digitalmars.D.bugs - [Issue 6205] New: Strongly-pure nothrow functions with ignored return value are entirely stripped even if it contains a failing 'assert'.
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http://d.puremagic.com/issues/show_bug.cgi?id=6205
Summary: Strongly-pure nothrow functions with ignored return
value are entirely stripped even if it contains a
failing 'assert'.
Product: D
Version: D2
Platform: Other
OS/Version: Mac OS X
Status: NEW
Keywords: wrong-code
Severity: normal
Priority: P2
Component: DMD
AssignedTo: nobody puremagic.com
ReportedBy: kennytm gmail.com
Test case:
---------------------------
int x() pure nothrow {
assert(false, "1");
}
void main() {
x();
}
---------------------------
This should throw an AssertError, but instead the generated program does
nothing. The AssertError will be thrown if the return value of 'x' is assigned
to some variable though.
This bug (?) causes 'runnable/test41.d' to fail since commit 4c9661f as nothrow
inference is also implemented, making 'imports.test41a.func' a strongly-pure
nothrow function, and the 'assert' inside fails to run.
https://github.com/D-Programming-Language/dmd/commit/4c9661fa9fbd427909a334133dfc7f3869e47c31
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Jun 24 2011
d-bugmail puremagic.com
http://d.puremagic.com/issues/show_bug.cgi?id=6205
Jonathan M Davis <jmdavisProg gmx.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |jmdavisProg gmx.com
PDT ---
I'm not sure that this is a bug. It's a strongly pure function. It _is_
nothrow, which means that it won't throw any Exception, and its return value
isn't used. assert is more of a debugging tool than anything. Sure,
assert(false) sticks around in release mode, but still. Based on the purity and
nothrow rules, this function can be optimized out of existance. I really don't
see a problem with this. Now, assuming that is indeed the correct behavior, the
obviously runnable/test41.d needs to be fixed, but it looks to me like having
the call to x optimized out of existance makes perfect sense. And if the assert
doesn't get hit, then it doesn't get hit. Asserts are intended primarily for
debugging purposes. Yes, it's an assert(false) and not a normal assert, but
still, if we start worrying about whether an assert would have killed a
function or not, then we won't be able to optimize out functions like this,
which wouldn't be good IMHO. Now, assuming that it's really only an issue when
you have a strongly pure function where you throw away its return value, then
maybe that's not a big deal, because that's bad code on the part of the
programmer anyway, but I'm still inclined to think that it makes sense for x to
never be called in this code (at least if optimizations are turned on).
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Jun 24 2011
http://d.puremagic.com/issues/show_bug.cgi?id=6205 Pull request for test41 if this is considered INVALID: https://github.com/D-Programming-Language/dmd/pull/162 -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Jun 24 2011
http://d.puremagic.com/issues/show_bug.cgi?id=6205
Don <clugdbug yahoo.com.au> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |clugdbug yahoo.com.au
The bug is that the compiler's behaviour isn't consistent.
It's reasonable to optimize the function away in this case -- but then, it
should generate an 'expression has no effect' warning. See bug 3882.
This test case is an excellent justification for treating 3882 as a bug, rather
than an enhancement.
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Jun 24 2011
http://d.puremagic.com/issues/show_bug.cgi?id=6205 I think this is 'too early optimization' bug. Mechanism: 1. The calling of a function that is strong-pure and nothrow is 'no side effect'. Then dmd marks it in IR level. https://github.com/D-Programming-Language/dmd/blob/master/src/e2ir.c#L286 2. OPucallns and OPcallns are completely removed in backend optimizer level. https://github.com/D-Programming-Language/dmd/blob/master/src/backend/cgelem.c#L4088 https://github.com/D-Programming-Language/dmd/blob/master/src/backend/cgelem.c#L4385 or halt), so all of function call with enabling assertion should disable 'remove no side effect calling' optimization. At least, a compilation without -O switch should not remove such calls. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Jan 04 2012
http://d.puremagic.com/issues/show_bug.cgi?id=6205
Kenji Hara <k.hara.pg gmail.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |patch
https://github.com/D-Programming-Language/dmd/pull/607
Only `-O -release` specification ignite the optimization.
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Jan 04 2012
http://d.puremagic.com/issues/show_bug.cgi?id=6205
Walter Bright <bugzilla digitalmars.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
CC| |bugzilla digitalmars.com
Resolution| |FIXED
12:34:26 PST ---
https://github.com/D-Programming-Language/dmd/commit/ead4a879100a43e44b0321f3d31341fd43b6aab7
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Jan 05 2012
http://d.puremagic.com/issues/show_bug.cgi?id=6205
Kenji Hara <k.hara.pg gmail.com> changed:
What |Removed |Added
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CC| |verylonglogin.reg gmail.com
*** Issue 6827 has been marked as a duplicate of this issue. ***
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Jan 09 2012