we do need conv/cast skipping
[libfirm] / ir / be / begnuas.c
index e8f3760..fc8dc4a 100644 (file)
 #include "beemitter.h"
 #include "be_dbgout.h"
 
-typedef struct obstack obstack_t;
-
 /** by default, we generate assembler code for the Linux gas */
-be_gas_flavour_t be_gas_flavour = GAS_FLAVOUR_NORMAL;
+be_gas_flavour_t be_gas_flavour = GAS_FLAVOUR_ELF;
+
+static be_gas_section_t current_section = (be_gas_section_t) -1;
 
 /**
  * Return the pseudo-instruction to be issued for a section switch
@@ -61,49 +61,141 @@ be_gas_flavour_t be_gas_flavour = GAS_FLAVOUR_NORMAL;
  * @return  the pseudo-instruction
  */
 static const char *get_section_name(be_gas_section_t section) {
-       static const char *text[GAS_FLAVOUR_MAX][GAS_SECTION_MAX] = {
-               {
+       static const char *text[GAS_FLAVOUR_LAST+1][GAS_SECTION_LAST+1] = {
+               { /* GAS_FLAVOUR_ELF */
                        ".section\t.text",
                        ".section\t.data",
                        ".section\t.rodata",
                        ".section\t.bss",
                        ".section\t.tbss,\"awT\",@nobits",
-                       ".section\t.ctors,\"aw\",@progbits"
+                       ".section\t.ctors,\"aw\",@progbits",
+                       NULL, /* no cstring section */
+                       NULL,
+                       NULL
                },
-               {
+               { /* GAS_FLAVOUR_MINGW */
                        ".section\t.text",
                        ".section\t.data",
                        ".section .rdata,\"dr\"",
                        ".section\t.bss",
                        ".section\t.tbss,\"awT\",@nobits",
-                       ".section\t.ctors,\"aw\",@progbits"
+                       ".section\t.ctors,\"aw\",@progbits",
+                       NULL,
+                       NULL,
+                       NULL
                },
-               {
+               { /* GAS_FLAVOUR_YASM */
                        ".section\t.text",
-                               ".section\t.data",
-                               ".section\t.rodata",
-                               ".section\t.bss",
-                               ".section\t.tbss,\"awT\",@nobits",
-                               ".section\t.ctors,\"aw\",@progbits"
+                       ".section\t.data",
+                       ".section\t.rodata",
+                       ".section\t.bss",
+                       ".section\t.tbss,\"awT\",@nobits",
+                       ".section\t.ctors,\"aw\",@progbits",
+                       NULL,
+                       NULL,
+                       NULL
+               },
+               { /* GAS_FLAVOUR_MACH_O */
+                       ".text",
+                       ".data",
+                       ".const",
+                       ".data",
+                       NULL,             /* TLS is not supported on Mach-O */
+                       ".mod_init_func",
+                       ".cstring",
+                       ".section\t__IMPORT,__jump_table,symbol_stubs,self_modifying_code+pure_instructions,5",
+                       ".section\t__IMPORT,__pointers,non_lazy_symbol_pointers"
                }
        };
 
-       assert((int) be_gas_flavour >= 0 && be_gas_flavour < GAS_FLAVOUR_MAX);
-       assert((int) section >= 0 && section < GAS_SECTION_MAX);
+       assert((int) be_gas_flavour >= 0 && be_gas_flavour <= GAS_FLAVOUR_LAST);
+       assert((int) section >= 0 && section <= GAS_SECTION_LAST);
        return text[be_gas_flavour][section];
 }
 
-/**
- * Emit necessary code to switch to a section.
- *
- * @param env      the emitter environment
- * @param section  the section to switch to
- */
 void be_gas_emit_switch_section(be_gas_section_t section) {
+       if(current_section == section)
+               return;
+
        be_emit_char('\t');
        be_emit_string(get_section_name(section));
        be_emit_char('\n');
        be_emit_write_line();
+       current_section = section;
+}
+
+void be_gas_emit_function_prolog(ir_entity *entity, unsigned alignment)
+{
+       const char *name = get_entity_ld_name(entity);
+       const char *fill_byte = "";
+       unsigned maximum_skip;
+
+       be_gas_emit_switch_section(GAS_SECTION_TEXT);
+
+       /* write the begin line (used by scripts processing the assembler... */
+       be_emit_write_line();
+       be_emit_cstring("# -- Begin  ");
+       be_emit_string(name);
+       be_emit_char('\n');
+       be_emit_write_line();
+
+       /* gcc fills space between function with 0x90, no idea if this is needed */
+       if (be_gas_flavour == GAS_FLAVOUR_MACH_O) {
+               fill_byte = "0x90";
+       }
+
+       if (alignment > 0) {
+               maximum_skip = (1 << alignment) - 1;
+               be_emit_cstring("\t.p2align ");
+               be_emit_irprintf("%u,%s,%u\n", alignment, fill_byte, maximum_skip);
+               be_emit_write_line();
+       }
+       if (get_entity_visibility(entity) == visibility_external_visible) {
+               be_emit_cstring(".globl ");
+               be_emit_string(name);
+               be_emit_char('\n');
+               be_emit_write_line();
+       }
+
+       switch (be_gas_flavour) {
+       case GAS_FLAVOUR_ELF:
+               be_emit_cstring("\t.type\t");
+               be_emit_string(name);
+               be_emit_cstring(", @function\n");
+               be_emit_write_line();
+               break;
+       case GAS_FLAVOUR_MINGW:
+               be_emit_cstring("\t.def\t");
+               be_emit_string(name);
+               be_emit_cstring(";\t.scl\t2;\t.type\t32;\t.endef\n");
+               be_emit_write_line();
+               break;
+       case GAS_FLAVOUR_MACH_O:
+       case GAS_FLAVOUR_YASM:
+               break;
+       }
+       be_emit_string(name);
+       be_emit_cstring(":\n");
+       be_emit_write_line();
+}
+
+void be_gas_emit_function_epilog(ir_entity *entity)
+{
+       const char *name = get_entity_ld_name(entity);
+
+       if (be_gas_flavour == GAS_FLAVOUR_ELF) {
+               be_emit_cstring("\t.size\t");
+               be_emit_string(name);
+               be_emit_cstring(", .-");
+               be_emit_string(name);
+               be_emit_char('\n');
+               be_emit_write_line();
+       }
+
+       be_emit_cstring("# -- End  ");
+       be_emit_string(name);
+       be_emit_char('\n');
+       be_emit_write_line();
 }
 
