[RFC][PATCH?] fixed some segfaults and bugs in mdebug support

[Zeck S <zeck654321@gmail.com>]

I'm not quite sure what to do.
I have done some testing using the qemu-mips board I made.
There are a lot of limitations I'm running into.
I can just run as much of the testsuite as I can and see what happens.


Here are the main problems:
1. IDO only supports ansi c. This is a problem for some headers in glibc which use c99.
2. Test code sometimes has GCC features in them like asm()
3. Test expectations sometimes assume features from nicer formats like DWARF.

I knew I probably couldn't get standard library stuff working.
Even if I hack past the C99 issues (variadic macros),
there's also problems
with compiler specific files like stddef.h.

I started testing by just running gdb.base/info-types-c.exp alone,
since I knew I fixed bugs in that area, and the test didn't use stdio.h.
Found that the .c file used asm() which IDO doesn't support.
Commented that code out, ran the test. Failed.
Fixed a segfault that had been introduced since I started this project.
Still failed.
Fixed some typedef handling to get closer to the expected output.
However, the expected output includes line numbers for types.
mdebug format doesn't include line information for types.
There are also differences in output stemming from
mdebug assuming the debugger knows size information etc about "basic"
types, unlike dwarf, which includes information about them.

So at this point, I realize, I've modified the .c file for the test
which already seems not great, and I realize due to limitations of mdebug,
I can't ever make the test pass.
Not sure how to demonstrate this as progress, but uh, it feels like progress?


For the curious, this is the bash script I wrapped IDO with.
stderr is directed to dev null, because qemu-irix puts some non fatal
errors there, which confuses the test runner.
Put the script in a directory in PATH.
Passing an executable path as CC_FOR_TARGET does not work.
It must be the name of a file in PATH.

#!/bin/sh

echo "$@" >> theargs

for arg do
  if [ "$arg" = "-static" ]
  then
    link=1
  fi
done

if [ "$link" = 1 ]
then
  mips-unknown-linux-gnu-gcc "$@"
else
for arg do
  shift
  [ "$arg" = "-fdiagnostics-color=never" ] && continue
  [ "$arg" = "-g" ] && continue
  set -- "$@" "$arg"
done

/path/to/qemu-irix -L /path/to/ido/ido7.1_compiler /path/to/ido/ido7.1_compiler/usr/bin/cc -Xcpluscomm -nostdlib -nostdinc -mips2 -g2 "$@" 2>/dev/null
fi


---
 gdb/mdebugread.c | 89 ++++++++++++++++++++++++++++--------------------
 1 file changed, 52 insertions(+), 37 deletions(-)

diff --git a/gdb/mdebugread.c b/gdb/mdebugread.c
index cd6638224e7..191932e91cd 100644
--- a/gdb/mdebugread.c
+++ b/gdb/mdebugread.c
@@ -237,7 +237,7 @@ static struct type *new_type (char *);
 enum block_type { FUNCTION_BLOCK, NON_FUNCTION_BLOCK };
 
 static struct block *new_block (struct objfile *objfile,
-				enum block_type, enum language);
+				enum block_type, enum language, bool isGlobal);
 
 static struct compunit_symtab *new_symtab (const char *, int, struct objfile *);
 
@@ -246,7 +246,7 @@ static struct linetable *new_linetable (int);
 static struct blockvector *new_bvect (int);
 
 static struct type *parse_type (int, union aux_ext *, unsigned int, int *,
-				int, const char *);
+				int, const char *, bool);
 
 static struct symbol *mylookup_symbol (const char *, const struct block *,
 				       domain_enum, enum address_class);
@@ -572,7 +572,7 @@ add_data_symbol (SYMR *sh, union aux_ext *ax, int bigend,
       || sh->sc == scNil || sh->index == indexNil)
     s->set_type (builtin_type (objfile)->nodebug_data_symbol);
   else
-    s->set_type (parse_type (cur_fd, ax, sh->index, 0, bigend, name));
+    s->set_type (parse_type (cur_fd, ax, sh->index, 0, bigend, name, false));
   /* Value of a data symbol is its memory address.  */
 }
 
