* [Bug translator/21173] New: odd translator behavior with overloaded functions
@ 2017-02-16 19:01 dsmith at redhat dot com
2017-02-20 18:37 ` [Bug translator/21173] " dsmith at redhat dot com
` (4 more replies)
0 siblings, 5 replies; 6+ messages in thread
From: dsmith at redhat dot com @ 2017-02-16 19:01 UTC (permalink / raw)
To: systemtap
https://sourceware.org/bugzilla/show_bug.cgi?id=21173
Bug ID: 21173
Summary: odd translator behavior with overloaded functions
Product: systemtap
Version: unspecified
Status: NEW
Severity: normal
Priority: P2
Component: translator
Assignee: systemtap at sourceware dot org
Reporter: dsmith at redhat dot com
Target Milestone: ---
Since bug #18431, the translator supports overloaded functions (2 functions
with the same name but different parameters). However, in certain situations,
this isn't acting correctly.
Here's a test script:
====
function foo:long(a:long, b:long)
{
return (a + b)
}
function foo:string(a:long, b:string, c:long)
{
return sprintf("%s %d", b, a + c)
}
probe begin
{
println(__inode_vfsmount(1))
println(foo(1, 2, 3))
}
====
====
stap --compatible=2.9 -vp4 ../src/test.stp
Pass 1: parsed user script and 465 library scripts using
135824virt/44664res/7380shr/37236data kb, in 240usr/50sys/293real ms.
WARNING: Eliding unused function 'foo': identifier 'foo' at
../src/test.stp:1:10
source: function foo:long(a:long, b:long)
^
semantic error: unknown type in dereference: operator '&' at
/usr/local/share/systemtap/tapset/linux/dentry.stp:93:24
source: head = &sb->s_mounts
^
Pass 2: analyzed script: 1 probe, 8 functions, 3 embeds, 0 globals using
285440virt/195264res/8548shr/186852data kb, in 1830usr/320sys/2167real ms.
Pass 2: analysis failed. [man error::pass2]
=====
There are at least 3 problems with that translator output:
- It doesn't warn/error on the fact the 'foo' function variants has 2 different
return values.
- Somehow this causes @cast() type errors to appear elsewhere.
- It doesn't realize that there is no overload that takes 3 longs.
It is possible the translator found the error earlier, but its message was
suppressed and it incidentally resulted in shortcuting some other processing
leading the @cast() or whatever to never be attempted.
Note that if the 'foo' function call is fixed to call either function
correctly, the script compiles just fine without any @cast-type errors. Also
note that I found this while debugging a systemtap.stress/tapset_functions.exp
failure.
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* [Bug translator/21173] odd translator behavior with overloaded functions
2017-02-16 19:01 [Bug translator/21173] New: odd translator behavior with overloaded functions dsmith at redhat dot com
@ 2017-02-20 18:37 ` dsmith at redhat dot com
2017-02-20 18:41 ` dsmith at redhat dot com
` (3 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: dsmith at redhat dot com @ 2017-02-20 18:37 UTC (permalink / raw)
To: systemtap
https://sourceware.org/bugzilla/show_bug.cgi?id=21173
--- Comment #1 from David Smith <dsmith at redhat dot com> ---
I did some investigation and this bug doesn't appear to be related to the
'--compatible=2.9' option. I edited the tapset/linux/dentry.stp file, removed
and 'private' keyword from the __inode_vfsmount() function, and I get the same
error when running stap without the '--comatible=2.9" option.
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* [Bug translator/21173] odd translator behavior with overloaded functions
2017-02-16 19:01 [Bug translator/21173] New: odd translator behavior with overloaded functions dsmith at redhat dot com
2017-02-20 18:37 ` [Bug translator/21173] " dsmith at redhat dot com
@ 2017-02-20 18:41 ` dsmith at redhat dot com
2017-02-20 21:16 ` dsmith at redhat dot com
` (2 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: dsmith at redhat dot com @ 2017-02-20 18:41 UTC (permalink / raw)
To: systemtap
https://sourceware.org/bugzilla/show_bug.cgi?id=21173
--- Comment #2 from David Smith <dsmith at redhat dot com> ---
If I comment out the call to __inode_vfsmount(), I get the expected error about
a type mismatch:
====
# cat ../src/test.stp
function foo:long(a:long, b:long)
{
return (a + b)
}
function foo:string(a:long, b:string, c:long)
{
return sprintf("%s %d", b, a + c)
}
probe begin
{
# println(__inode_vfsmount(1))
println(foo(1, 2, 3))
}
# stap -p2 ../src/test.stp
WARNING: Eliding unused function 'foo': identifier 'foo' at
../src/test.stp:1:10
source: function foo:long(a:long, b:long)
^
semantic error: type mismatch: expected long but found string: number '2' at
:14:17
source: println(foo(1, 2, 3))
^
Pass 2: analysis failed. [man error::pass2]
====
If I comment out the call to foo(), the script gets passes the semantic pass
with no problems (other than warning about unused function 'foo').