 /**
@@ -113,12 +205,9 @@ void be_gas_emit_switch_section(be_gas_section_t section) {
  * and even there NOT needed. So we might change it in the future.
  */
 typedef struct _be_gas_decl_env {
-       obstack_t *rodata_obst;        /**< An obstack that will be filled with all rodata entities. */
-       obstack_t *data_obst;          /**< An obstack that will be filled with the initialized entities. */
-       obstack_t *bss_obst;           /**< An obstack that will be filled with the uninitialized entities. */
-       obstack_t *ctor_obst;          /**< An obstack that will be filled with the constructor entities. */
        const be_main_env_t *main_env; /**< The main backend environment, used for it's debug handle. */
-       waitq     *worklist;           /**< A worklist we use to place not yet handled entities on. */
+       be_gas_section_t     section;
+       waitq               *worklist;           /**< A worklist we use to place not yet handled entities on. */
 } be_gas_decl_env_t;
 
 /************************************************************************/
@@ -126,39 +215,44 @@ typedef struct _be_gas_decl_env {
 /**
  * Output a tarval.
  *
- * @param obst   the obstack where the data is written too
  * @param tv     the tarval
  * @param bytes  the width of the tarvals value in bytes
  */
-static void dump_arith_tarval(obstack_t *obst, tarval *tv, int bytes)
+static void dump_arith_tarval(tarval *tv, int bytes)
 {
        switch (bytes) {
-
        case 1:
-               obstack_printf(obst, "0x%02x", get_tarval_sub_bits(tv, 0));
-               break;
+               be_emit_irprintf("0x%02x", get_tarval_sub_bits(tv, 0));
+               return;
 
        case 2:
-               obstack_printf(obst, "0x%02x%02x", get_tarval_sub_bits(tv, 1), get_tarval_sub_bits(tv, 0));
-               break;
+               be_emit_irprintf("0x%02x%02x", get_tarval_sub_bits(tv, 1), get_tarval_sub_bits(tv, 0));
+               return;
 
        case 4:
-               obstack_printf(obst, "0x%02x%02x%02x%02x",
+               be_emit_irprintf("0x%02x%02x%02x%02x",
                        get_tarval_sub_bits(tv, 3), get_tarval_sub_bits(tv, 2), get_tarval_sub_bits(tv, 1), get_tarval_sub_bits(tv, 0));
-               break;
+               return;
 
        case 8:
-               obstack_printf(obst, "0x%02x%02x%02x%02x%02x%02x%02x%02x",
+               be_emit_irprintf("0x%02x%02x%02x%02x%02x%02x%02x%02x",
                        get_tarval_sub_bits(tv, 7), get_tarval_sub_bits(tv, 6), get_tarval_sub_bits(tv, 5), get_tarval_sub_bits(tv, 4),
                        get_tarval_sub_bits(tv, 3), get_tarval_sub_bits(tv, 2), get_tarval_sub_bits(tv, 1), get_tarval_sub_bits(tv, 0));
-               break;
+               return;
 
-       case 10:
        case 12:
-               break;
+               be_emit_irprintf("0x%02x%02x%02x%02x%02x%02x%02x%02x"
+                                  "%02x%02x%02x%02x", get_tarval_sub_bits(tv, 11),
+                               get_tarval_sub_bits(tv, 10), get_tarval_sub_bits(tv, 9),
+                               get_tarval_sub_bits(tv, 8), get_tarval_sub_bits(tv, 7),
+                               get_tarval_sub_bits(tv, 6), get_tarval_sub_bits(tv, 5),
+                               get_tarval_sub_bits(tv, 4), get_tarval_sub_bits(tv, 3),
+                               get_tarval_sub_bits(tv, 2), get_tarval_sub_bits(tv, 1),
+                               get_tarval_sub_bits(tv, 0));
+               return;
 
        case 16:
-               obstack_printf(obst, "0x%02x%02x%02x%02x%02x%02x%02x%02x"
+               be_emit_irprintf("0x%02x%02x%02x%02x%02x%02x%02x%02x"
                                               "%02x%02x%02x%02x%02x%02x%02x%02x",
                        get_tarval_sub_bits(tv, 15), get_tarval_sub_bits(tv, 16),
                        get_tarval_sub_bits(tv, 13), get_tarval_sub_bits(tv, 12),
@@ -168,13 +262,10 @@ static void dump_arith_tarval(obstack_t *obst, tarval *tv, int bytes)
                        get_tarval_sub_bits(tv, 5), get_tarval_sub_bits(tv, 4),
                        get_tarval_sub_bits(tv, 3), get_tarval_sub_bits(tv, 2),
                        get_tarval_sub_bits(tv, 1), get_tarval_sub_bits(tv, 0));
-               break;
-
-
-       default:
-               fprintf(stderr, "Try to dump an tarval with %d bytes\n", bytes);
-               assert(0);
+               return;
        }
+
+       panic("Can't dump a tarval with %d bytes\n", bytes);
 }
 
