On 17/02/16 14:42, Richard Biener wrote:
On Wed, Feb 17, 2016 at 1:41 PM, Tom de Vries <tom_devr...@mentor.com> wrote:
Hi,
once in a while I'm in a gdb debug session debugging cc1, and want to print
the current function to file.
There's a debug function debug_function that prints a function to stderr,
and there are methods to redirect output of a command to a file (
https://sourceware.org/gdb/onlinedocs/gdb/Logging-Output.html ).
And there's a function dump_function_to_file that takes a FILE* parameter,
which could be combined with open/close calls in gdb.
But I think a short-hand is easier.
This patch adds a function debug_function_to_file. It can f.i. be called as:
...
(gdb) call debug_function_to_file (cfun.decl, "foo.1.txt", 0)
...
Hmm, now I wonder if the order 'cfun.decl, 0, "foo.1.txt"' would make more
sense (first two parameters the same as in debug_function).
OK for stage1 trunk if bootstrap and reg-test succeeds?
Bonus for making this a helper in gdbhooks.py instead, using
fopen/fclose and the existing inferior calls.
Using attached demonstrator patch, we can use command
debug-function-to-file in gdb:
...
(gdb) python import sys; sys.path.append('<path>/gcc'); import gdbhooks
Successfully loaded GDB hooks for GCC
(gdb) b tail_merge_optimize
Breakpoint 1 at 0x11be1cc: file gcc/tree-ssa-tail-merge.c, line 1633.
(gdb) r
Starting program: cc1 -quiet hello.c -O2 -o hello.s
Breakpoint 1, tail_merge_optimize (todo=0) at gcc/tree-ssa-tail-merge.c:1633
1633 int nr_bbs_removed_total = 0;
(gdb) debug-function-to-file "bla.txt"
$1 = 47180688
$2 = <function_decl 0x7ffff61a22a0 main>
$3 = 0
...
and we find that bla.txt contains the result of dump_function_to_file:
...
$ cat bla.txt
main ()
{
<bb 2>:
__builtin_puts (&"hello"[0]);
return 0;
}
...
I would be nice if we could avoid the ${1,2,3} printouts and value
history assignments, but I'm not sure how to do that.
And given that we have a command with a variable amount of arguments, we
should try to handle different number of arguments, say these three
giving the same result:
- debug-function-to-file "bla.txt"
- debug-function-to-file "bla.txt" cfun->decl
- debug-function-to-file "bla.txt" cfun->decl dump_flags
Or perhaps 0 for flags by default, as in pcfun.
Thanks,
- Tom
Add debug-function-to-file to gdbhooks.py
---
gcc/gdbhooks.py | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)
diff --git a/gcc/gdbhooks.py b/gcc/gdbhooks.py
index 0d5cc97..9c230f9 100644
--- a/gcc/gdbhooks.py
+++ b/gcc/gdbhooks.py
@@ -589,4 +589,22 @@ class BreakOnPass(gdb.Command):
BreakOnPass()
+class debug_function_to_file(gdb.Command):
+ """
+ """
+ def __init__(self):
+ gdb.Command.__init__(self, 'debug-function-to-file', gdb.COMMAND_USER)
+
+ def invoke(self, arg, from_tty):
+ gdb.execute("call fopen (%s, \"w\")" % arg)
+ fp = gdb.history (0)
+ gdb.execute("p cfun->decl")
+ fn = gdb.history (0)
+ flags = 0
+ dumpargs = "(tree)%u, (FILE *)%u, %u" % (fn, fp, flags)
+ gdb.execute("call dump_function_to_file (%s)" % dumpargs)
+ gdb.execute("call fclose ((FILE *)%u)" % fp)
+
+debug_function_to_file()
+
print('Successfully loaded GDB hooks for GCC')
