Commit c15d44f8 authored by Simon Marlow's avatar Simon Marlow Committed by Ben Gamari

Revert "Disable the SRT offset optimisation on MachO platforms"

This reverts commit bf10456e.
parent 279d69d3
......@@ -94,12 +94,10 @@ module CLabel (
-- * Predicates
needsCDecl, maybeLocalBlockLabel, externallyVisibleCLabel,
isCFunctionLabel, isGcPtrLabel, labelDynamic,
-- * Conversions
toClosureLbl, toSlowEntryLbl, toEntryLbl, toInfoLbl, hasHaskellName,
......@@ -976,29 +974,13 @@ idInfoLabelType info =
-- -----------------------------------------------------------------------------
-- Does a CLabel need dynamic linkage?
-- | Is a 'CLabel' defined in the current module being compiled?
-- Sometimes we can optimise references within a compilation unit in ways that
-- we couldn't for inter-module references. This provides a conservative
-- estimate of whether a 'CLabel' lives in the current module.
isLocalCLabel :: Module -> CLabel -> Bool
isLocalCLabel this_mod lbl =
case lbl of
IdLabel name _ _
| isInternalName name -> True
| otherwise -> nameModule name == this_mod
LocalBlockLabel _ -> True
_ -> False
-- -----------------------------------------------------------------------------
-- | Does a 'CLabel' need dynamic linkage?
-- When referring to data in code, we need to know whether
-- that data resides in a DLL or not. [Win32 only.]
-- @labelDynamic@ returns @True@ if the label is located
-- in a DLL, be it a data reference or not.
labelDynamic :: DynFlags -> Module -> CLabel -> Bool
labelDynamic dflags this_mod lbl =
case lbl of
......@@ -16,7 +16,6 @@ import Hoopl.Label
import Hoopl.Collections
import Hoopl.Dataflow
import Module
import Platform
import Digraph
import CLabel
import PprCmmDecl ()
......@@ -121,7 +120,7 @@ offset to the SRT can be stored in 32 bits (all code lives within a
the info table by storing the srt_offset in the srt field, which is
half a word.
On x86_64 with TABLES_NEXT_TO_CODE (except on MachO, due to #15169):
On x86_64 with TABLES_NEXT_TO_CODE:
- info->srt is zero if there's no SRT, otherwise:
- info->srt is an offset from the info pointer to the SRT object
......@@ -637,27 +636,14 @@ oneSRT dflags staticFuns blockids lbls isCAF cafs = do
let newSRTMap = Map.fromList [(cafLbl, srtEntry) | cafLbl <- lbls]
put (Map.union newSRTMap srtMap)
this_mod = thisModule topSRT
case Set.toList filtered of
[] -> do
srtTrace "oneSRT: empty" (ppr lbls) $ return ()
updateSRTMap Nothing
return ([], [], [])
-- When we have only one entry there is no need to build a new SRT at all.
[one@(SRTEntry lbl)]
| -- Info tables refer to SRTs by offset (as noted in the section
-- "Referring to an SRT from the info table" of Note [SRTs]). However,
-- when dynamic linking is used we cannot guarantee that the offset
-- between the SRT and the info table will fit in the offset field.
-- Consequently we build a singleton SRT in in this case.
not (labelDynamic dflags this_mod lbl)
-- MachO relocations can't express offsets between compilation units at
-- all, so we are always forced to build a singleton SRT in this case.
&& (not (osMachOTarget $ platformOS $ targetPlatform dflags)
|| isLocalCLabel this_mod lbl) -> do
| not (labelDynamic dflags (thisModule topSRT) lbl) -> do
updateSRTMap (Just one)
return ([], map (,lbl) blockids, [])
......@@ -271,10 +271,7 @@ mkSRTLit dflags _ Nothing = ([], CmmInt 0 (halfWordWidth dflags))
mkSRTLit dflags _ (Just lbl) = ([CmmLabel lbl], CmmInt 1 (halfWordWidth dflags))
-- | Is the SRT offset field inline in the info table on this platform?
-- See the section "Referring to an SRT from the info table" in
-- Note [SRTs] in CmmBuildInfoTables.hs
-- | is the SRT offset field inline in the info table on this platform?
inlineSRT :: DynFlags -> Bool
inlineSRT dflags = platformArch (targetPlatform dflags) == ArchX86_64
&& tablesNextToCode dflags
......@@ -156,9 +156,6 @@ typedef union {
#if defined(x86_64_TARGET_ARCH) && defined(TABLES_NEXT_TO_CODE)
// On x86_64 we can fit a pointer offset in half a word, so put the SRT offset
// in the info->srt field directly.
// See the section "Referring to an SRT from the info table" in
// Note [SRTs] in CmmBuildInfoTables.hs
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