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Re: Unexpected DW_AT_type for Ada strings on s390x?
- From: Joel Brobecker <brobecker at adacore dot com>
- To: Andreas Arnez <arnez at linux dot vnet dot ibm dot com>
- Cc: gdb at sourceware dot org, Eric Botcazou <botcazou at adacore dot com>
- Date: Tue, 4 Dec 2012 16:10:36 +0400
- Subject: Re: Unexpected DW_AT_type for Ada strings on s390x?
- References: <87fw3mhxbb.fsf@linux.vnet.ibm.com>
[Cc'ing Eric, as he is the compiler expert - GDB just represents what
the compiler tells us]
> Upstream gnat seems to create different debug data for string parameters
> on s390x than on x86, x86_64 or s390. On s390x the DW_AT_type of a
> string parameter is a constant /reference/ to the two-element structure
> "string___XUP". On the other platforms it is the constant structure,
> not a reference.
My first guess is that the variantion in type definition is caused
by differences in ABI. I don't know s390 platforms, so I can't
confirm offhand. But it seems like a plausible way to pass the
argument.
If Eric confirms my guess, the attached patch should fix the problem.
[the rest of your email is kept below - as a reference for Eric, in case
he needs it]
> Is the DW_AT_type output intentional? Why does it depend on the
> architecture? Note that for C or C++, gcc correctly declares structure
> parameters as /structures/ (not references) in their DW_AT_type.
>
> If the output is intentional, I suggest to relax the pattern in the test
> case accordingly. In any case it would be nice to differentiate the two
> "backtrace" test points, e.g. like this:
>
>
> --- a/gdb/testsuite/gdb.ada/lang_switch.exp
> +++ b/gdb/testsuite/gdb.ada/lang_switch.exp
> @@ -43,5 +43,5 @@ gdb_test "bt" \
> gdb_test "set lang c"
> gdb_test "bt" \
> ".*#1.*lang_switch\\.ada_procedure\\s*\\(msg={.*\\).*" \
> - "backtrace"
> + "backtrace (C)"
--
Joel
>From cdb4ea7d663ca7eab453f31a45f6fae068753803 Mon Sep 17 00:00:00 2001
From: Joel Brobecker <brobecker@adacore.com>
Date: Tue, 4 Dec 2012 16:04:26 +0400
Subject: [PATCH] gdb.ada/lang_switch: Allow msg parameter to be a reference.
gdb/testsuite/ChangeLog:
* gdb.ada/lang_switch.exp: The "msg" parameter may be a reference.
---
gdb/testsuite/gdb.ada/lang_switch.exp | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/gdb/testsuite/gdb.ada/lang_switch.exp b/gdb/testsuite/gdb.ada/lang_switch.exp
index 6ee4c23..a217d2e 100644
--- a/gdb/testsuite/gdb.ada/lang_switch.exp
+++ b/gdb/testsuite/gdb.ada/lang_switch.exp
@@ -42,6 +42,5 @@ gdb_test "bt" \
# if the current language is not "auto".
gdb_test "set lang c"
gdb_test "bt" \
- ".*#1.*lang_switch\\.ada_procedure\\s*\\(msg={.*\\).*" \
- "backtrace"
-
+ ".*#1.*lang_switch\\.ada_procedure\\s*\\(msg=(@$hex: +)?{.*\\).*" \
+ "backtrace with lang set to C"
--
1.7.10.4