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The creation of this patch was motivated by Tom's "Change handling of
'!' operator in stap probes" patch.
While reviewing his patch, I stumbled upon a few issues with the stap
expression parser. They are:
- As it turns out, even with Tom's patch applied the parser doesn't
properly handle the '!' operator. The underlying issue was the fact
that stap_parse_argument_conditionally also needed to be patched in
order to recognize '!' as an operator that is part of a single
operand, and parse it accordingly.
- While writing the testcase I'm proposing on this patch, I found that
parenthesized sub-expressions were not being parsed correctly when
there was another term after them. For example:
1 - (2 + 3) + 4
In this case, the parser was considering "1" to be the left-side of
the expression, and "(2 + 3) + 4" to be the right-side. The patch
fixes the parser by making it identify whether a parenthesized
sub-expression has just been parsed, and act accordingly.
I've tested this on my Debian testing amd64, and everything seems OK.
gdb/ChangeLog:
2021-01-20 Sergio Durigan Junior <sergiodj@sergiodj.net>
Tom Tromey <tom@tromey.com>
* stap-probe.c (stap_parse_single_operand): Handle '!'
operator.
(stap_parse_argument_conditionally): Likewise.
Skip spaces after processing open-parenthesis sub-expression.
(stap_parse_argument_1): Skip spaces after call to
stap_parse_argument_conditionally.
Handle case when right-side expression is a parenthesized
sub-expression.
Skip spaces after call to stap_parse_argument_1.
gdb/testsuite/ChangeLog:
2021-01-20 Sergio Durigan Junior <sergiodj@sergiodj.net>
* gdb.arch/amd64-stap-expressions.S: New file.
* gdb.arch/amd64-stap-expressions.exp: New file.
44 lines
1.4 KiB
ArmAsm
44 lines
1.4 KiB
ArmAsm
/* Copyright (C) 2021 Free Software Foundation, Inc.
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This file is part of GDB.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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#include <sys/sdt.h>
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.file "amd64-stap-expressions.S"
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.text
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.globl main
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main:
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/* We use a nop here because we don't want the first probe to
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be placed at the same location as the main label. */
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nop
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/* Single operands. */
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STAP_PROBE1(probe, log_neg, 8@!($0+$1))
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STAP_PROBE1(probe, minus, -8@-($3+$4))
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STAP_PROBE1(probe, bit_neg, -8@~$22)
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/* Arithmetic expressions. */
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STAP_PROBE1(probe, plus1, 8@$3+($10-$8)-$1)
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STAP_PROBE1(probe, plus2, 8@$100-( ($8+$10) -$50)+$3)
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STAP_PROBE1(probe, plus3, 8@$100-(($8+$10)-$50)+((($8 - $9) + $40) - $4)+$4)
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/* Bitwise expressions. */
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STAP_PROBE1(probe, and, 8@$128&$128)
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STAP_PROBE1(probe, or, 8@$8|$4)
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xor %rax,%rax
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ret
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