* config/rs6000/tm-rs6000.h (IN_SOLIB_RETURN_TRAMPOLINE): Define.

(rs6000_in_solib_return_trampoline): Declare.
	* rs6000-tdep.c (rs6000_in_solib_return_trampoline): New
	function.
	(rs6000_skip_trampoline_code): Skip bigtoc fixup code.
	* xcoffread.c (read_xcoff_symtab): Perform the ISFCN function
	check after the CSECT check rather than before it.  Allocate
	separate symtabs for CSECTs whose names begin with '@'.
	(scan_xcoff_symtab): Don't ignore symbols beginning with '@'.
	Activate the misc_func_recorded mechanism for whose names begin
	with '@'.

gdb/ChangeLog

@@ -1,3 +1,17 @@
+2001-05-01  Nicholas Duffek  <nsd@redhat.com>
+
+	* config/rs6000/tm-rs6000.h (IN_SOLIB_RETURN_TRAMPOLINE): Define.
+	(rs6000_in_solib_return_trampoline): Declare.
+	* rs6000-tdep.c (rs6000_in_solib_return_trampoline): New
+	function.
+	(rs6000_skip_trampoline_code): Skip bigtoc fixup code.
+	* xcoffread.c (read_xcoff_symtab): Perform the ISFCN function
+	check after the CSECT check rather than before it.  Allocate
+	separate symtabs for CSECTs whose names begin with '@'.
+	(scan_xcoff_symtab): Don't ignore symbols beginning with '@'.
+	Activate the misc_func_recorded mechanism for whose names begin
+	with '@'.
+
 2001-04-30  J.T. Conklin  <jtc@redback.com>
 
 	* ppcnbsd-nat.c (fetch_inferior_registers)

gdb/config/rs6000/tm-rs6000.h

@@ -32,6 +32,13 @@
 #undef CPLUS_MARKER
 #define CPLUS_MARKER '.'
 
+/* Return whether PC in function NAME is in code that should be skipped when
+   single-stepping.  */
+
+#define IN_SOLIB_RETURN_TRAMPOLINE(pc, name) \
+  rs6000_in_solib_return_trampoline (pc, name)
+extern int rs6000_in_solib_return_trampoline (CORE_ADDR, char *);
+
 /* If PC is in some function-call trampoline code, return the PC
    where the function itself actually starts.  If not, return NULL.  */
 

gdb/rs6000-tdep.c

@@ -1132,19 +1132,55 @@ rs6000_extract_return_value (struct type *valtype, char *regbuf, char *valbuf)
 
 static CORE_ADDR rs6000_struct_return_address;
 
-/* Indirect function calls use a piece of trampoline code to do context
-   switching, i.e. to set the new TOC table. Skip such code if we are on
-   its first instruction (as when we have single-stepped to here). 
-   Also skip shared library trampoline code (which is different from
+/* Return whether handle_inferior_event() should proceed through code
+   starting at PC in function NAME when stepping.
+
+   The AIX -bbigtoc linker option generates functions @FIX0, @FIX1, etc. to
+   handle memory references that are too distant to fit in instructions
+   generated by the compiler.  For example, if 'foo' in the following
+   instruction:
+
+     lwz r9,foo(r2)
+
+   is greater than 32767, the linker might replace the lwz with a branch to
+   somewhere in @FIX1 that does the load in 2 instructions and then branches
+   back to where execution should continue.
+
+   GDB should silently step over @FIX code, just like AIX dbx does.
+   Unfortunately, the linker uses the "b" instruction for the branches,
+   meaning that the link register doesn't get set.  Therefore, GDB's usual
+   step_over_function() mechanism won't work.
+
+   Instead, use the IN_SOLIB_RETURN_TRAMPOLINE and SKIP_TRAMPOLINE_CODE hooks
+   in handle_inferior_event() to skip past @FIX code.  */
+
+int
+rs6000_in_solib_return_trampoline (CORE_ADDR pc, char *name)
+{
+  return name && !strncmp (name, "@FIX", 4);
+}
+
+/* Skip code that the user doesn't want to see when stepping:
+
+   1. Indirect function calls use a piece of trampoline code to do context
+   switching, i.e. to set the new TOC table.  Skip such code if we are on
+   its first instruction (as when we have single-stepped to here).
+
+   2. Skip shared library trampoline code (which is different from
    indirect function call trampolines).
+
+   3. Skip bigtoc fixup code.
+
    Result is desired PC to step until, or NULL if we are not in
-   trampoline code.  */
+   code that should be skipped.  */
 
