weak_f2(void);
+extern int __attribute__((weak)) weak_v1;
+extern int __attribute__((weak)) weak_v2;
+
+void __attribute__((weak)) weak_test(void)
+{
+	printf("weak_f1=%d\n", weak_f1 ? weak_f1() : 123);
+	printf("weak_f2=%d\n", weak_f2 ? weak_f2() : 123);
+	printf("weak_v1=%d\n",&weak_v1 ? weak_v1   : 123);
+	printf("weak_v2=%d\n",&weak_v2 ? weak_v2   : 123);
+}
+
+int __attribute__((weak)) weak_f2() { return 222; }
+int __attribute__((weak)) weak_v2 = 222;
+
 void const_func(const int a)
 {
 }
-- 
2.11.4.GIT