@@ -705,7 +705,7 @@ parse_symbol (SYMR *sh, union aux_ext *ax, char *ext_sh, int bigend,
 	  break;
 	}
       s->set_value_longest (svalue);
-      s->set_type (parse_type (cur_fd, ax, sh->index, 0, bigend, name));
+      s->set_type (parse_type (cur_fd, ax, sh->index, 0, bigend, name, false));
       add_symbol (s, top_stack->cur_st, top_stack->cur_block);
       break;
 
@@ -761,7 +761,7 @@ parse_symbol (SYMR *sh, union aux_ext *ax, char *ext_sh, int bigend,
 	t = builtin_type (objfile)->builtin_int;
       else
 	{
-	  t = parse_type (cur_fd, ax, sh->index + 1, 0, bigend, name);
+	  t = parse_type (cur_fd, ax, sh->index + 1, 0, bigend, name, false);
 	  if (strcmp (name, "malloc") == 0
 	      && t->code () == TYPE_CODE_VOID)
 	    {
@@ -805,7 +805,7 @@ parse_symbol (SYMR *sh, union aux_ext *ax, char *ext_sh, int bigend,
 	s->type ()->set_is_prototyped (true);
 
       /* Create and enter a new lexical context.  */
-      b = new_block (objfile, FUNCTION_BLOCK, s->language ());
+      b = new_block (objfile, FUNCTION_BLOCK, s->language (), false);
       s->set_value_block (b);
       b->set_function (s);
       b->set_start (sh->value);
@@ -1135,7 +1135,7 @@ parse_symbol (SYMR *sh, union aux_ext *ax, char *ext_sh, int bigend,
 	}
 
       top_stack->blocktype = stBlock;
-      b = new_block (objfile, NON_FUNCTION_BLOCK, psymtab_language);
+      b = new_block (objfile, NON_FUNCTION_BLOCK, psymtab_language, false);
       b->set_start (sh->value + top_stack->procadr);
       b->set_superblock (top_stack->cur_block);
       top_stack->cur_block = b;
@@ -1247,7 +1247,7 @@ parse_symbol (SYMR *sh, union aux_ext *ax, char *ext_sh, int bigend,
 	f->set_loc_bitpos (sh->value);
 	bitsize = 0;
 	f->set_type (parse_type (cur_fd, ax, sh->index, &bitsize, bigend,
-				 name));
+				 name, false));
 	f->set_bitsize (bitsize);
       }
       break;
@@ -1269,7 +1269,7 @@ parse_symbol (SYMR *sh, union aux_ext *ax, char *ext_sh, int bigend,
       pend = is_pending_symbol (cur_fdr, ext_sh);
       if (pend == NULL)
 	{
-	  t = parse_type (cur_fd, ax, sh->index, NULL, bigend, name);
+	  t = parse_type (cur_fd, ax, sh->index, NULL, bigend, name, true);
 	  add_pending (cur_fdr, ext_sh, t);
 	}
       else
@@ -1382,7 +1382,7 @@ basic_type (int bt, struct objfile *objfile)
   if (map_bt[bt])
     return map_bt[bt];
 
-  type_allocator alloc (objfile, get_current_subfile ()->language);
+  type_allocator alloc (objfile, psymtab_language);
 
   switch (bt)
     {
@@ -1514,7 +1514,7 @@ basic_type (int bt, struct objfile *objfile)
 
 static struct type *
 parse_type (int fd, union aux_ext *ax, unsigned int aux_index, int *bs,
-	    int bigend, const char *sym_name)
+	    int bigend, const char *sym_name, bool isStTypedef)
 {
   TIR t[1];
   struct type *tp = 0;
@@ -1571,7 +1571,7 @@ parse_type (int fd, union aux_ext *ax, unsigned int aux_index, int *bs,
 	}
     }
 
-  type_allocator alloc (mdebugread_objfile, get_current_subfile ()->language);
+  type_allocator alloc (mdebugread_objfile, psymtab_language);
 
