diff options
| author | Ben Gamari <bgamari.foss@gmail.com> | 2015-10-30 20:49:35 +0100 |
|---|---|---|
| committer | Ben Gamari <ben@smart-cactus.org> | 2015-11-01 15:19:47 +0100 |
| commit | 6fb0ba65d27602ae9a81fe142936b06d54b20b2e (patch) | |
| tree | 223208e34e9d6d70b0232a5c56f3d8c8be6539e6 | |
| parent | 3431ad6faeb2b74e10c8ac4d42bdbc4521e07e33 (diff) | |
| download | haskell-6fb0ba65d27602ae9a81fe142936b06d54b20b2e.tar.gz | |
Dwarf: Preserve stack pointer register
Here we add a `same_value $sp` instruction to our default unwinding
rules to ensure that the implicit `$sp = CFA` rule (which `libdw`
appears to exhibit on x86_64) doesn't overwrite it (necessary since we
don't use $sp to track our call stack).
See Phab Diff D1189 for details on how we arrived at this resolution.
Reviewers: scpmw, austin, simonmar
Reviewed By: austin, simonmar
Subscribers: thomie, simonmar
Differential Revision: https://phabricator.haskell.org/D1224
| -rw-r--r-- | compiler/nativeGen/Dwarf/Types.hs | 12 |
1 files changed, 11 insertions, 1 deletions
diff --git a/compiler/nativeGen/Dwarf/Types.hs b/compiler/nativeGen/Dwarf/Types.hs index a2d07b87ba..d558c2d1fa 100644 --- a/compiler/nativeGen/Dwarf/Types.hs +++ b/compiler/nativeGen/Dwarf/Types.hs @@ -231,6 +231,13 @@ pprDwarfFrame DwarfFrame{dwCieLabel=cieLabel,dwCieInit=cieInit,dwCieProcs=procs} retReg = dwarfReturnRegNo plat wordSize = platformWordSize plat pprInit (g, uw) = pprSetUnwind plat g (Nothing, uw) + + -- Preserve C stack pointer: This necessary to override that default + -- unwinding behavior of setting $sp = CFA. + preserveSp = case platformArch plat of + ArchX86 -> pprByte dW_CFA_same_value $$ pprLEBWord 4 + ArchX86_64 -> pprByte dW_CFA_same_value $$ pprLEBWord 7 + _ -> empty in vcat [ ppr cieLabel <> colon , pprData4' length -- Length of CIE , ppr cieStartLabel <> colon @@ -250,8 +257,11 @@ pprDwarfFrame DwarfFrame{dwCieLabel=cieLabel,dwCieInit=cieInit,dwCieProcs=procs} pprByte (dW_CFA_offset+retReg) , pprByte 0 + -- Preserve C stack pointer + , preserveSp + -- Sp' = CFA - -- (we need to set this manually as our Sp register is + -- (we need to set this manually as our (STG) Sp register is -- often not the architecture's default stack register) , pprByte dW_CFA_val_offset , pprLEBWord (fromIntegral spReg) |