 /**
@@ -187,8 +278,8 @@ const char *be_gas_label_prefix(void) {
 /**
  * Dump a label.
  */
-static void dump_label(obstack_t *obst, ir_label_t label) {
-       obstack_printf(obst, "%s%ld", be_gas_label_prefix(), label);
+static void dump_label(ir_label_t label) {
+       be_emit_irprintf("%s%ld", be_gas_label_prefix(), label);
 }
 
 /**
@@ -247,11 +338,9 @@ static tarval *get_atomic_init_tv(ir_node *init)
  * Dump an atomic value.
  *
  * @param env   the gas output environment
- * @param obst  an obstack the output is written to
  * @param init  a node representing the atomic value (on the const code irg)
  */
-static void do_dump_atomic_init(be_gas_decl_env_t *env, obstack_t *obst,
-                                ir_node *init)
+static void do_dump_atomic_init(be_gas_decl_env_t *env, ir_node *init)
 {
        ir_mode *mode = get_irn_mode(init);
        int bytes     = get_mode_size_bytes(mode);
@@ -259,27 +348,28 @@ static void do_dump_atomic_init(be_gas_decl_env_t *env, obstack_t *obst,
        ir_label_t label;
        ir_entity *ent;
 
-       switch (get_irn_opcode(init)) {
+       init = skip_Id(init);
 
+       switch (get_irn_opcode(init)) {
        case iro_Cast:
-               do_dump_atomic_init(env, obst, get_Cast_op(init));
+               do_dump_atomic_init(env, get_Cast_op(init));
                return;
 
        case iro_Conv:
-               do_dump_atomic_init(env, obst, get_Conv_op(init));
+               do_dump_atomic_init(env, get_Conv_op(init));
                return;
 
        case iro_Const:
                tv = get_Const_tarval(init);
 
                /* it's a arithmetic value */
-               dump_arith_tarval(obst, tv, bytes);
+               dump_arith_tarval(tv, bytes);
                return;
 
        case iro_SymConst:
                switch (get_SymConst_kind(init)) {
                case symconst_addr_name:
-                       obstack_printf(obst, "%s", get_id_str(get_SymConst_name(init)));
+                       be_emit_ident(get_SymConst_name(init));
                        break;
 
                case symconst_addr_ent:
@@ -288,7 +378,7 @@ static void do_dump_atomic_init(be_gas_decl_env_t *env, obstack_t *obst,
                                waitq_put(env->worklist, ent);
                                set_entity_backend_marked(ent, 1);
                        }
-                       obstack_printf(obst, "%s", get_entity_ld_name(ent));
+                       be_emit_ident(get_entity_ld_ident(ent));
                        break;
 
                case symconst_ofs_ent:
@@ -299,25 +389,25 @@ static void do_dump_atomic_init(be_gas_decl_env_t *env, obstack_t *obst,
                                set_entity_backend_marked(ent, 1);
                        }
 #endif
-                       obstack_printf(obst, "%d", get_entity_offset(ent));
+                       be_emit_irprintf("%d", get_entity_offset(ent));
                        break;
 
                case symconst_type_size:
-                       obstack_printf(obst, "%u", get_type_size_bytes(get_SymConst_type(init)));
+                       be_emit_irprintf("%u", get_type_size_bytes(get_SymConst_type(init)));
                        break;
 
                case symconst_type_align:
-                       obstack_printf(obst, "%u", get_type_alignment_bytes(get_SymConst_type(init)));
+                       be_emit_irprintf("%u", get_type_alignment_bytes(get_SymConst_type(init)));
                        break;
 
                case symconst_enum_const:
                        tv = get_enumeration_value(get_SymConst_enum(init));
-                       dump_arith_tarval(obst, tv, bytes);
+                       dump_arith_tarval(tv, bytes);
                        break;
 
                case symconst_label:
                        label = get_SymConst_label(init);
-                       dump_label(obst, label);
+                       dump_label(label);
                        break;
 
                default:
@@ -326,21 +416,30 @@ static void do_dump_atomic_init(be_gas_decl_env_t *env, obstack_t *obst,
                return;
 
                case iro_Add:
-                       do_dump_atomic_init(env, obst, get_Add_left(init));
-                       obstack_printf(obst, " + ");
-                       do_dump_atomic_init(env, obst, get_Add_right(init));
+                       if (!mode_is_int(mode) && !mode_is_reference(mode)) {
+                               panic("Constant must be int or pointer for '+' to work");
+                       }
+                       do_dump_atomic_init(env, get_Add_left(init));
+                       be_emit_cstring(" + ");
+                       do_dump_atomic_init(env, get_Add_right(init));
                        return;
 
