gdb/testsuite: Introduce skip_ctf_tests guard function

Most versions of GCC in the wild don't support CTF debug format right
now, so, rather than attempting to compile the tests and failing each
time, this patch introduces a guard function to check if the compiler
supports CTF.  If we don't have CTF support then the CTF tests are
skipped.

This patch only updates 3 of the 4 CTF tests, the fourth will be
handled in the next patch.

gdb/testsuite/ChangeLog:

	* gdb.base/ctf-constvars.exp: Skip test if CTF is not supported in
	the compiler.  Clean up header comment a little.
	* gdb.base/ctf-ptype.exp: Likewise.
	* gdb.base/ctf-whatis.exp: Likewise.
	* lib/gdb.exp (skip_ctf_tests): New proc.

Change-Id: I505c11169a9bc9871a31fc0c61e119f92f32cc63

5 files changed, 42 insertions, 20 deletions

diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index de8712a..f924966 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,11 @@
+2019-11-19  Andrew Burgess  <andrew.burgess@embecosm.com>
+
+	* gdb.base/ctf-constvars.exp: Skip test if CTF is not supported in
+	the compiler.  Clean up header comment a little.
+	* gdb.base/ctf-ptype.exp: Likewise.
+	* gdb.base/ctf-whatis.exp: Likewise.
+	* lib/gdb.exp (skip_ctf_tests): New proc.
+
 2019-11-18  Sergio Durigan Junior  <sergiodj@redhat.com>
 
 	https://bugzilla.redhat.com/show_bug.cgi?id=1765117
diff --git a/gdb/testsuite/gdb.base/ctf-constvars.exp b/gdb/testsuite/gdb.base/ctf-constvars.exp
index 4a81a94..fd46d64 100644
--- a/gdb/testsuite/gdb.base/ctf-constvars.exp
+++ b/gdb/testsuite/gdb.base/ctf-constvars.exp
@@ -18,20 +18,21 @@
 #
 # This file is part of the gdb testsuite
 #
-# tests for const variables
-#           const pointers to vars
-#           pointers to const variables
-#           const pointers to const vars
-# with mixed types
+# Tests for: const variables,
+#            const pointers to vars
+#            pointers to const variables
+#            const pointers to const vars
+# with mixed types.
 
-#
-# test running programs
-#
-# -gt generates full-fledged CTF.
+if [skip_ctf_tests] {
+    unsupported "no ctf debug format support"
+    return 0
+}
 
 standard_testfile .c
-set opts "additional_flags=-gt"
 
+# Using `-gt` generates full-fledged CTF debug information.
+set opts "additional_flags=-gt"
 if { [prepare_for_testing "failed to prepare" ${testfile} \
 	  [list $srcfile] [list $opts nowarnings]] } {
     return 0
diff --git a/gdb/testsuite/gdb.base/ctf-ptype.exp b/gdb/testsuite/gdb.base/ctf-ptype.exp
index 9f54582..68a9662 100644
--- a/gdb/testsuite/gdb.base/ctf-ptype.exp
+++ b/gdb/testsuite/gdb.base/ctf-ptype.exp
@@ -15,14 +15,15 @@
 
 # This file is a subset of ptype.exp written by Rob Savoye. (rob@cygnus.com)
 
-#
-# test running programs
-#
-# -gt generates full-fledged CTF.
+if [skip_ctf_tests] {
+    unsupported "no ctf debug format support"
+    return 0
+}
 
 standard_testfile .c
-set opts "additional_flags=-gt"
 
+# Using `-gt` generates full-fledged CTF debug information.
+set opts "additional_flags=-gt"
 if { [prepare_for_testing "failed to prepare" ${testfile} \
 	  [list $srcfile] [list $opts nowarnings]] } {
     return 0
diff --git a/gdb/testsuite/gdb.base/ctf-whatis.exp b/gdb/testsuite/gdb.base/ctf-whatis.exp
index 3f26fc3..626aecb 100644
--- a/gdb/testsuite/gdb.base/ctf-whatis.exp
+++ b/gdb/testsuite/gdb.base/ctf-whatis.exp
@@ -15,14 +15,15 @@
 
 # This file is a subset of whatis.exp written by Rob Savoye. (rob@cygnus.com)
 
-#
-# test running programs
-#
-# -gt generates full-fledged CTF.
+if [skip_ctf_tests] {
+    unsupported "no ctf debug format support"
+    return 0
+}
 
 standard_testfile .c
-set opts "additional_flags=-gt"
 
+# Using `-gt` generates full-fledged CTF debug information.
+set opts "additional_flags=-gt"
 if { [prepare_for_testing "failed to prepare" ${testfile} \
           [list $srcfile] [list $opts nowarnings]] } {
     return 0
diff --git a/gdb/testsuite/lib/gdb.exp b/gdb/testsuite/lib/gdb.exp
index 2d395ef..828c91d 100644
--- a/gdb/testsuite/lib/gdb.exp
+++ b/gdb/testsuite/lib/gdb.exp
@@ -6787,5 +6787,16 @@ proc cmp_file_string { file str msg } {
     }
 }
 
+# Does the compiler support CTF debug output using '-gt' compiler
+# flag?  If not then we should skip these tests.
+
+gdb_caching_proc skip_ctf_tests {
+    return ![gdb_can_simple_compile ctfdebug {
+	int main () {
+	    return 0;
+	}
+    } executable "additional_flags=-gt"]
+}
+
 # Always load compatibility stuff.
 load_lib future.exp