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[vms/committed]: improve comments in gas

Tristan Gingold gingold@adacore.com
Mon May 31 15:52:00 GMT 2010 
Hi,

this patch adds some comments to EVAX specific part of gas, in the hope it will be easier to read the code.

Tristan.

gas/
2010-05-31  Tristan Gingold  <gingold@adacore.com>

	* config/tc-alpha.c: Add comments for evax.
	* config/obj-evax.c: Ditto.

Index: gas/config/obj-evax.c
===================================================================
RCS file: /cvs/src/src/gas/config/obj-evax.c,v
retrieving revision 1.7
diff -c -r1.7 obj-evax.c
*** gas/config/obj-evax.c	2 Sep 2009 07:24:20 -0000	1.7
--- gas/config/obj-evax.c	31 May 2010 15:42:14 -0000
***************
*** 145,150 ****
--- 145,151 ----
    subseg_set (alpha_link_section, 0);
    seginfo = seg_info (alpha_link_section);
  
+   /* Handle .linkage fixups.  */
    for (l = alpha_linkage_fixup_root; l != NULL; l = l->next)
      {
        if (S_GET_SEGMENT (l->fixp->fx_addsy) == alpha_link_section)
Index: gas/config/tc-alpha.c
===================================================================
RCS file: /cvs/src/src/gas/config/tc-alpha.c,v
retrieving revision 1.85
diff -c -r1.85 tc-alpha.c
*** gas/config/tc-alpha.c	14 Apr 2010 09:25:34 -0000	1.85
--- gas/config/tc-alpha.c	31 May 2010 15:42:15 -0000
***************
*** 86,92 ****
    /* bfd_reloc_code_real_type reloc; */
    extended_bfd_reloc_code_real_type reloc;
  #ifdef OBJ_EVAX
!   symbolS *xtrasym, *procsym;
  #endif
  };
  
--- 86,96 ----
    /* bfd_reloc_code_real_type reloc; */
    extended_bfd_reloc_code_real_type reloc;
  #ifdef OBJ_EVAX
!   /* The symbol of the item in the linkage section.  */
!   symbolS *xtrasym;
! 
!   /* The symbol of the procedure descriptor.  */
!   symbolS *procsym;
  #endif
  };
  
***************
*** 419,427 ****
--- 423,433 ----
    int handler_data;
  };
  
+ /* Linked list of .linkage fixups.  */
  struct alpha_linkage_fixups *alpha_linkage_fixup_root;
  static struct alpha_linkage_fixups *alpha_linkage_fixup_tail;
  
+ /* Current procedure descriptor.  */
  static struct alpha_evax_procs *alpha_evax_proc;
  
  static int alpha_flag_hash_long_names = 0;		/* -+ */
***************
*** 495,502 ****
  {
    fixS *master;			/* The literal reloc.  */
  #ifdef OBJ_EVAX
!   struct symbol *sym;
!   struct symbol *psym;
  #endif
    fixS *slaves;			/* Head of linked list of lituses.  */
    segT segment;			/* Segment relocs are in or undefined_section.  */
--- 501,508 ----
  {
    fixS *master;			/* The literal reloc.  */
  #ifdef OBJ_EVAX
!   struct symbol *sym;		/* Linkage section item symbol.  */
!   struct symbol *psym;		/* Pdesc symbol.  */
  #endif
    fixS *slaves;			/* Head of linked list of lituses.  */
    segT segment;			/* Segment relocs are in or undefined_section.  */
***************
*** 1333,1353 ****
  
  	if (exp->X_add_symbol == alpha_evax_proc->symbol)
  	  {
  	    if (range_signed_16 (addend))
  	      {
- 		set_tok_reg (newtok[0], targreg);
  		set_tok_const (newtok[1], addend);
- 		set_tok_preg (newtok[2], basereg);
- 		assemble_tokens_to_insn ("lda", newtok, 3, &insn);
  		addend = 0;
  	      }
  	    else
  	      {
- 		set_tok_reg (newtok[0], targreg);
  		set_tok_const (newtok[1], 0);
- 		set_tok_preg (newtok[2], basereg);
- 		assemble_tokens_to_insn ("lda", newtok, 3, &insn);
  	      }
  	  }
  	else
  	  {
--- 1339,1358 ----
  
  	if (exp->X_add_symbol == alpha_evax_proc->symbol)
  	  {
+             /* Linkage-relative expression.  */
+             set_tok_reg (newtok[0], targreg);
+ 
  	    if (range_signed_16 (addend))
  	      {
  		set_tok_const (newtok[1], addend);
  		addend = 0;
  	      }
  	    else
  	      {
  		set_tok_const (newtok[1], 0);
  	      }
+             set_tok_preg (newtok[2], basereg);
+             assemble_tokens_to_insn ("lda", newtok, 3, &insn);
  	  }
  	else
  	  {
***************
*** 1358,1363 ****
--- 1363,1370 ----
  	    if ((symlen > 4 &&
  		 strcmp (ptr2 = &symname [symlen - 4], "..lk") == 0))
  	      {
+                 /* Access to an item whose address is stored in the linkage
+                    section.  Just read the address.  */
  		set_tok_reg (newtok[0], targreg);
  
