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+# TensorFlow Bazel Clang
+
+This is a specialized toolchain that uses an old Debian with a new Clang that
+can cross compile to any x86_64 microarchitecture. It's intended to build Linux
+binaries that only require the following ABIs:
+
+- GLIBC_2.18
+- CXXABI_1.3.7 (GCC 4.8.3)
+- GCC_4.2.0
+
+Which are available on at least the following Linux platforms:
+
+- Ubuntu 14+
+- CentOS 7+
+- Debian 8+
+- SuSE 13.2+
+- Mint 17.3+
+- Manjaro 0.8.11
+
+# System Install
+
+On Debian 8 (Jessie) Clang 6.0 can be installed as follows:
+
+```sh
+cat >>/etc/apt/sources.list <<'EOF'
+deb http://apt.llvm.org/jessie/ llvm-toolchain-jessie main
+deb-src http://apt.llvm.org/jessie/ llvm-toolchain-jessie main
+EOF
+wget -O - https://apt.llvm.org/llvm-snapshot.gpg.key | apt-key add -
+apt-key fingerprint |& grep '6084 F3CF 814B 57C1 CF12  EFD5 15CF 4D18 AF4F 7421'
+apt-get update
+apt-get install clang lld
+```
+
+# Bazel Configuration
+
+This toolchain can compile TensorFlow in 2m30s on a 96-core Skylake GCE VM if
+the following `.bazelrc` settings are added:
+
+```
+startup --host_jvm_args=-Xmx30G
+startup --host_jvm_args=-Xms30G
+startup --host_jvm_args=-XX:MaxNewSize=3g
+startup --host_jvm_args=-XX:-UseAdaptiveSizePolicy
+startup --host_jvm_args=-XX:+UseConcMarkSweepGC
+startup --host_jvm_args=-XX:TargetSurvivorRatio=70
+startup --host_jvm_args=-XX:SurvivorRatio=6
+startup --host_jvm_args=-XX:+UseCMSInitiatingOccupancyOnly
+startup --host_jvm_args=-XX:CMSFullGCsBeforeCompaction=1
+startup --host_jvm_args=-XX:CMSInitiatingOccupancyFraction=75
+
+build --jobs=100
+build --local_resources=200000,100,100
+build --crosstool_top=@local_config_clang6//clang6
+build --noexperimental_check_output_files
+build --nostamp
+build --config=opt
+build --noexperimental_check_output_files
+build --copt=-march=native
+build --host_copt=-march=native
+```
+
+# x86_64 Microarchitectures
+
+## Intel CPU Line
+
+- 2003 P6 M           SSE SSE2
+- 2004 prescott       SSE3 SSSE3 (-march=prescott)
+- 2006 core           X64 SSE4.1 (only on 45nm variety) (-march=core2)
+- 2008 nehalem        SSE4.2 VT-x VT-d (-march=nehalem)
+- 2010 westmere       CLMUL AES (-march=westmere)
+- 2012 sandybridge    AVX TXT (-march=sandybridge)
+- 2012 ivybridge      F16C MOVBE (-march=ivybridge)
+- 2013 haswell        AVX2 TSX BMI2 FMA (-march=haswell)
+- 2014 broadwell      RDSEED ADCX PREFETCHW (-march=broadwell - works on trusty gcc4.9)
+- 2015 skylake        SGX ADX MPX AVX-512[xeon-only] (-march=skylake / -march=skylake-avx512 - needs gcc7)
+- 2018 cannonlake     AVX-512 SHA (-march=cannonlake - needs clang5)
+
+## Intel Low Power CPU Line
+
+- 2013 silvermont     SSE4.1 SSE4.2 VT-x (-march=silvermont)
+- 2016 goldmont       SHA (-march=goldmont - needs clang5)
+
+## AMD CPU Line
+
+- 2003 k8             SSE SSE2 (-march=k8)
+- 2005 k8 (Venus)     SSE3 (-march=k8-sse3)
+- 2008 barcelona      SSE4a?! (-march=barcelona)
+- 2011 bulldozer      SSE4.1 SSE4.2 CLMUL AVX AES FMA4?! (-march=bdver1)
+- 2011 piledriver     FMA (-march=bdver2)
+- 2015 excavator      AVX2 BMI2 MOVBE (-march=bdver4)
+
+## Google Compute Engine Supported CPUs
+
+- 2012 sandybridge 2.6gHz -march=sandybridge
+- 2012 ivybridge   2.5gHz -march=ivybridge
+- 2013 haswell     2.3gHz -march=haswell
+- 2014 broadwell   2.2gHz -march=broadwell
+- 2015 skylake     2.0gHz -march=skylake-avx512
+
+See: <https://cloud.google.com/compute/docs/cpu-platforms>