{-# LANGUAGE ScopedTypeVariables #-} ----------------------------------------------------------------------------- -- -- Compiler information functions -- -- (c) The GHC Team 2017 -- ----------------------------------------------------------------------------- module GHC.SysTools.Info where import GHC.Utils.Exception import GHC.Utils.Error import GHC.Driver.Session import GHC.Utils.Outputable import GHC.Utils.Misc import Data.List import Data.IORef import System.IO import GHC.Platform import GHC.Prelude import GHC.SysTools.Process {- Note [Run-time linker info] See also: #5240, #6063, #10110 Before 'runLink', we need to be sure to get the relevant information about the linker we're using at runtime to see if we need any extra options. For example, GNU ld requires '--reduce-memory-overheads' and '--hash-size=31' in order to use reasonable amounts of memory (see trac #5240.) But this isn't supported in GNU gold. Generally, the linker changing from what was detected at ./configure time has always been possible using -pgml, but on Linux it can happen 'transparently' by installing packages like binutils-gold, which change what /usr/bin/ld actually points to. Clang vs GCC notes: For gcc, 'gcc -Wl,--version' gives a bunch of output about how to invoke the linker before the version information string. For 'clang', the version information for 'ld' is all that's output. For this reason, we typically need to slurp up all of the standard error output and look through it. Other notes: We cache the LinkerInfo inside DynFlags, since clients may link multiple times. The definition of LinkerInfo is there to avoid a circular dependency. -} {- Note [ELF needed shared libs] Some distributions change the link editor's default handling of ELF DT_NEEDED tags to include only those shared objects that are needed to resolve undefined symbols. For Template Haskell we need the last temporary shared library also if it is not needed for the currently linked temporary shared library. We specify --no-as-needed to override the default. This flag exists in GNU ld and GNU gold. The flag is only needed on ELF systems. On Windows (PE) and Mac OS X (Mach-O) the flag is not needed. -} {- Note [Windows static libGCC] The GCC versions being upgraded to in #10726 are configured with dynamic linking of libgcc supported. This results in libgcc being linked dynamically when a shared library is created. This introduces thus an extra dependency on GCC dll that was not needed before by shared libraries created with GHC. This is a particular issue on Windows because you get a non-obvious error due to this missing dependency. This dependent dll is also not commonly on your path. For this reason using the static libgcc is preferred as it preserves the same behaviour that existed before. There are however some very good reasons to have the shared version as well as described on page 181 of https://gcc.gnu.org/onlinedocs/gcc-5.2.0/gcc.pdf : "There are several situations in which an application should use the shared ‘libgcc’ instead of the static version. The most common of these is when the application wishes to throw and catch exceptions across different shared libraries. In that case, each of the libraries as well as the application itself should use the shared ‘libgcc’. " -} neededLinkArgs :: LinkerInfo -> [Option] neededLinkArgs (GnuLD o) = o neededLinkArgs (GnuGold o) = o neededLinkArgs (LlvmLLD o) = o neededLinkArgs (DarwinLD o) = o neededLinkArgs (SolarisLD o) = o neededLinkArgs (AixLD o) = o neededLinkArgs UnknownLD = [] -- Grab linker info and cache it in DynFlags. getLinkerInfo :: DynFlags -> IO LinkerInfo getLinkerInfo dflags = do info <- readIORef (rtldInfo dflags) case info of Just v -> return v Nothing -> do v <- getLinkerInfo' dflags writeIORef (rtldInfo dflags) (Just v) return v -- See Note [Run-time linker info]. getLinkerInfo' :: DynFlags -> IO LinkerInfo getLinkerInfo' dflags = do let platform = targetPlatform dflags os = platformOS platform (pgm,args0) = pgm_l dflags args1 = map Option (getOpts dflags opt_l) args2 = args0 ++ args1 args3 = filter notNull (map showOpt args2) -- Try to grab the info from the process output. parseLinkerInfo stdo _stde _exitc | any ("GNU ld" `isPrefixOf`) stdo = -- GNU ld