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* [Bug tree-optimization/109440] New: Missed optimization of vector::at when a function is called inside the loop
@ 2023-04-06 18:15 hiraditya at msn dot com
2023-04-06 18:36 ` [Bug tree-optimization/109440] " pinskia at gcc dot gnu.org
2023-04-11 13:15 ` rguenth at gcc dot gnu.org
0 siblings, 2 replies; 3+ messages in thread
From: hiraditya at msn dot com @ 2023-04-06 18:15 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109440
Bug ID: 109440
Summary: Missed optimization of vector::at when a function is
called inside the loop
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: hiraditya at msn dot com
Target Milestone: ---
#include<vector>
#include<string>
using namespace std;
bool bar();
using T = int;
T vat(std::vector<T> v) {
T s;
for (auto i = 0; i < v.size(); ++i) {
if (bar())
s += v.at(i);
}
return s;
}
$ gcc -O2 -fexceptions -fno-unroll-loops
.LC0:
.string "vector::_M_range_check: __n (which is %zu) >= this->size()
(which is %zu)"
vat(std::vector<int, std::allocator<int> >):
mov rax, QWORD PTR [rdi]
cmp QWORD PTR [rdi+8], rax
je .L9
push r12
push rbp
mov rbp, rdi
push rbx
xor ebx, ebx
jmp .L6
.L14:
mov rax, QWORD PTR [rbp+8]
sub rax, QWORD PTR [rbp+0]
add rbx, 1
sar rax, 2
cmp rbx, rax
jnb .L13
.L6:
call bar()
test al, al
je .L14
mov rcx, QWORD PTR [rbp+0]
mov rdx, QWORD PTR [rbp+8]
sub rdx, rcx
sar rdx, 2
mov rax, rdx
cmp rbx, rdx
jnb .L15
add r12d, DWORD PTR [rcx+rbx*4]
add rbx, 1
cmp rbx, rax
jb .L6
.L13:
mov eax, r12d
pop rbx
pop rbp
pop r12
ret
.L9:
mov eax, r12d
ret
.L15:
mov rsi, rbx
mov edi, OFFSET FLAT:.LC0
xor eax, eax
call std::__throw_out_of_range_fmt(char const*, ...)
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug tree-optimization/109440] Missed optimization of vector::at when a function is called inside the loop
2023-04-06 18:15 [Bug tree-optimization/109440] New: Missed optimization of vector::at when a function is called inside the loop hiraditya at msn dot com
@ 2023-04-06 18:36 ` pinskia at gcc dot gnu.org
2023-04-11 13:15 ` rguenth at gcc dot gnu.org
1 sibling, 0 replies; 3+ messages in thread
From: pinskia at gcc dot gnu.org @ 2023-04-06 18:36 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109440
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |alias
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
There are a few things, the most obvious thing is the middle-end thinks the
content of v can change via the call to foo.
If you make a local copy, then there is a missing VRP which can be fixed by
changing the type of i to size_t.
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug tree-optimization/109440] Missed optimization of vector::at when a function is called inside the loop
2023-04-06 18:15 [Bug tree-optimization/109440] New: Missed optimization of vector::at when a function is called inside the loop hiraditya at msn dot com
2023-04-06 18:36 ` [Bug tree-optimization/109440] " pinskia at gcc dot gnu.org
@ 2023-04-11 13:15 ` rguenth at gcc dot gnu.org
1 sibling, 0 replies; 3+ messages in thread
From: rguenth at gcc dot gnu.org @ 2023-04-11 13:15 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109440
--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
There's that other bug which would be basically a duplicate, so I leave this
one tree-optimization, not C++.
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2023-04-11 13:15 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
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2023-04-06 18:15 [Bug tree-optimization/109440] New: Missed optimization of vector::at when a function is called inside the loop hiraditya at msn dot com
2023-04-06 18:36 ` [Bug tree-optimization/109440] " pinskia at gcc dot gnu.org
2023-04-11 13:15 ` rguenth at gcc dot gnu.org
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