Cavium port of flang7.

Includes LLVM, flang, clang, Polly, OpenMP, plus a large number of Cavium internal patches.

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Building Flang:

1. Create a directory where you will clone this Github repo:

%> cd /mnt/data/builds
%> mkdir flang-cavium

2. Clone this repo:

%> cd flang-cavium
%> git clone https://github.com/flang-cavium/flang7.git

3. Copy the build Makefile:

%> cp flang7/Makefile.build .

4. You will now need to edit the build Makefile to match your build environment. There are a few variables in the build Makefile that need to be edited to match your build environment:

# Edit the following 4 paths to match your installation:
CC = /path/to/your/local/gcc/bin/gcc
CXX = /path/to/your/local/gcc/bin/g++
FC = /path/to/your/local/flang/bin/flang
GCC_RUNPATH = /path/to/your/local/gcc/lib64

# Edit the following path to match your desired setup:
CMAKE_PREFIX = /path/to/your/desired/flang7/install

# Edit this path to match your build environment setup.
LIBFFI_INCDIR = /path/to/your/libffi/header/files

# Flang libpgmath target CPU optimization
CMAKE_OPTIONS += -DLLVM_FLANG_CPU_TARGET:STRING="thunderx2t99"

For building on X86_64, set the value above to 'core-avx2'.

5. That's it. There are several packages that you must have installed on your build system:

- a recent version of CMake
- libxml2
- libffi
- a recent version of GCC (GCC >= 7.3 preferred)
- a recent version of GNU Binutils (Binutils >= 2.30 preferred)

6. You are now ready to configure and build Flang 7:

%> gmake -f Makefile.build configure
%> cd build
%> gmake -j16 >& make.out # T-shell syntax

7. This version of Flang 7 supports math function vectorization via the SLEEF libraries:

https://sleef.org/

To build the SLEEF libraries, please follow the instructions at the SLEEF web site.

The compile-line option to enable SLEEF in clang is:

-fveclib=SLEEF

To link with the SLEEF library, pass:

-lsleefgnuabi

on link-line.