Re: [RFA/dwarf 2/2] Mark all functions as prototyped except C functions.

Joel Brobecker
2013-05-16T08:14:06Z

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> Hmmm, I am not 100% sure, but some internet searches suggest
> that this is probably true. Thanks! Attached is the updated patch,
> just adding language_objc to the condition, and adjusting the
> comment accordingly.
>
> gdb/ChangeLog:
>
> * dwarf2read.c (prototyped_function_p): New function.
> (read_subroutine_type): Use it.
>
> gdb/testsuite/ChangeLog:
>
> * gdb.ada/float_param: New testcase.
>
> Re-tested on x86_64-linux, no regression.

Pierre noticed a small typo in "asssume" (thank you!), so here is
a new version with the typo corrected.

--
Joel

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From 81149f0929162c08bbaa0686ca5d9285542a1e87 Mon Sep 17 00:00:00 2001
From: Joel Brobecker <brobecker@adacore.com>
Date: Tue, 15 Jan 2013 11:51:39 +0400
Subject: [PATCH] [dwarf] Mark all functions as prototyped except C functions.

This makes sure that the types of the arguments are taken into account
when performing an inferior function call to a non-C (or C-like)
function. In particular, this makes sure that the arguments are
appropriatly converted to the correct type.

For instance, on x86_64-linux, with the following Ada code:

procedure Set_Float (F : Float) is
begin
Global_Float := F;
end Set_Float;

The following sequence shows that Float arguments are incorrectly
passed (Ada's Float type is the equivalent of type "float" in C):

(gdb) call set_float (2.0)
(gdb) print global_float
$1 = 0.0

Putting a breakpoint inside set_float to inspect the value of
register xmm0 gives the first hint of the problem:

(gdb) p $xmm0
$2 = (v4_float => (0 => 0.0, 2.0, 0.0, 0.0),
v2_double => (0 => 2.0, 0.0),
[...]

It shows that the argument was passed as a double.

The code responsible for doing appropriate type conversions
for the arguments (value_arg_coerce) found that our function
was not prototyped, and thus could not use typing information
for the arguments. Instead, it defaulted to the value of "set
coerce-float-to-double", which by default is true, to determine
the argument type.

This patch fixes the problem by setting the PROTOTYPE flag
for all functions of any language except C and Objective C.

gdb/ChangeLog:

* dwarf2read.c (prototyped_function_p): New function.
(read_subroutine_type): Use it.

gdb/testsuite/ChangeLog:

* gdb.ada/float_param: New testcase.
---
gdb/dwarf2read.c | 44 +++++++++++++++++++++--------
gdb/testsuite/gdb.ada/float_param.exp | 43 ++++++++++++++++++++++++++++
gdb/testsuite/gdb.ada/float_param/foo.adb | 23 +++++++++++++++
gdb/testsuite/gdb.ada/float_param/pck.adb | 35 +++++++++++++++++++++++
gdb/testsuite/gdb.ada/float_param/pck.ads | 31 ++++++++++++++++++++
5 files changed, 164 insertions(+), 12 deletions(-)
create mode 100644 gdb/testsuite/gdb.ada/float_param.exp
create mode 100644 gdb/testsuite/gdb.ada/float_param/foo.adb
create mode 100644 gdb/testsuite/gdb.ada/float_param/pck.adb
create mode 100644 gdb/testsuite/gdb.ada/float_param/pck.ads

diff --git a/gdb/dwarf2read.c b/gdb/dwarf2read.c
index a17cd9d..6a12093 100644
--- a/gdb/dwarf2read.c
+++ b/gdb/dwarf2read.c
@@ -12600,6 +12600,37 @@ read_tag_string_type (struct die_info *die, struct dwarf2_cu *cu)
return set_die_type (die, type, cu);
}

+/* Assuming that DIE corresponds to a function, returns nonzero
+ if the function is prototyped. */
+
+static int
+prototyped_function_p (struct die_info *die, struct dwarf2_cu *cu)
+{
+ struct attribute *attr;
+
+ attr = dwarf2_attr (die, DW_AT_prototyped, cu);
+ if (attr && (DW_UNSND (attr) != 0))
+ return 1;
+
+ /* The DWARF standard implies that the DW_AT_prototyped attribute
+ is only meaninful for C, but the concept also extends to other
+ languages that allow unprototyped functions (Eg: Objective C).
+ For all other languages, assume that functions are always
+ prototyped. */
+ if (cu->language != language_c
+ && cu->language != language_objc)
+ return 1;
+
+ /* RealView does not emit DW_AT_prototyped. We can not distinguish
+ prototyped and unprototyped functions; default to prototyped,
+ since that is more common in modern code (and RealView warns
+ about unprototyped functions). */
+ if (producer_is_realview (cu->producer))
+ return 1;
+
+ return 0;
+}
+
/* Handle DIES due to C code like:

struct foo
@@ -12627,18 +12658,7 @@ read_subroutine_type (struct die_info *die, struct dwarf2_cu *cu)

ftype = lookup_function_type (type);

- /* All functions in C++, Pascal and Java have prototypes. */
- attr = dwarf2_attr (die, DW_AT_prototyped, cu);
- if ((attr && (DW_UNSND (attr) != 0))
- || cu->language == language_cplus
- || cu->language == language_java
- || cu->language == language_pascal)
- TYPE_PROTOTYPED (ftype) = 1;
- else if (producer_is_realview (cu->producer))
- /* RealView does not emit DW_AT_prototyped. We can not
- distinguish prototyped and unprototyped functions; default to
- prototyped, since that is more common in modern code (and
- RealView warns about unprototyped functions). */
+ if (prototyped_function_p (die, cu))
TYPE_PROTOTYPED (ftype) = 1;

