Fix the x87 FP register printout when issuing the “info float” command.

Consider the following simple program:

.globl  _start
.text
_start:
      fldt    val
.data
      val: .byte 0x00,0x00,0x45,0x07,0x11,0x19,0x22,0xe9,0xfe,0xbf

With current GDB on x86-64 GNU/Linux hosts, after the moment the fldt
command has been executed the register st(0) looks like this,
according to the “info regs” output (TOP=7):

  R7: Valid   0xffffffbffffffffeffffffe922191107450000 -0.910676542908976927

which is clearly wrong (just count its length).  The problem is due to
the printf statement (see patch) printing a promoted integer value of
a char argument "raw[i]", and, since char is signed on x86-64
GNU/Linux, the erroneous “ffffff” are printed for the first three
bytes which turn out to be "negative".  The fix is to use gdb_byte
instead which is unsigned (and is the type of value_contents(), the
type to be used for raw target bytes anyway).  After the fix the value
will be printed correctly:

  R7: Valid   0xbffee922191107450000 -0.910676542908976927

gdb/
2013-04-19  Vladimir Kargov <kargov@gmail.com>
	    Pedro Alves  <palves@redhat.com>

	* i387-tdep.c (i387_print_float_info): Use gdb_byte for pointer to
	value contents.

gdb/testsuite/
2013-04-19  Vladimir Kargov  <kargov@gmail.com>
	    Pedro Alves  <palves@redhat.com>

	* gdb.arch/i386-float.S: New file.
	* gdb.arch/i386-float.exp: New file.

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 85c32454c325e33a29c786e3059215d0ac4df2b8..80fb6de1cbc8e67fad0e8a6c5c1de7e51058939a 100644 (file)
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,9 @@
+2013-04-19  Vladimir Kargov <kargov@gmail.com>
+           Pedro Alves  <palves@redhat.com>
+
+       * i387-tdep.c (i387_print_float_info): Use gdb_byte for pointer to
+       value contents.
+
 2013-04-17  Doug Evans  <dje@google.com>
 
        * dwarf2read.c (struct signatured_type): New member type.

diff --git a/gdb/i387-tdep.c b/gdb/i387-tdep.c
index 65bb1038ac25b0f4f8fbb418ac0dd4a2b6936c86..48a00c36198540a064f22c8510e28d78556aeb09 100644 (file)
--- a/gdb/i387-tdep.c
+++ b/gdb/i387-tdep.c
@@ -298,7 +298,7 @@ i387_print_float_info (struct gdbarch *gdbarch, struct ui_file *file,
 
          if (value_entirely_available (regval))
            {
-             const char *raw = value_contents (regval);
+             const gdb_byte *raw = value_contents (regval);
 
              fputs_filtered ("0x", file);
              for (i = 9; i >= 0; i--)

diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index 4d69f41cf29796ac2f0761aca2f79628590f65e1..d262b8151f50f3606921449bd28d026981d8f89e 100644 (file)
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,9 @@
+2013-04-19  Vladimir Kargov  <kargov@gmail.com>
+           Pedro Alves  <palves@redhat.com>
+
+       * gdb.arch/i386-float.S: New file.
+       * gdb.arch/i386-float.exp: New file.
+
 2013-04-18  Luis Machado  <lgustavo@codesourcery.com>
 
        * gdb.mi/mi-var-create-rtti.exp: Create a variable of

diff --git a/gdb/testsuite/gdb.arch/i386-float.S b/gdb/testsuite/gdb.arch/i386-float.S
new file mode 100644 (file)
index 0000000..c4f6391
--- /dev/null
+++ b/gdb/testsuite/gdb.arch/i386-float.S
@@ -0,0 +1,34 @@
+/* Copyright 2009-2013 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/>.
+
+   This file is part of the gdb testsuite.  */
+
+#define CONCAT1(a, b) CONCAT2(a, b)
+#define CONCAT2(a, b) a ## b
+
+#ifdef SYMBOL_PREFIX
+# define SYMBOL(str)     CONCAT1(SYMBOL_PREFIX, str)
+#else
+# define SYMBOL(str)     str
+#endif
+
+       .text
+       .globl SYMBOL(main)
+SYMBOL(main):
+       fninit
+       fldt    val
+       ret
+.data
+       val: .byte 0x00,0x00,0x45,0x07,0x11,0x19,0x22,0xe9,0xfe,0xbf

diff --git a/gdb/testsuite/gdb.arch/i386-float.exp b/gdb/testsuite/gdb.arch/i386-float.exp
new file mode 100644 (file)
index 0000000..c417532
--- /dev/null
+++ b/gdb/testsuite/gdb.arch/i386-float.exp
@@ -0,0 +1,43 @@
+# Copyright (C) 2009-2013 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/>.
+
+
+# This file is part of the gdb testsuite.
+
+# Test the x87 floating point information printout.
+
+if { ![istarget "i?86-*-*"] && ![istarget "x86_64-*-*"] } then {
+    verbose "Skipping i386 tests for x87 floating point support."
+    return
+}
+
+standard_testfile .S
+
+# some targets have leading underscores on assembly symbols.
+set additional_flags [gdb_target_symbol_prefix_flags]
+
+if { [prepare_for_testing break.exp $testfile $srcfile [list debug $additional_flags]] } {
+    return -1
+}
+
+if ![runto_main] then {
+    fail "Can't run to main"
+    return 0
+}
+
+gdb_test "stepi" ".*fldt.*" "first stepi"
+gdb_test "info float" ".*R7: Empty   0x00000000000000000000\r\n.*"
+gdb_test "stepi" ".*ret.*" "second stepi"
+gdb_test "info float" ".*=>R7: Valid   0xbffee922191107450000 .*"