Re: command-line-dependent compiler "error"

At last this error has bitten me too.  I suspect it is also the cause of
the failures in the ANSI test suite that were happening here and there
and disappearing mysteriously in the next version.

One almost invisible but major difference between 2.2 and 2.3 is that
the implementation of FileStream>>#fileIn: has changed.  While in 2.2
the VM would take care of I/O, in 2.3 the VM calls back to the
FileStream in order to get the data; this has the advantage that we can
implement Stream>>#fileIn and possibly, in the future, implement nice
things like gzipped file-in in a completely transparent way.

However, there was an important bug in this.  When the VM calls
Stream>>#nextHunk, a GC could happen.  The GC can use the buffer in
str.c to manage finalization and, by doing so, it will ruin the contents
of the buffer (that lex.c uses to lex strings, large integers, and so on).

The resulting strings were already placed in an obstack, so the patch I
attach switches to using obstacks also to build the strings.  For me it
fixes the failures (which didn't always happen and showed different
error messages, but always involved "truncated" symbols or keywords).

Jochen, if this patch solves the problems you had on x86-64, just tell
me as I can release 2.3.2 pretty soon now.

Paolo

2006-12-21  Paolo Bonzini  <[hidden email]>

        * libgst/lex.c: Build strings on obstack instead of the
        str.c buffer.  Otherwise the buffer could be cleared out
        by oop.c when it uses it to store the live ephemeron OOPs.

--- orig/libgst/lex.c
+++ mod/libgst/lex.c
@@ -506,15 +504,15 @@ scan_symbol (int c,
       return '#';
     }
 
-  _gst_reset_buffer ();
-  _gst_add_str_buf_char (ic);
+  obstack_1grow (_gst_compilation_obstack, ic);
 
   while (((ic = _gst_next_char ()) != EOF)
          && (CHAR_TAB (ic)->char_class & SYMBOL_CHAR))
-    _gst_add_str_buf_char (ic);
+    obstack_1grow (_gst_compilation_obstack, ic);
 
   _gst_unread_char (ic);
-  lvalp->sval = _gst_obstack_cur_str_buf (_gst_compilation_obstack);
+  obstack_1grow (_gst_compilation_obstack, '\0');
+  lvalp->sval = obstack_finish (_gst_compilation_obstack);
   return SYMBOL_LITERAL;
 }
 
@@ -574,8 +572,6 @@ string_literal (int c,
 {
   int ic;
 
-  _gst_reset_buffer ();
-
   for (;;)
     {
       ic = _gst_next_char ();
@@ -595,9 +591,10 @@ string_literal (int c,
       break;
     }
  }
-      _gst_add_str_buf_char (ic);
+      obstack_1grow (_gst_compilation_obstack, ic);
     }
-  lvalp->sval = _gst_obstack_cur_str_buf (_gst_compilation_obstack);
+  obstack_1grow (_gst_compilation_obstack, '\0');
+  lvalp->sval = obstack_finish (_gst_compilation_obstack);
   return (STRING_LITERAL);
 }
 
@@ -607,14 +604,13 @@ scan_ident (int c,
 {
   int ic, identType;
 
-  _gst_reset_buffer ();
-  _gst_add_str_buf_char (c);
+  obstack_1grow (_gst_compilation_obstack, c);
 
   identType = IDENTIFIER;
 
   while (((ic = _gst_next_char ()) != EOF)
  && (CHAR_TAB (ic)->char_class & ID_CHAR))
-    _gst_add_str_buf_char (ic);
+    obstack_1grow (_gst_compilation_obstack, ic);
 
   /* Read a dot as '::' if followed by a letter.  */
   if (ic == '.')
@@ -638,7 +634,7 @@ scan_ident (int c,
  _gst_unread_char (':');
       else
  {
-          _gst_add_str_buf_char (':');
+          obstack_1grow (_gst_compilation_obstack, ':');
           identType = KEYWORD;
  }
     }
@@ -646,7 +642,8 @@ scan_ident (int c,
   else
     _gst_unread_char (ic);
 
-  lvalp->sval = _gst_obstack_cur_str_buf (_gst_compilation_obstack);
+  obstack_1grow (_gst_compilation_obstack, '\0');
+  lvalp->sval = obstack_finish (_gst_compilation_obstack);
   return (identType);
 }
 
@@ -850,6 +847,8 @@ scan_number (int c,
 
   if (float_type)
     {
+      obstack_blank_fast (_gst_compilation_obstack,
+  -obstack_object_size (_gst_compilation_obstack));
       lvalp->fval = num;
       return (float_type);
     }
@@ -858,6 +857,7 @@ scan_number (int c,
       lvalp->boval = scan_large_integer (isNegative, base);
       return (LARGE_INTEGER_LITERAL);
     }
+  else
     {
       lvalp->ival = (intptr_t) num;
       return (INTEGER_LITERAL);
@@ -873,9 +873,6 @@ scan_digits (int c,
   long double result;
   mst_Boolean oneDigit = false;
 
-  if (largeInteger)
-    _gst_reset_buffer ();
-
   while (c == '_')
     c = _gst_next_char ();
 
@@ -886,7 +883,7 @@ scan_digits (int c,
       result += digit_to_int (c, base);
       if (largeInteger)
  {
-  _gst_add_str_buf_char (digit_to_int (c, base));
+  obstack_1grow (_gst_compilation_obstack, digit_to_int (c, base));
   if (result > -MIN_ST_INT
       || (!negative && result > MAX_ST_INT))
     *largeInteger = true;
@@ -930,7 +927,7 @@ scan_fraction (int c,
 
       if (largeInteger)
         {
-          _gst_add_str_buf_char (digit_to_int (c, base));
+          obstack_1grow (_gst_compilation_obstack, digit_to_int (c, base));
           if (num > MAX_ST_INT)
             *largeInteger = true;
         }
@@ -1006,13 +1003,14 @@ scan_large_integer (mst_Boolean negative
   gst_uchar *digits, *result;
   byte_object bo;
 
-  size = _gst_buffer_size ();
+  /* Copy the contents of the currently grown obstack on the stack.  */
+  size = obstack_object_size (_gst_compilation_obstack);
   digits = (gst_uchar *) alloca (size);
-  _gst_copy_buffer (digits);
+  memcpy (digits, obstack_base (_gst_compilation_obstack), size);
 
-  bo =
-    (byte_object) obstack_alloc (_gst_compilation_obstack,
- sizeof (struct byte_object) + size);
+  /* And reuse the area on the obstack for a struct byte_object.  */
+  obstack_blank (_gst_compilation_obstack, sizeof (struct byte_object));
+  bo = (byte_object) obstack_finish (_gst_compilation_obstack);
 
   bo->class =
     negative ? _gst_large_negative_integer_class :

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