search for: ffreestand

On 27.10.2012, at 18:24, Benjamin Kramer <benny.kra at gmail.com> wrote: > > On 27.10.2012, at 18:15, Sean Silva <silvas at purdue.edu> wrote: > >> How does this affect freestanding implementations? > > This transform is disabled with -fno-builtin or -ffreestanding. Thinking a bit more about this, it looks like the way -ffreestanding is implemented in clang is too conservative. Currently -ffreestanding disables optimizing all builtin functions, just like -fno-builtin. However, the GCC manual says: > GCC requires the freestanding environment provide me...

New clang versions need the '-ffreestanding' flag because new changes convert system calls to their unlocked versions, which don't exist in the kernel library. Signed-off-by: Bill Wendling <morbo at google.com> diff --git a/scripts/Kbuild.klibc b/scripts/Kbuild.klibc index f500d535..9cf4b2d9 100644 --- a/scripts/Kbuild.kli...

Bill Wendling dixit: >New clang versions need the '-ffreestanding' flag because new changes >convert system calls to their unlocked versions, which don't exist in >the kernel library. This is probably wrong, a libc is not, in contrast to a bootloader or kernel, a freestanding environment. For the case of GCC, -ffreestanding is definitely wrong....

...ogle.com> wrote: >> >> On Tue, May 29, 2012 at 9:40 PM, Chandler Carruth <chandlerc at google.com> >> wrote: >>>>>>> >>>>>>> > How do I disable that feature? I've tried -fno-builtin and/or >>>>>>> > -ffreestanding >>>>>>> > with no success. >>>>>>> clang (as well as gcc) requires that freestanding environment >>>>>>> provides >>>>>>> memcpy, memmove, memset and memcmp. >>>>>>> >>>>>&g...

When we add -ffreestanding the compiler won't get to inline this any more. Signed-off-by: David Woodhouse <dwmw2 at infradead.org> --- com32/lib/math/fabs.S | 15 +++++++++++++++ mk/lib.mk | 2 +- 2 files changed, 16 insertions(+), 1 deletion(-) create mode 100644 com32/lib/math/fabs.S diff --gi...

...t; >> On Tue, May 29, 2012 at 9:40 PM, Chandler Carruth <chandlerc at google.com > > > >> wrote: > >>>>>>> > >>>>>>> > How do I disable that feature? I've tried -fno-builtin and/or > >>>>>>> > -ffreestanding > >>>>>>> > with no success. > >>>>>>> clang (as well as gcc) requires that freestanding environment > >>>>>>> provides > >>>>>>> memcpy, memmove, memset and memcmp. > >>>>>>&g...

On Tue, May 29, 2012 at 9:40 PM, Chandler Carruth <chandlerc at google.com>wrote: > > How do I disable that feature? I've tried -fno-builtin and/or >>>>> -ffreestanding >>>>> > with no success. >>>>> clang (as well as gcc) requires that freestanding environment provides >>>>> memcpy, memmove, memset and memcmp. >>>>> >>>>> PS: Consider emailing cfedev, not llvmdev. >>>>&gt...

...; > $ clang -emit-llvm -fno-builtin -o3 --target=mips -S matrix_float.c -o vl_matrix_float.ll > > Technically -fno-bultin prevents the compiler from understand the > memset in the original code. The right option to prevent the compiler > from insert libc calls “out-of-the-blue” is -ffreestanding. Huh? The -fno-builtin is not the problem. The compiler is *expected* to call certain functions even for -ffreestanding. memcpy and memset are two of those. It is certainly perfectly valid target lowering for llvm.memcpy to be turned back into a libcall. Joerg

On Tue, May 29, 2012 at 10:46 AM, Dmitry Vyukov <dvyukov at google.com> wrote: > On Tue, May 29, 2012 at 9:40 PM, Chandler Carruth <chandlerc at google.com>wrote: > >> > How do I disable that feature? I've tried -fno-builtin and/or >>>>>> -ffreestanding >>>>>> > with no success. >>>>>> clang (as well as gcc) requires that freestanding environment provides >>>>>> memcpy, memmove, memset and memcmp. >>>>>> >>>>>> PS: Consider emailing cfedev, not llvmdev....

Even with -ffreestanding LLVM generates memcpy/memset? Does this mean some passes do not honor this flag? If you really wanted to prevent libcalls, you could technically translate those memcpy/memset to loops in lowering. Kevin On Sat, Oct 15, 2016 at 4:10 PM, Wolfgang McSneed via llvm-dev < llvm-dev at lists.llvm.o...

