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[Bug translator/16615] don't require access to dwarf_query in has_single_line_record()
- From: "jlebon at redhat dot com" <sourceware-bugzilla at sourceware dot org>
- To: systemtap at sourceware dot org
- Date: Tue, 08 Apr 2014 14:29:34 +0000
- Subject: [Bug translator/16615] don't require access to dwarf_query in has_single_line_record()
- Auto-submitted: auto-generated
- References: <bug-16615-6586 at http dot sourceware dot org/bugzilla/>
https://sourceware.org/bugzilla/show_bug.cgi?id=16615
--- Comment #2 from Jonathan Lebon <jlebon at redhat dot com> ---
Looking at this again, I took the opportunity to try and do this uncoupling
properly and at the same time improve the way func@file:N statements are
implemented. The branch jlebon/pr16615 contains the relevant patch series.
I will just go through the main ways in which behaviour has changed:
1. Handling of linenos with multiple line records
We previously completely skipped those lines and threw a semantic error with
suggestions on nearby lines with single line records. This behaviour is kept
for ABSOLUTE and RELATIVE line types (i.e. the user specified a specific
lineno, so better not be ambiguous). However, for WILDCARD and RANGE line
types, we simply pick the first line record (rather than skip over them as we
did before).
$ nl -b a statement.c
1 #include <stdio.h>
2
3 int foo(int a)
4 {
5 int b = 2;
6 return b + a * 3;
7 }
8
9 void bar(int b) { b += 2; printf("single line! %d\n", b); }
10
11 int main(int argc, char** argv)
12 {
13 if (argc != 1)
14 return 42;
15 foo(argv[0][0]); bar(argv[0][1]); return 0; }
$ gcc statement.c -g -o statement
$ stap -l 'process("./statement").statement("main@statement.c:*")' # OLD STAP
process("/tmp/statement").statement("main@/tmp/statement.c:12")
process("/tmp/statement").statement("main@/tmp/statement.c:13")
process("/tmp/statement").statement("main@/tmp/statement.c:14")
$ stap -l 'process("./statement").statement("main@statement.c:*")' # NEW STAP
process("/tmp/statement").statement("main@/tmp/statement.c:12")
process("/tmp/statement").statement("main@/tmp/statement.c:13")
process("/tmp/statement").statement("main@/tmp/statement.c:14")
process("/tmp/statement").statement("main@/tmp/statement.c:15")
$ stap -p2 -e 'probe process("./statement").statement("main@statement.c:15")
{}' # OLD AND NEW STAP
semantic error: multiple addresses for /tmp/statement.c:15 [man error::dwarf]
(try /tmp/statement.c:14)
semantic error: while resolving probe point: identifier 'process' at
<input>:1:7
source: probe process("./statement").statement("main@statement.c:15")
{}
^
semantic error: no match
Pass 2: analysis failed. [man error::pass2]
$
2. Handling of RELATIVE and WILDCARD line types
We previously applied RELATIVE and WILDCARD line types to only one of the
filtered functions. Now, these are applied *per* function, so that e.g. the
following works as expected:
$ stap -l 'process("./statement").statement("[fm]*@statement.c+2")' # OLD STAP
process("/tmp/statement").statement("foo@/tmp/statement.c:6")
$ stap -l 'process("./statement").statement("[fm]*@statement.c+2")' # NEW STAP
process("/tmp/statement").statement("foo@/tmp/statement.c:6")
process("/tmp/statement").statement("main@/tmp/statement.c:14")
$
Other issues such as the one described in PR14774 then also become non-issues
and do not require special treatment.
3. Bug fixes
E.g. properly freeing memory, guarding from duplicate linenos, better handling
of libdw failures, and better error messages.
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