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MSAN, ASAN, & TSAN
==================
*Testing Skia with memory, address, and thread santizers.*
Compiling Skia with ASAN, UBSAN, or TSAN can be done with the latest version of Clang.
- UBSAN works on Linux, Mac, Android, and Windows, though some checks are platform-specific.
- ASAN works on Linux, Mac, Android.
- TSAN works on Linux and Mac.
- MSAN works on Linux[1].
We find that testing sanitizer builds with libc++ uncovers more issues than
with the system-provided C++ standard library, which is usually libstdc++.
libc++ proactively hooks into sanitizers to help their analyses.
We ship a copy of libc++ with our Linux toolchain in /lib.
[1]To compile and run with MSAN, an MSAN-instrumented version of libc++ is needed.
It's generally easiest to run one of the following 2 steps to build/download a recent version
of Clang and the instrumented libc++, located in /msan.
Downloading Clang binaries (Googlers Only)
------------------------------------------
This requires gsutil, part of the [gcloud sdk](https://cloud.google.com/sdk/downloads).
CLANGDIR="${HOME}/clang"
python infra/bots/assets/clang_linux/download.py -t $CLANGDIR
Building Clang binaries from scratch (Other users)
---------------------------
CLANGDIR="${HOME}/clang"
python tools/git-sync-deps
CC= CXX= infra/bots/assets/clang_linux/create.py -t "$CLANGDIR"
Configure and Compile Skia with MSAN
------------------------------------
CLANGDIR="${HOME}/clang"
mkdir -p out/msan
cat > out/msan/args.gn <<- EOF
cc = "${CLANGDIR}/bin/clang"
cxx = "${CLANGDIR}/bin/clang++"
extra_cflags = [ "-B${CLANGDIR}/bin" ]
extra_ldflags = [ "-B${CLANGDIR}/bin", "-fuse-ld=lld", "-L${CLANGDIR}/msan" ]
sanitize = "MSAN"
skia_use_fontconfig = false
skia_use_system_freetype2 = false
skia_enable_gpu = false
EOF
python tools/git-sync-deps
bin/gn gen out/msan
ninja -C out/msan
When you run a binary built with MSAN, make sure you force it to use our
MSAN-instrumented libc++:
env LD_LIBRARY_PATH=$CLANGDIR/msan out/dm ...
Configure and Compile Skia with ASAN
------------------------------------
CLANGDIR="${HOME}/clang"
mkdir -p out/asan
cat > out/asan/args.gn <<- EOF
cc = "${CLANGDIR}/bin/clang"
cxx = "${CLANGDIR}/bin/clang++"
sanitize = "ASAN"
EOF
python tools/git-sync-deps
bin/gn gen out/asan
ninja -C out/asan
To use the libc++ that comes with the above Clang asset:
env LD_LIBRARY_PATH=$CLANGDIR/lib out/dm ...
Configure and Compile Skia with TSAN
------------------------------------
CLANGDIR="${HOME}/clang"
mkdir -p out/tsan
cat > out/tsan/args.gn <<- EOF
cc = "${CLANGDIR}/bin/clang"
cxx = "${CLANGDIR}/bin/clang++"
sanitize = "TSAN"
is_debug = false
EOF
python tools/git-sync-deps
bin/gn gen out/tsan
ninja -C out/tsan
|