 CORE_ADDR
 rs6000_skip_trampoline_code (CORE_ADDR pc)
 {
   register unsigned int ii, op;
+  int rel;
   CORE_ADDR solib_target_pc;
+  struct minimal_symbol *msymbol;
 
   static unsigned trampoline_code[] =
   {
@@ -1158,6 +1194,21 @@ rs6000_skip_trampoline_code (CORE_ADDR pc)
     0
   };
 
+  /* Check for bigtoc fixup code.  */
+  msymbol = lookup_minimal_symbol_by_pc (pc);
+  if (msymbol && rs6000_in_solib_return_trampoline (pc, SYMBOL_NAME (msymbol)))
+    {
+      /* Double-check that the third instruction from PC is relative "b".  */
+      op = read_memory_integer (pc + 8, 4);
+      if ((op & 0xfc000003) == 0x48000000)
+	{
+	  /* Extract bits 6-29 as a signed 24-bit relative word address and
+	     add it to the containing PC.  */
+	  rel = ((int)(op << 6) >> 6);
+	  return pc + 8 + rel;
+	}
+    }
+
   /* If pc is in a shared library trampoline, return its target.  */
   solib_target_pc = find_solib_trampoline_target (pc);
   if (solib_target_pc)

gdb/xcoffread.c

@@ -1081,14 +1081,6 @@ read_xcoff_symtab (struct partial_symtab *pst)
 	  /* done with all files, everything from here on is globals */
 	}
 
-      /* if explicitly specified as a function, treat is as one. */
-      if (ISFCN (cs->c_type) && cs->c_sclass != C_TPDEF)
-	{
-	  bfd_coff_swap_aux_in (abfd, raw_auxptr, cs->c_type, cs->c_sclass,
-				0, cs->c_naux, &main_aux);
-	  goto function_entry_point;
-	}
-
       if ((cs->c_sclass == C_EXT || cs->c_sclass == C_HIDEXT)
 	  && cs->c_naux == 1)
 	{
@@ -1158,7 +1150,8 @@ read_xcoff_symtab (struct partial_symtab *pst)
 						SECT_OFF_TEXT (objfile));
 		      file_end_addr = file_start_addr + CSECT_LEN (&main_aux);
 
-		      if (cs->c_name && cs->c_name[0] == '.')
+		      if (cs->c_name && (cs->c_name[0] == '.'
+					 || cs->c_name[0] == '@'))
 			{
 			  last_csect_name = cs->c_name;
 			  last_csect_val = cs->c_value;
@@ -1232,6 +1225,16 @@ read_xcoff_symtab (struct partial_symtab *pst)
 	    }
 	}
 
+      /* If explicitly specified as a function, treat is as one.  This check
+	 evaluates to true for @FIX* bigtoc CSECT symbols, so it must occur
+	 after the above CSECT check.  */
+      if (ISFCN (cs->c_type) && cs->c_sclass != C_TPDEF)
+	{
+	  bfd_coff_swap_aux_in (abfd, raw_auxptr, cs->c_type, cs->c_sclass,
+				0, cs->c_naux, &main_aux);
+	  goto function_entry_point;
+	}
+
       switch (cs->c_sclass)
 	{
 
@@ -2243,14 +2246,8 @@ scan_xcoff_symtab (struct objfile *objfile)
 	    else
 	      csect_aux = main_aux[0];
 
-	    /* If symbol name starts with ".$" or "$", ignore it. 
-
-	       A symbol like "@FIX1" introduces a section for -bbigtoc jump
-	       tables, which contain anonymous linker-generated code. 
-	       Ignore those sections to avoid "pc 0x... in read in psymtab,
-	       but not in symtab" warnings from find_pc_sect_symtab.  */
-
-	    if (namestring[0] == '$' || namestring[0] == '@'
+	    /* If symbol name starts with ".$" or "$", ignore it.  */
+	    if (namestring[0] == '$'
 		|| (namestring[0] == '.' && namestring[1] == '$'))
 	      break;
 
@@ -2296,7 +2293,11 @@ scan_xcoff_symtab (struct objfile *objfile)
 			       objfile->static_psymbols.next);
 			  }
 		      }
-		    if (namestring && namestring[0] == '.')
+		    /* Activate the misc_func_recorded mechanism for
+		       compiler- and linker-generated CSECTs like ".strcmp"
+		       and "@FIX1".  */ 
+		    if (namestring && (namestring[0] == '.'
+				       || namestring[0] == '@'))
 		      {
 			last_csect_name = namestring;
 			last_csect_val = symbol.n_value;