Bug 16345

Summary:	ada cross-compiler for arm generates bad code - resulting executable segfaults
Product:	gcc	Reporter:	Keenan Pepper <cherylgpepper>
Component:	ada	Assignee:	Not yet assigned to anyone <unassigned>
Status:	RESOLVED INVALID
Severity:	normal	CC:	gcc-bugs
Priority:	P2
Version:	3.4.1
Target Milestone:	---
Host:	i686-pc-linux-gnu	Target:	arm-unknown-linux-gnu
Build:	i686-pc-linux-gnu	Known to work:
Known to fail:		Last reconfirmed:

Description Keenan Pepper 2004-07-03 08:49:26 UTC

The program available at this address:

http://users.erols.com/whitaker/wordsall.zip

compiles and executes correctly on native i686, but when cross-compiled for arm
the resulting "words" executable prints out some introductory text and a prompt,
but then segfaults as soon as any input is entered. The three helper programs
"makedict", "makestem", and "makeinfl" execute and generate their output files
correctly on arm, only the "words" program appears to be broken. It compiles
with no warnings even with -pedantic and -Wall options, so if there are any
errors in the code the compiler is not detecting them. I wouldn't expect bad Ada
code to just segfault, anyway, because Ada has bounds checking and lacks
pointers. I am trying to isolate the problem and produce a test case, but that
is difficult because I don't know Ada very well. I'd be happy to provide any
extra information that could be helpful.

Comment 1 Keenan Pepper 2004-07-04 03:55:10 UTC

I just cross-built ada-enabled gdb so hopefully I will be able to provide some
more helpful information.

Comment 2 Keenan Pepper 2004-07-04 20:37:00 UTC

OK, gnat-gdb-5.3 is up and running on my zaurus, but it's still not much help
because there's some problem with the debugging format (I compiled with the
command "gnatmake -g words"):

Die: DW_TAG_subrange_type (abbrev = 5, offset = 351607)
        has children: FALSE
        attributes:
                DW_AT_name (DW_FORM_string) string: "natural___XDLU_0__2147483647"
                DW_AT_lower_bound (DW_FORM_data1) constant: 0
                DW_AT_upper_bound (DW_FORM_data4) constant: 2147483647
                DW_AT_type (DW_FORM_ref4) constant: 121
Dwarf Error: Cannot find type of die.

I'm experimenting with different debugging formats to see if I can get an actual
backtrace or something.

Comment 3 Keenan Pepper 2004-07-04 20:48:27 UTC

I deleted all the binary files and recompiled with "gnatmake -gstabs words", but
gdb still had dwarf errors. So either gdb isn't recognizing the correct
debugging format or the gnat compiler is putting in broken debugging info. This
happens both on native i686 and cross-compiling for arm. Of course I know next
to nothing about stabs, dwarf, etc. so I could really use some help.

Comment 4 Keenan Pepper 2004-07-04 21:23:32 UTC

Tried it again and now I realize it doesn't always segfault on every input, in
fact I noticed that if you type in, for example, "remotus" as the first word, it
segfaults, but if you type in "in", "de", "quam", and "remotus" in order it
parses and analyzes all of them perfectly without segfaulting. It seems pretty
random which combinations of words make it work, but it definitely makes me
think it's a problem with memory allocation or garbage collecting or something.
Someone please help!

Comment 5 Arnaud Charlet 2004-09-09 08:49:16 UTC

This report is really too general: could you please reduce the problem to a
workable test case, with very precise intructions on how to reproduce
the bug.

Also, it's likely a code generation problem from what you are saying, rather
than an Ada bug.

Arno

Comment 6 Andrew Pinski 2004-12-05 16:55:06 UTC

No feedback in 3 months (T-4 days).