Bug #17646: Check for `__builtin_mul_overflow` with `long long` arguments

• Status: Closed
• Assignee: -
• Target version: -
• ruby -v: ruby 3.1.0dev (2021-02-19 master a319c04818) [i686-linux]
• Backport: 2.5: UNKNOWN, 2.6: UNKNOWN, 2.7: UNKNOWN, 3.0: UNKNOWN

[xtkoba (Tee KOBAYASHI)]

For some 32-bit targets, when Clang/LLVM is set up without compiler-rt, __builtin_mul_overflow does exist but is not usable with long long arguments. In this situation, make stops with the following message:

linking miniruby
ld.lld: error: undefined symbol: __mulodi4
>>> referenced by process.c:8037
>>>               process.o:(timetick2integer)
clang-11: error: linker command failed with exit code 1 (use -v to see invocation)
make: *** [Makefile:278: miniruby] Error 1

The usability of __builtin_mul_overflow with long long arguments have to be checked within ./configure. A patch is attached for that. Note that optimizations have to be disabled for the compilation of the test code.

• Status changed from Open to Closed

Applied in changeset git|b635388a900206b673fc23b5442345236b84cd75.

---

Check that __builtin_mul_overflow can handle long long

Fixes [Bug #17646]

Patch from xtkoba (Tee KOBAYASHI)