Switch from Travis to Github Actions CI (#2041)

* Fix .run_formal_checks for Github Actions instead of Travis
* Remove .run_chisel_tests

Because we publish SNAPSHOTs on every merge to master, the Chisel repo
checks against master of FIRRTL regularly

* Only run unidoc for Scala 2.12

Under Travis we ran for 2.11, 2.12, and 2.13, but it doesn't work when
using ++2.<major>.<minor> when major != to 2.12. It seems if we want to
run all 3, we have to run as `sbt +unidoc`. It's not clear how much
benefit we get from building on the other versions, so stick with 2.12
for now.

* Generate .mergify.yml with script in chisel-repo-tools

Generated with config:

conditions:
  - status-success=all tests passed
branches:
  - 1.2.x
  - 1.3.x
  - 1.4.x

8 files changed, 235 insertions, 298 deletions

diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
new file mode 100644
index 00000000..3f57a1a6
--- /dev/null
+++ b/.github/workflows/test.yml
@@ -0,0 +1,108 @@
+name: Continuous Integration
+
+on:
+  pull_request:
+  push:
+    branches:
+      - master
+      - 1.4.x
+      - 1.3.x
+      - 1.2.x
+
+jobs:
+  test:
+    name: sbt test
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        scala: [2.13.2, 2.12.12, 2.11.12]
+    container:
+      image: ucbbar/chisel3-tools
+      options: --user github --entrypoint /bin/bash
+    env:
+      CONTAINER_HOME: /home/github
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+      - name: Setup Scala
+        uses: olafurpg/setup-scala@v10
+        with:
+          java-version: adopt@1.8
+      - name: Cache Scala
+        uses: coursier/cache-action@v5
+      - name: Unidoc builds (Scala 2.12 only)
+        if: matrix.scala == '2.12.12'
+        run: sbt ++${{ matrix.scala }} unidoc
+      - name: Sanity check benchmarking scripts (Scala 2.12 only)
+        if: matrix.scala == '2.12.12'
+        run: |
+          benchmark/scripts/benchmark_cold_compile.py -N 2 --designs regress/ICache.fir --versions HEAD
+          benchmark/scripts/find_heap_bound.py -- -cp firrtl*jar firrtl.stage.FirrtlMain -i regress/ICache.fir -o out -X verilog
+      - name: Test
+        run: sbt ++${{ matrix.scala }} test
+      - name: Binary compatibility
+        run: sbt ++${{ matrix.scala }} mimaReportBinaryIssues
+
+  # TODO find better way to express Ops and AddNot as single test
+  equiv:
+    name: formal equivalence
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        design: [RocketCore, FPU, ICache, Ops, AddNot]
+    container:
+      image: ucbbar/chisel3-tools
+      options: --user github --entrypoint /bin/bash
+    env:
+      CONTAINER_HOME: /home/github
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+      - name: Setup Scala
+        uses: olafurpg/setup-scala@v10
+        with:
+          java-version: adopt@1.8
+      - name: Cache Scala
+        uses: coursier/cache-action@v5
+      - name: Run Formal Equivalence
+        run: ./.run_formal_checks.sh ${{ matrix.design }}
+
+  # Sentinel job to simplify how we specify which checks need to pass in branch
+  # protection and in Mergify
+  #
+  # When adding new jobs, please add them to `needs` below
+  all_tests_passed:
+    name: "all tests passed"
+    needs: [test, equiv]
+    runs-on: ubuntu-latest
+    steps:
+      - run: echo Success!
+
+  # sbt ci-release publishes all cross versions so this job needs to be
+  # separate from a Scala versions build matrix to avoid duplicate publishing
