ldionne added inline comments.
================ Comment at: bolt/docs/OptimizingClang.md:228-236 $ CPATH=${TOPLEV}/stage1/install/bin/ -$ cmake -G Ninja ${TOPLEV}/llvm-project/llvm -DLLVM_TARGETS_TO_BUILD=X86 \ +$ cmake -G Ninja -S ${TOPLEV}/llvm-project/llvm -B ${TOPLEV}/stage2-prof-gen \ + -DLLVM_TARGETS_TO_BUILD=X86 \ -DCMAKE_BUILD_TYPE=Release \ -DCMAKE_C_COMPILER=$CPATH/clang -DCMAKE_CXX_COMPILER=$CPATH/clang++ \ -DLLVM_ENABLE_PROJECTS="clang;lld" \ -DLLVM_USE_LINKER=lld -DLLVM_BUILD_INSTRUMENTED=ON \ ---------------- Quuxplusone wrote: > ldionne wrote: > > Quuxplusone wrote: > > > FWIW, I personally prefer to run cmake and ninja //from// the build > > > directory, i.e. > > > ``` > > > $ mkdir ${TOPLEV}/llvm-project/llvm/stage2-prof-gen > > > $ cd ${TOPLEV}/llvm-project/llvm/stage2-prof-gen > > > $ CPATH=${TOPLEV}/stage1/install/bin > > > $ cmake -G Ninja \ > > > -DLLVM_TARGETS_TO_BUILD=X86 \ > > > ~~~ > > > -DCMAKE_INSTALL_PREFIX=${TOPLEV}/stage2-prof-gen/install \ > > > ../llvm-project/llvm > > > $ ninja install > > > ``` > > > This is the style that was used in `DataFlowSanitizer.rst` below, which > > > you explicitly moved away from into `-B`/`-S`/`-C` land (where I find it > > > harder to keep straight all the different extra options that are needed). > > > > > > Orthogonally, I'm worried that the advice on lines 73–74 of README.md > > > doesn't mention `CMAKE_INSTALL_PREFIX`. When I'm building libc++ locally > > > as part of my development workflow, I //absolutely do not// want to blow > > > away my computer's default standard library installation; but what //do// > > > I want to do? Should I use something like > > > `-DCMAKE_INSTALL_PREFIX=$(pwd)/install` as depicted here? Can I really > > > not get away with "running it out of the buildroot" the way I'm used to?— > > > I //must// install it somewhere on my system in order to test it at all? > > > Re: `-C` `-B` `-S` > > > > I really like using those flags because it makes the command relocatable, > > i.e. it works regardless of where it is being run. As such, it's way more > > copy-pasteable too. However, since that's orthogonal to this change, I'll > > revert to the old style just so we have fewer things to argue about. But in > > general, for libc++/libc++abi/libunwind instructions, you'll find that I > > want things documented this way for that reason. > > > > > Re: `CMAKE_INSTALL_PREFIX` > > > > You don't necessarily need to install it in order to test it -- we test > > libc++ all the time without running the `install-cxx` target. Furthermore, > > I would expect that most systems nowadays have some sort of integrity > > protection that prevents you from doing something bad like that. Apple > > platforms certainly do -- you simply can't overwrite your `libc++.1.dylib` > > anymore and render your system unusable. Still, I'll add a word of caution > > to `CMAKE_INSTALL_PREFIX` above even though it's orthogonal to this patch > > -- it's easy enough to do. > FWIW, the `CMAKE_INSTALL_PREFIX` change is an improvement but only > //slightly// more reassuring than before. ;) Part of my paranoia is that I > happen to know that Homebrew stores things in `/usr/local/...` as well > (although probably entirely under `/usr/local/Cellar/...`?) and I wouldn't > want to blow those away //either//. > Apparently on my Apple system I have `/usr/lib/libc++.dylib`, > `/System/DriverKit/usr/lib/libc++.dylib`, and > `/usr/local/Cellar/llvm/12.0.1/lib/libc++.dylib`. > > > we test libc++ all the time without running the `install-cxx` target > > Well, I know I do, but I don't use ENABLE_RUNTIMES yet... and the how-to > below //does// end with the line `ninja -C build install-cxx`. If there's a > supported/expected-to-work way to build and test libc++ that doesn't use > `ninja install-cxx`, it'd be cool to mention it. > > Anyway, this is all just me fudding and shouldn't block this PR. :) I think your comments are valid, but I think I would defer to @rafauler if they want to change the Bolt documentation in that way. > Well, I know I do, but I don't use ENABLE_RUNTIMES yet... FWIW, `LLVM_ENABLE_RUNTIMES` won't change anything with respect to that. Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D119351/new/ https://reviews.llvm.org/D119351 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits