<div dir="ltr"><div dir="ltr"><div>There's CLANG_DEFAULT_LINKER to set the default linker. There are other similar flags like CLANG_DEFAULT_OBJCOPY, CLANG_DEFAULT_CXX_STDLIB, CLANG_DEFAULT_RTLIB.</div><div><br></div><div>One issue I ran into is these settings are currently global and not per-target. This is an issue e.g. on macOS where using CLANG_DEFAULT_LINKER=lld makes even the Darwin target use lld which is a problem. This is something we should address by either this setting a per-target or change Darwin to always use system linker and ignore that option.</div><div><br></div><div>There isn't CLANG_DEFAULT_SYSROOT right now. We could probably introduce it but it'd have the same problem as CLANG_DEFAULT_LINKER where a single option isn't going to work for all targets.</div><div><br></div><div>One thing we wanted to do for Fuchsia is implementing support for finding sysroot in tooldir/sys-root/<target> which is already supported by GCC.</div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Wed, Nov 6, 2019 at 12:11 PM Chris Hanson via cfe-dev <<a href="mailto:cfe-dev@lists.llvm.org">cfe-dev@lists.llvm.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="auto">I’ve built clang, compiler_rt, and lld on Linux from LLVM master as of last night targeting MIPS like so:<div><br></div><blockquote style="margin:0px 0px 0px 40px;border:none;padding:0px"><div><div>cmake \</div></div><div><div> -G Ninja \</div></div><div><div> $CMHPROJECTS/llvm-project/llvm \</div></div><div><div> -DLLVM_ENABLE_PROJECTS="clang;compiler-rt;lld" \</div></div><div><div> -DCMAKE_INSTALL_PREFIX="/opt/llvm-mips" \</div></div><div><div> -DLLVM_TARGETS_TO_BUILD="Mips"</div></div><div><br></div><div>ninja -j8 -k8</div></blockquote><div><div><br></div><div>(A couple things fail to link but clang, lld, etc. do get built.)</div><div><br></div><div>Unfortunately the built clang does two things I don’t want: It looks in my Linux system’s / for headers even when I specify -isysroot and it uses my Linux system’s ld instead of the built lld even when I specify -fuse-ld=lld.</div><div><br></div><div>Are there CMake flags that I can use to force the built clang to only ever use headers from the provided sysroot? (And of course, I’d love the same for forcing lld to only look in sysroot for libraries.) How about CMake flags to force the built clang to only use its paired lld?</div><div><br></div><div>I also have to specify a number of options to get the (IRIX MIPS IV n64 ABI) code generation I desire; I’m compiling hello.c in my LLVM build directory with:</div><div><br></div></div><blockquote style="margin:0px 0px 0px 40px;border:none;padding:0px"><blockquote style="margin:0px 0px 0px 40px;border:none;padding:0px"><blockquote style="margin:0px 0px 0px 40px;border:none;padding:0px"><div><div>./bin/clang -g --std=c99 -D_LANGUAGE_C=1 -D__sgi=1 -D_SGIAPI=1 -D_SGI_SOURCE=1 -D_MIPSABI_SOURCE=1 --target=mips-sgi-irix -march=mips4 -m64 -isysroot $IRIXSDK -isystem $IRIXSDK/usr/include -c hello.c</div></div></blockquote></blockquote></blockquote><div><div><br></div><div>Obviously the target tuple mips-sgi-irix isn’t supported, it does at least result in MIPS codegen and the rest winds up getting me MIPS IV n64. If I eventually add support for the sgi-irix part of the target tuple I know I can easily make it imply the preprocessor macros, but is that also necessary to force the use of the MIPS n64 ABI? Or is there some other way to select which MIPS ABI that I get? And is there a CMake option I can use to make all of that the default for the built clang?</div><div><br></div><div> — Chris</div><div><br></div><div>Sent from my iPad</div></div></div>_______________________________________________<br>
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