+  publish:
+    needs: [all_tests_passed]
+    runs-on: ubuntu-latest
+    if: github.event_name == 'push'
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+      - name: Setup Scala
+        uses: olafurpg/setup-scala@v10
+        with:
+          java-version: adopt@1.8
+      - name: Cache Scala
+        uses: coursier/cache-action@v5
+      - name: Setup GPG (for Publish)
+        uses: olafurpg/setup-gpg@v3
+      - name: Publish
+        run: sbt ci-release
+        env:
+          PGP_PASSPHRASE: ${{ secrets.PGP_PASSPHRASE }}
+          PGP_SECRET: ${{ secrets.PGP_SECRET }}
+          SONATYPE_PASSWORD: ${{ secrets.SONATYPE_PASSWORD }}
+          SONATYPE_USERNAME: ${{ secrets.SONATYPE_USERNAME }}
+
diff --git a/.mergify.yml b/.mergify.yml
index b09c861a..a4b8697f 100644
--- a/.mergify.yml
+++ b/.mergify.yml
@@ -1,116 +1,107 @@
 pull_request_rules:
-  - name: remove outdated reviews
-    conditions:
-      - base=master
-    actions:
-      dismiss_reviews:
+- name: automatic squash-and-merge on CI success and review
+  conditions:
+  - status-success=all tests passed
+  - '#approved-reviews-by>=1'
+  - '#changes-requested-reviews-by=0'
+  - base=master
+  - label="Please Merge"
+  - label!="DO NOT MERGE"
+  - label!="bp-conflict"
+  actions:
+    merge:
+      method: squash
+      strict: smart
+      strict_method: merge
+- name: backport to 1.4.x
+  conditions:
+  - merged
+  - base=master
+  - milestone=1.4.x
+  actions:
+    backport:
+      branches:
+      - 1.4.x
+      ignore_conflicts: true
+      label_conflicts: bp-conflict
+    label:
+      add:
+      - Backported
+- name: backport to 1.3.x, 1.4.x
+  conditions:
+  - merged
+  - base=master
+  - milestone=1.3.x
+  actions:
+    backport:
+      branches:
+      - 1.3.x
+      - 1.4.x
+      ignore_conflicts: true
+      label_conflicts: bp-conflict
+    label:
+      add:
+      - Backported
+- name: backport to 1.2.x, 1.3.x, 1.4.x
+  conditions:
+  - merged
+  - base=master
+  - milestone=1.2.x
+  actions:
+    backport:
+      branches:
+      - 1.2.x
+      - 1.3.x
+      - 1.4.x
+      ignore_conflicts: true
+      label_conflicts: bp-conflict
+    label:
+      add:
+      - Backported
+- name: label Mergify backport PR
+  conditions:
+  - body~=This is an automated backport of pull request \#\d+ done by Mergify
+  actions:
+    label:
+      add:
+      - Backport
+- name: automatic squash-and-mege of 1.2.x backport PRs
+  conditions:
+  - status-success=all tests passed
+  - '#changes-requested-reviews-by=0'
+  - base=1.2.x
+  - label="Backport"
+  - label!="DO NOT MERGE"
+  - label!="bp-conflict"
+  actions:
+    merge:
+      method: squash
+      strict: smart
+      strict_method: merge
+- name: automatic squash-and-mege of 1.3.x backport PRs
+  conditions:
+  - status-success=all tests passed
+  - '#changes-requested-reviews-by=0'
+  - base=1.3.x
+  - label="Backport"
+  - label!="DO NOT MERGE"
+  - label!="bp-conflict"
+  actions:
+    merge:
+      method: squash
+      strict: smart
+      strict_method: merge
+- name: automatic squash-and-mege of 1.4.x backport PRs
+  conditions:
+  - status-success=all tests passed
+  - '#changes-requested-reviews-by=0'
+  - base=1.4.x
+  - label="Backport"
+  - label!="DO NOT MERGE"
+  - label!="bp-conflict"
+  actions:
+    merge:
+      method: squash
+      strict: smart
+      strict_method: merge
 
