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Define __start/__stop symbols when there is only a dynamic def

Alan Modra amodra@gmail.com
Tue Jan 30 14:03:00 GMT 2018 
On Mon, Jan 29, 2018 at 08:07:09PM -0800, H.J. Lu wrote:
> On Mon, Jan 29, 2018 at 6:18 PM, Alan Modra <amodra@gmail.com> wrote:
> > On Mon, Jan 29, 2018 at 05:17:10PM -0800, H.J. Lu wrote:
> >> Can you add another testcase with -Wl,--gc-sections on executable?
> >
> > Do you suspect something goes wrong with --gc-sections?  With the
> 
> I hope not.  A test is reassuring.  We had quite some issues with --gc-sections
> and __start/__stop symbols before.

I think we are already covered.  There isn't much difference between
--gc-sections on shared libs and --gc-sections on executables except
that ld acts like --export-dynamic is given for -shared.  The
ld-elf/pr21562* series covers -shared, thanks to your efforts.
There's also ld-gc/start.d, ld-gc/pr19161.d, and ld-gc/pr2022d for
executables.

Hmm, maybe we could do with a test that --gc-sections removes
__start/__stop symbols.

>From 040b4a9eb8430dc5e0fc657da88b08ab730b97ee Mon Sep 17 00:00:00 2001
From: Alan Modra <amodra@gmail.com>
Date: Tue, 30 Jan 2018 22:11:00 +1030
Subject: [PATCH 1/4] Add --gc-sections test checking removal of __start/__stop
 symbols.

Well, just __stop__foo but that should be good enough.

	* testsuite/ld-gc/stop.d,
	* testsuite/ld-gc/stop.s: New test.
	* testsuite/ld-gc/gc.exp: Run it.

diff --git a/ld/ChangeLog b/ld/ChangeLog
index 83c9689..f29d51a 100644
--- a/ld/ChangeLog
+++ b/ld/ChangeLog
@@ -1,3 +1,9 @@
+2018-01-30  Alan Modra  <amodra@gmail.com>
+
+	* testsuite/ld-gc/stop.d,
+	* testsuite/ld-gc/stop.s: New test.
+	* testsuite/ld-gc/gc.exp: Run it.
+
 2018-01-30  Maciej W. Rozycki  <macro@mips.com>
 
 	PR ld/22649
diff --git a/ld/testsuite/ld-gc/gc.exp b/ld/testsuite/ld-gc/gc.exp
index eaaa8e1..ad983ef 100644
--- a/ld/testsuite/ld-gc/gc.exp
+++ b/ld/testsuite/ld-gc/gc.exp
@@ -104,6 +104,7 @@ test_gc "Check --gc-section/-r/-u" "gcrel" $ld "-r --gc-sections -u used_func"
 run_dump_test "noent"
 run_dump_test "abi-note"
 run_dump_test "start"
+run_dump_test "stop"
 run_dump_test "pr19167"
 if { [is_elf_format] } then {
     run_dump_test "all-debug-sections"
diff --git a/ld/testsuite/ld-gc/stop.d b/ld/testsuite/ld-gc/stop.d
new file mode 100644
index 0000000..f8a32d6
--- /dev/null
+++ b/ld/testsuite/ld-gc/stop.d
@@ -0,0 +1,10 @@
+#name: --gc-sections removing __stop_
+#ld: --gc-sections -e _start
+#nm: -n
+#target: *-*-linux* *-*-gnu*
+#notarget: *-*-*aout *-*-*oldld frv-*-linux* metag-*-linux*
+
+#failif
+#...
+[0-9a-f]+ D +__stop__foo
+#...
diff --git a/ld/testsuite/ld-gc/stop.s b/ld/testsuite/ld-gc/stop.s
new file mode 100644
index 0000000..cb46d04
--- /dev/null
+++ b/ld/testsuite/ld-gc/stop.s
@@ -0,0 +1,8 @@
+	.text
+	.globl _start
+_start:
+	.dc.a	0
+
+	.section	_foo,"aw",%progbits
+foo:
+	.long	1

-- 
Alan Modra
Australia Development Lab, IBM
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