Bug 1657544 - clang++ linking fails with undefined reference to __muloti4
Summary: clang++ linking fails with undefined reference to __muloti4
Alias: None
Product: Fedora
Classification: Fedora
Component: clang
Version: 29
Hardware: Unspecified
OS: Unspecified
Target Milestone: ---
Assignee: Tom Stellard
QA Contact: Fedora Extras Quality Assurance
Depends On:
TreeView+ depends on / blocked
Reported: 2018-12-09 20:38 UTC by Georg Sauthoff
Modified: 2019-02-18 02:04 UTC (History)
5 users (show)

Fixed In Version: clang-7.0.1-2.fc29
Doc Type: If docs needed, set a value
Doc Text:
Clone Of:
Last Closed: 2019-02-18 02:04:04 UTC
Type: Bug

Attachments (Terms of Use)
minimal reproducing C++ example (281 bytes, text/x-csrc)
2018-12-09 20:38 UTC, Georg Sauthoff
no flags Details

System ID Private Priority Status Summary Last Updated
LLVM 34920 0 P RESOLVED __builtin_mul_overflow unsupported for mixed-sign 64-bit operands on 32-bit architectures 2020-04-24 12:27:42 UTC

Description Georg Sauthoff 2018-12-09 20:38:42 UTC
Created attachment 1512902 [details]
minimal reproducing C++ example

Description of problem:
When compiling a program that calls std::from_chars() clang++ cannot resolve the symbol __muloti4 during linking.

Version-Release number of selected component (if applicable):

How reproducible:

Steps to Reproduce:
1. get attached minimal example
2. clang++ -Wall  tochars_clang_fail.cc -o tochars
3. ./tochars 123

Actual results:
/usr/bin/ld: /tmp/tochars_clang_fail-e603f8.o: in function `bool std::__detail::__raise_and_add<unsigned long>(unsigned long&, int, unsigned char)':
tochars_clang_fail.cc:(.text._ZNSt8__detail15__raise_and_addImEEbRT_ih[_ZNSt8__detail15__raise_and_addImEEbRT_ih]+0x4c): undefined reference to `__muloti4'
clang-7: error: linker command failed with exit code 1 (use -v to see invocation

Expected results:
successful compilation and as output:

Additional info:

Compiling with GCC works as expected:

g++ -Wall  tochars_clang_fail.cc -o tochars

Linking with libc++ also does work:

clang++ -Wall -stdlib=libc++  tochars_clang_fail.cc -o tochars

Comment 1 Tom Stellard 2018-12-18 06:35:31 UTC
Possibly related upstream commit: https://reviews.llvm.org/rL320902

Comment 2 Tom Stellard 2018-12-18 06:46:31 UTC
Simplified test case:

#include <stddef.h>
void mul(size_t a, int b) {
        size_t res;
        __builtin_mul_overflow(a, b, &res);

Comment 3 Tom Stellard 2018-12-21 03:48:56 UTC
Fixed in rawhide: clang-7.0.1-2.fc30.  I will backport this back to f29 too.

Comment 4 Tom Stellard 2019-02-12 20:31:41 UTC
Submitted PR: https://src.fedoraproject.org/rpms/clang/pull-request/33

Comment 5 Fedora Update System 2019-02-14 16:09:51 UTC
clang-7.0.1-2.fc29 has been submitted as an update to Fedora 29. https://bodhi.fedoraproject.org/updates/FEDORA-2019-5065cb8af8

Comment 6 Fedora Update System 2019-02-15 02:57:23 UTC
clang-7.0.1-2.fc29 has been pushed to the Fedora 29 testing repository. If problems still persist, please make note of it in this bug report.
See https://fedoraproject.org/wiki/QA:Updates_Testing for
instructions on how to install test updates.
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2019-5065cb8af8

Comment 7 Fedora Update System 2019-02-18 02:04:04 UTC
clang-7.0.1-2.fc29 has been pushed to the Fedora 29 stable repository. If problems still persist, please make note of it in this bug report.

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