-pull_request_rules:
-  - name: automatic squash-and-merge on CI success and review
-    conditions:
-      - status-success=Travis CI - Pull Request
-      - "#approved-reviews-by>=1"
-      - "#changes-requested-reviews-by=0"
-      - base=master
-      - label="Please Merge"
-      - label!="DO NOT MERGE"
-      - label!="bp-conflict"
-    actions:
-      merge:
-        method: squash
-        strict: smart
-        strict_method: merge
-
-  - name: backport to 1.4.x
-    conditions:
-      - merged
-      - base=master
-      - milestone=1.4.x
-    actions:
-      backport:
-        branches:
-          - 1.4.x
-        ignore_conflicts: True
-        label_conflicts: "bp-conflict"
-      label:
-        add: [Backported]
-
-  - name: backport to 1.3.x and 1.4.x
-    conditions:
-      - merged
-      - base=master
-      - milestone=1.3.x
-    actions:
-      backport:
-        branches:
-          - 1.3.x
-          - 1.4.x
-        ignore_conflicts: True
-        label_conflicts: "bp-conflict"
-      label:
-        add: [Backported]
-
-  - name: backport to 1.2.x, 1.3.x, and 1.4.x
-    conditions:
-      - merged
-      - base=master
-      - milestone=1.2.X
-    actions:
-      backport:
-        branches:
-          - 1.2.x
-          - 1.3.x
-          - 1.4.x
-        ignore_conflicts: True
-        label_conflicts: "bp-conflict"
-      label:
-        add: [Backported]
-
-  - name: label Mergify backport PR
-    conditions:
-      - body~=This is an automated backport of pull request \#\d+ done by Mergify
-    actions:
-      label:
-        add: [Backport]
-        
-  - name: automatic squash-and-merge of 1.4.x backport PRs
-    conditions:
-      - status-success=Travis CI - Pull Request
-      - "#changes-requested-reviews-by=0"
-      - base=1.4.x
-      - label="Backport"
-      - label!="DO NOT MERGE"
-      - label!="bp-conflict"
-    actions:
-      merge:
-        method: squash
-        strict: smart
-        strict_method: merge      
-
-  - name: automatic squash-and-merge of 1.3.x backport PRs
-    conditions:
-      - status-success=Travis CI - Pull Request
-      - "#changes-requested-reviews-by=0"
-      - base=1.3.x
-      - label="Backport"
-      - label!="DO NOT MERGE"
-      - label!="bp-conflict"
-    actions:
-      merge:
-        method: squash
-        strict: smart
-        strict_method: merge
-
-  - name: automatic squash-and-merge of 1.2.x backport PRs
-    conditions:
-      - status-success=Travis CI - Pull Request
-      - "#changes-requested-reviews-by=0"
-      - base=1.2.x
-      - label="Backport"
-      - label!="DO NOT MERGE"
-      - label!="bp-conflict"
-    actions:
-      merge:
-        method: squash
-        strict: smart
-        strict_method: merge
diff --git a/.run_chisel_tests.sh b/.run_chisel_tests.sh
deleted file mode 100644
index dbec894e..00000000
--- a/.run_chisel_tests.sh
+++ /dev/null
@@ -1,20 +0,0 @@
-# SPDX-License-Identifier: Apache-2.0
-set -e
-
-# Use appropriate branches.
-# Each stable branch of FIRRTL should have a fixed value for these branches.
-CHISEL_BRANCH="master"
-TREADLE_BRANCH="master"
-
-# Skip chisel tests if the commit message says to
-# Replace ... with .. in TRAVIS_COMMIT_RANGE, see https://github.com/travis-ci/travis-ci/issues/4596
-if git log --format=%B --no-merges ${TRAVIS_COMMIT_RANGE/.../..} | grep '\[skip chisel tests\]'; then
-  exit 0
-else
-  sbt $SBT_ARGS publishLocal
-  git clone https://github.com/freechipsproject/treadle.git --single-branch -b ${TREADLE_BRANCH} --depth 10
-  (cd treadle && sbt $SBT_ARGS publishLocal)
-  git clone https://github.com/ucb-bar/chisel3.git --single-branch -b ${CHISEL_BRANCH}
-  cd chisel3
-  sbt $SBT_ARGS test
-fi
diff --git a/.run_formal_checks.sh b/.run_formal_checks.sh
index f5ffec25..0a28a1d1 100755
--- a/.run_formal_checks.sh
+++ b/.run_formal_checks.sh
@@ -11,23 +11,25 @@ fi
 
