From: Ian Lance Taylor <iant@google.com>
To: sotrdg sotrdg <euloanty@live.com>
Cc: "binutils@sourceware.org" <binutils@sourceware.org>
Subject: Re: How does ld and gold deal with C++ duplicate templates?
Date: Wed, 16 Sep 2020 13:56:50 -0700 [thread overview]
Message-ID: <CAKOQZ8yfia-_oFwjvX5v8e1rE36Qvjmw8un0ocQu6W093wPbcQ@mail.gmail.com> (raw)
In-Reply-To: <CH2PR02MB65229068B8565970341AE0E2B2210@CH2PR02MB6522.namprd02.prod.outlook.com>
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
>
>
prev parent reply other threads:[~2020-09-16 20:57 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-16 9:26 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 [this message]
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