http://sourceware.org/ml/gdb-patches/2016-10/msg00652.html
Subject: [testsuite patch] Fix false FAIL for gdb.base/morestack.exp
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Hi,
since
[commit] [testsuite patch] Fix gcc_compiled for gcc 6 & 7
https://sourceware.org/ml/gdb-patches/2016-10/msg00620.html
there has started running again
Running gdb/testsuite/gdb.base/morestack.exp ...
+FAIL: gdb.base/morestack.exp: continue
+PASS: gdb.base/morestack.exp: up 3000
but as you can see it FAILs now - on Fedora 24 x86_64 (although for example it
still PASSes on CentOS-7.2 x86_64).
Program received signal SIGSEGV, Segmentation fault.
0x00007ffff787c7bb in malloc_consolidate (av=av@entry=0x7ffff7bbcb00 <main_arena>) at malloc.c:4181
4181 unlink(av, nextchunk, bck, fwd);
(gdb) bt
#0 0x00007ffff787c7bb in malloc_consolidate (av=av@entry=0x7ffff7bbcb00 <main_arena>) at malloc.c:4181
#1 0x00007ffff787f235 in _int_malloc (av=av@entry=0x7ffff7bbcb00 <main_arena>, bytes=bytes@entry=1024) at malloc.c:3448
[...]
#8 0x00007ffff784c5ac in _IO_vfprintf_internal (s=0x7ffff7bbd600 <_IO_2_1_stdout_>, format=<optimized out>, ap=ap@entry=0x7ffff77fd7f8) at vfprintf.c:1631
#9 0x00007ffff7853939 in __printf (format=<optimized out>) at printf.c:33
#10 0x0000000000400d6b in down ()
#11 0x0000000000400f2c in __morestack ()
#12 0x0000000000400dda in down ()
[...]
This apparently is due to - man gcc - -fsplit-stack:
When code compiled with -fsplit-stack calls code compiled without
-fsplit-stack, there may not be much stack space available for the
latter code to run. If compiling all code, including library code,
with -fsplit-stack is not an option, then the linker can fix up these
calls so that the code compiled without -fsplit-stack always has
a large stack. Support for this is implemented in the gold linker in
GNU binutils release 2.21 and later.
Personally I do not understand why gold is not the default linker as GNU ld is
unusably slow (6x) for C++ but that is off-topic here.
OK for check-in?
Thanks,
Jan
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gdb/testsuite/ChangeLog
2016-10-22 Jan Kratochvil <jan.kratochvil@redhat.com>
* gdb.base/morestack.exp: Try to build it using -fuse-ld=gold first.
diff --git a/gdb/testsuite/gdb.base/morestack.exp b/gdb/testsuite/gdb.base/morestack.exp
index 12f5d28..caa85b8 100644
--- a/gdb/testsuite/gdb.base/morestack.exp
+++ b/gdb/testsuite/gdb.base/morestack.exp
@@ -23,7 +23,11 @@ if {$gcc_compiled == 0} {
standard_testfile
-if { [prepare_for_testing ${testfile}.exp ${testfile} $srcfile {additional_flags=-fsplit-stack}] } {
+# -fuse-ld=gold is used for calling printf code built without -fsplit-stack
+# which could crash otherise. See GCC documentation of -fsplit-stack.
+set opts "additional_flags=-fsplit-stack"
+if { [prepare_for_testing ${testfile}.exp ${testfile} $srcfile [list $opts additional_flags=-fuse-ld=gold]] \
+ && [prepare_for_testing ${testfile}.exp ${testfile} $srcfile $opts] } {
return -1
}
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