gchatelet marked an inline comment as done. gchatelet added inline comments.
================ Comment at: llvm/trunk/lib/Target/AArch64/AArch64StackTagging.cpp:65 -static constexpr unsigned kTagGranuleSize = 16; +static const Align kTagGranuleSize = Align(16); ---------------- arichardson wrote: > gchatelet wrote: > > arichardson wrote: > > > Can't the Align ctor be constexpr? Will this result in a `Log2` call at > > > runtime? > > The implementation of Log2 is quite complex and depends on the > > implementation of [[ > > https://github.com/llvm/llvm-project/blob/02ada9bd2b41d850876a483bede59715e7550c1e/llvm/include/llvm/Support/MathExtras.h#L127 > > | countLeadingZeros ]]. > > GCC, clang, ICC can compute the value at compile time but there may be some > > compiler that can't. > > https://godbolt.org/z/ytwWHn > > > > I could solve this issue by introducing a `LogAlign()` function returning > > an `Align`. This function could be `constexpr`. What do you think? Is it > > worth the additional complexity? > Since there won't a global ctor at -O2 or higher it probably doesn't matter. > > I'm not sure if there have been any of these cases yet, but I would think > that having a `LogAlign/Align::fromLog()/etc.` might still be useful for some > cases where you get the alignment as log2 instead of in bytes? > This would avoid additional work for the compiler and might be easier to read > since you can omit the `1<<N`. I'll wait a bit for the `LogAlign` to check if it's useful. Meanwhile you may want to have a look at D68329 where I allow `constexpr` `Align`. Repository: rL LLVM CHANGES SINCE LAST ACTION https://reviews.llvm.org/D68141/new/ https://reviews.llvm.org/D68141 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
