# Ampere Computing LLVM Release Notes

These are the release notes the Ampere Computing LLVM release

# Build Instructions

This section depicts the commands used top build the release

## Setup the Source

### Setup envirionment

Select a build version and select the envirionment variables according to section  [Build Tags](#buildtags) in section below

### Clone and Checkout the LLVM base rpository (modify `LLVMREPOSITORY` accordingly)

```
export LLVMREPOSITORY=git@gitlab.lan:armv8
git clone $LLVMREPOSITORY/llvm.git llvm
cd llvm
git checkout $LLVMRELEASETAG
```

### Clone and Chekout the remaining repositories

```
pushd projects
git clone https://git.llvm.org/git/compiler-rt.git compiler-rt
cd compiler-rt
git checkout $LLVMCOMPILERRTTAG
cd ..
git clone https://git.llvm.org/git/libcxx.git libcxx
cd libcxx
git checkout $LLVMLIBCXXTAG
cd ..
git clone https://git.llvm.org/git/libcxxabi.git libcxxabi
cd libcxxabi
git checkout $LLVMLIBCXXABITAG
popd
pushd tools
git clone $LLVMREPOSITORY/clang.git clang
cd clang
git checkout $LLVMRELEASETAG
popd
```

#### [optional] Only checkout the correct tags from existing checkout

If you alreade have cloned the repos you can use the following commands to update to a defferent release

```
git fetch
git checkout $LLVMRELEASETAG
pushd projects
cd compiler-rt
git fetch
git checkout $LLVMCOMPILERRTTAG
cd ..
cd libcxx
git fetch
git checkout $LLVMLIBCXXTAG
cd ..
cd libcxxabi
git fetch
git checkout $LLVMLIBCXXABITAG
popd
pushd tools
cd clang
git fetch
git checkout $LLVMRELEASETAG
popd
```

## Build the source

Follow the instructions below to build the LLVM and libraries

### Build LLVM

You might want to adjust the variable `BUILDDIR` and `INSTALL_DIR` for your build

```
export BUILDDIR=build
export INSTALL_DIR=/compilers/llvm/$LLVMRELEASETAG
export LLVMSRC=$(pwd)
mkdir -p $BUILDDIR
pushd $BUILDDIR
cmake \
      -DCMAKE_BUILD_TYPE=Release \
      -DLLVM_BINUTILS_INCDIR=/usr/include \
      -DCMAKE_INSTALL_PREFIX=$INSTALL_DIR \
      -DLLVM_TARGETS_TO_BUILD="AArch64" \
      $LLVMSRC
make -j $(($(nproc)*2))
make -j $(($(nproc)*2)) install
popd
```

## Build tcmalloc

```
git clone https://github.com/gperftools/gperftools.git
cd gperftools
git checkout $PERFTOOLSTAG
./autogen.sh
export BUILDDIR=build
export BUILDSRC=$(pwd)
export INSTALL_DIR=/compilers/llvm/$LLVMRELEASETAG
mkdir -p $BUILDDIR
pushd $BUILDDIR
export CC="$INSTALL_DIR/bin/clang -mtune=xgene"
export CXX="$INSTALL_DIR/bin/clang++ -mtune=xgene"
export CPP="$INSTALL_DIR/bin/clang-cpp -mtune=xgene"
export CXXXPP="$INSTALL_DIR/bin/clang-cpp -mtune=xgene"
$BUILDSRC/configure --prefix=$INSTALL_DIR --with-tcmalloc-pagesize=32 --enable-static
make -j $(($(nproc)*2))
make -j $(($(nproc)*2)) install
popd
```

# Using llvm

In order to use llvm follow the instructions on llvm.org. In order to
use the exgene processor model add the option `-mtune=xgene`.

# <a name="buildtags"></a> Build Tags

## Envirionment for llvm_60-amp-20180630

```
export LLVMRELEASETAG=llvm_60-amp-20180630
export LLVMCOMPILERRTTAG=9d61c78bced84866cc886f1f1111c8e51c1d52d5
export LLVMLIBCXXTAG=48a89ecb9fd90f403ad8a7b061ff1bb18f34e132
export LLVMLIBCXXABITAG=9245d481eb3e890f708ff2d7dadf2a10c04748ba
export PERFTOOLSTAG=f47a52ce85c3d8d559aaae7b7a426c359fbca225
```

# Testing

The following test have been executed:

* SPEC2006 Int: Score 399
* make check