   /* Move on to next aux.  */
   ax++;
@@ -1628,7 +1628,7 @@ parse_type (int fd, union aux_ext *ax, unsigned int aux_index, int *bs,
       xref_fh = get_rfd (fd, rf);
       xref_fd = xref_fh - debug_info->fdr;
       tp = parse_type (xref_fd, debug_info->external_aux + xref_fh->iauxBase,
-		    rn->index, NULL, xref_fh->fBigendian, sym_name);
+		    rn->index, NULL, xref_fh->fBigendian, sym_name, false);
     }
 
   /* All these types really point to some (common) MIPS type
@@ -1785,6 +1785,13 @@ parse_type (int fd, union aux_ext *ax, unsigned int aux_index, int *bs,
   if (t->continued)
     complaint (_("illegal TIR continued for %s"), sym_name);
 
+  if (isStTypedef)
+  {
+	struct type *wrap = alloc.new_type (TYPE_CODE_TYPEDEF, 0, sym_name);
+	wrap->set_target_type(tp);
+	tp = wrap;
+  }
+
   return tp;
 }
 
@@ -1839,7 +1846,7 @@ upgrade_type (int fd, struct type **tpp, int tq, union aux_ext *ax, int bigend,
 
       indx = parse_type (fh - debug_info->fdr,
 			 debug_info->external_aux + fh->iauxBase,
-			 id, NULL, bigend, sym_name);
+			 id, NULL, bigend, sym_name, false);
 
       /* The bounds type should be an integer type, but might be anything
 	 else due to corrupt aux entries.  */
@@ -2154,8 +2161,7 @@ parse_external (EXTR *es, int bigend, const section_offsets &section_offsets,
    with that and do not need to reorder our linetables.  */
 
 static void
-parse_lines (FDR *fh, PDR *pr, struct linetable *lt, int maxlines,
-	     CORE_ADDR lowest_pdr_addr)
+parse_lines (FDR *fh, PDR *pr, struct linetable *lt, int maxlines)
 {
   unsigned char *base;
   int j, k;
@@ -2169,7 +2175,6 @@ parse_lines (FDR *fh, PDR *pr, struct linetable *lt, int maxlines,
   for (j = 0; j < fh->cpd; j++, pr++)
     {
       CORE_ADDR l;
-      CORE_ADDR adr;
       unsigned char *halt;
 
       /* No code for this one.  */
@@ -2186,9 +2191,7 @@ parse_lines (FDR *fh, PDR *pr, struct linetable *lt, int maxlines,
 	halt = base + fh->cbLine;
       base += pr->cbLineOffset;
 
-      adr = pr->adr - lowest_pdr_addr;
-
-      l = adr >> 2;		/* in words */
+      l = pr->adr >> 2;		/* in words */
       for (lineno = pr->lnLow; base < halt;)
 	{
 	  count = *base & 0x0f;
@@ -4053,6 +4056,14 @@ mdebug_expand_psymtab (legacy_psymtab *pst, struct objfile *objfile)
 	    {
 	      (*swap_pdr_in) (cur_bfd, pdr_ptr, pdr_in);
 
+	      char *sym_ptr = (char *)(debug_info->external_sym) +
+	        (fh->isymBase + pdr_in->isym) * external_sym_size;
+
+	      SYMR sh;
+	      (*swap_sym_in) (cur_bfd, sym_ptr, &sh);
+
+	      pdr_in->adr = sh.value;
+
 	      /* Determine lowest PDR address, the PDRs are not always
 		 sorted.  */
 	      if (pdr_in == pr_block.data ())
@@ -4154,16 +4165,16 @@ mdebug_expand_psymtab (legacy_psymtab *pst, struct objfile *objfile)
 		{
 		  (*swap_pdr_in) (cur_bfd, pdr_ptr, pdr_in);
 
-		  /* Determine lowest PDR address, the PDRs are not always
-		     sorted.  */
-		  if (pdr_in == pr_block.data ())
-		    lowest_pdr_addr = pdr_in->adr;
-		  else if (pdr_in->adr < lowest_pdr_addr)
-		    lowest_pdr_addr = pdr_in->adr;
+                  sym_ptr = (char *)(debug_info->external_sym) +
+                    (fh->isymBase + pdr_in->isym) * external_sym_size;
+
+                  SYMR sh;
+                  (*swap_sym_in) (cur_bfd, sym_ptr, &sh);
+
+                  pdr_in->adr = sh.value;
 		}
 
-	      parse_lines (fh, pr_block.data (), lines, maxlines,
-			   lowest_pdr_addr);
+	      parse_lines (fh, pr_block.data (), lines, maxlines);
 	      if (lines->nitems < fh->cline)
 		lines = shrink_linetable (lines);
 
@@ -4291,7 +4302,7 @@ cross_ref (int fd, union aux_ext *ax, struct type **tpp,
       rf = rn->rfd;
     }
 
-  type_allocator alloc (mdebugread_objfile, get_current_subfile ()->language);
+  type_allocator alloc (mdebugread_objfile, psymtab_language);
 
   /* mips cc uses a rf of -1 for opaque struct definitions.
      Set TYPE_STUB for these types so that check_typedef will
@@ -4412,7 +4423,8 @@ cross_ref (int fd, union aux_ext *ax, struct type **tpp,
 				 sh.index,
 				 NULL,
 				 fh->fBigendian,
-				 debug_info->ss + fh->issBase + sh.iss);
+				 debug_info->ss + fh->issBase + sh.iss,
+				 sh.st == stTypedef);
 	      add_pending (fh, esh, *tpp);
 	      break;
 
@@ -4438,7 +4450,8 @@ cross_ref (int fd, union aux_ext *ax, struct type **tpp,
 			     sh.index,
 			     NULL,
 			     fh->fBigendian,
-			     debug_info->ss + fh->issBase + sh.iss);
+			     debug_info->ss + fh->issBase + sh.iss,
+			     true);
 	}
       else
 	{
@@ -4542,6 +4555,7 @@ add_line (struct linetable *lt, int lineno, CORE_ADDR adr, int last)
     return lineno;
 
   lt->item[lt->nitems].line = lineno;
+  lt->item[lt->nitems].is_stmt = 1;
   lt->item[lt->nitems++].set_unrelocated_pc (unrelocated_addr (adr << 2));
   return lineno;
 }
@@ -4634,9 +4648,10 @@ new_symtab (const char *name, int maxlines, struct objfile *objfile)
 
   /* All symtabs must have at least two blocks.  */
   bv = new_bvect (2);
-  bv->set_block (GLOBAL_BLOCK, new_block (objfile, NON_FUNCTION_BLOCK, lang));
-  bv->set_block (STATIC_BLOCK, new_block (objfile, NON_FUNCTION_BLOCK, lang));
+  bv->set_block (GLOBAL_BLOCK, new_block (objfile, NON_FUNCTION_BLOCK, lang, true));
+  bv->set_block (STATIC_BLOCK, new_block (objfile, NON_FUNCTION_BLOCK, lang, false));
   bv->static_block ()->set_superblock (bv->global_block ());
+  bv->global_block ()->set_compunit_symtab(cust);
   cust->set_blockvector (bv);
 
   cust->set_debugformat ("ECOFF");
@@ -4723,9 +4738,10 @@ new_bvect (int nblocks)
 
 static struct block *
 new_block (struct objfile *objfile, enum block_type type,
-	   enum language language)
+	   enum language language, bool isGlobal)
 {
-  struct block *retval = new (&objfile->objfile_obstack) block;
+  struct block *retval = isGlobal ? new (&objfile->objfile_obstack) global_block
+    : new (&objfile->objfile_obstack) block;
 
   if (type == FUNCTION_BLOCK)
     retval->set_multidict (mdict_create_linear_expandable (language));
@@ -4754,8 +4770,7 @@ new_type (char *name)
 {
   struct type *t;
 
-  t = type_allocator (mdebugread_objfile,
-		      get_current_subfile ()->language).new_type ();
+  t = type_allocator (mdebugread_objfile, psymtab_language).new_type ();
   t->set_name (name);
   INIT_CPLUS_SPECIFIC (t);
   return t;
-- 
2.41.0