[PATCH] GAS: Consistently fix labels at the `.end' pseudo-op

["Maciej W. Rozycki" <macro at imgtec dot com>]

Fix a functional regression with the `.end' pseudo-op, introduced with 
commit ecb4347adecd ("Last take: approval for MIPS_STABS_ELF killing"), 
<https://sourceware.org/ml/binutils/2002-06/msg00443.html>, and commit 
dcd410fe1544 ("GNU as 2.14 on IRIX 6: crashes with shared libs"), 
<https://sourceware.org/ml/binutils/2003-07/msg00415.html>, which caused 
symbol values for labels placed between the end of a function's contents 
and its terminating `.end' followed by one of the alignment pseudo-ops 
to be different depending on whether either `-mdebug', or `-mno-pdr', or 
neither of the command-line options is in effect, be it implied or 
specified.

Given debug-label-end.s as follows and the `mips-linux' target we have:

$ cat debug-label-end.s
	.text

	.globl	foo
	.globl	bar
	.align	4, 0
	.ent	foo
foo:
	nop
	.aent	bar
bar:
	.insn
	.end	foo
	.align	4, 0
	.space	16

	.globl	baz
	.ent	baz
baz:
	nop
	.end	baz
	.align	4, 0
	.space	16
$ as -o debug-label-end.o debug-label-end.s
$ readelf -s debug-label-end.o | grep bar
     9: 00000004     0 FUNC    GLOBAL DEFAULT    1 bar
$ as -mdebug -o debug-label-end.o debug-label-end.s
$ readelf -s debug-label-end.o | grep bar
     9: 00000010     0 FUNC    GLOBAL DEFAULT    1 bar
$ as -mno-pdr -o debug-label-end.o debug-label-end.s
$ readelf -s debug-label-end.o | grep bar
     8: 00000010     0 FUNC    GLOBAL DEFAULT    1 bar
$ 

The reason is the call to `md_flush_pending_output', which in the case 
of `mips*-*-*' targets expands to `mips_emit_delays', which in turn 
calls `mips_no_prev_insn', which calls `mips_clear_insn_labels', which 
clears the list of outstanding labels.  That list is in turn consulted 
in `mips_align', called in the interpretation of alignment directives, 
and the labels adjusted to the current location.

A call to `md_flush_pending_output' is only made from `s_mips_end' and 
then only if `-mpdr' is in effect, which is the default for `*-*-linux*' 
and some other `mips*-*-*' targets.  A call to `md_flush_pending_output' 
is never made from `ecoff_directive_end', which is used in place of 
`s_mips_end' when `-mdebug' is in effect.  Consequently if `-mno-pdr' or 
`-mdebug' is in effect the list of outstanding labels makes it through 
to any alignment directive that follows and the labels are differently 
interpreted depending on the command-lines options used.  And we want 
code produced to be always the same.

Call `md_flush_pending_output' unconditionally then in `s_mips_end' and 
add such a call from `ecoff_directive_end' as well, as long as the macro 
is defined.  While `ecoff_directive_end' is shared among targets, the 
only one other than `mips*-*-*' actually using it is `alpha*-*-*' and it 
does not define `md_flush_pending_output'.  So the semantics isn't going 
to change for it and neither it has to have its `s_alpha_end' updated 
or have code in `ecoff_directive_end' conditionalized.

	gas/
	* ecoff.c (ecoff_directive_end) [md_flush_pending_output]: Call 
	`md_flush_pending_output'.
	* config/tc-mips.c (s_mips_end) [md_flush_pending_output]: Call
	`md_flush_pending_output' unconditionally.
	* testsuite/gas/mips/debug-label-end-1.d: New test.
	* testsuite/gas/mips/debug-label-end-2.d: New test.
	* testsuite/gas/mips/debug-label-end-3.d: New test.
	* testsuite/gas/mips/debug-label-end.s: New test source.
	* testsuite/gas/mips/mips.exp: Run the new tests.
---
 There's little non-MIPS stuff here, but this is changing generic ECOFF
code, so OK to apply?  No regressions with my usual targets.

