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|
{-# LANGUAGE Trustworthy #-}
{-# LANGUAGE UnboxedTuples #-}
{-# LANGUAGE MagicHash #-}
{-# LANGUAGE NoImplicitPrelude #-}
-----------------------------------------------------------------------------
-- |
-- Module : GHC.InfoProv
-- Copyright : (c) The University of Glasgow 2011
-- License : see libraries/base/LICENSE
--
-- Maintainer : cvs-ghc@haskell.org
-- Stability : internal
-- Portability : non-portable (GHC Extensions)
--
-- Access to GHC's info-table provenance metadata.
--
-- @since 4.18.0.0
-----------------------------------------------------------------------------
module GHC.InfoProv
( InfoProv(..)
, ipeProv
, whereFrom
-- * Internals
, InfoProvEnt
, peekInfoProv
) where
#include "Rts.h"
import GHC.Base
import GHC.Show
import GHC.Ptr (Ptr(..), plusPtr, nullPtr)
import GHC.Foreign (CString, peekCString)
import GHC.IO.Encoding (utf8)
import Foreign.Storable (peekByteOff)
data InfoProv = InfoProv {
ipName :: String,
ipDesc :: String,
ipTyDesc :: String,
ipLabel :: String,
ipMod :: String,
ipLoc :: String
} deriving (Eq, Show)
data InfoProvEnt
getIPE :: a -> IO (Ptr InfoProvEnt)
getIPE obj = IO $ \s ->
case whereFrom## obj s of
(## s', addr ##) -> (## s', Ptr addr ##)
ipeProv :: Ptr InfoProvEnt -> Ptr InfoProv
ipeProv p = (#ptr InfoProvEnt, prov) p
peekIpName, peekIpDesc, peekIpLabel, peekIpModule, peekIpSrcLoc, peekIpTyDesc :: Ptr InfoProv -> IO CString
peekIpName p = (# peek InfoProv, table_name) p
peekIpDesc p = (# peek InfoProv, closure_desc) p
peekIpLabel p = (# peek InfoProv, label) p
peekIpModule p = (# peek InfoProv, module) p
peekIpSrcLoc p = (# peek InfoProv, srcloc) p
peekIpTyDesc p = (# peek InfoProv, ty_desc) p
peekInfoProv :: Ptr InfoProv -> IO InfoProv
peekInfoProv infop = do
name <- peekCString utf8 =<< peekIpName infop
desc <- peekCString utf8 =<< peekIpDesc infop
tyDesc <- peekCString utf8 =<< peekIpTyDesc infop
label <- peekCString utf8 =<< peekIpLabel infop
mod <- peekCString utf8 =<< peekIpModule infop
loc <- peekCString utf8 =<< peekIpSrcLoc infop
return InfoProv {
ipName = name,
ipDesc = desc,
ipTyDesc = tyDesc,
ipLabel = label,
ipMod = mod,
ipLoc = loc
}
-- | Get information about where a value originated from.
-- This information is stored statically in a binary when `-finfo-table-map` is
-- enabled. The source positions will be greatly improved by also enabled debug
-- information with `-g3`. Finally you can enable `-fdistinct-constructor-tables` to
-- get more precise information about data constructor allocations.
--
-- The information is collect by looking at the info table address of a specific closure and
-- then consulting a specially generated map (by `-finfo-table-map`) to find out where we think
-- the best source position to describe that info table arose from.
--
-- @since 4.16.0.0
whereFrom :: a -> IO (Maybe InfoProv)
whereFrom obj = do
ipe <- getIPE obj
-- The primop returns the null pointer in two situations at the moment
-- 1. The lookup fails for whatever reason
-- 2. -finfo-table-map is not enabled.
-- It would be good to distinguish between these two cases somehow.
if ipe == nullPtr
then return Nothing
else do
infoProv <- peekInfoProv (ipeProv ipe)
return $ Just infoProv
|
