Re: [PATCH v2 1/5] Extend test gdb.python/py-recurse-unwind.exp

[Kevin Buettner <kevin at buettner dot to>]

This patch modifies the unwinder (sniffer) defined in
py-recurse-unwind.py so that, depending upon the value of one of its
class variables, it will take different paths through the code,
testing different functionality.

The original test attempted to obtain the value of an undefined
symbol.

This somewhat expanded test checks to see if 'pc' can be read via
gdb.PendingFrame.read_register() and also via gdb.parse_and_eval().

gdb/testsuite/ChangeLog:
    
    	* gdb.python/py-recurse-unwind.c (ccc): Delete.
    	(ccc0, ccc1, ccc2): New functions.
    	(bbb): Call ccc0, ccc1, and ccc2.
    	* gdb.python/py-recurse-unwind.py (TestUnwinder): Add calls
    	to read_register() and gdb.parse_and_eval().  Make each code
    	call a separate case that can be individually tested.
    	* gdb.python/py-recurse-unwind.exp (cont_and_backtrace): New
    	proc. Call cont_and_backtrace for each of the code paths that
    	we want to test in the unwinder.
---
 gdb/testsuite/gdb.python/py-recurse-unwind.c   | 16 ++++++-
 gdb/testsuite/gdb.python/py-recurse-unwind.exp | 61 ++++++++++++++++----------
 gdb/testsuite/gdb.python/py-recurse-unwind.py  | 29 +++++++++---
 3 files changed, 76 insertions(+), 30 deletions(-)

diff --git a/gdb/testsuite/gdb.python/py-recurse-unwind.c b/gdb/testsuite/gdb.python/py-recurse-unwind.c
index 02a835a..bd0330a 100644
--- a/gdb/testsuite/gdb.python/py-recurse-unwind.c
+++ b/gdb/testsuite/gdb.python/py-recurse-unwind.c
@@ -18,14 +18,26 @@
 /* This is the test program loaded into GDB by the py-recurse-unwind test.  */
 
 void
-ccc (int arg)
+ccc0 (int arg)
+{
+}
+
+void
+ccc1 (int arg)
+{
+}
+
+void
+ccc2 (int arg)
 {
 }
 
 void
 bbb (int arg)
 {
-  ccc (789);
+  ccc0 (789);
+  ccc1 (789);
+  ccc2 (789);
 }
 
 void
diff --git a/gdb/testsuite/gdb.python/py-recurse-unwind.exp b/gdb/testsuite/gdb.python/py-recurse-unwind.exp
index 9629a97..ed5e600 100644
--- a/gdb/testsuite/gdb.python/py-recurse-unwind.exp
+++ b/gdb/testsuite/gdb.python/py-recurse-unwind.exp
@@ -45,29 +45,44 @@ if ![runto_main] then {
     return 0
 }
 
-gdb_breakpoint "ccc"
 
-gdb_continue_to_breakpoint "ccc"
-
-# If the unwinder is active, the usage count will increment while
-# running to the breakpoint.  Reset it prior to doing the backtrace.
-gdb_test_no_output "python TestUnwinder.reset_count()"
-
-# The python based unwinder should be called a number of times while
-# generating the backtrace, but its sniffer always returns None.  So
-# it doesn't really contribute to generating any of the frames below.
-#
-# But that's okay.  Our goal here is to make sure that GDB doesn't
-# get hung up in potentially infinite recursion when invoking the
-# Python-based unwinder.
-
-gdb_test_sequence "bt"  "backtrace" {
-    "\\r\\n#0 .* ccc \\(arg=789\\) at "
-    "\\r\\n#1 .* bbb \\(arg=456\\) at "
-    "\\r\\n#2 .* aaa \\(arg=123\\) at "
-    "\\r\\n#3 .* main \\(.*\\) at"
+proc cont_and_backtrace { tst func } {
+
+    gdb_breakpoint "$func"
+
+    # We're testing different code paths within the unwinder's sniffer.
+    # Set the current path to be tested here.
+    gdb_test_no_output "python TestUnwinder.set_test(\"$tst\")" \
+                       "set code path within python unwinder to $tst"
+
+    # If the unwinder is active, the usage count will increment while
+    # running to the breakpoint.  Reset it prior to doing the backtrace.
+    gdb_test_no_output "python TestUnwinder.reset_count()" \
+                       "reset count for $tst"
+
+    gdb_continue_to_breakpoint "$func"
+
+    # The python based unwinder should be called a number of times while
+    # generating the backtrace, but its sniffer always returns None.  So
+    # it doesn't really contribute to generating any of the frames below.
+    #
+    # But that's okay.  Our goal here is to make sure that GDB doesn't
+    # get hung up in potentially infinite recursion when invoking the
+    # Python-based unwinder.
+
+    gdb_test_sequence "bt"  "backtrace for $tst" {
+	"\\r\\n#0 .* ccc. \\(arg=789\\) at "
+	"\\r\\n#1 .* bbb \\(arg=456\\) at "
+	"\\r\\n#2 .* aaa \\(arg=123\\) at "
+	"\\r\\n#3 .* main \\(.*\\) at"
+    }
+
+    # Test that the python-based unwinder / sniffer was actually called
+    # during generation of the backtrace.
+    gdb_test "python print(TestUnwinder.count > 0)" "True" \
+             "python unwinder called for $tst"
 }
 
-# Test that the python-based unwinder / sniffer was actually called
-# during generation of the backtrace.
-gdb_test "python print(TestUnwinder.count > 0)" "True"
+cont_and_backtrace "check_undefined_symbol" "ccc0"
+cont_and_backtrace "check_user_reg_pc" "ccc1"
+cont_and_backtrace "check_pae_pc" "ccc2"
diff --git a/gdb/testsuite/gdb.python/py-recurse-unwind.py b/gdb/testsuite/gdb.python/py-recurse-unwind.py
index 1da7aca..5eb87bb 100644
--- a/gdb/testsuite/gdb.python/py-recurse-unwind.py
+++ b/gdb/testsuite/gdb.python/py-recurse-unwind.py
@@ -40,13 +40,18 @@ class TestUnwinder(Unwinder):
     def inc_count (cls):
         cls.count += 1
 
+    test = 'check_undefined_symbol'
+
+    @classmethod
+    def set_test (cls, test) :
+       cls.test = test
+
     def __init__(self):
         Unwinder.__init__(self, "test unwinder")
         self.recurse_level = 0
 
     def __call__(self, pending_frame):
 
-
         if self.recurse_level > 0:
             gdb.write("TestUnwinder: Recursion detected - returning early.\n")
             return None
@@ -54,11 +59,25 @@ class TestUnwinder(Unwinder):
         self.recurse_level += 1
         TestUnwinder.inc_count()
 
-        try:
-            val = gdb.parse_and_eval("undefined_symbol")
+        if TestUnwinder.test == 'check_user_reg_pc' :
+
+            pc = pending_frame.read_register('pc')
+            pc_as_int = int(pc.cast(gdb.lookup_type('int')))
+            # gdb.write("In unwinder: pc=%x\n" % pc_as_int)
+
+        elif TestUnwinder.test == 'check_pae_pc' :
+
+            pc = gdb.parse_and_eval('$pc')
+            pc_as_int = int(pc.cast(gdb.lookup_type('int')))
+            # gdb.write("In unwinder: pc=%x\n" % pc_as_int)
+
+        elif TestUnwinder.test == 'check_undefined_symbol' :
+
+            try:
+                val = gdb.parse_and_eval("undefined_symbol")
 
-        except Exception as arg:
-            pass
+            except Exception as arg:
+                pass
 
         self.recurse_level -= 1