 DUT=$1
 
-# Run formal check only for PRs
-if [ $TRAVIS_PULL_REQUEST = "false" ]; then
-    echo "Not a pull request, no formal check"
-    exit 0
-else
-    # $TRAVIS_BRANCH is branch targeted by PR
-    # Travis does a shallow clone, checkout PR target so that we have it
-    # THen return to previous branch so HEAD points to the commit we're testing
-    git remote set-branches origin $TRAVIS_BRANCH && git fetch
-    git checkout $TRAVIS_BRANCH
+# See https://docs.github.com/en/actions/reference/environment-variables
+# for info about these variables
+
+# Run formal check only for PRs, GITHUB_BASE_REF is only set for PRs
+if [ ! -z "$GITHUB_BASE_REF" ]; then
+    # Github Actions does a shallow clone, checkout PR target so that we have it
+    # Then return to previous branch so HEAD points to the commit we're testing
+    git remote set-branches origin $GITHUB_BASE_REF && git fetch
+    git checkout $GITHUB_BASE_REF
     git checkout -
     # Skip if '[skip formal checks]' shows up in any of the commit messages in the PR
-    if git log --format=%B --no-merges $TRAVIS_BRANCH..HEAD | grep '\[skip formal checks\]'; then
+    if git log --format=%B --no-merges $GITHUB_BASE_REF..HEAD | grep '\[skip formal checks\]'; then
         echo "Commit message says to skip formal checks"
         exit 0
     else
         cp regress/$DUT.fir $DUT.fir
-        ./scripts/formal_equiv.sh HEAD $TRAVIS_BRANCH $DUT
+        ./scripts/formal_equiv.sh HEAD $GITHUB_BASE_REF $DUT
     fi
+else
+    echo "Not a pull request, no formal check"
+    exit 0
 fi
diff --git a/.travis.yml b/.travis.yml
deleted file mode 100644
index efcb6434..00000000
--- a/.travis.yml
+++ /dev/null
@@ -1,151 +0,0 @@
-language: scala
-sudo: false
-
-jdk: openjdk8
-
-branches:
-  only:
-    - master
-    - 1.4.x
-    - 1.3.x
-    - 1.2.x
-
-cache:
-  directories:
-    $HOME/.cache/coursier
-    $HOME/.sbt
-    $INSTALL_DIR
-
-git:
-  depth: 10
-
-env:
-  global:
-    INSTALL_DIR=$TRAVIS_BUILD_DIR/install
-    VERILATOR_ROOT=$INSTALL_DIR
-    PATH=$PATH:$VERILATOR_ROOT/bin:$TRAVIS_BUILD_DIR/utils/bin
-    SBT_ARGS="-Dsbt.log.noformat=true"
-
-before_script:
-  - OLDEST_SHARED=`git log --format=%H $TRAVIS_COMMIT_RANGE | tail -n1`
-  - OLDEST_COMMIT=`git log --format=%H | tail -n1`
-  - if [ $OLDEST_SHARED == $OLDEST_COMMIT ]; then git fetch --unshallow; fi
-
-stages:
-  - name: prepare
-  - name: test
-  - name: release
-    if: (branch IN (master, 1.4.x, 1.3.x, 1.2.x)) AND (type = push) AND (NOT fork)
-
-# We do not use the built-in tests as generated by using multiple Scala
-# versions because the cache is not shared between stages with any
-# environmental differences.
-# Instead, we specify the version of Scala manually for each test (or leave it
-# as the default as defined in FIRRTL's build.sbt).
-jobs:
-  include:
-    # Because these write to the same install directory, they must run in the
-    # same script
-    - stage: prepare
-      name: "Install: [Verilator, Yosys, Z3]"
-      script:
-        - bash .install_verilator.sh
-        - verilator --version
-        - bash .install_yosys.sh
-        - yosys -V
-        - bash .install_z3.sh
-        - z3 -version
-    - stage: prepare
-      name: "Compile FIRRTL to share with subsequent stages"
-      script:
-        - sbt $SBT_ARGS assembly
-      workspaces:
-        create:
-          name: firrtl_build
-          paths:
-            - target/
-            - utils/bin/firrtl.jar
-            - project/project/
-            - project/target/
-    - stage: test
-      name: "All files must be formatted with scalafmt"
-      workspaces:
-        use: firrtl_build
-      script:
-        - sbt scalafmtCheckAll
-    - stage: test
-      name: "Unidoc builds (no warnings)"
-      workspaces:
-        use: firrtl_build
-      script:
-        - sbt $SBT_ARGS +unidoc
-    - stage: test
-      name: "Tests: FIRRTL (2.13)"
-      workspaces:
-        use: firrtl_build
-      script:
-        - verilator --version
-        - sbt ++2.13.2 $SBT_ARGS test
-    - stage: test
-      name: "Tests: FIRRTL (2.12)"
-      workspaces:
-        use: firrtl_build
-      script:
-        - verilator --version
-        - sbt $SBT_ARGS test
-    - stage: test
-      name: "Tests: FIRRTL (2.11)"
-      script:
-        - verilator --version
-        - sbt ++2.11.12 $SBT_ARGS test
-    - stage: test
-      name: "Tests: chisel3 (2.12)"
-      workspaces:
-        use: firrtl_build
-      script:
-        - verilator --version
-        - bash .run_chisel_tests.sh
-    - stage: test
-      name: "Formal equivalence: RocketCore"
-      workspaces:
-        use: firrtl_build
-      script:
-        - yosys -V
-        - "travis_wait 30 sleep 1800 &"
-        - ./.run_formal_checks.sh RocketCore
-    - stage: test
-      name: "Formal equivalence: FPU"
-      workspaces:
-        use: firrtl_build
-      script:
-        - yosys -V
-        - "travis_wait 30 sleep 1800 &"
-        - ./.run_formal_checks.sh FPU
-    - stage: test
-      name: "Formal equivalence: ICache"
-      workspaces:
-        use: firrtl_build
-      script:
-        - yosys -V
-        - "travis_wait 30 sleep 1800 &"
-        - ./.run_formal_checks.sh ICache
-    - stage: test
-      name: "Formal equivalence: small expression-tree stress tests"
-      workspaces:
-        use: firrtl_build
-      script:
-        - yosys -V
-        - "travis_wait 30 sleep 1800 &"
-        - ./.run_formal_checks.sh Ops
-        - ./.run_formal_checks.sh AddNot
-    - stage: test
-      name: "Sanity check benchmarking scripts"
-      workspaces:
-        use: firrtl_build
-      script:
-        - benchmark/scripts/benchmark_cold_compile.py -N 2 --designs regress/ICache.fir --versions HEAD
-        - benchmark/scripts/find_heap_bound.py -- -cp firrtl*jar firrtl.stage.FirrtlMain -i regress/ICache.fir -o out -X verilog
-    # run ci-release only if previous stages passed
-    - stage: release
-      name: "Publish SNAPSHOT release"
-      script: sbt ci-release
diff --git a/build.sbt b/build.sbt
index 14aafe1b..f5a6a611 100644
--- a/build.sbt
+++ b/build.sbt
@@ -55,6 +55,10 @@ lazy val commonSettings = Seq(
   )
 )
 