                case iro_Sub:
-                       do_dump_atomic_init(env, obst, get_Sub_left(init));
-                       obstack_printf(obst, " - ");
-                       do_dump_atomic_init(env, obst, get_Sub_right(init));
+                       if (!mode_is_int(mode) && !mode_is_reference(mode)) {
+                               panic("Constant must be int or pointer for '-' to work");
+                       }
+                       do_dump_atomic_init(env, get_Sub_left(init));
+                       be_emit_cstring(" - ");
+                       do_dump_atomic_init(env, get_Sub_right(init));
                        return;
 
                case iro_Mul:
-                       do_dump_atomic_init(env, obst, get_Mul_left(init));
-                       obstack_printf(obst, " * ");
-                       do_dump_atomic_init(env, obst, get_Mul_right(init));
+                       if (!mode_is_int(mode) && !mode_is_reference(mode)) {
+                               panic("Constant must be int or pointer for '*' to work");
+                       }
+                       do_dump_atomic_init(env, get_Mul_left(init));
+                       be_emit_cstring(" * ");
+                       do_dump_atomic_init(env, get_Mul_right(init));
                        return;
 
                default:
@@ -351,26 +450,24 @@ static void do_dump_atomic_init(be_gas_decl_env_t *env, obstack_t *obst,
 /**
  * Dumps the type for given size (.byte, .long, ...)
  *
- * @param obst  an obstack the output is written to
  * @param size  the size in bytes
  */
-static void dump_size_type(obstack_t *obst, size_t size) {
+static void dump_size_type(size_t size) {
        switch (size) {
-
        case 1:
-               obstack_printf(obst, "\t.byte\t");
+               be_emit_cstring("\t.byte\t");
                break;
 
        case 2:
-               obstack_printf(obst, "\t.value\t");
+               be_emit_cstring("\t.word\t");
                break;
 
        case 4:
-               obstack_printf(obst, "\t.long\t");
+               be_emit_cstring("\t.long\t");
                break;
 
        case 8:
-               obstack_printf(obst, "\t.quad\t");
+               be_emit_cstring("\t.quad\t");
                break;
 
        case 10:
@@ -379,31 +476,29 @@ static void dump_size_type(obstack_t *obst, size_t size) {
                break;
 
        case 16:
-               obstack_printf(obst, "\t.octa\t");
+               be_emit_cstring("\t.octa\t");
                break;
 
        default:
-               fprintf(stderr, "Try to dump a type with %d bytes\n", size);
-               assert(0);
+               panic("Try to dump a type with %u bytes\n", (unsigned) size);
        }
 }
 
 /**
- * Dump an atomic value to an obstack.
+ * Emit an atomic value.
  *
  * @param env   the gas output environment
- * @param obst  an obstack the output is written to
  * @param init  a node representing the atomic value (on the const code irg)
  */
-static void dump_atomic_init(be_gas_decl_env_t *env, obstack_t *obst,
-                             ir_node *init)
+static void dump_atomic_init(be_gas_decl_env_t *env, ir_node *init)
 {
        ir_mode *mode = get_irn_mode(init);
        int bytes     = get_mode_size_bytes(mode);
 
-       dump_size_type(obst, bytes);
-       do_dump_atomic_init(env, obst, init);
-       obstack_printf(obst, "\n");
+       dump_size_type(bytes);
+       do_dump_atomic_init(env, init);
+       be_emit_char('\n');
+       be_emit_write_line();
 }
 
 /************************************************************************/
@@ -413,11 +508,14 @@ static void dump_atomic_init(be_gas_decl_env_t *env, obstack_t *obst,
 static int initializer_is_string_const(const ir_initializer_t *initializer)
 {
        size_t i, len;
+       int found_printable = 0;
 
        if(initializer->kind != IR_INITIALIZER_COMPOUND)
                return 0;
 
        len = initializer->compound.n_initializers;
+       if (len < 1)
+               return 0;
        for(i = 0; i < len; ++i) {
                int               c;
                tarval           *tv;
@@ -436,12 +534,16 @@ static int initializer_is_string_const(const ir_initializer_t *initializer)
                        return 0;
 
                c = get_tarval_long(tv);
-               if((i < len - 1 && !(isgraph(c) || isspace(c)))
-                               || (i >= len - 1 && c != 0))
+               if (isgraph(c) || isspace(c))
+                       found_printable = 1;
+               else if(c != 0)
+                       return 0;
+
+               if (i == len - 1 && c != '\0')
                        return 0;
        }
 
-       return 1;
+       return found_printable;
 }
 
 /**
@@ -454,6 +556,7 @@ static int ent_is_string_const(ir_entity *ent)
        ir_type *type, *element_type;
        ir_mode *mode;
        int i, c, n;
+       int found_printable = 0;
 
        type = get_entity_type(ent);
 
@@ -487,34 +590,42 @@ static int ent_is_string_const(ir_entity *ent)
 
                        c = (int) get_tarval_long(get_Const_tarval(irn));
 
-                       if((i < n - 1 && !(isgraph(c) || isspace(c)))
-                                       || (i == n - 1 && c != '\0'))
+                       if (isgraph(c) || isspace(c))
+                               found_printable = 1;
+                       else if(c != 0)
+                               return 0;
+
+                       if (i == n - 1 && c != '\0')
                                return 0;
                }
        }
 
        /* then we can emit it as a string constant */
-       return 1;
+       return found_printable;
 }
 
