gas: improve C_BSTAT and C_STSYM symbols handling on XCOFF

A C_BSTAT debug symbol specifies the beginning of a static block.
Its n_value is the index of the csect containing static symbols.
A C_STSYM debug symbol represents the stabstring of a statically
allocated symbol. Its n_value is the offset in the csect pointed
by the containing C_BSTAT.

These two special n_value were not correctly handled both when
generating object files with gas or when reading them with objdump.
This patch tries to improve that and, above all, to allow gas-generated
object files with such symbols to be accepted by AIX ld.

bfd/
	* coff-bfd.c (bfd_coff_get_syment): Adjust n_value of symbols
	having fix_value = 1 in order to be an index and not a memory
	offset.
	* coffgen.c (coff_get_symbol_info): Likewize.
	(coff_print_symbol): Likewize.

gas/
	* config/tc-ppc.c (ppc_frob_label): Don't change within if
	already set.
	(ppc_stabx): Remove workaround changing exp.X_add_symbol's
	within.
	* config/tc-ppc.h (struct ppc_tc_sy): Update comments.
	* symbols.c (resolve_symbol_value): Remove symbol update
	when final_val is 0 and it's an AIX debug symbol.
	* testsuite/gas/ppc/aix.exp: Add new tests.
	* testsuite/gas/ppc/xcoff-stsym-32.d: New test.
	* testsuite/gas/ppc/xcoff-stsym-64.d: New test.
	* testsuite/gas/ppc/xcoff-stsym.s: New test.

1 files changed, 6 insertions, 2 deletions

diff --git a/gas/config/tc-ppc.c b/gas/config/tc-ppc.c
index 6eeb98c..8c3b0a8 100644
--- a/gas/config/tc-ppc.c
+++ b/gas/config/tc-ppc.c
@@ -2901,8 +2901,13 @@ ppc_frob_label (symbolS *sym)
       symbol_remove (sym, &symbol_rootP, &symbol_lastP);
       symbol_append (sym, symbol_get_tc (ppc_current_csect)->within,
 		     &symbol_rootP, &symbol_lastP);
+      /* Update last csect symbol.  */
       symbol_get_tc (ppc_current_csect)->within = sym;
-      symbol_get_tc (sym)->within = ppc_current_csect;
+
+      /* Some labels like .bs are using within differently.
+         So avoid changing it, if it's already set.  */
+      if (symbol_get_tc (sym)->within == NULL)
+	symbol_get_tc (sym)->within = ppc_current_csect;
     }
 #endif
 
@@ -5056,7 +5061,6 @@ ppc_stabx (int ignore ATTRIBUTE_UNUSED)
             as_bad (_(".stabx of storage class stsym must be within .bs/.es"));
 
           symbol_get_tc (sym)->within = ppc_current_block;
-          symbol_get_tc (exp.X_add_symbol)->within = ppc_current_block;
         }
     }