rewrite backtrace iteration to eliminate special-case for top stack e…

…lement this eliminates essentially duplicate code
parrot · Sep 2, 2011 · bab687c · bab687c
1 parent d52dba8
commit bab687c
Showing 1 changed file with 21 additions and 77 deletions.
diff --git a/src/debug.c b/src/debug.c
@@ -3651,94 +3651,45 @@ Returns an string with the backtrace of interpreter's call chain for the given c
 PARROT_WARN_UNUSED_RESULT
 PARROT_CANNOT_RETURN_NULL
 static STRING *
-PDB_get_continuation_backtrace(PARROT_INTERP, ARGMOD(PMC * ctx))
+PDB_get_continuation_backtrace(PARROT_INTERP, ARGIN(PMC *ctx))
 {
     ASSERT_ARGS(PDB_get_continuation_backtrace)
-    PMC    *sub         = Parrot_pcc_get_sub(interp, ctx);
-    STRING *str;
-    PMC    *old         = PMCNULL;
-    PMC    *output      = Parrot_pmc_new(interp, enum_class_StringBuilder);
-    int     rec_level   = 0;
-    int     limit_count = 0;
-
-    if (!PMC_IS_NULL(sub)) {
-        str = Parrot_sub_Context_infostr(interp, ctx);
-        if (str) {
-            PackFile_ByteCode *seg = PARROT_SUB(CONTEXT_STRUCT(ctx)->current_sub)->seg;
-            VTABLE_push_string(interp, output, str);
-            if (seg->annotations) {
-                PMC *annot = PackFile_Annotations_lookup(interp, seg->annotations,
-                        Parrot_pcc_get_pc(interp, ctx) - seg->base.data + 1, NULL);
-                if (!PMC_IS_NULL(annot)) {
-                    PMC *pfile = VTABLE_get_pmc_keyed_str(interp, annot,
-                            Parrot_str_new_constant(interp, "file"));
-                    PMC *pline = VTABLE_get_pmc_keyed_str(interp, annot,
-                            Parrot_str_new_constant(interp, "line"));
-                    if ((!PMC_IS_NULL(pfile)) && (!PMC_IS_NULL(pline))) {
-                        STRING * const file = VTABLE_get_string(interp, pfile);
-                        INTVAL line = VTABLE_get_integer(interp, pline);
-                        STRING * const fmt =
-                            Parrot_sprintf_c(interp, " (%Ss:%li)", file, (long)line);
-                        VTABLE_push_string(interp, output, fmt);
-                    }
-                }
-            }
-            VTABLE_push_string(interp, output, CONST_STRING(interp, "\n"));
-        }
-    }
+    PMC    *output     = Parrot_pmc_new(interp, enum_class_StringBuilder);
+    int     rec_level  = 0;
+    int     loop_count;
+    PMC    *prev_ctx;
 
     /* backtrace: follow the continuation chain */
-    while (1) {
-        Parrot_Continuation_attributes *sub_cont;
-
-        /* Limit the levels dumped, no segfault on infinite recursion */
-        if (++limit_count > RECURSION_LIMIT)
+    for (prev_ctx = PMCNULL, loop_count = 0;
+        ctx && loop_count < RECURSION_LIMIT;
+        loop_count++, prev_ctx = ctx, ctx = Parrot_pcc_get_caller_ctx(interp, ctx)) {
+        STRING *info_str = Parrot_sub_Context_infostr(interp, ctx);
+        if (!info_str)
             break;
 
-        sub = Parrot_pcc_get_continuation(interp, ctx);
-
-        if (PMC_IS_NULL(sub))
-            break;
-
-
-        sub_cont = PARROT_CONTINUATION(sub);
-
-        if (!sub_cont)
-            break;
-
-
-        str = Parrot_sub_Context_infostr(interp, Parrot_pcc_get_caller_ctx(interp, ctx));
-
-
-        if (!str)
-            break;
-
-
         /* recursion detection */
-        if (ctx == sub_cont->to_ctx) {
+        if (ctx == prev_ctx) {
             ++rec_level;
         }
-        else if (!PMC_IS_NULL(old) && PMC_cont(old) &&
-            Parrot_pcc_get_pc(interp, PMC_cont(old)->to_ctx) ==
-            Parrot_pcc_get_pc(interp, PMC_cont(sub)->to_ctx) &&
-            Parrot_pcc_get_sub(interp, PMC_cont(old)->to_ctx) ==
-            Parrot_pcc_get_sub(interp, PMC_cont(sub)->to_ctx)) {
-                ++rec_level;
+        else if (!PMC_IS_NULL(prev_ctx)
+        &&       Parrot_pcc_get_pc(interp,  ctx) == Parrot_pcc_get_pc(interp,  prev_ctx)
+        &&       Parrot_pcc_get_sub(interp, ctx) == Parrot_pcc_get_sub(interp, prev_ctx)) {
+            ++rec_level;
         }
         else if (rec_level != 0) {
             STRING * const fmt =
                 Parrot_sprintf_c(interp, "... call repeated %d times\n", rec_level);
             VTABLE_push_string(interp, output, fmt);
             rec_level = 0;
         }
-
-        /* print the context description */
-        if (rec_level == 0) {
-            PackFile_ByteCode *seg = sub_cont->seg;
-            VTABLE_push_string(interp, output, str);
+        else {
+            /* print the context description */
+            PMC               *sub = Parrot_pcc_get_sub(interp, ctx);
+            PackFile_ByteCode *seg = PARROT_SUB(sub)->seg;
+            VTABLE_push_string(interp, output, info_str);
             if (seg->annotations) {
                 PMC *annot = PackFile_Annotations_lookup(interp, seg->annotations,
-                        Parrot_pcc_get_pc(interp, sub_cont->to_ctx) - seg->base.data,
+                        Parrot_pcc_get_pc(interp, ctx) - seg->base.data,
                         NULL);
 
                 if (!PMC_IS_NULL(annot)) {
@@ -3757,13 +3708,6 @@ PDB_get_continuation_backtrace(PARROT_INTERP, ARGMOD(PMC * ctx))
             }
             VTABLE_push_string(interp, output, CONST_STRING(interp, "\n"));
         }
-
-        /* get the next Continuation */
-        ctx = Parrot_pcc_get_caller_ctx(interp, ctx);
-        old = sub;
-
-        if (!ctx)
-            break;
     }
 
     if (rec_level != 0) {