 /**
  * Dump a string constant.
  * No checks are made!!
  *
- * @param obst The obst to dump on.
  * @param ent  The entity to dump.
  */
-static void dump_string_cst(obstack_t *obst, ir_entity *ent)
+static void dump_string_cst(ir_entity *ent)
 {
-       int      i, n;
+       int      i, len;
        ir_type *type;
        int      type_size;
        int      remaining_space;
 
-       obstack_printf(obst, "\t.string \"");
-       n = get_compound_ent_n_values(ent);
+       len = get_compound_ent_n_values(ent);
+       if (be_gas_flavour == GAS_FLAVOUR_MACH_O) {
+               be_emit_cstring("\t.ascii \"");
+       } else {
+               be_emit_cstring("\t.string \"");
+               len -= 1;
+       }
 
-       for (i = 0; i < n-1; ++i) {
+       for (i = 0; i < len; ++i) {
                ir_node *irn;
                int c;
 
@@ -522,39 +633,44 @@ static void dump_string_cst(obstack_t *obst, ir_entity *ent)
                c = (int) get_tarval_long(get_Const_tarval(irn));
 
                switch (c) {
-               case '"' : obstack_printf(obst, "\\\""); break;
-               case '\n': obstack_printf(obst, "\\n"); break;
-               case '\r': obstack_printf(obst, "\\r"); break;
-               case '\t': obstack_printf(obst, "\\t"); break;
-               case '\\': obstack_printf(obst, "\\\\"); break;
+               case '"' : be_emit_cstring("\\\""); break;
+               case '\n': be_emit_cstring("\\n"); break;
+               case '\r': be_emit_cstring("\\r"); break;
+               case '\t': be_emit_cstring("\\t"); break;
+               case '\\': be_emit_cstring("\\\\"); break;
                default  :
                        if (isprint(c))
-                               obstack_printf(obst, "%c", c);
+                               be_emit_char(c);
                        else
-                               obstack_printf(obst, "\\%o", c);
+                               be_emit_irprintf("\\%o", c);
                        break;
                }
        }
-       obstack_printf(obst, "\"\n");
+       be_emit_cstring("\"\n");
+       be_emit_write_line();
 
        type            = get_entity_type(ent);
        type_size       = get_type_size_bytes(type);
-       remaining_space = type_size - n;
+       remaining_space = type_size - len;
        assert(remaining_space >= 0);
        if(remaining_space > 0) {
-               obstack_printf(obst, "\t.skip\t%d\n", remaining_space);
+               be_emit_irprintf("\t.skip\t%d\n", remaining_space);
        }
 }
 
-static void dump_string_initializer(obstack_t *obst,
-                                    const ir_initializer_t *initializer)
+static void dump_string_initializer(const ir_initializer_t *initializer)
 {
        size_t i, len;
 
-       obstack_printf(obst, "\t.string \"");
-
        len = initializer->compound.n_initializers;
-       for(i = 0; i < len - 1; ++i) {
+       if(be_gas_flavour == GAS_FLAVOUR_MACH_O) {
+               be_emit_cstring("\t.ascii \"");
+       } else {
+               be_emit_cstring("\t.string \"");
+               len -= 1;
+       }
+
+       for(i = 0; i < len; ++i) {
                const ir_initializer_t *sub_initializer
                        = get_initializer_compound_value(initializer, i);
 
@@ -562,20 +678,21 @@ static void dump_string_initializer(obstack_t *obst,
                int     c  = get_tarval_long(tv);
 
                switch (c) {
-               case '"' : obstack_printf(obst, "\\\""); break;
-               case '\n': obstack_printf(obst, "\\n"); break;
-               case '\r': obstack_printf(obst, "\\r"); break;
-               case '\t': obstack_printf(obst, "\\t"); break;
-               case '\\': obstack_printf(obst, "\\\\"); break;
+               case '"' : be_emit_cstring("\\\""); break;
+               case '\n': be_emit_cstring("\\n"); break;
+               case '\r': be_emit_cstring("\\r"); break;
+               case '\t': be_emit_cstring("\\t"); break;
+               case '\\': be_emit_cstring("\\\\"); break;
                default  :
                        if (isprint(c))
-                               obstack_printf(obst, "%c", c);
+                               be_emit_char(c);
                        else
-                               obstack_printf(obst, "\\%o", c);
+                               be_emit_irprintf("\\%o", c);
                        break;
                }
        }
-       obstack_printf(obst, "\"\n");
+       be_emit_cstring("\"\n");
+       be_emit_write_line();
 }
 
 enum normal_or_bitfield_kind {
@@ -790,8 +907,7 @@ static void dump_ir_initializer(normal_or_bitfield *vals,
        panic("invalid ir_initializer kind found");
 }
 
-static void dump_initializer(be_gas_decl_env_t *env, obstack_t *obst,
-                             ir_entity *entity)
+static void dump_initializer(be_gas_decl_env_t *env, ir_entity *entity)
 {
        const ir_initializer_t *initializer = entity->attr.initializer;
        ir_type                *type;
@@ -800,13 +916,16 @@ static void dump_initializer(be_gas_decl_env_t *env, obstack_t *obst,
        size_t                  k;
 
        if(initializer_is_string_const(initializer)) {
-               dump_string_initializer(obst, initializer);
+               dump_string_initializer(initializer);
                return;
        }
 
        type = get_entity_type(entity);
        size = get_initializer_size(initializer, type);
 