/* Store the calling convention in the type if it's available in
diff --git a/gdb/testsuite/gdb.ada/float_param.exp b/gdb/testsuite/gdb.ada/float_param.exp
new file mode 100644
index 0000000..f0a7eac
--- /dev/null
+++ b/gdb/testsuite/gdb.ada/float_param.exp
@@ -0,0 +1,43 @@
+# Copyright 2013 Free Software Foundation, Inc.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+load_lib "ada.exp"
+
+if { [skip_ada_tests] } { return -1 }
+
+standard_ada_testfile foo
+
+if {[gdb_compile_ada "${srcfile}" "${binfile}" executable {debug}] != ""} {
+ return -1
+}
+
+clean_restart ${testfile}
+
+set bp_location [gdb_get_line_number "START" ${testdir}/foo.adb]
+runto "foo.adb:$bp_location"
+
+gdb_test_no_output "call set_float(2.0)"
+gdb_test "print global_float" \
+ " = 2\\.0"
+
+gdb_test_no_output "call set_double(1, 3.0)"
+gdb_test "print global_double" \
+ " = 3\\.0"
+
+gdb_test_no_output "call set_long_double(1, global_small_struct, 4.0)"
+gdb_test "print global_long_double" \
+ " = 4\\.0"
+
+
diff --git a/gdb/testsuite/gdb.ada/float_param/foo.adb b/gdb/testsuite/gdb.ada/float_param/foo.adb
new file mode 100644
index 0000000..2b08681
--- /dev/null
+++ b/gdb/testsuite/gdb.ada/float_param/foo.adb
@@ -0,0 +1,23 @@
+-- Copyright 2013 Free Software Foundation, Inc.
+--
+-- This program is free software; you can redistribute it and/or modify
+-- it under the terms of the GNU General Public License as published by
+-- the Free Software Foundation; either version 3 of the License, or
+-- (at your option) any later version.
+--
+-- This program is distributed in the hope that it will be useful,
+-- but WITHOUT ANY WARRANTY; without even the implied warranty of
+-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+-- GNU General Public License for more details.
+--
+-- You should have received a copy of the GNU General Public License
+-- along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+with Pck; use Pck;
+
+procedure Foo is
+begin
+ Set_Float (1.0); -- START
+ Set_Double (1, 1.0);
+ Set_Long_Double (1, (I => 2), 1.0);
+end Foo;
diff --git a/gdb/testsuite/gdb.ada/float_param/pck.adb b/gdb/testsuite/gdb.ada/float_param/pck.adb
new file mode 100644
index 0000000..18967e4
--- /dev/null
+++ b/gdb/testsuite/gdb.ada/float_param/pck.adb
@@ -0,0 +1,35 @@
+-- Copyright 2013 Free Software Foundation, Inc.
+--
+-- This program is free software; you can redistribute it and/or modify
+-- it under the terms of the GNU General Public License as published by
+-- the Free Software Foundation; either version 3 of the License, or
+-- (at your option) any later version.
+--
+-- This program is distributed in the hope that it will be useful,
+-- but WITHOUT ANY WARRANTY; without even the implied warranty of
+-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+-- GNU General Public License for more details.
+--
+-- You should have received a copy of the GNU General Public License
+-- along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+package body Pck is
+
+ procedure Set_Float (F : Float) is
+ begin
+ Global_Float := F;
+ end Set_Float;
+
+ procedure Set_Double (Dummy : Integer; D : Long_Float) is
+ begin
+ Global_Double := D;
+ end Set_Double;
+
+ procedure Set_Long_Double (Dummy : Integer;
+ DS : Small_Struct;
+ LD : Long_Long_Float) is
+ begin
+ Global_Long_Double := LD;
+ end Set_Long_Double;
+
+end Pck;
diff --git a/gdb/testsuite/gdb.ada/float_param/pck.ads b/gdb/testsuite/gdb.ada/float_param/pck.ads
new file mode 100644
index 0000000..093a32d
--- /dev/null
+++ b/gdb/testsuite/gdb.ada/float_param/pck.ads
@@ -0,0 +1,31 @@
+-- Copyright 2013 Free Software Foundation, Inc.
+--
+-- This program is free software; you can redistribute it and/or modify
+-- it under the terms of the GNU General Public License as published by
+-- the Free Software Foundation; either version 3 of the License, or
+-- (at your option) any later version.
+--
+-- This program is distributed in the hope that it will be useful,
+-- but WITHOUT ANY WARRANTY; without even the implied warranty of
+-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+-- GNU General Public License for more details.
+--
+-- You should have received a copy of the GNU General Public License
+-- along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+package Pck is
+ Global_Float : Float := 0.0;
+ Global_Double : Long_Float := 0.0;
+ Global_Long_Double : Long_Long_Float := 0.0;
+
+ type Small_Struct is record
+ I : Integer;
+ end record;
+ Global_Small_Struct : Small_Struct := (I => 0);
+
+ procedure Set_Float (F : Float);
+ procedure Set_Double (Dummy : Integer; D : Long_Float);
+ procedure Set_Long_Double (Dummy : Integer;
+ DS: Small_Struct;
+ LD : Long_Long_Float);
+end Pck;
--
1.7.10.4