[flang] Avoid undefined behaviour when parsing format expressions (#147539) The test flang/test/Semantics/io08.f90 was failing when UBSAN was enabled: ``` /home/david.spickett/llvm-project/flang/include/flang/Common/format.h:224:26: runtime error: signed integer overflow: 10 * 987654321098765432 cannot be represented in type 'int64_t' (aka 'long') SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior /home/david.spickett/llvm-project/flang/include/flang/Common/format.h:224:26 ``` This is because the code was effectively: * Take the risk of UB happening * Check whether it happened or not Which UBSAN is obviously not going to like. Instead of checking after the fact, use llvm's helpers that catch overflow without actually doing it.
Welcome to the LLVM project!
This repository contains the source code for LLVM, a toolkit for the construction of highly optimized compilers, optimizers, and run-time environments.
The LLVM project has multiple components. The core of the project is itself called “LLVM”. This contains all of the tools, libraries, and header files needed to process intermediate representations and convert them into object files. Tools include an assembler, disassembler, bitcode analyzer, and bitcode optimizer.
C-like languages use the Clang frontend. This component compiles C, C++, Objective-C, and Objective-C++ code into LLVM bitcode -- and from there into object files, using LLVM.
Other components include: the libc++ C++ standard library, the LLD linker, and more.
Consult the Getting Started with LLVM page for information on building and running LLVM.
For information on how to contribute to the LLVM project, please take a look at the Contributing to LLVM guide.
Join the LLVM Discourse forums, Discord chat, LLVM Office Hours or Regular sync-ups.
The LLVM project has adopted a code of conduct for participants to all modes of communication within the project.