...Add "-fno-common" > > > > > - 1e876662002eac9662357c7feaee12be04107d32 - Use proper libc > > > > > - f07a8f75b8ebfea71254cd8829c0476b6b6683e1 - Adjust some flags for ld.lld > > > > > - 7f0aa03493dc9ab8c1d2798f6586bfbc5f1de702 - Use "-ffreestanding" > > > > > (fixes using unlocked versions of calls) > > > > > > > > > > There are also a bunch of clang warnings Michael Davidson fixed in the > > > > > klibc tree. > > > > > > > > *Which* klibc tree? >...

...3dc803e2cae06ac5c803dc89cb - Add "-fno-common" > > > - 1e876662002eac9662357c7feaee12be04107d32 - Use proper libc > > > - f07a8f75b8ebfea71254cd8829c0476b6b6683e1 - Adjust some flags for ld.lld > > > - 7f0aa03493dc9ab8c1d2798f6586bfbc5f1de702 - Use "-ffreestanding" > > > (fixes using unlocked versions of calls) > > > > > > There are also a bunch of clang warnings Michael Davidson fixed in the > > > klibc tree. > > > > *Which* klibc tree? > > > > Ben. > > > The one here I think:...

(summarising IRC) Rethinking a little, I would be inclined to agree that combined hosted and freestanding modules should not be compiled in hosted mode. Here's one scenario where we may break: suppose I LTO-link an implementation of memset compiled with -ffreestanding with a program compiled with -fhosted. With the proposed rule, the loop idiom recognizer may transform the body of the memset function into a self-call. So that leaves either compile in freestanding or error out. Freestanding would produce a conservatively correct result, but it may lead to uni...

On Tue, May 29, 2012 at 9:16 PM, Chandler Carruth <chandlerc at google.com>wrote: > > How do I disable that feature? I've tried -fno-builtin and/or >>> -ffreestanding >>> > with no success. >>> clang (as well as gcc) requires that freestanding environment provides >>> memcpy, memmove, memset and memcmp. >>> >>> PS: Consider emailing cfedev, not llvmdev. >>> >> >> Hi, >> >> Thanks...

...Eric and Akira (for thoughts on module flags) > On 2016-Sep-16, at 12:47, Mehdi Amini <mehdi.amini at apple.com> wrote: > >> On Sep 16, 2016, at 12:30 PM, Peter Collingbourne <peter at pcc.me.uk> wrote: >> >> In PR30403 we've been discussing how to encode -ffreestanding when using LTO. This bit is currently dropped during LTO because its only representation is in the TargetLibraryInfo created by clang (http://llvm-cs.pcc.me.uk/tools/clang/lib/CodeGen/BackendUtil.cpp#258). >> >> The proposal is to introduce a module flag that we set in any translati...

On Tue, May 29, 2012 at 10:28 AM, Dmitry Vyukov <dvyukov at google.com> wrote: > On Tue, May 29, 2012 at 9:16 PM, Chandler Carruth <chandlerc at google.com>wrote: > >> > How do I disable that feature? I've tried -fno-builtin and/or >>>> -ffreestanding >>>> > with no success. >>>> clang (as well as gcc) requires that freestanding environment provides >>>> memcpy, memmove, memset and memcmp. >>>> >>>> PS: Consider emailing cfedev, not llvmdev. >>>> >>> >>&...

On Tue, May 29, 2012 at 9:50 PM, Chandler Carruth <chandlerc at google.com>wrote: > > How do I disable that feature? I've tried -fno-builtin and/or >>>>>>> -ffreestanding >>>>>>> > with no success. >>>>>>> clang (as well as gcc) requires that freestanding environment >>>>>>> provides >>>>>>> memcpy, memmove, memset and memcmp. >>>>>>> >>>>>&g...

james woodyatt wrote: > everyone-- > > I don't know whether this is a bug or not. I assume you're using llvm-gcc? Does it still turn memcpy into llvm.memcpy if you pass llvm-gcc -ffreestanding? If so, that's certainly a bug. Either way, you should be using -ffreestanding! Nick > I'm trying to bootstrap an embedded application and using LLVM tools > to generate the assembly code, which I then assemble and link with > traditional tools. The bootstrap loader, of...

Hi David and Mats, Thanks for your explanation. If my understanding is correct, it means we don't need to consider the side-effect of malloc/free unless compiling with -ffreestanding. Because without -ffreestanding, user defined malloc/free should be compatible with std library. It makes sense to me. My point is, in std library, malloc is allowed to return null if this malloc failed. Why compiler knows it must succeed at compile time? I slightly modified the regression cas...

On Thu, 2019-02-07 at 20:17 -0800, H. Peter Anvin wrote: > CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you recognize the sender and know the content is safe. > > > On 2/7/19 1:53 PM, Joakim Tjernlund wrote: > \>>> > > > > -z muldefs would bloat the libraries unnecessarily, but worse it might