[PATCH version 2] Fix gdb.base/step-indirect-call-thunk.exp

[Carl Love <cel@us.ibm.com>]

GDB maintainers:

version 2:  Updated the commit message per comments from Bruno Larsen.

The gdb regression test gdb.base/step-indirect-call-thunk.exp currently
does not run on X86 due to a compile error related to incompatible gcc
command line argument.  Secondly, the gcc command line arguments that
are used are specific to Intel thus generating an unsupported command
line error when compiled on other architectures.

This patch fixes the command line arguments so the test will compile on
X86.  It also adds a check so the test will only run on X86.

Please let me know if this patch is acceptable for mainline.

                           Carl Love


-------------------------------------
Fix gdb.base/step-indirect-call-thunk.exp

Due to recent changes in the default value of -fcf-protection for gcc, the
test gdb.base/step-indirect-call-thunk.exp fails on Intel X86-64 with the error:

Executing on host: gcc  -fno-stack-protector  -fdiagnostics-color=never
-mindirect-branch=thunk -mfunction-return=thunk -c -g
-o /.../gdb/testsuite/outputs/gdb.base/step-indirect-call-thunk/step-indirect-call-thunk0.o
/.../gdb/testsuite/gdb.base/step-indirect-call-thunk.c
(timeout = 300) builtin_spawn -ignore SIGHUP gcc -fno-stack-protector
-fdiagnostics-color=never -mindirect-branch=thunk -mfunction-return=thunk -c
-g -o /.../gdb/testsuite/outputs/gdb.base/step-indirect-call-thunk/step-indirect-call-thunk0.o
/.../binutils-gdb-current/gdb/testsuite/gdb.base/step-indirect-call-thunk.c
/.../gdb/testsuite/gdb.base/step-indirect-call-thunk.c:
 In function 'inc': /.../gdb/testsuite/gdb.base/step-indirect-call-thunk.c:
22:1: error: '-mindirect-branch' and '-fcf-protection' are not compatible
   22 | {                /* inc.1 */

As stated in the error message the default "-fcf-protection" and
"-mindirect-branch' are in compatible.  The fcf-protection argument needs to be
"-fcf-protection=none" for the test to compile on Intel.

The gcc command line "-mindirect-branch' is an Intel specific and will give an
error on other platforms.  A check for X86 is added so the test will only run
on X86 platforms.

The patch has been tested and verified on Power 10 and Intel X86-64 systems with
no regressions.
---
 gdb/testsuite/gdb.base/step-indirect-call-thunk.exp | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/gdb/testsuite/gdb.base/step-indirect-call-thunk.exp b/gdb/testsuite/gdb.base/step-indirect-call-thunk.exp
index 761e1d9a280..7c1b53c99be 100644
--- a/gdb/testsuite/gdb.base/step-indirect-call-thunk.exp
+++ b/gdb/testsuite/gdb.base/step-indirect-call-thunk.exp
@@ -15,7 +15,11 @@
 
 standard_testfile
 
-set cflags "-mindirect-branch=thunk -mfunction-return=thunk"
+if { ![istarget "x86*"] } {
+    return
+}
+
+set cflags "-mindirect-branch=thunk -mfunction-return=thunk -fcf-protection=none"
 if { [prepare_for_testing "failed to prepare" $testfile $srcfile \
         [list debug "additional_flags=$cflags"]] } {
     return -1
-- 
2.31.1