diff options
Diffstat (limited to 'ghc/compiler/nativeGen')
| -rw-r--r-- | ghc/compiler/nativeGen/PositionIndependentCode.hs | 98 | ||||
| -rw-r--r-- | ghc/compiler/nativeGen/PprMach.hs | 11 |
2 files changed, 71 insertions, 38 deletions
diff --git a/ghc/compiler/nativeGen/PositionIndependentCode.hs b/ghc/compiler/nativeGen/PositionIndependentCode.hs index a6a7b27425..5b6dda8150 100644 --- a/ghc/compiler/nativeGen/PositionIndependentCode.hs +++ b/ghc/compiler/nativeGen/PositionIndependentCode.hs @@ -63,7 +63,7 @@ import MachRegs import MachInstrs import NCGMonad ( NatM, getNewRegNat, getNewLabelNat ) -import CmdLineOpts ( opt_PIC ) +import CmdLineOpts ( opt_PIC, opt_Static ) import Pretty import qualified Outputable @@ -195,46 +195,30 @@ howToAccessLabel False lbl | opt_PIC && externallyVisibleCLabel lbl = AccessViaSymbolPtr howToAccessLabel _ _ = AccessDirectly -#elif linux_TARGET_OS && powerpc_TARGET_ARCH --- PowerPC Linux --- --- PowerPC Linux is just plain broken. --- While it's theoretically possible to use GOT offsets larger --- than 16 bit, the standard crt*.o files don't, which leads to --- linker errors as soon as the GOT size exceeds 16 bit. --- Also, the assembler doesn't support @gotoff labels. --- In order to be able to use a larger GOT, we circumvent the --- entire GOT mechanism and do it ourselves (this is what GCC does). - --- In this scheme, we need to do _all data references_ (even refs --- to static data) via a SymbolPtr when we are generating PIC. --- Luckily, the PLT works as expected, so we can simply access --- dynamically linked code via the PLT. +#elif linux_TARGET_OS && powerpc64_TARGET_ARCH +-- ELF PPC64 (powerpc64-linux), AIX, MacOS 9, BeOS/PPC -howToAccessLabel _ _ | not opt_PIC = AccessDirectly -howToAccessLabel True lbl - = if labelDynamic lbl then AccessViaStub - else AccessDirectly -howToAccessLabel False lbl - = AccessViaSymbolPtr +howToAccessLabel True lbl = AccessDirectly -- actually, .label instead of label +howToAccessLabel _ lbl = AccessViaSymbolPtr #elif linux_TARGET_OS -- ELF (Linux) -- +-- ELF tries to pretend to the main application code that dynamic linking does +-- not exist. While this may sound convenient, it tends to mess things up in +-- very bad ways, so we have to be careful when we generate code for the main +-- program (-dynamic but no -fPIC). +-- -- Indirect access is required for references to imported symbols --- from position independent code. --- It is always possible to access something indirectly, --- even when it's not necessary. - --- For code, we can use a relative jump to a piece of --- stub code instead (this allows lazy binding of imported symbols). +-- from position independent code. It is also required from the main program +-- when dynamic libraries containing Haskell code are used. howToAccessLabel isJump lbl - -- no PIC -> the dynamic linker does everything for us - | not opt_PIC = AccessDirectly - -- if it's not imported, we need no indirection - -- ("foo" will end up being accessed as "foo@GOTOFF") - | not (labelDynamic lbl) = AccessDirectly + -- no PIC -> the dynamic linker does everything for us; + -- if we don't dynamically link to Haskell code, + -- it actually manages to do so without messing thins up. + | not opt_PIC && opt_Static = AccessDirectly + #if !i386_TARGET_ARCH -- for Intel, we temporarily disable the use of the -- Procedure Linkage Table, because PLTs on intel require the @@ -242,9 +226,35 @@ howToAccessLabel isJump lbl -- a jump through the PLT is made. -- TODO: make the i386 NCG ensure this before jumping to a -- CodeStub label, so we can remove this special case. - | isJump = AccessViaStub + + -- As long as we're in a shared library ourselves, + -- we can use the plt. + -- NOTE: We might want to disable this, because this + -- prevents -fPIC code from being linked statically. + | isJump && labelDynamic lbl && opt_PIC = AccessViaStub + + -- TODO: it would be OK to access non-Haskell code via a stub +-- | isJump && labelDynamic lbl && not isHaskellCode lbl = AccessViaStub + + -- Using code stubs for jumps from the main program to an entry + -- label in a dynamic library is deadly; this will cause the dynamic + -- linker to replace all references (even data references) to that + -- label by references to the stub, so we won't find our info tables + -- any more. +#endif + + -- A dynamic label needs to be accessed via a symbol pointer. + -- NOTE: It would be OK to jump to foreign code via a PLT stub. + | labelDynamic lbl = AccessViaSymbolPtr + +#if powerpc_ARGET_ARCH + -- For PowerPC32 -fPIC, we have to access even static data + -- via a symbol pointer (see below for an explanation why + -- PowerPC32 Linux is especially broken). + | opt_PIC && not isJump = AccessViaSymbolPtr #endif - | otherwise = AccessViaSymbolPtr + + | otherwise = AccessDirectly #else -- @@ -375,8 +385,22 @@ pprImportedSymbol importedLbl #elif powerpc_TARGET_ARCH && linux_TARGET_OS --- For PowerPC linux, we don't do anything unless we're generating PIC. -needImportedSymbols = opt_PIC +-- PowerPC Linux +-- +-- PowerPC Linux is just plain broken. +-- While it's theoretically possible to use GOT offsets larger +-- than 16 bit, the standard crt*.o files don't, which leads to +-- linker errors as soon as the GOT size exceeds 16 bit. +-- Also, the assembler doesn't support @gotoff labels. +-- In order to be able to use a larger GOT, we circumvent the +-- entire GOT mechanism and do it ourselves (this is what GCC does). + +-- In this scheme, we need to do _all data references_ (even refs +-- to static data) via a SymbolPtr when we are generating PIC. + +-- We need to do this whenever we explicitly access something via +-- a symbol pointer. +needImportedSymbols = opt_PIC || not opt_Static -- If we're generating PIC, we need to create our own "fake GOT". diff --git a/ghc/compiler/nativeGen/PprMach.hs b/ghc/compiler/nativeGen/PprMach.hs index 846a855508..a807cc2a05 100644 --- a/ghc/compiler/nativeGen/PprMach.hs +++ b/ghc/compiler/nativeGen/PprMach.hs @@ -34,7 +34,7 @@ import Pretty import FastString import qualified Outputable -import CmdLineOpts ( opt_PIC ) +import CmdLineOpts ( opt_PIC, opt_Static ) #if __GLASGOW_HASKELL__ >= 504 import Data.Array.ST @@ -512,6 +512,15 @@ pprAddr (AddrRegImm r1 imm) = hcat [ pprImm imm, char '(', pprReg r1, char ')' ] -- ----------------------------------------------------------------------------- -- pprData: print a 'CmmStatic' +#if defined(linux_TARGET_OS) +#if defined(powerpc_TARGET_ARCH) || defined(i386_TARGET_ARCH) + -- Hack to make dynamic linking work +pprSectionHeader ReadOnlyData + | not opt_PIC && not opt_Static + = pprSectionHeader Data +#endif +#endif + pprSectionHeader Text = ptext IF_ARCH_alpha(SLIT("\t.text\n\t.align 3") {-word boundary-} |