+       if (size == 0)
+               return;
+
        /*
         * In the worst case, every initializer allocates one byte.
         * Moreover, initializer might be big, do not allocate on stack.
@@ -822,13 +941,14 @@ static void dump_initializer(be_gas_decl_env_t *env, obstack_t *obst,
 
        /* now write values sorted */
        for (k = 0; k < size; ) {
-               int space = 0, skip = 0;
+               int space     = 0;
+               int elem_size = 1;
                if (vals[k].kind == NORMAL) {
                        if(vals[k].v.value != NULL) {
-                               dump_atomic_init(env, obst, vals[k].v.value);
-                               skip = get_mode_size_bytes(get_irn_mode(vals[k].v.value)) - 1;
+                               dump_atomic_init(env, vals[k].v.value);
+                               elem_size = get_mode_size_bytes(get_irn_mode(vals[k].v.value));
                        } else {
-                               space = 1;
+                               elem_size = 0;
                        }
                } else if(vals[k].kind == TARVAL) {
                        tarval *tv   = vals[k].v.tarval;
@@ -836,43 +956,43 @@ static void dump_initializer(be_gas_decl_env_t *env, obstack_t *obst,
 
                        assert(tv != NULL);
 
-                       skip = size - 1;
-                       dump_size_type(obst, size);
-                       dump_arith_tarval(obst, tv, size);
-                       obstack_1grow(obst, '\n');
+                       elem_size = size;
+                       dump_size_type(size);
+                       dump_arith_tarval(tv, size);
+                       be_emit_char('\n');
+                       be_emit_write_line();
                } else {
                        assert(vals[k].kind == BITFIELD);
-                       obstack_printf(obst, "\t.byte\t%d\n", vals[k].v.bf_val);
+                       be_emit_irprintf("\t.byte\t%d\n", vals[k].v.bf_val);
+                       be_emit_write_line();
                }
 
-               ++k;
+               k += elem_size;
                while (k < size && vals[k].kind == NORMAL && vals[k].v.value == NULL) {
                        ++space;
                        ++k;
                }
-               space -= skip;
-               assert(space >= 0);
 
                /* a gap */
-               if (space > 0)
-                       obstack_printf(obst, "\t.skip\t%d\n", space);
+               if (space > 0) {
+                       be_emit_irprintf("\t.skip\t%d\n", space);
+                       be_emit_write_line();
+               }
        }
        xfree(vals);
-
 }
 
 /**
  * Dump an initializer for a compound entity.
  */
-static void dump_compound_init(be_gas_decl_env_t *env, obstack_t *obst,
-                               ir_entity *ent)
+static void dump_compound_init(be_gas_decl_env_t *env, ir_entity *ent)
 {
        normal_or_bitfield *vals;
        int i, j, n;
        unsigned k, last_ofs;
 
        if(ent->has_initializer) {
-               dump_initializer(env, obst, ent);
+               dump_initializer(env, ent);
                return;
        }
 
@@ -948,14 +1068,14 @@ static void dump_compound_init(be_gas_decl_env_t *env, obstack_t *obst,
                int space = 0, skip = 0;
                if (vals[k].kind == NORMAL) {
                        if(vals[k].v.value != NULL) {
-                               dump_atomic_init(env, obst, vals[k].v.value);
+                               dump_atomic_init(env, vals[k].v.value);
                                skip = get_mode_size_bytes(get_irn_mode(vals[k].v.value)) - 1;
                        } else {
                                space = 1;
                        }
                } else {
                        assert(vals[k].kind == BITFIELD);
-                       obstack_printf(obst, "\t.byte\t%d\n", vals[k].v.bf_val);
+                       be_emit_irprintf("\t.byte\t%d\n", vals[k].v.bf_val);
                }
 
                ++k;
@@ -967,106 +1087,141 @@ static void dump_compound_init(be_gas_decl_env_t *env, obstack_t *obst,
                assert(space >= 0);
 
                /* a gap */
-               if (space > 0)
-                       obstack_printf(obst, "\t.skip\t%d\n", space);
+               if (space > 0) {
+                       be_emit_irprintf("\t.skip\t%d\n", space);
+                       be_emit_write_line();
+               }
        }
        xfree(vals);
 }
 
+static void emit_align(unsigned alignment)
+{
+       if (!is_po2(alignment))
+               panic("alignment not a power of 2");
+
+       be_emit_irprintf(".p2align\t%u\n", log2_floor(alignment));
+       be_emit_write_line();
+}
+
 /**
  * Dump a global entity.
  *
  * @param env           the gas output environment
  * @param ent           the entity to be dumped
- * @param emit_commons  if non-zero, emit commons (non-local uninitialized entities)
  */
-static void dump_global(be_gas_decl_env_t *env, ir_entity *ent, int emit_commons)
+static void dump_global(be_gas_decl_env_t *env, ir_entity *ent)
 {
-       obstack_t *obst;
-       ir_type *type = get_entity_type(ent);
-       const char *ld_name = get_entity_ld_name(ent);
-       unsigned align = get_type_alignment_bytes(type);
-       int emit_as_common = 0;
-       ir_variability variability;
-       ir_visibility visibility;
-
-       obst = env->data_obst;
-       if (is_Method_type(type)) {
-               if (get_method_img_section(ent) == section_constructors) {
-                       obst = env->ctor_obst;
-                       obstack_printf(obst, ".balign\t%u\n", align);
-                       dump_size_type(obst, align);
-                       obstack_printf(obst, "%s\n", ld_name);
-               }
+       ir_type          *type           = get_entity_type(ent);
+       ident            *ld_ident       = get_entity_ld_ident(ent);
+       unsigned          align          = get_type_alignment_bytes(type);
+       int               emit_as_common = 0;
+       be_gas_section_t  section        = env->section;
+       ir_variability    variability    = get_entity_variability(ent);
+       ir_visibility     visibility     = get_entity_visibility(ent);
+
+       if (is_Method_type(type) && section != GAS_SECTION_PIC_TRAMPOLINES) {
                return;
        }
 
-       variability = get_entity_variability(ent);
-       visibility = get_entity_visibility(ent);
-       if (variability == variability_constant) {
+       if (section != (be_gas_section_t) -1) {
+               emit_as_common = 0;
+       } else if (variability == variability_constant) {
                /* a constant entity, put it on the rdata */
-               obst = env->rodata_obst;
+               section = GAS_SECTION_RODATA;
+               if (be_gas_flavour == GAS_FLAVOUR_MACH_O
+                               && ent_is_string_const(ent)) {
+                       section = GAS_SECTION_CSTRING;
+               }
        } else if (variability == variability_uninitialized) {
                /* uninitialized entity put it in bss segment */
-               obst = env->bss_obst;
-               if (emit_commons && visibility != visibility_local)
+               section = GAS_SECTION_COMMON;
+               if (visibility != visibility_local)
                        emit_as_common = 1;
+       } else {
+               section = GAS_SECTION_DATA;
+       }
+
+       if(!emit_as_common) {
+               be_gas_emit_switch_section(section);
        }
 
-       be_dbg_variable(env->main_env->db_handle, obst, ent);
+       be_dbg_variable(ent);
 
        /* global or not global */
        if (visibility == visibility_external_visible && !emit_as_common) {
-               obstack_printf(obst, ".global\t%s\n", ld_name);
+               be_emit_cstring(".globl\t");
+               be_emit_ident(ld_ident);
+               be_emit_char('\n');
+               be_emit_write_line();
        } else if(visibility == visibility_external_allocated) {
-               obstack_printf(obst, ".global\t%s\n", ld_name);
+               be_emit_cstring(".globl\t");
+               be_emit_ident(ld_ident);
+               be_emit_char('\n');
+               be_emit_write_line();
                /* we can return now... */
                return;
        }
        /* alignment */
-       if (align > 1 && !emit_as_common) {
-               obstack_printf(obst, ".balign\t%u\n", align);
+       if (align > 1 && !emit_as_common && section != GAS_SECTION_PIC_TRAMPOLINES
+                       && section != GAS_SECTION_PIC_SYMBOLS) {
+               emit_align(align);
        }
 
        if (!emit_as_common) {
-               obstack_printf(obst, "%s:\n", ld_name);
+               be_emit_ident(ld_ident);
+               be_emit_cstring(":\n");
+               be_emit_write_line();
        }
 
        if (variability == variability_uninitialized) {
                if (emit_as_common) {
                        switch (be_gas_flavour) {
-                       case GAS_FLAVOUR_NORMAL:
+                       case GAS_FLAVOUR_ELF:
+                       case GAS_FLAVOUR_MACH_O:
                        case GAS_FLAVOUR_YASM:
-                               obstack_printf(obst, "\t.comm %s,%u,%u\n",
-                                       ld_name, get_type_size_bytes(type), align);
+                               be_emit_irprintf("\t.comm %s,%u,%u\n",
+                                       get_id_str(ld_ident), get_type_size_bytes(type), align);
+                               be_emit_write_line();
                                break;
                        case GAS_FLAVOUR_MINGW:
-                               obstack_printf(obst, "\t.comm %s,%u # %u\n",
-                                       ld_name, get_type_size_bytes(type), align);
+                               be_emit_irprintf("\t.comm %s,%u # %u\n",
+                                       get_id_str(ld_ident), get_type_size_bytes(type), align);
+                               be_emit_write_line();
                                break;
-                       case GAS_FLAVOUR_MAX:
-                               panic("invalid gas flavour selected");
+                       }
+               } else if (section == GAS_SECTION_PIC_TRAMPOLINES) {
+                       if (be_gas_flavour == GAS_FLAVOUR_MACH_O) {
+                               be_emit_cstring("\t.indirect_symbol ");
+                               be_emit_ident(get_entity_ident(ent));
+                               be_emit_char('\n');
+                               be_emit_write_line();
+                               be_emit_cstring("\thlt ; hlt ; hlt ; hlt ; hlt\n");
+                               be_emit_write_line();
+                       } else {
+                               panic("PIC trampolines not yet supported in this gas mode");
                        }
                } else {
-                       obstack_printf(obst, "\t.zero %u\n", get_type_size_bytes(type));
+                       be_emit_irprintf("\t.space %u\n", get_type_size_bytes(type));
+                       be_emit_write_line();
                }
        } else {
                if (is_atomic_entity(ent)) {
-                       dump_atomic_init(env, obst, get_atomic_ent_value(ent));
+                       dump_atomic_init(env, get_atomic_ent_value(ent));
                } else {
                        /* sort_compound_ent_values(ent); */
 