====
# cat ../src/test.stp
function foo:long(a:long, b:long)
{
return (a + b)
}
function foo:string(a:long, b:string, c:long)
{
return sprintf("%s %d", b, a + c)
}
probe begin
{
println(__inode_vfsmount(1))
# println(foo(1, 2, 3))
}
# stap -p2 ../src/test.stp > /dev/null
WARNING: Eliding unused function 'foo': identifier 'foo' at
../src/test.stp:1:10
source: function foo:long(a:long, b:long)
^
Number of similar warning messages suppressed: 1.
Rerun with -v to see them.
====
Somehow it is the combination of the two that causes the odd behavior.
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* [Bug translator/21173] odd translator behavior with overloaded functions
2017-02-16 19:01 [Bug translator/21173] New: odd translator behavior with overloaded functions dsmith at redhat dot com
2017-02-20 18:37 ` [Bug translator/21173] " dsmith at redhat dot com
2017-02-20 18:41 ` dsmith at redhat dot com
@ 2017-02-20 21:16 ` dsmith at redhat dot com
2017-02-20 22:47 ` dsmith at redhat dot com
2020-11-14 18:43 ` fche at redhat dot com
4 siblings, 0 replies; 6+ messages in thread
From: dsmith at redhat dot com @ 2017-02-20 21:16 UTC (permalink / raw)
To: systemtap
https://sourceware.org/bugzilla/show_bug.cgi?id=21173
--- Comment #3 from David Smith <dsmith at redhat dot com> ---
It looks like an overloaded function doesn't have to be involved, just a
function call with the right number of arguments but the wrong types:
====
# cat ../src/test.stp
#function foo:long(a:long, b:long)
#{
# return (a + b)
#}
function foo:string(a:long, b:string, c:long)
{
return sprintf("%s %d", b, a + c)
}
probe begin
{
println(__inode_vfsmount(1))
println(foo(1, 2, 3))
}
# stap -p2 ../src/test.stp
semantic error: unknown type in dereference: operator '&' at
/usr/local/share/systemtap/tapset/linux/dentry.stp:93:24
source: head = &sb->s_mounts
^
Pass 2: analysis failed. [man error::pass2]
====
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* [Bug translator/21173] odd translator behavior with overloaded functions
2017-02-16 19:01 [Bug translator/21173] New: odd translator behavior with overloaded functions dsmith at redhat dot com
` (2 preceding siblings ...)
2017-02-20 21:16 ` dsmith at redhat dot com
@ 2017-02-20 22:47 ` dsmith at redhat dot com
2020-11-14 18:43 ` fche at redhat dot com
4 siblings, 0 replies; 6+ messages in thread
From: dsmith at redhat dot com @ 2017-02-20 22:47 UTC (permalink / raw)
To: systemtap
https://sourceware.org/bugzilla/show_bug.cgi?id=21173
--- Comment #4 from David Smith <dsmith at redhat dot com> ---
A 'git bisect' shows this was introduced by commit 6540f55, part of the fix for
bug #18455.
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* [Bug translator/21173] odd translator behavior with overloaded functions
2017-02-16 19:01 [Bug translator/21173] New: odd translator behavior with overloaded functions dsmith at redhat dot com
` (3 preceding siblings ...)
2017-02-20 22:47 ` dsmith at redhat dot com
@ 2020-11-14 18:43 ` fche at redhat dot com
4 siblings, 0 replies; 6+ messages in thread
From: fche at redhat dot com @ 2020-11-14 18:43 UTC (permalink / raw)
To: systemtap
https://sourceware.org/bugzilla/show_bug.cgi?id=21173
Frank Ch. Eigler <fche at redhat dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Resolution|--- |WORKSFORME
CC| |fche at redhat dot com
Status|NEW |RESOLVED
--- Comment #5 from Frank Ch. Eigler <fche at redhat dot com> ---
stap 4.3+ish reports the errors correctly:
% stap --compatible=2.9 -p4 -e [...]
semantic error: unknown type in dereference: operator '&' at
/usr/share/systemtap/tapset/linux/dentry.stp:93:24
source: head = &sb->s_mounts
^
semantic error: type mismatch: expected long but found string: number '2' at
<input>:15:17
source: println(foo(1, 2, 3))
^
Pass 2: analysis failed. [man error::pass2]
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2017-02-16 19:01 [Bug translator/21173] New: odd translator behavior with overloaded functions dsmith at redhat dot com
2017-02-20 18:37 ` [Bug translator/21173] " dsmith at redhat dot com
2017-02-20 18:41 ` dsmith at redhat dot com
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