Detect GHC 9.4 and use -fprof-late

.stan.toml

@@ -245,16 +245,16 @@
 
 # Anti-pattern: unsafe functions
 [[ignore]]
-  id = "OBS-STAN-0212-5rtOmw-499:33"
+  id = "OBS-STAN-0212-5rtOmw-503:33"
 # ✦ Description:   Usage of unsafe functions breaks referential transparency
 # ✦ Category:      #Unsafe #AntiPattern
 # ✦ File:          src\Stack\Constants.hs
 #
-#  498 ┃
-#  499 ┃ setupGhciShimCode = byteString $(do
-#  500 ┃     path <- makeRelativeToProject "src/setup-shim/StackSetupShim.hs"
-#  501 ┃     embedFile path)
 #  502 ┃
+#  503 ┃ setupGhciShimCode = byteString $(do
+#  504 ┃     path <- makeRelativeToProject "src/setup-shim/StackSetupShim.hs"
+#  505 ┃     embedFile path)
+#  506 ┃
 
 # Anti-pattern: unsafe functions
 [[ignore]]

ChangeLog.md

@@ -10,6 +10,12 @@ Major changes:
 
 Behavior changes:
 
+* With GHC 9.4.1 or later, when building with profiling, Stack passes GHC's
+  `-fprof-late` flag (rather than `-fprof-auto`) and Cabal's
+  `--profiling-detail=none` and `--library-profiling-detail=none` options. Cost
+  centres are then inserted after optimisation, so the profile reflects the
+  optimised program. Existing profiling builds will be rebuilt.
+
 Other enhancements:
 
 * Consider Cabal 3.18 to be a tested library and remove warnings.

src/Stack/Build/Source.hs

@@ -32,6 +32,7 @@ import           Distribution.Version ( mkVersion )
 import qualified Pantry.SHA256 as SHA256
 import           Stack.Build.Cache ( tryGetBuildCache )
 import           Stack.Build.Haddock ( shouldHaddockDeps )
+import           Stack.Constants ( ghcSupportsProfLate )
 import           Stack.Package
                    ( buildableBenchmarks, buildableExes, buildableTestSuites
                    , hasBuildableMainLibrary, resolvePackage
@@ -113,7 +114,6 @@ loadSourceMap targets boptsCli sma = do
   bconfig <- view buildConfigL
   let errsPackages = mapMaybe checkPackage packagesWithCliFlags
       compiler = sma.compiler
-      ghcVersion = getGhcVersion compiler
       buildOpts = bconfig.config.build
       infoTableProfSupported = ghcVersion >= mkVersion [9, 2, 1]
       infoTableProfUnsupportedWarning =
@@ -146,6 +146,7 @@ loadSourceMap targets boptsCli sma = do
     , globalPkgs
     }
  where
+  ghcVersion = getGhcVersion sma.compiler
   cliFlags = boptsCli.flags
   targetsAndSmaDeps = targets.deps <> sma.deps
   packagesWithCliFlags = mapMaybe maybeProjectWithCliFlags $ Map.toList cliFlags
@@ -212,6 +213,7 @@ loadSourceMap targets boptsCli sma = do
             ghcOptions = generalGhcOptions
               bconfig
               boptsCli
+              ghcVersion
               isTarget
               isProjectPackage
               isInfoTableProf
@@ -276,7 +278,7 @@ hashSourceMapData boptsCli sm = do
       isInfoTableProf =
         ghcVersion >= mkVersion [9, 2, 1] && bc.config.build.infoTableProf
       bootGhcOpts =
-        map display (generalGhcOptions bc boptsCli False False isInfoTableProf)
+        map display (generalGhcOptions bc boptsCli ghcVersion False False isInfoTableProf)
       hashedContent =
            toLazyByteString $ compilerPath
         <> compilerInfo
@@ -337,11 +339,12 @@ generalCabalConfigOpts bconfig boptsCli name isTarget isLocal = concat
 generalGhcOptions ::
      BuildConfig
   -> BuildOptsCLI
+  -> Version
   -> Bool
   -> Bool
   -> Bool
   -> [Text]
-generalGhcOptions bconfig boptsCli isTarget isLocal isInfoTableProf = concat
+generalGhcOptions bconfig boptsCli ghcVersion isTarget isLocal isInfoTableProf = concat
   [ Map.findWithDefault [] AGOEverything config.ghcOptionsByCat
   , if isLocal
       then Map.findWithDefault [] AGOLocals config.ghcOptionsByCat
@@ -351,7 +354,7 @@ generalGhcOptions bconfig boptsCli isTarget isLocal isInfoTableProf = concat
       else []
   , concat [["-fhpc"] | isLocal && bopts.testOpts.coverage]
   , if bopts.libProfile || bopts.exeProfile
-      then ["-fprof-auto", "-fprof-cafs"]
+      then [costCentreInsertion, "-fprof-cafs"]
       else []
   , [ "-g" | not $ bopts.libStrip || bopts.exeStrip ]
   , if isInfoTableProf
@@ -364,6 +367,8 @@ generalGhcOptions bconfig boptsCli isTarget isLocal isInfoTableProf = concat
  where
   bopts =  config.build
   config = view configL bconfig
+  costCentreInsertion =
+    if ghcSupportsProfLate ghcVersion then "-fprof-late" else "-fprof-auto"
   includeExtraOptions =
     case config.applyGhcOptions of
       AGOTargets -> isTarget

