Relicense IREE under the LLVM license (iree-org#6020)

To facilitate easy movement between IREE and upstream LLVM, we are
relicensing under the same license: the Apache 2.0 License with LLVM
Exceptions (https://llvm.org/LICENSE.txt, SPDX-License-Identifier:
Apache-2.0 WITH LLVM-exception).

In addition, we are moving to a Copyright header format that attributes
copyright to "The IREE Authors" and uses a separate AUTHORS file to
keep track of contributions. For this PR, I am just listing Google, but
I will send follow-ups to list Fraunhofer IML and Nod Labs (keeping it
separate so I can get those folks approval for the precise wording).

Note that the change to the header format is to recognize the valuable
contributions from our external collaborators and as always copyright is
retained by the author.

See the announcement at
https://groups.google.com/g/iree-discuss/c/NJohLQ5rOBg

The script I used to update (almost) all the headers is at
https://gist.github.com/GMNGeoffrey/8e85e1a088f59822ab61eff01f8d4ef6

The updates from that script are all in one commit. I recommend
reviewing the other commits separately from that one. You can also see
the raw diff from that change at
https://github.com/google/iree/commit/bdb5800ea51.diff

As part of this, I had to manually fiddle with ipynb files (actually
that was the most time-consuming aspect). I changed the format of the
license headers there to just be a block of markdown text rather than
something that was for some reason executable. Also had to manually give
the cells IDs, which hopefully will have worked.

To resolve the inevitable merge conflicts, I will likely drop the
changes from the script and rerun.

Tested:
```
$ grep -r --exclude-dir=third_party "Google LLC" . | grep -v website/site
./AUTHORS:Google LLC
```

Author: GMNGeoffrey

.bazelignore

@@ -1,16 +1,8 @@
-# Copyright 2019 Google LLC
+# Copyright 2019 The IREE Authors
 #
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#      https://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
+# Licensed under the Apache License v2.0 with LLVM Exceptions.
+# See https://llvm.org/LICENSE.txt for license information.
+# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
 # Ignore 'experimental' folders. These builds are not regularly maintained.
 # If you wish to build/run a target under experimental/, you must remove this

.bazelrc

@@ -1,16 +1,8 @@
-# Copyright 2019 Google LLC
+# Copyright 2019 The IREE Authors
 #
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#      https://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
+# Licensed under the Apache License v2.0 with LLVM Exceptions.
+# See https://llvm.org/LICENSE.txt for license information.
+# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
 # Import the main bazelrc config. This is in a separate file so that it's
 # possible to turn off some or all user and system bazelrc options by specifying

.clang-format

@@ -1,16 +1,8 @@
-# Copyright 2019 Google LLC
+# Copyright 2019 The IREE Authors
 #
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#      https://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
+# Licensed under the Apache License v2.0 with LLVM Exceptions.
+# See https://llvm.org/LICENSE.txt for license information.
+# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
 # All of IREE is in the Google style except for iree/compiler/, which follows
 # mostly LLVM style (for naming/etc) but the Google formatting (because internal

.github/workflows/copybara_fixup.yml

@@ -1,16 +1,8 @@
-# Copyright 2019 Google LLC
+# Copyright 2019 The IREE Authors
 #
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#      https://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
+# Licensed under the Apache License v2.0 with LLVM Exceptions.
+# See https://llvm.org/LICENSE.txt for license information.
+# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
 # Edits the HEAD commit if it is tagged with the Copybara tag to use the
 # submodule state specified in SUBMODULE_VERSIONS.txt and merge from the

.github/workflows/lint.yml

@@ -1,16 +1,8 @@
-# Copyright 2019 Google LLC
+# Copyright 2019 The IREE Authors
 #
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#      https://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
+# Licensed under the Apache License v2.0 with LLVM Exceptions.
+# See https://llvm.org/LICENSE.txt for license information.
+# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
 name: Lint
 

.github/workflows/update_llvm_dependent_submodules.yml

@@ -1,16 +1,8 @@
-# Copyright 2020 Google LLC
+# Copyright 2020 The IREE Authors
 #
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#      https://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
+# Licensed under the Apache License v2.0 with LLVM Exceptions.
+# See https://llvm.org/LICENSE.txt for license information.
+# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
 # Creates a PR to update all LLVM-dependent submodules to the current LLVM
 # commit in the repo.

.yamllint.yml

@@ -1,16 +1,8 @@
-# Copyright 2020 Google LLC
+# Copyright 2020 The IREE Authors
 #
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#      https://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
+# Licensed under the Apache License v2.0 with LLVM Exceptions.
+# See https://llvm.org/LICENSE.txt for license information.
+# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
 extends: default
 

AUTHORS

@@ -0,0 +1,10 @@
+# This is the list of IREE's significant contributors.
+#
+# This does not necessarily list everyone who has contributed code, especially
+# since many employees of one corporation may be contributing. To see the full
+# list of contributors, see the revision history in source control.
+#
+# Please only add individuals if they are not contributing on behalf of a
+# company (who should be listed instead). Add new entries at the bottom of the
+# file.
+Google LLC

BUILD.bazel

@@ -1,16 +1,8 @@
-# Copyright 2019 Google LLC
+# Copyright 2019 The IREE Authors
 #
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#      https://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
+# Licensed under the Apache License v2.0 with LLVM Exceptions.
+# See https://llvm.org/LICENSE.txt for license information.
+# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
 # Note that project-wide, bazel repo aliases are used. Various scripts and helpers operate on the
 # following prefixes textually, so avoid doing any systematic construction that would break the

CMakeLists.txt

@@ -1,16 +1,8 @@
-# Copyright 2019 Google LLC
+# Copyright 2019 The IREE Authors
 #
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#      https://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
+# Licensed under the Apache License v2.0 with LLVM Exceptions.
+# See https://llvm.org/LICENSE.txt for license information.
+# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
 cmake_minimum_required(VERSION 3.13.4)
 # Do not set MSVC warning flags like /W3 by default (since 3.15):