  Maciej

binutils-mips-gas-debug-label-end.diff
Index: binutils/gas/config/tc-mips.c
===================================================================
--- binutils.orig/gas/config/tc-mips.c	2017-02-15 13:49:49.794611971 +0000
+++ binutils/gas/config/tc-mips.c	2017-02-15 21:51:45.371877241 +0000
@@ -19080,6 +19080,10 @@ s_mips_end (int x ATTRIBUTE_UNUSED)
       cur_proc_ptr->func_end_sym = exp->X_add_symbol;
     }
 
+#ifdef md_flush_pending_output
+  md_flush_pending_output ();
+#endif
+
   /* Generate a .pdr section.  */
   if (!ECOFF_DEBUGGING && mips_flag_pdr)
     {
@@ -19088,10 +19092,6 @@ s_mips_end (int x ATTRIBUTE_UNUSED)
       expressionS exp;
       char *fragp;
 
-#ifdef md_flush_pending_output
-      md_flush_pending_output ();
-#endif
-
       gas_assert (pdr_seg);
       subseg_set (pdr_seg, 0);
 
Index: binutils/gas/ecoff.c
===================================================================
--- binutils.orig/gas/ecoff.c	2017-02-15 21:51:15.575639506 +0000
+++ binutils/gas/ecoff.c	2017-02-15 21:51:45.582737448 +0000
@@ -3025,6 +3025,10 @@ ecoff_directive_end (int ignore ATTRIBUT
 					 frag_now),
 			     (bfd_vma) 0, (symint_t) 0, (symint_t) 0);
 
+#ifdef md_flush_pending_output
+  md_flush_pending_output ();
+#endif
+
   cur_proc_ptr = (proc_t *) NULL;
 
