[PATCH v2] gdb/testsuite: Regenerate the testglue if it is not in path

[Shahab Vahedi <shahab dot vahedi at gmail dot com>]

From: Shahab Vahedi <shahab@synopsys.com>

For running the  DejaGnu  tests,  some  esoteric  configurations
may require a testglue.   This,  for  instance,  is  true  about
testing ARC  targets  which  uses  its  own  DejaGnu  board  and
a simulator which does not support returning the  pass  or  fail
through the exit code.  Therefore,  for  those  tests  that  use
"gdb_compile" a "gdb_tg.o" file is compiled and  linked  to  the
final executable.

There  are  tests  that  invoke  "gdb_compile"  from   different
directories.   Let's  take  a   look   at   an   example   test:
gdb.base/fullname.exp.  The purpose of this  test  is  to  build
the executable from different directories (absolute vs. relative
vs.  other) and then check if gdb can handle setting breakpoints
accordingly.

When  "gdb_compile"  generates  the  "gdb_tg.o",  it  does   not
do it again  for  the  same  test.   Although  this  might  seem
efficient, it can lead to  problems  when  changing  directories
before the next compile:

  gdb compile failed, arc-elf32-gcc: error: gdb_tg.o:
  No such file or directory

This patch checks if the wrapper file ("gdb_tg.o") is  still  in
reach and if it is not, it will stimulate the generation of  the
wrapper again.

It is worth mentioning that GCC's  DejaGnu  tests  handle  these
scenarios as well and they seem to be more efficient in doing so
by saving the library paths and manipulating them  if  necessary
[1].  However, for GDB tests, that  require  less  compilations,
I think the proposed solution should be fine compared to a  more
full fledged solution from GCC.  The glue file in  our  case  is
only 2 KiB.

Last but not least, I ran the x86_64 tests on an x86_64 host and
found no regression.

[1]
Avid  coders  may  look  for  "set_ld_library_path_env_vars"  in
gcc/testsuite/lib/target-libpath.exp.

gdb/testsuite/ChangeLog:

	* lib/gdb.exp (gdb_wrapper_init): Reset
	"gdb_wrapper_initialized" to 0 if "wrapper_file" does
	not exist.
---
 gdb/testsuite/lib/gdb.exp | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/gdb/testsuite/lib/gdb.exp b/gdb/testsuite/lib/gdb.exp
index d5e22957039..8f55c4fcb2d 100644
--- a/gdb/testsuite/lib/gdb.exp
+++ b/gdb/testsuite/lib/gdb.exp
@@ -3565,6 +3565,15 @@ proc gdb_wrapper_init { args } {
     global gdb_wrapper_flags
     global gdb_wrapper_target
 
+    # if the wrapper is initialized but the wrapper file cannot be
+    # found anymore, the wrapper file must be built again.
+    if { $gdb_wrapper_initialized == 1 && \
+	    [info exists gdb_wrapper_file] && \
+	    ![file exists $gdb_wrapper_file] } {
+	verbose "reinitializing the wrapper"
+	set gdb_wrapper_initialized 0
+    }
+
     if { $gdb_wrapper_initialized == 1 } { return; }
 
     if {[target_info exists needs_status_wrapper] && \
@@ -3812,7 +3821,7 @@ proc gdb_compile {source dest type options} {
     verbose "options are $options"
     verbose "source is $source $dest $type $options"
 
-    if { $gdb_wrapper_initialized == 0 } { gdb_wrapper_init }
+    gdb_wrapper_init
 
     if {[target_info exists needs_status_wrapper] && \
 	    [target_info needs_status_wrapper] != "0" && \
-- 
2.25.0