gdb/testsuite: Test for a backtrace through object without debuginfo

Fedora has been carrying this test since back in the Project Archer
days. A change back then caused GDB to stop being able to backtrace when
only some of the object files had debug information. Even though the
changed code never seems to have made its way into the main GDB project,
I think it makes sense to bring the test along to ensure something like
this doesn't pass unnoticed.

diff --git a/gdb/testsuite/gdb.base/backtrace-through-cu-nodebug-caller.c b/gdb/testsuite/gdb.base/backtrace-through-cu-nodebug-caller.c
new file mode 100644 (file)
index 0000000..a33f86d
--- /dev/null
+++ b/gdb/testsuite/gdb.base/backtrace-through-cu-nodebug-caller.c
@@ -0,0 +1,28 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2005-2023 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+typedef int (*callback_t) (void);
+
+int
+caller (callback_t callback)
+{
+  /* Ensure some frame content to push away the return address.  */
+  volatile const long one = 1;
+
+  /* Modify the return value to prevent any tail-call optimization.  */
+  return (*callback) () - one;
+}

diff --git a/gdb/testsuite/gdb.base/backtrace-through-cu-nodebug-main.c b/gdb/testsuite/gdb.base/backtrace-through-cu-nodebug-main.c
new file mode 100644 (file)
index 0000000..f958c02
--- /dev/null
+++ b/gdb/testsuite/gdb.base/backtrace-through-cu-nodebug-main.c
@@ -0,0 +1,32 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2005-2023 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+typedef int (*callback_t) (void);
+
+extern int caller (callback_t callback);
+
+int
+callback (void)
+{
+  return 1;
+}
+
+int
+main (void)
+{
+  return caller (callback);
+}

diff --git a/gdb/testsuite/gdb.base/backtrace-through-cu-nodebug.exp b/gdb/testsuite/gdb.base/backtrace-through-cu-nodebug.exp
new file mode 100644 (file)
index 0000000..ae9f60a
--- /dev/null
+++ b/gdb/testsuite/gdb.base/backtrace-through-cu-nodebug.exp
@@ -0,0 +1,91 @@
+# Copyright 2010-2023 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# Test that GDB can generate accurate backtraces even if some of the stack
+# trace goes through a function with no debug information.
+
+standard_testfile -caller.c -main.c
+set objmainfile ${testfile}-main.o
+set objcallerfile ${testfile}-caller.o
+
+# recompile the inferior with or without CFI information, then run the
+# inferior until the point where the important test starts
+# returns TRUE on an ERROR.
+proc prepare_test {has_cfi} {
+    global srcdir subdir srcfile srcfile2 objmainfile objcallerfile binfile
+    if {$has_cfi} {
+       set extension "cfi"
+       if {[gdb_compile "${srcdir}/${subdir}/${srcfile}" ${objcallerfile} \
+            object [list {additional_flags=-fomit-frame-pointer \
+                -funwind-tables -fasynchronous-unwind-tables}]] != "" } {
+           untested "couldn't compile without cfi"
+           return true
+      }
+    } else {
+       set extension "no-cfi"
+       if {[gdb_compile "${srcdir}/${subdir}/${srcfile}" ${objcallerfile} \
+            object [list {additional_flags=-fomit-frame-pointer \
+                -fno-unwind-tables \
+                -fno-asynchronous-unwind-tables}]] != "" } {
+           untested "couldn't compile with cfi"
+           return true
+      }
+    }
+    if {[gdb_compile "${objmainfile} ${objcallerfile}" \
+           "${binfile}-${extension}" binfile {}] != ""} {
+       untested "couldn't link object files"
+       return true
+    }
+
+    clean_restart "$binfile-${extension}"
+
+    if ![runto callback] then {
+       fail "has_cfi=$has_cfi: Can't run to callback"
+       return true
+    }
+    return false
+}
+
+if {[gdb_compile "${srcdir}/${subdir}/${srcfile2}" ${objmainfile} \
+       object {debug}] != "" } {
+    untested "couldn't compile main file"
+    return
+}
+
+if { [prepare_test false] } {
+     untested ${testfile}.exp
+} else {
+    gdb_test_multiple "bt" "verify unwinding breaks without CFI" {
+       -re -wrap " in \[?\]\[?\] .*" {
+           # It may backtrace through some random frames even to main().
+           pass $gdb_test_name
+       }
+       -re -wrap " in main .*" {
+           fail $gdb_test_name
+       }
+    }
+}
+
+if { [prepare_test true] } {
+     untested ${testfile}.exp
+} else {
+
+    # #0  callback () at ...
+    # #1  0x00000000004004e9 in caller ()
+    # #2  0x00000000004004cd in main () at ...
+    gdb_test "bt" \
+       "#0 +callback \[^\r\n\]+\r\n#1 \[^\r\n\]+ in caller \[^\r\n\]+\r\n#2 \[^\r\n\]+ in main \[^\r\n\]+" \
+       "verify unwinding works for CFI without DIEs"
+}