Re: thumb_skip_prologue too adventurous

[Jonathan Larmour <jlarmour at redhat dot co dot uk>]

Fernando Nasser wrote:
> I am not sure if there isn't a better solution for this, but for now I
> would say that you should check your change in as an emergency fix.

I don't have checkin rights to the "src" repository, so I'd be grateful if
you could do this for me.

>  I
> am assuming you ran the testsuite and it did not cause any regressions,
> right?  (I don't think it will cause any)

Nope - no regressions.
 
> I may latter add another change to check first if there is information
> about the prologue end in the symbol table.  I don't know why this was
> not checked before, I just noticed it now, looking at you patch.

Don't worry - it is checked, but it is done in arm_skip_prologue, before
thumb_skip_prologue is called.

> I wrote this thumb prologue scan code to match the new compiler (gcc)
> prologue generation.  As everything is new, both Nick and I used the
> testsuite results to verify our work. The case you mention does not have
> a testsuite case.  I wonder if you could add a test case?

I've never done a GDB testcase before, but here goes - I've attached one. It
runs at the end of break.exp. The complication is that we need to start
over, because the problematic programs are the ones compiled with
optimization. So we have to jump through all the same hoops as at the start
of the file. Some of this stuff might be overkill, but it definitely seems
to work.

I agree the addition of this test is A Good Thing as we've had these types
of problems before on other targets with optimized code.

Hope this helps. Obviously let me know if there are any problems with it.

Jifl

2000-03-19  Jonathan Larmour  <jlarmour@redhat.co.uk>

	* gdb.base/break.exp: Add new test for setting breakpoints on
	optimized code so we can test breakpoints work even when function
	prologues may be optimized away


-- 
Red Hat, 35 Cambridge Place, Cambridge, UK. CB2 1NS  Tel: +44 (1223) 728762
"Plan to be spontaneous tomorrow."  ||  These opinions are all my own fault
Index: gdb/testsuite/gdb.base/break.exp
===================================================================
RCS file: /cvs/src/src/gdb/testsuite/gdb.base/break.exp,v
retrieving revision 1.2
diff -u -5 -p -r1.2 break.exp
--- gdb/testsuite/gdb.base/break.exp	2000/02/16 00:11:07	1.2
+++ gdb/testsuite/gdb.base/break.exp	2000/03/19 20:26:34
@@ -799,10 +799,83 @@ proc test_next_with_recursion {} { 
 }
 
 test_clear_command
 test_next_with_recursion
 
+
+#********
+
+# build a new file with optimization enabled so that we can try breakpoints
+# on targets with optimized prologues
+
+set binfileo2 ${objdir}/${subdir}/${testfile}o2
+
+if  { [gdb_compile "${srcdir}/${subdir}/${srcfile}" "${binfileo2}" executable {debug additional_flags="-O2" }] != "" } {
+    gdb_suppress_entire_file "Testcase compile failed, so all tests in this file will automatically fail."
+}
+
+if [get_compiler_info ${binfileo2}] {
+    return -1
+}
+
+gdb_exit
+gdb_start
+gdb_reinitialize_dir $srcdir/$subdir
+gdb_load ${binfileo2}
+
+if [target_info exists gdb_stub] {
+    gdb_step_for_stub;
+}
+
+#
+# test break at function
+#
+gdb_test "break main" \
+    "Breakpoint.*at.* file .*$srcfile, line.*" \
+    "breakpoint function, optimized file"
+
+#
+# test break at function
+#
+gdb_test "break marker4" \
+    "Breakpoint.*at.* file .*$srcfile, line.*" \
+    "breakpoint small function, optimized file"
+
+#
+# run until the breakpoint at main is hit. For non-stubs-using targets.
+#
+if ![target_info exists use_gdb_stub] {
+  if [istarget "*-*-vxworks*"] then {
+    send_gdb "run vxmain \"2\"\n"
+    set timeout 120
+    verbose "Timeout is now $timeout seconds" 2
+  } else {
+	send_gdb "run\n"
+  }
+  gdb_expect {
+    -re "The program .* has been started already.*y or n. $" {
+	send_gdb "y\n"
+	exp_continue
+    }
+    -re "Starting program.*Breakpoint \[0-9\]+,.*main .*argc.*argv.* at .*$srcfile:75.*75\[\t \]+if .argc.* \{.*$gdb_prompt $"\
+	                    { pass "run until function breakpoint, optimized file" }
+    -re ".*$gdb_prompt $"       { fail "run until function breakpoint, optimized file" }
+    timeout	            { fail "run until function breakpoint, optimized file (timeout)" }
+  }
+} else {
+    if ![target_info exists gdb_stub] {
+	gdb_test continue ".*Continuing\\..*Breakpoint \[0-9\]+, main \\(argc=.*, argv=.*, envp=.*\\) at .*$srcfile:75.*75\[\t \]+if .argc.*\{.*" "stub continue, optimized file"
+    }
+}
+
+#
+# run until the breakpoint at a small function
+#
+gdb_test continue "Continuing\\..*Breakpoint \[0-9\]+, marker4 \\(d=177601976\\) at .*$srcfile:51.*51\[\t \]+void.*marker4.*" \
+			"run until breakpoint set at small function, optimized file"
+
+
 # Reset the default arguments for VxWorks
 if [istarget "*-*-vxworks*"] {
     set timeout 10
     verbose "Timeout is now $timeout seconds" 2
     send_gdb "set args main\n"