BugFix: fixed list_for_each_safe() instance.

[libfirm] / ir / be / beemitter_binary.c

diff --git a/ir/be/beemitter_binary.c b/ir/be/beemitter_binary.c
index 5765078..f80246f 100644 (file)
--- a/ir/be/beemitter_binary.c
+++ b/ir/be/beemitter_binary.c
@@ -43,8 +43,8 @@ struct obstack code_fragment_obst;
     be_emit(8/16/32/entity) call!) */
 code_fragment_t *be_get_current_fragment(void)
 {
-       assert(obstack_object_size(&code_fragment_obst) >= sizeof(code_fragment_t));
        code_fragment_t *fragment = obstack_base(&code_fragment_obst);
+       assert(obstack_object_size(&code_fragment_obst) >= sizeof(code_fragment_t));
        assert(fragment->magic == CODE_FRAGMENT_MAGIC);
 
        return fragment;
@@ -121,7 +121,8 @@ static unsigned align(unsigned offset, unsigned alignment)
        return offset;
 }
 
-static bool determine_jumpsize_pass(const binary_emiter_interface_t *interface)
+static bool determine_jumpsize_iteration(
+               const binary_emiter_interface_t *interface)
 {
        unsigned         offset     = 0;
        unsigned         max_offset = 0;
@@ -137,7 +138,7 @@ static bool determine_jumpsize_pass(const binary_emiter_interface_t *interface)
            max_offset = align(max_offset, alignment);
 
                if (offset != fragment->offset) {
-                       changed = true;
+                       changed          = true;
                        fragment->offset = offset;
                }
            fragment->max_offset = max_offset;
@@ -161,9 +162,14 @@ static void determine_offsets(const binary_emiter_interface_t *interface)
        first_fragment->offset     = 0;
        first_fragment->max_offset = 0;
 
-       /* pass1: encode minimum/maximum offsets into fragments */
+       /* The algorithm calculates a lower and upper bound for the offset of each
+        * fragment. With this information we can calculate a lower and upper bound
+        * for the size of each jump instruction.
+        * A single iteration updates the offset bounds for all fragments and jump
+        * sizes for each fragment. We iterate until we had an iteration where
+        * none of the minimum offsets changed. */
        do {
-               changed = determine_jumpsize_pass(interface);
+               changed = determine_jumpsize_iteration(interface);
                /* TODO: we should have an abort mode for the case when the offsets
                   don't converge fast enough. We could simply use a pessimistic
                   solution after a few iterations... */
@@ -186,10 +192,11 @@ void be_emit_code(FILE *output, const binary_emiter_interface_t *interface)
        for (fragment = first_fragment; fragment != NULL;
             fragment = fragment->next) {
            unsigned char *jmpbuffer;
+               unsigned nops;
 
            /* assure alignment by emitting nops */
            assert(fragment->offset >= offset);
-           unsigned nops = fragment->offset - offset;
+           nops = fragment->offset - offset;
            if (nops > 0) {
                unsigned char *nopbuffer = obstack_alloc(&code_fragment_obst, nops);
                interface->create_nops(nopbuffer, nops);