[PATCH v4 03/15] Change gdb.base/skip-solib.exp deal with lack of epilogue information

[Bruno Larsen <blarsen@redhat.com>]

When running gdb.base/skip-solib.exp, the backtrace tests could fail with
compilers that associated epilogue instructions with the last statement
line of the function, instead of associating it with the closing brace,
despite the feature being fully functional.  As an example, when testing
skipping the function square, the testsuite would show

Breakpoint 1, main () at (...)/binutils-gdb/gdb/testsuite/gdb.base/skip-solib-main.c:5
5         return square(0);
(gdb) step
0x00007ffff7cef560 in __libc_start_call_main () from /lib64/libc.so.6
(gdb) PASS: gdb.base/skip-solib.exp: ignoring solib file: step
bt
 #0  0x00007ffff7cef560 in __libc_start_call_main () from /lib64/libc.so.6
 #1  0x00007ffff7cef60c in __libc_start_main_impl () from /lib64/libc.so.6
 #2  0x0000000000401065 in _start ()
(gdb) FAIL: gdb.base/skip-solib.exp: ignoring solib file: bt

Which means that the feature is working, the testsuite is just
mis-identifying it.  To avoid this problem, the skipped function calls
have been sent to a line before `return`, so epilogues won't factor in.

This commit has also changed a few hardcoded steps to leave functions to
the newly introduced gdb_step_until to leave those functions.
---
 gdb/testsuite/gdb.base/skip-inline.exp   | 23 ++++++++++++++++-------
 gdb/testsuite/gdb.base/skip-solib-lib.c  |  3 ++-
 gdb/testsuite/gdb.base/skip-solib-main.c |  3 ++-
 gdb/testsuite/gdb.base/skip-solib.exp    | 12 ++++++++++--
 4 files changed, 30 insertions(+), 11 deletions(-)

diff --git a/gdb/testsuite/gdb.base/skip-inline.exp b/gdb/testsuite/gdb.base/skip-inline.exp
index f6e9926b66c..3fbaa5469dd 100644
--- a/gdb/testsuite/gdb.base/skip-inline.exp
+++ b/gdb/testsuite/gdb.base/skip-inline.exp
@@ -15,6 +15,11 @@
 
 standard_testfile
 
+set epilogue 1
+if {![have_epilogue_line_info]} {
+    set epilogue 0
+}
+
 if { [prepare_for_testing "failed to prepare" "skip-inline" \
 			  {skip-inline.c skip1.c } \
 			  {debug nowarnings}] } {
@@ -35,16 +40,20 @@ gdb_test "skip function foo" "Function foo will be skipped when stepping\."
 gdb_test "bt" "\\s*\\#0\\s+main.*" "in the main"
 gdb_test "step" ".*" "step into baz, since foo will be skipped"
 gdb_test "bt" "\\s*\\#0\\s+baz.*" "in the baz, since foo was skipped"
-gdb_test "step" ".*" "step in the baz"
-gdb_test "bt" "\\s*\\#0\\s+baz.*" "still in the baz"
-gdb_test "step" ".*" "step back to main"
+gdb_step_until ".*x = 0; x = baz \\(foo \\(\\)\\).*"
 gdb_test "bt" "\\s*\\#0\\s+main.*" "again in the main"
 gdb_test "step" ".*" "step again into baz, since foo will be skipped"
 gdb_test "bt" "\\s*\\#0\\s+baz.*" "again in the baz"
-gdb_test "step" ".*" "step in the baz, again"
-gdb_test "bt" "\\s*\\#0\\s+baz.*" "still in the baz, again"
-gdb_test "step" ".*" "step back to main, again"
-gdb_test "bt" "\\s*\\#0\\s+main.*" "again back to main"
+gdb_step_until "main \\(\\) at .*" "step back to main, again"
+gdb_test "bt" "\\s*\\#0.*main.*" "again back to main"
+
+# Because clang doesn't add epilogue information, having a set number of
+# steps puts clang more and more out of sync with gcc.  It is unlikely that
+# the effort of keeping both outputs will be useful.
+if {$epilogue == 0} {
+    untested "Multiple steps tests are not supported with this compiler"
+    return
+}
 
 if ![runto_main] {
     return
diff --git a/gdb/testsuite/gdb.base/skip-solib-lib.c b/gdb/testsuite/gdb.base/skip-solib-lib.c
index b2c4d86d703..341f1440a3b 100644
--- a/gdb/testsuite/gdb.base/skip-solib-lib.c
+++ b/gdb/testsuite/gdb.base/skip-solib-lib.c
@@ -7,5 +7,6 @@ int multiply(int a, int b)
 
 int square(int num)
 {
-  return multiply(num, num);
+  int res = multiply(num, num);
+  return res;
 }
diff --git a/gdb/testsuite/gdb.base/skip-solib-main.c b/gdb/testsuite/gdb.base/skip-solib-main.c
index 746bb5f36bb..a3b6d417935 100644
--- a/gdb/testsuite/gdb.base/skip-solib-main.c
+++ b/gdb/testsuite/gdb.base/skip-solib-main.c
@@ -2,5 +2,6 @@ int square(int num);
 
 int main()
 {
-  return square(0);
+  int s = square(0);
+  return s;
 }
diff --git a/gdb/testsuite/gdb.base/skip-solib.exp b/gdb/testsuite/gdb.base/skip-solib.exp
index 0f2ce7e1ad8..8e61725ad1b 100644
--- a/gdb/testsuite/gdb.base/skip-solib.exp
+++ b/gdb/testsuite/gdb.base/skip-solib.exp
@@ -82,7 +82,7 @@ with_test_prefix "ignoring solib file" {
     # We shouldn't step into square(), since we skipped skip-solib-lib.c.
     #
     gdb_test "step" ""
-    gdb_test "bt" "#0\\s+main.*"
+    gdb_test "bt 1" "#0\\s+main.*"
 }
 
 #
@@ -114,5 +114,13 @@ with_test_prefix "ignoring solib function" {
     # the last line of square.
     #
     gdb_test "step" ""
-    gdb_test "bt" "#0\\s+square.*"
+    gdb_test "bt 1" "#0\\s+square.*" "skipped multiply"
+#    gdb_test_multiple "bt 1" "skipped multiply" {
+#	-re "#0\\s+square.*" {
+#	    pass "skipped multiply"
+#	}
+#	-re "#0.*main.*" {
+#	    pass "skipped multiply"
+#	}
+#    }
 }
-- 
2.31.1