[benchmark] add warmups (#1323)

Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

Author: pepeiborra

ghcide/bench/hist/Main.hs

@@ -116,7 +116,7 @@ createBuildSystem config = do
   let build = outputFolder configStatic
 
   buildRules build ghcideBuildRules
-  benchRules build (MkBenchRules (askOracle $ GetSamples ()) benchGhcide "ghcide")
+  benchRules build (MkBenchRules (askOracle $ GetSamples ()) benchGhcide warmupGhcide "ghcide")
   csvRules build
   svgRules build
   heapProfileRules build
@@ -170,3 +170,15 @@ benchGhcide samples buildSystem args BenchProject{..} = do
     [ "--stack" | Stack == buildSystem
     ]
 
+warmupGhcide :: BuildSystem -> FilePath -> [CmdOption] -> Example -> Action ()
+warmupGhcide buildSystem exePath args example = do
+  command args "ghcide-bench" $
+    [ "--no-clean",
+      "-v",
+      "--samples=1",
+      "--ghcide=" <> exePath,
+      "--select=hover"
+    ] ++
+    exampleToOptions example ++
+    [ "--stack" | Stack == buildSystem
+    ]

shake-bench/src/Development/Benchmark/Rules.hs

@@ -233,6 +233,8 @@ data MkBenchRules buildSystem example =  forall setup. MkBenchRules
     setupProject :: Action setup
   -- | An action that invokes the executable to run the benchmark
   , benchProject :: setup -> buildSystem -> [CmdOption] -> BenchProject example -> Action ()
+  -- | An action that performs any necessary warmup. Will only be invoked once
+  , warmupProject :: buildSystem -> FilePath -> [CmdOption] -> example -> Action ()
   -- | Name of the executable to benchmark. Should match the one used to 'MkBuildRules'
   , executableName :: String
   }
@@ -262,6 +264,26 @@ benchRules :: RuleResultForExample example => FilePattern -> MkBenchRules BuildS
 benchRules build MkBenchRules{..} = do
 
   benchResource <- newResource "ghcide-bench" 1
+  -- warmup an example
+  build -/- "binaries/*/*.warmup" %> \out -> do
+        let [_, _, ver, exampleName] = splitDirectories (dropExtension out)
+        let exePath = build </> "binaries" </> ver </> executableName
+            ghcPath = build </> "binaries" </> ver </> "ghc.path"
+        need [exePath, ghcPath]
+        buildSystem <- askOracle  $ GetBuildSystem ()
+        example <- fromMaybe (error $ "Unknown example " <> exampleName)
+                    <$> askOracle (GetExample exampleName)
+        let exeExtraArgs = []
+            outcsv = ""
+            experiment = Escaped "hover"
+        withResource benchResource 1 $ warmupProject buildSystem exePath
+              [ EchoStdout False,
+                FileStdout out,
+                RemEnv "NIX_GHC_LIBDIR",
+                RemEnv "GHC_PACKAGE_PATH",
+                AddPath [takeDirectory ghcPath, "."] []
+              ]
+              example
   -- run an experiment
   priority 0 $
     [ build -/- "*/*/*/*.csv",
@@ -287,8 +309,9 @@ benchRules build MkBenchRules{..} = do
                  | CheapHeapProfiling i <- [prof]]
              ++ ["-RTS"]
             ghcPath    = build </> "binaries" </> ver </> "ghc.path"
+            warmupPath = build </> "binaries" </> ver </> exampleName <.> "warmup"
             experiment = Escaped $ dropExtension exp
-        need [exePath, ghcPath]
+        need [exePath, ghcPath, warmupPath]
         ghcPath <- readFile' ghcPath
         withResource benchResource 1 $ do
           benchProject setupRes buildSystem