   (void) restore_line_pointer (name_end);
Index: binutils/gas/testsuite/gas/mips/debug-label-end-1.d
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ binutils/gas/testsuite/gas/mips/debug-label-end-1.d	2017-02-15 21:51:49.000000000 +0000
@@ -0,0 +1,21 @@
+#readelf: -s
+#name: MIPS ECOFF/PDR debug interaction with labels at .end 1
+#as: -32 -no-mdebug -mpdr
+#source: debug-label-end.s
+
+# Verify that .end finalizes any labels outstanding
+# where PDR debug generation is enabled, e.g.:
+#    Num:    Value  Size Type    Bind   Vis      Ndx Name
+#      7: 00000000     4 FUNC    GLOBAL DEFAULT    1 foo
+#      8: 00000004     0 FUNC    GLOBAL DEFAULT    1 bar
+#      9: 00000020     4 FUNC    GLOBAL DEFAULT    1 baz
+# vs:
+#    Num:    Value  Size Type    Bind   Vis      Ndx Name
+#      7: 00000000     4 FUNC    GLOBAL DEFAULT    1 foo
+#      8: 00000010     0 FUNC    GLOBAL DEFAULT    1 bar
+#      9: 00000020     4 FUNC    GLOBAL DEFAULT    1 baz
+#...
+ *[0-9]+: +0+000000 +4 +FUNC +GLOBAL +DEFAULT +[0-9]+ foo
+ *[0-9]+: +0+000004 +0 +FUNC +GLOBAL +DEFAULT +[0-9]+ bar
+ *[0-9]+: +0+000020 +4 +FUNC +GLOBAL +DEFAULT +[0-9]+ baz
+#pass
Index: binutils/gas/testsuite/gas/mips/debug-label-end-2.d
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ binutils/gas/testsuite/gas/mips/debug-label-end-2.d	2017-02-15 21:51:49.000000000 +0000
@@ -0,0 +1,17 @@
+#readelf: -s
+#name: MIPS ECOFF/PDR debug interaction with labels at .end 2
+#as: -32 -mdebug -mno-pdr
+#source: debug-label-end.s
+#dump: debug-label-end-1.d
+
+# Verify that .end finalizes any labels outstanding
+# where ECOFF debug generation is enabled, e.g.:
+#    Num:    Value  Size Type    Bind   Vis      Ndx Name
+#      7: 00000000     4 FUNC    GLOBAL DEFAULT    1 foo
+#      8: 00000004     0 FUNC    GLOBAL DEFAULT    1 bar
+#      9: 00000020     4 FUNC    GLOBAL DEFAULT    1 baz
+# vs:
+#    Num:    Value  Size Type    Bind   Vis      Ndx Name
+#      7: 00000000     4 FUNC    GLOBAL DEFAULT    1 foo
+#      8: 00000010     0 FUNC    GLOBAL DEFAULT    1 bar
+#      9: 00000020     4 FUNC    GLOBAL DEFAULT    1 baz
Index: binutils/gas/testsuite/gas/mips/debug-label-end-3.d
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ binutils/gas/testsuite/gas/mips/debug-label-end-3.d	2017-02-15 21:51:49.000000000 +0000
@@ -0,0 +1,17 @@
+#readelf: -s
+#name: MIPS ECOFF/PDR debug interaction with labels at .end 3
+#as: -32 -no-mdebug -mno-pdr
+#source: debug-label-end.s
+#dump: debug-label-end-1.d
+
+# Verify that .end finalizes any labels outstanding
+# where both ECOFF and PDR generation is disabled, e.g.:
+#    Num:    Value  Size Type    Bind   Vis      Ndx Name
+#      7: 00000000     4 FUNC    GLOBAL DEFAULT    1 foo
+#      8: 00000004     0 FUNC    GLOBAL DEFAULT    1 bar
+#      9: 00000020     4 FUNC    GLOBAL DEFAULT    1 baz
+# vs:
+#    Num:    Value  Size Type    Bind   Vis      Ndx Name
+#      7: 00000000     4 FUNC    GLOBAL DEFAULT    1 foo
+#      8: 00000010     0 FUNC    GLOBAL DEFAULT    1 bar
+#      9: 00000020     4 FUNC    GLOBAL DEFAULT    1 baz
Index: binutils/gas/testsuite/gas/mips/debug-label-end.s
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ binutils/gas/testsuite/gas/mips/debug-label-end.s	2017-02-15 21:51:49.000000000 +0000
@@ -0,0 +1,22 @@
+	.text
+
+	.globl	foo
+	.globl	bar
+	.align	4, 0
+	.ent	foo
+foo:
+	nop
+	.aent	bar
+bar:
+	.insn
+	.end	foo
+	.align	4, 0
+	.space	16
+
+	.globl	baz
+	.ent	baz
+baz:
+	nop
+	.end	baz
+	.align	4, 0
+	.space	16
Index: binutils/gas/testsuite/gas/mips/mips.exp
===================================================================
--- binutils.orig/gas/testsuite/gas/mips/mips.exp	2017-02-15 21:51:23.039574256 +0000
+++ binutils/gas/testsuite/gas/mips/mips.exp	2017-02-15 21:51:49.000000000 +0000
@@ -1794,6 +1794,10 @@ if { [istarget mips*-*-vxworks*] } {
     run_dump_test_arches "isa-override-1" "" [mips_arch_list_matching mips1]
     run_list_test_arches "isa-override-2" "-32" [mips_arch_list_matching mips1]
 
+    run_dump_test "debug-label-end-1"
+    run_dump_test "debug-label-end-2"
+    run_dump_test "debug-label-end-3"
+
     run_dump_test_arches "r6"		[mips_arch_list_matching mips32r6]
     if $has_newabi {
 	run_dump_test_arches "r6-n32"	[mips_arch_list_matching mips64r6]