[ATfL] Add changelog (#272)

It's a cherry-pick from the arm-software branch.

Author: pawosm-arm

arm-software/linux/CHANGELOG.md

@@ -0,0 +1,35 @@
+# Changelog
+
+All notable changes to this project will be documented in this file.
+
+## [20.1.0]
+
+This is the first release of the Arm Toolchain for Linux (ATfL), a successor of
+the Arm Compiler for Linux (ACfL).
+
+Although ATfL is based entirely on LLVM version 20.1, several changes have been
+introduced specifically for this toolchain. The most notable include:
+
+- The compiler uses a config file by default, which improves
+  performance-specific optimizations; most notably, it encourages the use of the
+  vectorized mathematical routines in the Loop Vectorizer which enables the
+  possibility of vectorizing loops containing the calls to the mathematical
+  library functions.
+
+- For function whose `vscale_range` is limited to a single value, ATfL can size
+  scalable vectors. The compiler can now perform bitcast-like operations between
+  fixed and scalable vectors, improving optimization opportunities for code
+  utilizing scalable vector types.
+  See [this pull request](https://github.com/llvm/llvm-project/pull/130973) for
+  more details.
+
+- A part of transformation in the Loop Vectorizer causing 'Verification Error'
+  on the WRF benchmark has been deactivated.
+  See [this bug report](https://github.com/llvm/llvm-project/issues/126836) for
+  more details.
+
+- The Bash autocompletion has been extended to cover `armclang`, `armclang++`
+  and `armflang`.
+
+Please examine the `docs` directory for more details specific to the Arm
+Toolchain for Linux.

arm-software/linux/build.sh

@@ -11,6 +11,7 @@ fi
 
 BASE_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 README_MD_PATH=${README_MD_PATH:-"${BASE_DIR}/README.md"}
+CHANGELOG_MD_PATH=${CHANGELOG_MD_PATH:-"${BASE_DIR}/CHANGELOG.md"}
 SBOM_FILE_PATH=${SBOM_FILE_PATH:-"${BASE_DIR}/SBOM_Files/ATfL-SBOM.spdx.json"}
 MKMODULEDIRS_PATH=${MKMODULEDIRS_PATH:-"${BASE_DIR}/mkmoduledirs.sh.var"}
 SOURCES_DIR=${SOURCES_DIR:-"$(git -C "${BASE_DIR}" rev-parse --show-toplevel)"}
@@ -177,6 +178,8 @@ Environment Variables:
 
     README_MD_PATH      Specifies the location of the README.md file to bundle
                         (default: ${README_MD_PATH})
+    CHANGELOG_MD_PATH   Specifies the location of the CHANGELOG.md file to bundle
+                        (default: ${CHANGELOG_MD_PATH})
     SBOM_FILE_PATH      Specifies the location of the SBOM JSON file to bundle
                         (default: ${SBOM_FILE_PATH})
     MKMODULEDIRS_PATH   Specifies the location of mkmoduledirs.sh.var to tweak
@@ -386,6 +389,7 @@ shared_lib_build() {
 
 package() {
     cp "${README_MD_PATH}" "${ATFL_DIR}/README.md"
+    cp "${CHANGELOG_MD_PATH}" "${ATFL_DIR}/CHANGELOG.md"
     cp "${SBOM_FILE_PATH}" "${ATFL_DIR}/ATfL-SBOM.spdx.json"
     mkdir -p "${ATFL_DIR}/arm"
     cp "${MKMODULEDIRS_PATH}" "${ATFL_DIR}/arm/mkmoduledirs.sh"
@@ -497,6 +501,12 @@ then
   exit 1
 fi
 
+if ! [[ -f "${CHANGELOG_MD_PATH}" ]]
+then
+  echo "The path to CHANGELOG.md file is configured incorrectly or does not exist."
+  exit 1
+fi
+
 if ! [[ -f "${MKMODULEDIRS_PATH}" ]]
 then
   echo "The path to mkmoduledirs.sh.var file is configured incorrectly or does not exist."

arm-software/linux/build.sh-HOWTO.md

@@ -137,6 +137,8 @@ The `build.sh` script reads the following environment variables:
 
 - `README_MD_PATH` - Specifies the location of the README.md file to bundle
   (default: `arm-software/linux/README.md`)
+- `CHANGELOG_MD_PATH` - Specifies the location of the CHANGELOG.md file to bundle
+  (default: `arm-software/linux/CHANGELOG.md`)
 - `SBOM_FILE_PATH` - Specifies the location of the SBOM JSON file to bundle
   (default: `arm-software/linux/SBOM_Files/ATfL-SBOM.spdx.json`)
 - `MKMODULEDIRS_PATH` - Specifies the location of mkmoduledirs.sh.var to tweak