src/Stack/ConfigureOpts.hs

@@ -26,11 +26,12 @@ import           Path ( (</>), parseRelDir )
 import           Path.Extra ( toFilePathNoTrailingSep )
 import           Stack.Constants
                    ( bindirSuffix, compilerOptionsCabalFlag, docDirSuffix
-                   , relDirEtc, relDirLib, relDirLibexec, relDirShare
+                   , ghcSupportsProfLate, relDirEtc, relDirLib, relDirLibexec
+                   , relDirShare
                    )
 import           Stack.Prelude
 import           Stack.Types.BuildOpts ( BuildOpts (..) )
-import           Stack.Types.Compiler ( whichCompiler )
+import           Stack.Types.Compiler ( getGhcVersion, whichCompiler )
 import           Stack.Types.Config ( Config (..), HasConfig (..) )
 import           Stack.Types.ConfigureOpts
                    ( BaseConfigOpts (..), ConfigureOpts (..)
@@ -123,10 +124,11 @@ configureOptsNonPathRelated ::
   -> [String]
 configureOptsNonPathRelated econfig bco deps isLocal package = concat
   [ depOptions
-  , [ "--enable-library-profiling"
-    | bopts.libProfile || bopts.exeProfile
-    ]
+  , ["--enable-library-profiling" | profiling]
   , ["--enable-profiling" | bopts.exeProfile && isLocal]
+  , if profiling && ghcSupportsProfLate ghcVersion
+      then ["--profiling-detail=none", "--library-profiling-detail=none"]
+      else []
   , ["--enable-split-objs" | bopts.splitObjs]
   , [ "--disable-library-stripping"
     | not $ bopts.libStrip || bopts.exeStrip
@@ -176,11 +178,13 @@ configureOptsNonPathRelated econfig bco deps isLocal package = concat
     in  concatMap (\x -> [compilerOptionsCabalFlag wc, T.unpack x]) newArgs
 
   wc = view (actualCompilerVersionL . to whichCompiler) econfig
+  ghcVersion = view (actualCompilerVersionL . to getGhcVersion) econfig
 
   hideSourcePaths = config.hideSourcePaths
 
   config = view configL econfig
   bopts = bco.buildOpts
+  profiling = bopts.libProfile || bopts.exeProfile
   mapAndAppend fn = Map.foldrWithKey' (fmap (:) . fn)
   -- Unioning atop defaults is needed so that all flags are specified with
   -- --exact-configuration.

src/Stack/Constants.hs

@@ -37,6 +37,7 @@ module Stack.Constants
   , defaultGlobalConfigPath
   , platformVariantEnvVar
   , compilerOptionsCabalFlag
+  , ghcSupportsProfLate
   , ghcColorForceFlag
   , minTerminalWidth
   , maxTerminalWidth
@@ -357,6 +358,9 @@ platformVariantEnvVar = stackProgNameUpper ++ "_PLATFORM_VARIANT"
 compilerOptionsCabalFlag :: WhichCompiler -> String
 compilerOptionsCabalFlag Ghc = "--ghc-options"
 
+ghcSupportsProfLate :: Version -> Bool
+ghcSupportsProfLate ghcVersion = ghcVersion >= mkVersion [9, 4, 1]
+
 -- | The flag to pass to GHC when we want to force its output to be
 -- colorized.
 ghcColorForceFlag :: String