diff options
Diffstat (limited to 'compiler/GHC/Driver/Pipeline.hs')
| -rw-r--r-- | compiler/GHC/Driver/Pipeline.hs | 61 |
1 files changed, 28 insertions, 33 deletions
diff --git a/compiler/GHC/Driver/Pipeline.hs b/compiler/GHC/Driver/Pipeline.hs index 36010a76af..e422624fa6 100644 --- a/compiler/GHC/Driver/Pipeline.hs +++ b/compiler/GHC/Driver/Pipeline.hs @@ -2133,6 +2133,23 @@ We must enable bigobj output in a few places: Unfortunately the big object format is not supported on 32-bit targets so none of this can be used in that case. + + +Note [Merging object files for GHCi] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +GHCi can usually loads standard linkable object files using GHC's linker +implementation. However, most users build their projects with -split-sections, +meaning that such object files can have an extremely high number of sections. +As the linker must map each of these sections individually, loading such object +files is very inefficient. + +To avoid this inefficiency, we use the linker's `-r` flag and a linker script +to produce a merged relocatable object file. This file will contain a singe +text section section and can consequently be mapped far more efficiently. As +gcc tends to do unpredictable things to our linker command line, we opt to +invoke ld directly in this case, in contrast to our usual strategy of linking +via gcc. + -} joinObjectFiles :: DynFlags -> [FilePath] -> FilePath -> IO () @@ -2140,34 +2157,13 @@ joinObjectFiles dflags o_files output_fn = do let toolSettings' = toolSettings dflags ldIsGnuLd = toolSettings_ldIsGnuLd toolSettings' osInfo = platformOS (targetPlatform dflags) - ld_r args cc = GHC.SysTools.runLink dflags ([ - GHC.SysTools.Option "-nostdlib", - GHC.SysTools.Option "-Wl,-r" - ] - -- See Note [No PIE while linking] in GHC.Driver.Session - ++ (if toolSettings_ccSupportsNoPie toolSettings' - then [GHC.SysTools.Option "-no-pie"] - else []) - - ++ (if any (cc ==) [Clang, AppleClang, AppleClang51] - then [] - else [GHC.SysTools.Option "-nodefaultlibs"]) - ++ (if osInfo == OSFreeBSD - then [GHC.SysTools.Option "-L/usr/lib"] - else []) - -- gcc on sparc sets -Wl,--relax implicitly, but - -- -r and --relax are incompatible for ld, so - -- disable --relax explicitly. - ++ (if platformArch (targetPlatform dflags) - `elem` [ArchSPARC, ArchSPARC64] - && ldIsGnuLd - then [GHC.SysTools.Option "-Wl,-no-relax"] - else []) + ld_r args = GHC.SysTools.runMergeObjects dflags ( -- See Note [Produce big objects on Windows] - ++ [ GHC.SysTools.Option "-Wl,--oformat,pe-bigobj-x86-64" - | OSMinGW32 == osInfo - , not $ target32Bit (targetPlatform dflags) - ] + concat + [ [GHC.SysTools.Option "--oformat", GHC.SysTools.Option "pe-bigobj-x86-64"] + | OSMinGW32 == osInfo + , not $ target32Bit (targetPlatform dflags) + ] ++ map GHC.SysTools.Option ld_build_id ++ [ GHC.SysTools.Option "-o", GHC.SysTools.FileOption "" output_fn ] @@ -2176,25 +2172,24 @@ joinObjectFiles dflags o_files output_fn = do -- suppress the generation of the .note.gnu.build-id section, -- which we don't need and sometimes causes ld to emit a -- warning: - ld_build_id | toolSettings_ldSupportsBuildId toolSettings' = ["-Wl,--build-id=none"] + ld_build_id | toolSettings_ldSupportsBuildId toolSettings' = ["--build-id=none"] | otherwise = [] - ccInfo <- getCompilerInfo dflags if ldIsGnuLd then do script <- newTempName dflags TFL_CurrentModule "ldscript" cwd <- getCurrentDirectory let o_files_abs = map (\x -> "\"" ++ (cwd </> x) ++ "\"") o_files writeFile script $ "INPUT(" ++ unwords o_files_abs ++ ")" - ld_r [GHC.SysTools.FileOption "" script] ccInfo + ld_r [GHC.SysTools.FileOption "" script] else if toolSettings_ldSupportsFilelist toolSettings' then do filelist <- newTempName dflags TFL_CurrentModule "filelist" writeFile filelist $ unlines o_files - ld_r [GHC.SysTools.Option "-Wl,-filelist", - GHC.SysTools.FileOption "-Wl," filelist] ccInfo + ld_r [GHC.SysTools.Option "-filelist", + GHC.SysTools.FileOption "" filelist] else do - ld_r (map (GHC.SysTools.FileOption "") o_files) ccInfo + ld_r (map (GHC.SysTools.FileOption "") o_files) -- ----------------------------------------------------------------------------- -- Misc. |