specifically needs to use less memory. This especially -- hurts on small object files. #5240. -- Set DT_NEEDED for all shared libraries. #10110. -- TODO: Investigate if these help or hurt when using split sections. return (GnuLD $ map Option ["-Wl,--hash-size=31", "-Wl,--reduce-memory-overheads", -- ELF specific flag -- see Note [ELF needed shared libs] "-Wl,--no-as-needed"]) | any ("GNU gold" `isPrefixOf`) stdo = -- GNU gold only needs --no-as-needed. #10110. -- ELF specific flag, see Note [ELF needed shared libs] return (GnuGold [Option "-Wl,--no-as-needed"]) | any ("LLD" `isPrefixOf`) stdo = return (LlvmLLD $ map Option [ -- see Note [ELF needed shared libs] "-Wl,--no-as-needed"]) -- Unknown linker. | otherwise = fail "invalid --version output, or linker is unsupported" -- Process the executable call info <- catchIO (do case os of OSSolaris2 -> -- Solaris uses its own Solaris linker. Even all -- GNU C are recommended to configure with Solaris -- linker instead of using GNU binutils linker. Also -- all GCC distributed with Solaris follows this rule -- precisely so we assume here, the Solaris linker is -- used. return $ SolarisLD [] OSAIX -> -- IBM AIX uses its own non-binutils linker as well return $ AixLD [] OSDarwin -> -- Darwin has neither GNU Gold or GNU LD, but a strange linker -- that doesn't support --version. We can just assume that's -- what we're using. return $ DarwinLD [] OSMinGW32 -> -- GHC doesn't support anything but GNU ld on Windows anyway. -- Process creation is also fairly expensive on win32, so -- we short-circuit here. return $ GnuLD $ map Option [ -- Reduce ld memory usage "-Wl,--hash-size=31" , "-Wl,--reduce-memory-overheads" -- Emit gcc stack checks -- Note [Windows stack usage] , "-fstack-check" -- Force static linking of libGCC -- Note [Windows static libGCC] , "-static-libgcc" ] _ -> do -- In practice, we use the compiler as the linker here. Pass -- -Wl,--version to get linker version info. (exitc, stdo, stde) <- readProcessEnvWithExitCode pgm (["-Wl,--version"] ++ args3) c_locale_env -- Split the output by lines to make certain kinds -- of processing easier. In particular, 'clang' and 'gcc' -- have slightly different outputs for '-Wl,--version', but -- it's still easy to figure out. parseLinkerInfo (lines stdo) (lines stde) exitc ) (\err -> do debugTraceMsg dflags 2 (text "Error (figuring out linker information):" <+> text (show err)) errorMsg dflags $ hang (text "Warning:") 9 $ text "Couldn't figure out linker information!" $$ text "Make sure you're using GNU ld, GNU gold" <+> text "or the built in OS X linker, etc." return UnknownLD) return info -- Grab compiler info and cache it in DynFlags. getCompilerInfo :: DynFlags -> IO CompilerInfo getCompilerInfo dflags = do info <- readIORef (rtccInfo dflags) case info of Just v -> return v Nothing -> do v <- getCompilerInfo' dflags writeIORef (rtccInfo dflags) (Just v) return v -- See Note [Run-time linker info]. getCompilerInfo' :: DynFlags -> IO CompilerInfo getCompilerInfo' dflags = do let pgm = pgm_c dflags -- Try to grab the info from the process output. parseCompilerInfo _stdo stde _exitc -- Regular GCC | any ("gcc version" `isInfixOf`) stde = return GCC -- Regular clang | any ("clang version" `isInfixOf`) stde = return Clang -- FreeBSD clang | any ("FreeBSD clang version" `isInfixOf`) stde = return Clang -- Xcode 5.1 clang | any ("Apple LLVM version 5.1" `isPrefixOf`) stde = return AppleClang51 -- Xcode 5 clang | any ("Apple LLVM version" `isPrefixOf`) stde = return AppleClang -- Xcode 4.1 clang | any ("Apple clang version" `isPrefixOf`) stde = return AppleClang -- Unknown linker. | otherwise = fail $ "invalid -v output, or compiler is unsupported: " ++ unlines stde -- Process the executable call info <- catchIO (do (exitc, stdo, stde) <- readProcessEnvWithExitCode pgm ["-v"] c_locale_env -- Split the output by lines to make certain kinds -- of processing easier. parseCompilerInfo (lines stdo) (lines stde) exitc ) (\err -> do debugTraceMsg dflags 2 (text "Error (figuring out C compiler information):" <+> text (show err)) errorMsg dflags $ hang (text "Warning:") 9 $ text "Couldn't figure out C compiler information!" $$ text "Make sure you're using GNU gcc, or clang" return UnknownCC) return info