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* [Bug tree-optimization/50385] New: missed-optimization: jump to __builtin_unreachable() not removed
@ 2011-09-13 15:21 wouter.vermaelen at scarlet dot be
2011-11-11 1:39 ` [Bug middle-end/50385] " pinskia at gcc dot gnu.org
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: wouter.vermaelen at scarlet dot be @ 2011-09-13 15:21 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50385
Bug #: 50385
Summary: missed-optimization: jump to __builtin_unreachable()
not removed
Classification: Unclassified
Product: gcc
Version: 4.7.0
Status: UNCONFIRMED
Severity: enhancement
Priority: P3
Component: tree-optimization
AssignedTo: unassigned@gcc.gnu.org
ReportedBy: wouter.vermaelen@scarlet.be
I'm not sure, but this issue might be the same as bug 49054 (if so, feel free
to delete this one).
#include <vector>
struct S { int a, b; };
std::vector<S> v;
int search_1(int a) {
for (auto it = v.begin(); /**/; ++it)
if (it->a == a) return it->b;
}
int search_2(int a) {
for (auto& e : v)
if (e.a == a) return e.b;
__builtin_unreachable();
}
I expected to see the same generated code for both functions. Instead the 2nd
one still contains some useless comparisons and jumps past the end of the
function. Since such a (conditional) jump is anyway undefined behavior it can
as well be removed (including the instructions required to calculate the
condition).
Tested with SVN revision 178775 (20110912) on Linux x86_64.
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug middle-end/50385] missed-optimization: jump to __builtin_unreachable() not removed
2011-09-13 15:21 [Bug tree-optimization/50385] New: missed-optimization: jump to __builtin_unreachable() not removed wouter.vermaelen at scarlet dot be
@ 2011-11-11 1:39 ` pinskia at gcc dot gnu.org
2013-09-08 8:10 ` glisse at gcc dot gnu.org
2015-02-24 20:54 ` law at redhat dot com
2 siblings, 0 replies; 4+ messages in thread
From: pinskia at gcc dot gnu.org @ 2011-11-11 1:39 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50385
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |missed-optimization
Status|UNCONFIRMED |NEW
Last reconfirmed| |2011-11-11
Component|tree-optimization |middle-end
Ever Confirmed|0 |1
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> 2011-11-11 00:39:55 UTC ---
Confirmed with a much simpler testcase:
int
f (int i)
{
if (i <= 1)
return 1;
__builtin_unreachable();
}
--- CUT ---
I found this while adding a basic block reordering pass to the tree level and I
got a failure with builtin-unreachable-2.c .
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug middle-end/50385] missed-optimization: jump to __builtin_unreachable() not removed
2011-09-13 15:21 [Bug tree-optimization/50385] New: missed-optimization: jump to __builtin_unreachable() not removed wouter.vermaelen at scarlet dot be
2011-11-11 1:39 ` [Bug middle-end/50385] " pinskia at gcc dot gnu.org
@ 2013-09-08 8:10 ` glisse at gcc dot gnu.org
2015-02-24 20:54 ` law at redhat dot com
2 siblings, 0 replies; 4+ messages in thread
From: glisse at gcc dot gnu.org @ 2013-09-08 8:10 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50385
--- Comment #2 from Marc Glisse <glisse at gcc dot gnu.org> ---
This seems to work on current trunk. Can you confirm, and if so close the PR?
(well, we may want to add the testcases)
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug middle-end/50385] missed-optimization: jump to __builtin_unreachable() not removed
2011-09-13 15:21 [Bug tree-optimization/50385] New: missed-optimization: jump to __builtin_unreachable() not removed wouter.vermaelen at scarlet dot be
2011-11-11 1:39 ` [Bug middle-end/50385] " pinskia at gcc dot gnu.org
2013-09-08 8:10 ` glisse at gcc dot gnu.org
@ 2015-02-24 20:54 ` law at redhat dot com
2 siblings, 0 replies; 4+ messages in thread
From: law at redhat dot com @ 2015-02-24 20:54 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=50385
Jeffrey A. Law <law at redhat dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
CC| |law at redhat dot com
Resolution|--- |FIXED
--- Comment #3 from Jeffrey A. Law <law at redhat dot com> ---
Trunk produces the desired code.
^ permalink raw reply [flat|nested] 4+ messages in thread
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2011-09-13 15:21 [Bug tree-optimization/50385] New: missed-optimization: jump to __builtin_unreachable() not removed wouter.vermaelen at scarlet dot be
2011-11-11 1:39 ` [Bug middle-end/50385] " pinskia at gcc dot gnu.org
2013-09-08 8:10 ` glisse at gcc dot gnu.org
2015-02-24 20:54 ` law at redhat dot com
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