+lazy val mimaSettings = Seq(
+  mimaPreviousArtifacts := Set()
+)
+
 lazy val protobufSettings = Seq(
   sourceDirectory in ProtobufConfig := baseDirectory.value / "src" / "main" / "proto",
   protobufRunProtoc in ProtobufConfig := (args =>
@@ -179,6 +183,7 @@ lazy val firrtl = (project in file("."))
     buildInfoUsePackageAsPath := true,
     buildInfoKeys := Seq[BuildInfoKey](buildInfoPackage, version, scalaVersion, sbtVersion)
   )
+  .settings(mimaSettings)
 
 lazy val benchmark = (project in file("benchmark"))
   .dependsOn(firrtl)
diff --git a/project/plugins.sbt b/project/plugins.sbt
index 346e2560..3ed7accf 100644
--- a/project/plugins.sbt
+++ b/project/plugins.sbt
@@ -24,6 +24,8 @@ addSbtPlugin("com.thoughtworks.sbt-api-mappings" % "sbt-api-mappings" % "3.0.0")
 
 addSbtPlugin("org.scalameta" % "sbt-scalafmt" % "2.4.0")
 
+addSbtPlugin("com.typesafe" % "sbt-mima-plugin" % "0.8.1")
+
 addSbtPlugin("com.geirsson" % "sbt-ci-release" % "1.5.4")
 
 libraryDependencies += "com.github.os72" % "protoc-jar" % "3.11.4"
diff --git a/scripts/formal_equiv.sh b/scripts/formal_equiv.sh
index 2304b74e..c3d45357 100755
--- a/scripts/formal_equiv.sh
+++ b/scripts/formal_equiv.sh
@@ -28,7 +28,7 @@ make_verilog () {
     git checkout $1
     local filename="$DUT.$1.v"
 
-    sbt "runMain firrtl.Driver -i $DUT.fir -o $filename -X verilog"
+    sbt "runMain firrtl.stage.FirrtlMain -i $DUT.fir -o $filename -X verilog"
     RET=$filename
 }