Treat GCC cross compiler as a native compiler?

Treat GCC cross compiler as a native compiler?

[unlvsur unlvsur]

I want to make –host=aarch64-linux-musl –target=aarch64-linux-android to be a native compiler instead of just a cross compiler for aarch64-linux-android. Is that possible? (Since use aarch64-linux-android as host is difficult due to issues with -fPIC to stderr)

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Re: Treat GCC cross compiler as a native compiler?

[Richard Sandiford]

unlvsur unlvsur via Gcc-help <gcc-help@gcc.gnu.org> writes:
> I want to make –host=aarch64-linux-musl –target=aarch64-linux-android to be a native compiler instead of just a cross compiler for aarch64-linux-android. Is that possible? (Since use aarch64-linux-android as host is difficult due to issues with -fPIC to stderr)

No, I don't think this is possible.  The usual definition of
"native compiler" is that the host and target are (exactly) the same.

It's possible (but difficult) to build a cross-native toolchain,
(build!=host, host==target).

Thanks,
Richard

RE: Treat GCC cross compiler as a native compiler?

[unlvsur unlvsur]

“cross-native” toolchain should be called canadian toolchain.


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From: Richard Sandiford<mailto:richard.sandiford@arm.com>
Sent: Wednesday, June 29, 2022 03:44
To: unlvsur unlvsur via Gcc-help<mailto:gcc-help@gcc.gnu.org>
Cc: unlvsur unlvsur<mailto:unlvsur@live.com>
Subject: Re: Treat GCC cross compiler as a native compiler?

unlvsur unlvsur via Gcc-help <gcc-help@gcc.gnu.org> writes:
> I want to make –host=aarch64-linux-musl –target=aarch64-linux-android to be a native compiler instead of just a cross compiler for aarch64-linux-android. Is that possible? (Since use aarch64-linux-android as host is difficult due to issues with -fPIC to stderr)

No, I don't think this is possible.  The usual definition of
"native compiler" is that the host and target are (exactly) the same.

It's possible (but difficult) to build a cross-native toolchain,
(build!=host, host==target).

Thanks,
Richard

Re: Treat GCC cross compiler as a native compiler?

[Segher Boessenkool]

On Wed, Jun 29, 2022 at 03:15:27PM +0000, unlvsur unlvsur via Gcc-help wrote:
> “cross-native” toolchain should be called canadian toolchain.

build=host=target makes a "native compiler".
host=target otherwise is a "cross-built native compiler".
build=host otherwise is a "cross-compiler".
build=target otherwise is sometimes called a "cross-back compiler".
And all three of build, host, and target different is what is called a
"Canadian cross".


The main difficulty with doing cross-built native is that many checks
for native compilers only work on the systems themselves, and do not
usually have a convenient way to override that either.  It's a fight
you cannot win, just build your native compilers on the system itself,
everyone else does!


Segher

RE: Treat GCC cross compiler as a native compiler?

[unlvsur unlvsur]

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No. Canadian simply means build != host which is building compilers for other platforms.

It does not necessarily mean it is a native or cross.

And for clang, it does not differentiate native and cross at all. Clang only has native and Canadian compilation.

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From: Segher Boessenkool<mailto:segher@kernel.crashing.org>
Sent: Wednesday, June 29, 2022 13:00
To: unlvsur unlvsur<mailto:unlvsur@live.com>
Cc: Richard Sandiford<mailto:richard.sandiford@arm.com>; unlvsur unlvsur via Gcc-help<mailto:gcc-help@gcc.gnu.org>
Subject: Re: Treat GCC cross compiler as a native compiler?

On Wed, Jun 29, 2022 at 03:15:27PM +0000, unlvsur unlvsur via Gcc-help wrote:
> “cross-native” toolchain should be called canadian toolchain.

build=host=target makes a "native compiler".
host=target otherwise is a "cross-built native compiler".
build=host otherwise is a "cross-compiler".
build=target otherwise is sometimes called a "cross-back compiler".
And all three of build, host, and target different is what is called a
"Canadian cross".


The main difficulty with doing cross-built native is that many checks
for native compilers only work on the systems themselves, and do not
usually have a convenient way to override that either.  It's a fight
you cannot win, just build your native compilers on the system itself,
everyone else does!


Segher


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Re: Treat GCC cross compiler as a native compiler?

[Segher Boessenkool]

On Wed, Jun 29, 2022 at 05:03:17PM +0000, unlvsur unlvsur via Gcc-help wrote:
> 
> No. Canadian simply means build != host which is building compilers for other platforms.

Please don't top-post.

> It does not necessarily mean it is a native or cross.

Sure it does.  <https://gcc.gnu.org/onlinedocs/gccint/Configure-Terms.html>

> And for clang, it does not differentiate native and cross at all. Clang only has native and Canadian compilation.

That is either their problem, or your misunderstanding.  This is a GCC
mailing list, we deal with GCC here.  These concepts are all older than
LLVM, I doubt they want to use different names than the well-established
ones.


Segher

RE: Treat GCC cross compiler as a native compiler?

[unlvsur unlvsur]

No.
clang does not have cross compilation. The native compiler is also cross compiler. There are no differences.

Native compilation:
clang++ -o hello hello.cc -Ofast -std=c++2b -s -flto=thin -fuse-ld=lld

“Cross” compilation
clang++ -o hello hello.cc -Ofast -std=c++2b -s -flto=thin -fuse-ld=lld –target=x86_64-windows-gnu

You just give –target to clang and it is a “cross” compiler now. It is just a compiler flag.

So for clang, it completely eliminates the idea of cross compiler.

The only thing that makes more sense is to build compilers that would run on another machine (Like building clang on linux that would run on windows). This new compiler can also do “native” or “cross” compilation with just a toggle.

So for clang, the only thing that matters is the difference between native and Canadian. Cross, Canadian cross or cross-back does not even exist for clang.


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From: Segher Boessenkool<mailto:segher@kernel.crashing.org>
Sent: Wednesday, June 29, 2022 13:53
To: unlvsur unlvsur<mailto:unlvsur@live.com>
Cc: unlvsur unlvsur via Gcc-help<mailto:gcc-help@gcc.gnu.org>; Richard Sandiford<mailto:richard.sandiford@arm.com>
Subject: Re: Treat GCC cross compiler as a native compiler?

On Wed, Jun 29, 2022 at 05:03:17PM +0000, unlvsur unlvsur via Gcc-help wrote:
>
> No. Canadian simply means build != host which is building compilers for other platforms.

Please don't top-post.

> It does not necessarily mean it is a native or cross.

Sure it does.  <https://gcc.gnu.org/onlinedocs/gccint/Configure-Terms.html>

> And for clang, it does not differentiate native and cross at all. Clang only has native and Canadian compilation.

That is either their problem, or your misunderstanding.  This is a GCC
mailing list, we deal with GCC here.  These concepts are all older than
LLVM, I doubt they want to use different names than the well-established
ones.


Segher