https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110819
Bug ID: 110819
Summary: Missed optimization: when vector size is 0 but
vector::reserve has been called.
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: hiraditya at msn dot com
Target Milestone: ---
#include<vector>
void f(int);
void use_idx_const_size_reserve() {
std::vector<int> v;
v.reserve(100000);
auto s = v.size();
for (std::vector<int>::size_type i = 0; i < s; i++)
f(v[i]);
}
$ g++ -O3
use_idx_const_size_reserve():
sub rsp, 8
mov edi, 400000
call operator new(unsigned long)
mov esi, 400000
add rsp, 8
mov rdi, rax
jmp operator delete(void*, unsigned long)
$ clang++ -O3 -stdlib=libc++
use_idx_const_size_reserve(): # @use_idx_const_size_reserve()
ret
