1d4453a671
Fix #120190. The hlfir.forall lowering code was not properly checking for forall index reference in mask value computation before trying to hoist it: it was only looking at the ops directly nested in the hlfir.forall_mask region, but not the operation indirectly nested. This caused triggered bogus hoisting in #120190 leading to undefined behavior (reference to uinitialized data). The added regression test would die at compile time with a dominance error. Fix this by doing a deep walk of the region operation instead. Also clean-up the region cloning to use without_terminator.
Flang
Flang is a ground-up implementation of a Fortran front end written in modern C++. It started off as the f18 project (https://github.com/flang-compiler/f18) with an aim to replace the previous flang project (https://github.com/flang-compiler/flang) and address its various deficiencies. F18 was subsequently accepted into the LLVM project and rechristened as Flang.
Please note that flang is not ready yet for production usage.
Getting Started
Read more about flang in the docs directory. Start with the compiler overview.
To better understand Fortran as a language and the specific grammar accepted by flang, read Fortran For C Programmers and flang's specifications of the Fortran grammar and the OpenMP grammar.
Treatment of language extensions is covered in this document.
To understand the compilers handling of intrinsics, see the discussion of intrinsics.
To understand how a flang program communicates with libraries at runtime, see the discussion of runtime descriptors.
If you're interested in contributing to the compiler, read the style guide and also review how flang uses modern C++ features.
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Consult the Getting Started with Flang for information on building and running flang.