Author: inglorion Date: Fri Sep 15 17:16:13 2017 New Revision: 313425 URL: http://llvm.org/viewvc/llvm-project?rev=313425&view=rev Log: [docs] add Windows examples to ThinLTO.rst
Reviewers: pcc, ruiu Reviewed By: ruiu Subscribers: mehdi_amini, eraman, cfe-commits Differential Revision: https://reviews.llvm.org/D37943 Modified: cfe/trunk/docs/ThinLTO.rst Modified: cfe/trunk/docs/ThinLTO.rst URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/docs/ThinLTO.rst?rev=313425&r1=313424&r2=313425&view=diff ============================================================================== --- cfe/trunk/docs/ThinLTO.rst (original) +++ cfe/trunk/docs/ThinLTO.rst Fri Sep 15 17:16:13 2017 @@ -63,7 +63,7 @@ ThinLTO is currently supported for the f - **ld64**: Starting with `Xcode 8 <https://developer.apple.com/xcode/>`_. - **lld**: - Starting with r284050 (ELF only). + Starting with r284050 for ELF, r298942 for COFF. Usage ===== @@ -78,6 +78,13 @@ To utilize ThinLTO, simply add the -flto % clang -flto=thin -O2 file1.c file2.c -c % clang -flto=thin -O2 file1.o file2.o -o a.out +When using lld-link, the -flto option need only be added to the compile step: + +.. code-block:: console + + % clang-cl -flto=thin -O2 -c file1.c file2.c + % lld-link /out:a.exe file1.obj file2.obj + As mentioned earlier, by default the linkers will launch the ThinLTO backend threads in parallel, passing the resulting native object files back to the linker for the final native link. As such, the usage model the same as @@ -111,6 +118,8 @@ be reduced to ``N`` via: ``-Wl,-mllvm,-threads=N`` - lld: ``-Wl,--thinlto-jobs=N`` +- lld-link: + ``/opt:lldltojobs=N`` Incremental ----------- @@ -125,7 +134,7 @@ which currently must be enabled through ``-Wl,-cache_path_lto,/path/to/cache`` - ELF lld (as of LLVM 5.0): ``-Wl,--thinlto-cache-dir=/path/to/cache`` -- COFF lld (as of LLVM 6.0): +- COFF lld-link (as of LLVM 6.0): ``/lldltocache:/path/to/cache`` Cache Pruning @@ -138,7 +147,7 @@ policy string. The cache policy must be - ELF lld (as of LLVM 5.0): ``-Wl,--thinlto-cache-policy,POLICY`` -- COFF lld (as of LLVM 6.0): +- COFF lld-link (as of LLVM 6.0): ``/lldltocachepolicy:POLICY`` A policy string is a series of key-value pairs separated by ``:`` characters. @@ -187,13 +196,20 @@ To bootstrap clang/LLVM with ThinLTO, fo when configuring the bootstrap compiler build: * ``-DLLVM_ENABLE_LTO=Thin`` - * ``-DLLVM_PARALLEL_LINK_JOBS=1`` - (since the ThinLTO link invokes parallel backend jobs) * ``-DCMAKE_C_COMPILER=/path/to/host/clang`` * ``-DCMAKE_CXX_COMPILER=/path/to/host/clang++`` * ``-DCMAKE_RANLIB=/path/to/host/llvm-ranlib`` * ``-DCMAKE_AR=/path/to/host/llvm-ar`` + Or, on Windows: + + * ``-DLLVM_ENABLE_LTO=Thin`` + * ``-DCMAKE_C_COMPILER=/path/to/host/clang-cl.exe`` + * ``-DCMAKE_CXX_COMPILER=/path/to/host/clang-cl.exe`` + * ``-DCMAKE_LINKER=/path/to/host/lld-link.exe`` + * ``-DCMAKE_RANLIB=/path/to/host/llvm-ranlib.exe`` + * ``-DCMAKE_AR=/path/to/host/llvm-ar.exe`` + #. To use additional linker arguments for controlling the backend parallelism_ or enabling incremental_ builds of the bootstrap compiler, after configuring the build, modify the resulting CMakeCache.txt file in the _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits