Weak symbols.

5 files changed, 39 insertions, 20 deletions

diff --git a/asm.peg b/asm.peg
index 596852b..bbc00f1 100644
--- a/asm.peg
+++ b/asm.peg
@@ -35,6 +35,8 @@ directive =
     { $$.dirquad = (Quad){.kind = ASM_DIR_QUAD, .value = v.value }; }
   | "set" ws s:ident ws? ',' ws? v:value
     { $$.set = (Set){.kind = ASM_DIR_SET, .sym = s.charptr, .value = v.value }; }
+  | "weak" ws s:ident
+    { $$.weak = (Weak){.kind = ASM_DIR_WEAK, .sym = s.charptr}; }
   | fd:fill-directive
     { $$ = fd; }
   | sd:section-directive
diff --git a/main.c b/main.c
index 38ad138..56df5b5 100644
--- a/main.c
+++ b/main.c
@@ -55,6 +55,8 @@ getsym(const char *name)
         **ps = (Symbol) {
             .name = name,
             .wco = -1,
+            .bind = STB_LOCAL,
+            .type = STT_NOTYPE,
         };
     }
     s = *ps;
@@ -716,7 +718,11 @@ assemble(void)
             break;
         case ASM_DIR_GLOBL:
             sym = getsym(v->globl.name);
-            sym->global = 1;
+            sym->bind = STB_GLOBAL;
+            break;
+        case ASM_DIR_WEAK:
+            sym = getsym(v->weak.sym);
+            sym->bind = STB_WEAK;
             break;
         case ASM_DIR_SECTION: {
             const char *fp;
@@ -857,16 +863,16 @@ relaxreset(void)
 /* Try to resolve the address of a symbol, this will recursively look
    for the symbol address if it is defined relative to another symbol. */
 static int
-resolvesymrecurse(Symbol *sym, int n)
+resolvesym2(Symbol *sym, int depth)
 {
     Symbol *indirect;
 
-    if (n > 64)
+    if (depth > 64)
         fatal("recursion limit hit when resolving symbol location");
 
     if (sym->value.l) {
         indirect = getsym(sym->value.l);
-        if (!resolvesymrecurse(indirect, n + 1))
+        if (!resolvesym2(indirect, depth + 1))
             return 0;
         sym->section = indirect->section;
         sym->value.l = NULL;
@@ -885,7 +891,7 @@ resolvesymrecurse(Symbol *sym, int n)
 static int
 resolvesym(Symbol *sym)
 {
-    return resolvesymrecurse(sym, 0);
+    return resolvesym2(sym, 0);
 }
 
 /* Resolve all symbols to their final location if we can. */
@@ -905,22 +911,13 @@ static void
 addtosymtab(Symbol *sym)
 {
     Elf64_Sym elfsym;
-    int stype;
-    int sbind;
-
-    stype = 0;
-    if (sym->defined) {
-        sbind = sym->global ? STB_GLOBAL : STB_LOCAL;
-    } else {
-        sbind = STB_GLOBAL;
-    }
 
     sym->idx = symtab->hdr.sh_size / symtab->hdr.sh_entsize;
 
     elfsym.st_name = elfstr(strtab, sym->name);
     elfsym.st_value = sym->value.c;
     elfsym.st_size = sym->size;
-    elfsym.st_info = ELF64_ST_INFO(sbind, stype);
+    elfsym.st_info = ELF64_ST_INFO(sym->bind, sym->type);
     elfsym.st_shndx = sym->section ? sym->section->idx : SHN_UNDEF;
     elfsym.st_other = 0;
     secaddbytes(symtab, &elfsym, sizeof(Elf64_Sym));
@@ -937,7 +934,7 @@ fillsymtab(void)
         if (!symbols->keys[i].str)
             continue;
         sym = symbols->vals[i];
-        if (!sym->defined || sym->global)
+        if (sym->bind != STB_LOCAL)
             continue;
         addtosymtab(sym);
     }
@@ -951,7 +948,7 @@ fillsymtab(void)
             continue;
 
         sym = symbols->vals[i];
-        if (sym->defined && !sym->global)
+        if (sym->bind == STB_LOCAL)
             continue;
         addtosymtab(sym);
     }
diff --git a/minias.h b/minias.h
index ccef65b..3e4f225 100644
--- a/minias.h
+++ b/minias.h
@@ -31,7 +31,8 @@ typedef struct {
     Value value;
     int64_t wco; /* worst case offset */
     int64_t size;
-    int global;
+    int bind; /* STB_GLOBAL, STB_LOCAL, STB_WEAK */
+    int type;
     int defined;
     Section *section;
 } Symbol;
@@ -54,6 +55,7 @@ typedef enum {
     ASM_MEMARG,
     // Directives.
     ASM_DIR_GLOBL,
+    ASM_DIR_WEAK,
     ASM_DIR_SECTION,
     ASM_DIR_ASCII,
     ASM_DIR_ASCIIZ,
@@ -182,6 +184,11 @@ typedef struct Set {
     Value value;
 } Set;
 
+typedef struct Weak {
+    AsmKind kind;
+    const char *sym;
+} Weak;
+
 typedef struct DirSection {
     AsmKind kind;
     int32_t type;
@@ -306,6 +313,7 @@ union Parsev {
     Jmp jmp;
     Fill fill;
     Set set;
+    Weak weak;
     Byte dirbyte;
     Short dirshort;
     Int dirint;
diff --git a/parse.c b/parse.c
index 9e955f7..5c2f5cb 100644
--- a/parse.c
+++ b/parse.c
@@ -75,9 +75,9 @@ decodestring(char *s)
                 c = '\\';
             } else {
                 for (i = 0; i < 3 && *s >= '0' && *s <= '7'; i++, s++)
-                  c = c * 8 + (*s - '0');
+                    c = c * 8 + (*s - '0');
                 if (i == 0)
-                  unreachable();
+                    unreachable();
                 s--;
             }
         } else {
diff --git a/test/execute/0003-weaksym.s b/test/execute/0003-weaksym.s
new file mode 100644
index 0000000..f6c12ce
--- /dev/null
+++ b/test/execute/0003-weaksym.s
@@ -0,0 +1,12 @@
+.data
+.weak foo
+foo:
+  .quad 0
+
+.text
+.globl main
+main:
+  movq foo(%rip), %rax
+  ret
+
+.section .note.GNU-stack,"",@progbits