  		newtok[1] = *exp;
***************
*** 1373,1382 ****
--- 1380,1391 ----
  
  		if (alpha_flag_replace && targreg == 26)
  		  {
+                     /* Add a NOP fixup for 'ldX $26,YYY..NAME..lk'.  */
  		    char *ensymname;
  		    symbolS *ensym;
  		    volatile asymbol *dummy;
  
+                     /* Build the entry name as 'NAME..en'.  */
  		    ptr1 = strstr (symname, "..") + 2;
  		    if (ptr1 > ptr2)
  		      ptr1 = symname;
***************
*** 1404,1418 ****
--- 1413,1430 ----
  		  }
  		else if (alpha_flag_replace && targreg == 27)
  		  {
+                     /* Add a lda fixup for 'ldX $27,YYY.NAME..lk+8'.  */
  		    char *psymname;
  		    symbolS *psym;
  
+                     /* Extract NAME.  */
  		    ptr1 = strstr (symname, "..") + 2;
  		    if (ptr1 > ptr2)
  		      ptr1 = symname;
  		    psymname = (char *) xmalloc (ptr2 - ptr1 + 1);
  		    memcpy (psymname, ptr1, ptr2 - ptr1);
  		    psymname [ptr2 - ptr1] = 0;
+ 
  		    gas_assert (insn.nfixups + 1 <= MAX_INSN_FIXUPS);
  		    insn.fixups[insn.nfixups].reloc = BFD_RELOC_ALPHA_LDA;
  		    psym = symbol_find_or_make (psymname);
***************
*** 1426,1436 ****
  		    insn.nfixups++;
  		  }
  
! 		emit_insn(&insn);
  		return 0;
  	      }
  	    else
  	      {
  		symbolS *linkexp;
  
  		if (!range_signed_32 (addend))
--- 1438,1450 ----
  		    insn.nfixups++;
  		  }
  
! 		emit_insn (&insn);
  		return 0;
  	      }
  	    else
  	      {
+                 /* Not in the linkage section.  Put the value into the linkage
+                    section.  */
  		symbolS *linkexp;
  
  		if (!range_signed_32 (addend))
***************
*** 2868,2877 ****
--- 2882,2893 ----
        && tok[tokidx].X_add_symbol
        && alpha_linkage_symbol)
      {
+       /* Create a BOH reloc for 'jsr $27,NAME'.  */
        const char *symname = S_GET_NAME (tok[tokidx].X_add_symbol);
        int symlen = strlen (symname);
        char *ensymname;
  
+       /* Build the entry name as 'NAME..en'.  */
        ensymname = (char *) xmalloc (symlen + 5);
        memcpy (ensymname, symname, symlen);
        memcpy (ensymname + symlen, "..en", 5);
***************
*** 4457,4462 ****
--- 4473,4480 ----
    alpha_evax_proc->rsa_offset = get_absolute_expression ();
  }
  
+ /* Parse .prologue.  */
+ 
  static void
  s_alpha_prologue (int ignore ATTRIBUTE_UNUSED)
  {
***************
*** 4468,4473 ****
--- 4486,4494 ----
      (FAKE_LABEL_NAME, now_seg, (valueT) frag_now_fix (), frag_now);
  }
  
+ /* Parse .pdesc <entry_name>.
+    Insert a procedure descriptor.  */
+ 
  static void
  s_alpha_pdesc (int ignore ATTRIBUTE_UNUSED)
  {
***************
*** 4686,4691 ****
--- 4707,4715 ----
    fix_new_exp (frag_now, p - frag_now->fr_literal, 8, &exp, 0, BFD_RELOC_64);
  }
  
+ /* Parse .linkage <symbol>.
+    Create a linkage pair relocation.  */
+ 
  static void
  s_alpha_linkage (int ignore ATTRIBUTE_UNUSED)
  {
***************
*** 4738,4743 ****
--- 4762,4770 ----
    demand_empty_rest_of_line ();
  }
  
+ /* Parse .code_address <symbol>.
+    Create a code address relocation.  */
+ 
  static void
  s_alpha_code_address (int ignore ATTRIBUTE_UNUSED)
  {
***************
*** 6281,6286 ****
--- 6308,6314 ----
        int pname_len;
  
      case BFD_RELOC_ALPHA_LINKAGE:
+       /* Copy the linkage index.  */
        reloc->addend = fixp->fx_addnumber;
        break;
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