https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92300
Bug ID: 92300
Summary: Useless allocator call in std::map, when insert does
not perform any insertion.
Product: gcc
Version: 7.4.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libstdc++
Assignee: unassigned at gcc dot gnu.org
Reporter: antonio.di.monaco at sap dot com
Target Milestone: ---
Created attachment 47142
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=47142&action=edit
code example
The fix related to the bug 78595 introduced a regression in the std::map insert
call.
When a key already exists, an allocation is performed anyway.
std::map< int, int, std::less< int >, MyAlloc< std::pair< const int, int > > >
a;
assert(a.insert(std::make_pair(1, 1)).second);
assert(a.insert(std::make_pair(2, 2)).second);
assert(!a.insert(std::make_pair(1, 3)).second);
GCC 6:
map:
allocate 1 element(s) of size 40
allocated at: 0x13d8c20
allocate 1 element(s) of size 40
allocated at: 0x13d8c50
GCC >= 7.4.0:
map:
allocate 1 element(s) of size 40
allocated at: 0x14f1c20
allocate 1 element(s) of size 40
allocated at: 0x14f1c50
allocate 1 element(s) of size 40
allocated at: 0x14f1c80
Other associative containers have not been affected by the change.
