Re: [Xtensa] change relaxation of calls to weak symbols

[Bob Wilson <bwilson at tensilica dot com>]

Bob Wilson wrote:
> I noticed yesterday that the Xtensa port of GAS has been relaxing all 
> calls to weak symbols, even when the --longcalls option is disabled.  
> This seems wrong to me.  The assembler doesn't know the final address of 
> a weak symbol, but that is no different than a call to a different 
> section.  This patch changes GAS to handle both of those cases (weak 
> symbol and different section) in the same way.  Tested with an 
> xtensa-elf build and committed.

The GAS testsuite for Xtensa is not worth much....  This change broke GCC's 
g++.dg/warn/weak1.C test.  It seems like the best solution is to distinguish 
weak references (which may resolve to zero) from weak definitions.  Fixed with 
the following patch, which I have committed.  In an effort to improve the 
testsuite, I also added a test for this.

2007-12-13  Bob Wilson  <bob.wilson@acm.org>

gas/
	* config/tc-xtensa.c (xg_symbolic_immeds_fit): Relax for weak
	references but not weak definitions.

gas/testsuite/
	* gas/xtensa/all.exp: Run new weak-call test.
	* gas/xtensa/weak-call.d: New.
	* gas/xtensa/weak-call.s: New.

Index: config/tc-xtensa.c
===================================================================
RCS file: /cvs/src/src/gas/config/tc-xtensa.c,v
retrieving revision 1.94
diff -u -p -r1.94 tc-xtensa.c
--- config/tc-xtensa.c	12 Dec 2007 21:16:47 -0000	1.94
+++ config/tc-xtensa.c	13 Dec 2007 18:59:43 -0000
@@ -3241,9 +3241,15 @@ xg_symbolic_immeds_fit (const TInsn *ins
 	      || S_GET_SEGMENT (expr->X_add_symbol) != pc_seg)
 	    {
 	      /* For a direct call with --no-longcalls, be optimistic and
-		 assume it will be in range.  */
+		 assume it will be in range.  If the symbol is weak and
+		 undefined, it may remain undefined at link-time, in which
+		 case it will have a zero value and almost certainly be out
+		 of range for a direct call; thus, relax for undefined weak
+		 symbols even if longcalls is not enabled.  */
 	      if (is_direct_call_opcode (insn->opcode)
-		  && ! pc_frag->tc_frag_data.use_longcalls)
+		  && ! pc_frag->tc_frag_data.use_longcalls
+		  && (! S_IS_WEAK (expr->X_add_symbol)
+		      || S_IS_DEFINED (expr->X_add_symbol)))
 		return TRUE;
 
 	      return FALSE;
Index: testsuite/gas/xtensa/all.exp
===================================================================
RCS file: /cvs/src/src/gas/testsuite/gas/xtensa/all.exp,v
retrieving revision 1.4
diff -u -p -r1.4 all.exp
--- testsuite/gas/xtensa/all.exp	7 Dec 2007 22:52:10 -0000	1.4
+++ testsuite/gas/xtensa/all.exp	13 Dec 2007 18:59:47 -0000
@@ -80,6 +80,7 @@ if [istarget xtensa*-*-*] then {
 
     run_dump_test "short_branch_offset"
     run_dump_test "pcrel"
+    run_dump_test "weak-call"
 }
 
 if [info exists errorInfo] then {
Index: testsuite/gas/xtensa/weak-call.d
===================================================================
RCS file: testsuite/gas/xtensa/weak-call.d
diff -N testsuite/gas/xtensa/weak-call.d
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ testsuite/gas/xtensa/weak-call.d	13 Dec 2007 18:59:47 -0000
@@ -0,0 +1,11 @@
+#as: 
+#objdump: -r -j .text
+#name: relaxing calls to weak symbols
+
+.*: +file format .*xtensa.*
+
+RELOCATION RECORDS FOR \[\.text\]:
+OFFSET   TYPE              VALUE 
+00000000 R_XTENSA_SLOT0_OP  weakdef
+00000003 R_XTENSA_SLOT0_OP  \.literal
+00000003 R_XTENSA_ASM_EXPAND  weakref
Index: testsuite/gas/xtensa/weak-call.s
===================================================================
RCS file: testsuite/gas/xtensa/weak-call.s
diff -N testsuite/gas/xtensa/weak-call.s
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ testsuite/gas/xtensa/weak-call.s	13 Dec 2007 18:59:47 -0000
@@ -0,0 +1,8 @@
+	.text
+	.begin	no-longcalls
+	.weak	weakdef
+	call8	weakdef
+weakdef:
+	.weak	weakref
+	call8	weakref
+	.end	no-longcalls