Thread (63 messages) 63 messages, 11 authors, 2017-11-09

[PATCH 00/15] Add support for clang LTO

From: mark.rutland@arm.com (Mark Rutland)
Date: 2017-11-03 18:49:18
Also in: lkml

On Fri, Nov 03, 2017 at 11:36:33AM -0700, Nick Desaulniers wrote:
On Fri, Nov 3, 2017 at 11:29 AM, Mark Rutland [off-list ref] wrote:
quoted
On Fri, Nov 03, 2017 at 11:07:04AM -0700, Nick Desaulniers wrote:
quoted
On Fri, Nov 3, 2017 at 10:51 AM, Mark Rutland [off-list ref] wrote:
quoted
I had to create an aarch64-linux-gnu-clang wrapper, too. I'm not sure if
there's build system help to avoid needing that?
Gah!  So a BIG difference with Clang vs GCC for cross compiling is
that Clang by default ships with all backends enabled, and uses a
`-target <triple>` CFLAG to determine the arch to cross compile for,
while GCC is configured at compile time to support one back end, IIUC.
Yup.

I initally tried passing CC=clang\ --target=aarch64-linux-gnu

... but since that conflicts with CROSS_COMPILE, you then have to
override AS, LD, OBJCOPY, etc, separately too.
make CC=clang CROSS_COMPILE=aarch64-linux-gnu-

I think you may need a trailing hyphen on your target as it gets
prefixed onto as and ld:

Makefile:

 348 # Make variables (CC, etc...)
 349 AS    = $(CROSS_COMPILE)as
 350 LD    = $(CROSS_COMPILE)ld
I thought CC=clang CROSS_COMPILE=foo- would result in foo-clang, but
evidently this is not the case.

I must've meseed up something else; sorry for the noise.

Thanks for correcting me; now I can go delete my wrapper. :)

Thanks,
Mark.
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