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Diffstat (limited to 'compiler/GHC/SysTools/Info.hs')
| -rw-r--r-- | compiler/GHC/SysTools/Info.hs | 262 |
1 files changed, 262 insertions, 0 deletions
diff --git a/compiler/GHC/SysTools/Info.hs b/compiler/GHC/SysTools/Info.hs new file mode 100644 index 0000000000..8051570755 --- /dev/null +++ b/compiler/GHC/SysTools/Info.hs @@ -0,0 +1,262 @@ +{-# LANGUAGE ScopedTypeVariables #-} +----------------------------------------------------------------------------- +-- +-- Compiler information functions +-- +-- (c) The GHC Team 2017 +-- +----------------------------------------------------------------------------- +module GHC.SysTools.Info where + +import Exception +import ErrUtils +import GHC.Driver.Session +import Outputable +import Util + +import Data.List +import Data.IORef + +import System.IO + +import GHC.Platform +import GhcPrelude + +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!" $$ + text "Make sure you're using GNU ld, GNU gold" <+> + text "or the built in OS X linker, etc." + return UnknownLD) + return info + +-- Grab compiler info and cache it in DynFlags. +getCompilerInfo :: DynFlags -> IO CompilerInfo +getCompilerInfo dflags = do + info <- readIORef (rtccInfo dflags) + case info of + Just v -> return v + Nothing -> do + v <- getCompilerInfo' dflags + writeIORef (rtccInfo dflags) (Just v) + return v + +-- See Note [Run-time linker info]. +getCompilerInfo' :: DynFlags -> IO CompilerInfo +getCompilerInfo' dflags = do + let pgm = pgm_c dflags + -- Try to grab the info from the process output. + parseCompilerInfo _stdo stde _exitc + -- Regular GCC + | any ("gcc version" `isInfixOf`) stde = + return GCC + -- Regular clang + | any ("clang version" `isInfixOf`) stde = + return Clang + -- FreeBSD clang + | any ("FreeBSD clang version" `isInfixOf`) stde = + return Clang + -- Xcode 5.1 clang + | any ("Apple LLVM version 5.1" `isPrefixOf`) stde = + return AppleClang51 + -- Xcode 5 clang + | any ("Apple LLVM version" `isPrefixOf`) stde = + return AppleClang + -- Xcode 4.1 clang + | any ("Apple clang version" `isPrefixOf`) stde = + return AppleClang + -- Unknown linker. + | otherwise = fail "invalid -v output, or compiler is unsupported" + + -- Process the executable call + info <- catchIO (do + (exitc, stdo, stde) <- + readProcessEnvWithExitCode pgm ["-v"] c_locale_env + -- Split the output by lines to make certain kinds + -- of processing easier. + parseCompilerInfo (lines stdo) (lines stde) exitc + ) + (\err -> do + debugTraceMsg dflags 2 + (text "Error (figuring out C compiler information):" <+> + text (show err)) + errorMsg dflags $ hang (text "Warning:") 9 $ + text "Couldn't figure out C compiler information!" $$ + text "Make sure you're using GNU gcc, or clang" + return UnknownCC) + return info |