                        switch (get_type_tpop_code(get_entity_type(ent))) {
                        case tpo_array:
                                if (ent_is_string_const(ent))
-                                       dump_string_cst(obst, ent);
+                                       dump_string_cst(ent);
                                else
-                                       dump_compound_init(env, obst, ent);
+                                       dump_compound_init(env, ent);
                                break;
                        case tpo_struct:
                        case tpo_class:
                        case tpo_union:
-                               dump_compound_init(env, obst, ent);
+                               dump_compound_init(env, ent);
                                break;
                        default:
                                assert(0);
@@ -1080,12 +1235,11 @@ static void dump_global(be_gas_decl_env_t *env, ir_entity *ent, int emit_commons
  *
  * @param gt                a global like type, either the global or the TLS one
  * @param env               an environment
- * @param emit_commons      if non-zero, emit commons (non-local uninitialized entities)
  * @param only_emit_marked  if non-zero, external allocated entities that do not have
  *                          its visited flag set are ignored
  */
 static void be_gas_dump_globals(ir_type *gt, be_gas_decl_env_t *env,
-                              int emit_commons, int only_emit_marked)
+                                int only_emit_marked)
 {
        int i, n = get_compound_n_members(gt);
        waitq *worklist = new_waitq();
@@ -1112,7 +1266,7 @@ static void be_gas_dump_globals(ir_type *gt, be_gas_decl_env_t *env,
        while (!waitq_empty(worklist)) {
                ir_entity *ent = waitq_get(worklist);
 
-               dump_global(env, ent, emit_commons);
+               dump_global(env, ent);
        }
 
        del_waitq(worklist);
@@ -1126,83 +1280,29 @@ void be_gas_emit_decls(const be_main_env_t *main_env,
                        int only_emit_marked_entities)
 {
        be_gas_decl_env_t env;
-       obstack_t         rodata;
-       obstack_t         data;
-       obstack_t         bss;
-       obstack_t         ctor;
-       int               size;
-       char              *cp;
-
-       /* dump the global type */
-       obstack_init(&rodata);
-       obstack_init(&data);
-       obstack_init(&bss);
-       obstack_init(&ctor);
-
-       env.rodata_obst = &rodata;
-       env.data_obst   = &data;
-       env.bss_obst    = &bss;
-       env.ctor_obst   = &ctor;
-       env.main_env    = main_env;
-
-       be_gas_dump_globals(get_glob_type(), &env, 1, only_emit_marked_entities);
-
-       size = obstack_object_size(&data);
-       cp   = obstack_finish(&data);
-       if (size > 0) {
-               be_gas_emit_switch_section(GAS_SECTION_DATA);
-               be_emit_string_len(cp, size);
-               be_emit_write_line();
-       }
-
-       size = obstack_object_size(&rodata);
-       cp   = obstack_finish(&rodata);
-       if (size > 0) {
-               be_gas_emit_switch_section(GAS_SECTION_RODATA);
-               be_emit_string_len(cp, size);
-               be_emit_write_line();
-       }
-
-       size = obstack_object_size(&bss);
-       cp   = obstack_finish(&bss);
-       if (size > 0) {
-               be_gas_emit_switch_section(GAS_SECTION_COMMON);
-               be_emit_string_len(cp, size);
-               be_emit_write_line();
-       }
-
-       size = obstack_object_size(&ctor);
-       cp   = obstack_finish(&ctor);
-       if (size > 0) {
-               be_gas_emit_switch_section(GAS_SECTION_CTOR);
-               be_emit_string_len(cp, size);
-               be_emit_write_line();
-       }
-
-       obstack_free(&rodata, NULL);
-       obstack_free(&data, NULL);
-       obstack_free(&bss, NULL);
-       obstack_free(&ctor, NULL);
-
-       /* dump the Thread Local Storage */
-       obstack_init(&data);
-
-       env.rodata_obst = &data;
-       env.data_obst   = &data;
-       env.bss_obst    = &data;
-       env.ctor_obst   = NULL;
-
-       be_gas_dump_globals(get_tls_type(), &env, 0, only_emit_marked_entities);
-
-       size = obstack_object_size(&data);
-       cp   = obstack_finish(&data);
-       if (size > 0) {
-               be_gas_emit_switch_section(GAS_SECTION_TLS);
-               be_emit_cstring(".balign\t32\n");
-               be_emit_write_line();
-               be_emit_string_len(cp, size);
-               be_emit_write_line();
+       memset(&env, 0, sizeof(env));
+
+       env.main_env = main_env;
+
+       /* dump global type */
+       env.section = (be_gas_section_t) -1;
+       be_gas_dump_globals(get_glob_type(), &env, only_emit_marked_entities);
+       env.section = GAS_SECTION_TLS;
+       be_gas_dump_globals(get_tls_type(), &env, only_emit_marked_entities);
+       env.section = GAS_SECTION_CTOR;
+       be_gas_dump_globals(get_constructors_type(), &env,
+                           only_emit_marked_entities);
+       env.section = GAS_SECTION_PIC_SYMBOLS;
+       be_gas_dump_globals(main_env->pic_symbols_type, &env,
+                           only_emit_marked_entities);
+
+       if (get_compound_n_members(main_env->pic_trampolines_type) > 0) {
+               env.section = GAS_SECTION_PIC_TRAMPOLINES;
+               be_gas_dump_globals(main_env->pic_trampolines_type, &env,
+                                   only_emit_marked_entities);
+               if (be_gas_flavour == GAS_FLAVOUR_MACH_O) {
+                       be_emit_cstring("\t.subsections_via_symbols\n");
+                       be_emit_write_line();
+               }
        }
-
-       obstack_free(&data, NULL);
 }