* How does ld and gold deal with C++ duplicate templates?
@ 2020-09-16 9:26 sotrdg sotrdg
2020-09-16 19:23 ` Ian Lance Taylor
0 siblings, 1 reply; 4+ messages in thread
From: sotrdg sotrdg @ 2020-09-16 9:26 UTC (permalink / raw)
To: binutils@sourceware.org
Like the bug I reported a month ago.
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96577
https://godbolt.org/z/haG4E7
https://godbolt.org/z/M8e7Kb
First:
#include<vector>
#include<array>
#include<algorithm>
template<std::contiguous_iterator Iter>
void f(Iter a,Iter b)
{
std::sort(a,b);
}
void g(std::vector<int>::iterator b,std::vector<int>::iterator e)
{
f(b,e);
}
void h(int* b,int* e)
{
f(b,e);
}
Second:
#include<vector>
#include<array>
#include<algorithm>
template<std::contiguous_iterator Iter>
void f(Iter a,Iter b)
{
std::sort(a,b);
}
void g(std::vector<int>::iterator b,std::vector<int>::iterator e)
{
f(std::to_address(b),std::to_address(e));
}
void h(int* b,int* e)
{
f(b,e);
}
The two sort function should generate exactly the same binary. However the first which is none to_address version generates twice as much as code as the second one.
Will the GNU ld remove the duplication definitions?
Sent from Mail<https://go.microsoft.com/fwlink/?LinkId=550986> for Windows 10
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: How does ld and gold deal with C++ duplicate templates?
2020-09-16 9:26 How does ld and gold deal with C++ duplicate templates? sotrdg sotrdg
@ 2020-09-16 19:23 ` Ian Lance Taylor
2020-09-16 19:38 ` sotrdg sotrdg
0 siblings, 1 reply; 4+ messages in thread
From: Ian Lance Taylor @ 2020-09-16 19:23 UTC (permalink / raw)
To: sotrdg sotrdg; +Cc: binutils
On Wed, Sep 16, 2020 at 2:26 AM sotrdg sotrdg via Binutils
<binutils@sourceware.org> wrote:
>
> Like the bug I reported a month ago.
>
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96577
>
>
>
> https://godbolt.org/z/haG4E7
>
> https://godbolt.org/z/M8e7Kb
>
>
>
> First:
>
>
>
> #include<vector>
>
> #include<array>
>
> #include<algorithm>
>
>
>
> template<std::contiguous_iterator Iter>
>
> void f(Iter a,Iter b)
>
> {
>
> std::sort(a,b);
>
> }
>
>
>
> void g(std::vector<int>::iterator b,std::vector<int>::iterator e)
>
> {
>
> f(b,e);
>
> }
>
>
>
> void h(int* b,int* e)
>
> {
>
> f(b,e);
>
> }
>
>
>
> Second:
>
>
>
>
>
> #include<vector>
>
> #include<array>
>
> #include<algorithm>
>
>
>
> template<std::contiguous_iterator Iter>
>
> void f(Iter a,Iter b)
>
> {
>
> std::sort(a,b);
>
> }
>
>
>
> void g(std::vector<int>::iterator b,std::vector<int>::iterator e)
>
> {
>
> f(std::to_address(b),std::to_address(e));
>
> }
>
>
>
> void h(int* b,int* e)
>
> {
>
> f(b,e);
>
> }
>
>
>
>
>
> The two sort function should generate exactly the same binary. However the first which is none to_address version generates twice as much as code as the second one.
>
> Will the GNU ld remove the duplication definitions?
For gold, see the --icf option.
Ian
^ permalink raw reply [flat|nested] 4+ messages in thread* RE: How does ld and gold deal with C++ duplicate templates?
2020-09-16 19:23 ` Ian Lance Taylor
@ 2020-09-16 19:38 ` sotrdg sotrdg
2020-09-16 20:56 ` Ian Lance Taylor
0 siblings, 1 reply; 4+ messages in thread
From: sotrdg sotrdg @ 2020-09-16 19:38 UTC (permalink / raw)
To: Ian Lance Taylor, binutils
But gold linker is said to be removed in the future since no one is willing to maintain it any more. BTW, I am using MinGW on Windows where gold does not seem to be available.
Does ld provide the same options?
And why these optimizations are not applied by default?
Sent from Mail<https://go.microsoft.com/fwlink/?LinkId=550986> for Windows 10
From: Ian Lance Taylor<mailto:iant@google.com>
Sent: Wednesday, September 16, 2020 15:23
To: sotrdg sotrdg<mailto:euloanty@live.com>
Cc: binutils@sourceware.org<mailto:binutils@sourceware.org>
Subject: Re: How does ld and gold deal with C++ duplicate templates?
On Wed, Sep 16, 2020 at 2:26 AM sotrdg sotrdg via Binutils
<binutils@sourceware.org> wrote:
>
> Like the bug I reported a month ago.
