[BOLT] Increase nfc-test coverage (#467)

Use `--check-bolt-sources` from nfc-check-setup.py to run tests when
source
files change between the current and previous revisions.

Skip markers are used to indicate which tests should run: when not
present the
tests run. Examples:
- If NFC check setup fails to execute for any reason, the tests run
unconditionally.
- If the current and previous llvm-bolt binaries are identical, we
create two
  skip markers for in-tree and out-of-tree tests.
- If there are other BOLT source changes, we delete the in-tree skip
marker so
   those test can proceed.

Author: paschalis-mpeis

zorg/buildbot/builders/BOLTBuilder.py

@@ -4,7 +4,7 @@
 from zorg.buildbot.builders.UnifiedTreeBuilder import getLLVMBuildFactoryAndSourcecodeSteps, addCmakeSteps, addNinjaSteps
 from zorg.buildbot.commands.LitTestCommand import LitTestCommand
 from zorg.buildbot.commands.CmakeCommand import CmakeCommand
-from zorg.buildbot.conditions.FileConditions import FileExists
+from zorg.buildbot.conditions.FileConditions import FileDoesNotExist
 from zorg.buildbot.process.factory import LLVMBuildFactory
 
 def getBOLTCmakeBuildFactory(
@@ -90,14 +90,23 @@ def getBOLTCmakeBuildFactory(
     logic.
     """
     if is_nfc:
+        # Marker for relevant source code changes, e.g., when updating tests.
+        # Generated by nfc-check-setup.py and used to trigger the in-tree tests.
+        hasSrcChanges = ".llvm-bolt.changes"
+        # Individual markers to skip either in-tree or out-of-tree tests.
+        skipInTree = ".llvm-bolt.skip.in-tree"
+        skipOutOfTree = ".llvm-bolt.skip.out-of-tree"
+
         f.addSteps([
             ShellCommand(
                 name='nfc-check-setup',
                 command=[
-                        f"../{f.monorepo_dir}/bolt/utils/nfc-check-setup.py",
-                        "--switch-back"
+                         f"../{f.monorepo_dir}/bolt/utils/nfc-check-setup.py",
+                        "--switch-back",
+                        "--check-bolt-sources"
                         ],
                 description=('Setup NFC testing'),
+                descriptionDone=["NFC-Mode setup"],
                 warnOnFailure=True,
                 haltOnFailure=False,
                 flunkOnFailure=False,
@@ -124,9 +133,13 @@ def getBOLTCmakeBuildFactory(
                 env=env),
             ShellCommand(
                 name='nfc-check-bolt-different',
-                command=('rm -f .llvm-bolt.diff; '
-                         'cmp -s bin/llvm-bolt.old bin/llvm-bolt.new || '
-                         'touch .llvm-bolt.diff'),
+                command=(
+                          f'rm -f {skipInTree} {skipOutOfTree}; '
+                          f'cmp -s bin/llvm-bolt.old bin/llvm-bolt.new && ('
+                          f'touch {skipInTree}; touch {skipOutOfTree}); '
+                          f'[ -f {hasSrcChanges} ] && rm -f {skipInTree};'
+                          f'rm -f {hasSrcChanges}; '
+                         ),
                 description=('Check if llvm-bolt binaries are different and '
                              'skip the following nfc-check steps'),
                 haltOnFailure=False,
@@ -139,7 +152,7 @@ def getBOLTCmakeBuildFactory(
                 warnOnFailure=True,
                 haltOnFailure=False,
                 flunkOnFailure=True,
-                doStepIf=FileExists('build/.llvm-bolt.diff'),
+                doStepIf=FileDoesNotExist(f"build/{skipInTree}"),
                 env=env),
             LitTestCommand(
                 name='nfc-check-large-bolt',
@@ -150,7 +163,7 @@ def getBOLTCmakeBuildFactory(
                 warnOnFailure=True,
                 haltOnFailure=False,
                 flunkOnFailure=True,
-                doStepIf=FileExists('build/.llvm-bolt.diff'),
+                doStepIf=FileDoesNotExist(f"build/{skipOutOfTree}"),
                 env=env),
             ])