>
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96577
>
>
>
> https://godbolt.org/z/haG4E7
>
> https://godbolt.org/z/M8e7Kb
>
>
>
> First:
>
>
>
> #include<vector>
>
> #include<array>
>
> #include<algorithm>
>
>
>
> template<std::contiguous_iterator Iter>
>
> void f(Iter a,Iter b)
>
> {
>
> std::sort(a,b);
>
> }
>
>
>
> void g(std::vector<int>::iterator b,std::vector<int>::iterator e)
>
> {
>
> f(b,e);
>
> }
>
>
>
> void h(int* b,int* e)
>
> {
>
> f(b,e);
>
> }
>
>
>
> Second:
>
>
>
>
>
> #include<vector>
>
> #include<array>
>
> #include<algorithm>
>
>
>
> template<std::contiguous_iterator Iter>
>
> void f(Iter a,Iter b)
>
> {
>
> std::sort(a,b);
>
> }
>
>
>
> void g(std::vector<int>::iterator b,std::vector<int>::iterator e)
>
> {
>
> f(std::to_address(b),std::to_address(e));
>
> }
>
>
>
> void h(int* b,int* e)
>
> {
>
> f(b,e);
>
> }
>
>
>
>
>
> The two sort function should generate exactly the same binary. However the first which is none to_address version generates twice as much as code as the second one.
>
> Will the GNU ld remove the duplication definitions?
For gold, see the --icf option.
Ian
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: How does ld and gold deal with C++ duplicate templates?
2020-09-16 19:38 ` sotrdg sotrdg
@ 2020-09-16 20:56 ` Ian Lance Taylor
0 siblings, 0 replies; 4+ messages in thread
From: Ian Lance Taylor @ 2020-09-16 20:56 UTC (permalink / raw)
To: sotrdg sotrdg; +Cc: binutils
On Wed, Sep 16, 2020 at 12:38 PM sotrdg sotrdg <euloanty@live.com> wrote:
>
> But gold linker is said to be removed in the future since no one is willing to maintain it any more. BTW, I am using MinGW on Windows where gold does not seem to be available.
Seems a pity, but OK. It's true that I don't have time to maintain
it. And it's true that it doesn't work on Windows.
> Does ld provide the same options?
Not to my knowledge.
> And why these optimizations are not applied by default?
Because they measurably increase link times.
Ian
> From: Ian Lance Taylor
> Sent: Wednesday, September 16, 2020 15:23
> To: sotrdg sotrdg
> Cc: binutils@sourceware.org
> Subject: Re: How does ld and gold deal with C++ duplicate templates?
>
>
>
> On Wed, Sep 16, 2020 at 2:26 AM sotrdg sotrdg via Binutils
> <binutils@sourceware.org> wrote:
> >
> > Like the bug I reported a month ago.
> >
> > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96577
> >
> >
> >
> > https://godbolt.org/z/haG4E7
> >
> > https://godbolt.org/z/M8e7Kb
> >
> >
> >
> > First:
> >
> >
> >
> > #include<vector>
> >
> > #include<array>
> >
> > #include<algorithm>
> >
> >
> >
> > template<std::contiguous_iterator Iter>
> >
> > void f(Iter a,Iter b)
> >
> > {
> >
> > std::sort(a,b);
> >
> > }
> >
> >
> >
> > void g(std::vector<int>::iterator b,std::vector<int>::iterator e)
> >
> > {
> >
> > f(b,e);
> >
> > }
> >
> >
> >
> > void h(int* b,int* e)
> >
> > {
> >
> > f(b,e);
> >
> > }
> >
> >
> >
> > Second:
> >
> >
> >
> >
> >
> > #include<vector>
> >
> > #include<array>
> >
> > #include<algorithm>
> >
> >
> >
> > template<std::contiguous_iterator Iter>
> >
> > void f(Iter a,Iter b)
> >
> > {
> >
> > std::sort(a,b);
> >
> > }
> >
> >
> >
> > void g(std::vector<int>::iterator b,std::vector<int>::iterator e)
> >
> > {
> >
> > f(std::to_address(b),std::to_address(e));
> >
> > }
> >
> >
> >
> > void h(int* b,int* e)
> >
> > {
> >
> > f(b,e);
> >
> > }
> >
> >
> >
> >
> >
> > The two sort function should generate exactly the same binary. However the first which is none to_address version generates twice as much as code as the second one.
> >
> > Will the GNU ld remove the duplication definitions?
>
>
> For gold, see the --icf option.
>
> Ian
>
>
^ permalink raw reply [flat|nested] 4+ messages in thread
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2020-09-16 9:26 How does ld and gold deal with C++ duplicate templates? sotrdg sotrdg
2020-09-16 19:23 ` Ian Lance Taylor
2020-09-16 19:38 ` sotrdg sotrdg
2020-09-16 20:56 ` Ian Lance Taylor
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