llvm-pretty-bc-parser-0.5.0.0: src/Data/LLVM/BitCode/IR/Metadata.hs
{-# LANGUAGE DeriveDataTypeable #-}
{-# LANGUAGE DeriveGeneric #-}
{-# LANGUAGE ExplicitForAll #-}
{-# LANGUAGE LambdaCase #-}
{-# LANGUAGE RecordWildCards #-}
{-# LANGUAGE RecursiveDo #-}
{-# LANGUAGE TupleSections #-}
{-# LANGUAGE ViewPatterns #-}
module Data.LLVM.BitCode.IR.Metadata (
parseMetadataBlock
, parseMetadataKindEntry
, PartialUnnamedMd(..)
, finalizePartialUnnamedMd
, finalizePValMd
, dedupMetadata
, InstrMdAttachments
, PFnMdAttachments
, PKindMd
, PGlobalAttachments
) where
import Data.LLVM.BitCode.Bitstream
import Data.LLVM.BitCode.IR.Constants
import Data.LLVM.BitCode.Match
import Data.LLVM.BitCode.Parse
import Data.LLVM.BitCode.Record
import Text.LLVM.AST
import Text.LLVM.Labels
import qualified Codec.Binary.UTF8.String as UTF8 (decode)
import Control.Applicative ((<|>))
import Control.Exception (throw)
import Control.Monad (foldM, guard, mplus, when)
import Data.Bits (shiftR, testBit, shiftL, (.&.), (.|.), bit, complement)
import Data.Data (Data)
import Data.Typeable (Typeable)
import qualified Data.ByteString as S
import qualified Data.ByteString.Char8 as Char8 (unpack)
import Data.Either (partitionEithers)
import Data.Generics.Uniplate.Data
import qualified Data.IntMap as IntMap
import Data.List (mapAccumL, foldl')
import Data.Map (Map)
import qualified Data.Map as Map
import Data.Maybe (fromMaybe, mapMaybe)
import qualified Data.Sequence as Seq
import Data.Sequence (Seq)
import Data.Word (Word8,Word32,Word64)
import GHC.Generics (Generic)
import GHC.Stack (HasCallStack, callStack)
import Data.Bifunctor (bimap)
-- Parsing State ---------------------------------------------------------------
data MetadataTable = MetadataTable
{ mtEntries :: MdTable
, mtNextNode :: !Int
, mtNodes :: IntMap.IntMap (Bool, Bool, Int)
-- ^ The entries in the map are: is the entry function local,
-- is the entry distinct, and the implicit id for the node.
} deriving (Show)
emptyMetadataTable ::
Int {- ^ globals seen so far -} ->
MdTable -> MetadataTable
emptyMetadataTable globals es = MetadataTable
{ mtEntries = es
, mtNextNode = globals
, mtNodes = IntMap.empty
}
metadata :: PValMd -> Typed PValue
metadata = Typed (PrimType Metadata) . ValMd
addMetadata :: PValMd -> MetadataTable -> (Int,MetadataTable)
addMetadata val mt = (ix, mt { mtEntries = es' })
where
(ix,es') = addValue' (metadata val) (mtEntries mt)
addMdValue :: Typed PValue -> MetadataTable -> MetadataTable
addMdValue tv mt = mt { mtEntries = addValue tv' (mtEntries mt) }
where
-- explicitly make a metadata value out of a normal value
tv' = Typed { typedType = PrimType Metadata
, typedValue = ValMd (ValMdValue tv)
}
nameNode :: Bool -> Bool -> Int -> MetadataTable -> MetadataTable
nameNode fnLocal isDistinct ix mt = mt
{ mtNodes = IntMap.insert ix (fnLocal,isDistinct,mtNextNode mt) (mtNodes mt)
, mtNextNode = mtNextNode mt + 1
}
addString :: String -> PartialMetadata -> PartialMetadata
addString str pm =
let (ix, mt) = addMetadata (ValMdString str) (pmEntries pm)
in pm { pmEntries = mt
, pmStrings = Map.insert ix str (pmStrings pm)
}
addStrings :: [String] -> PartialMetadata -> PartialMetadata
addStrings strs pm = foldl' (flip addString) pm strs
addLoc :: Bool -> PDebugLoc -> MetadataTable -> MetadataTable
addLoc isDistinct loc mt = nameNode False isDistinct ix mt'
where
(ix,mt') = addMetadata (ValMdLoc loc) mt
addDebugInfo
:: Bool
-> DebugInfo' Int
-> MetadataTable
-> MetadataTable
addDebugInfo isDistinct di mt = nameNode False isDistinct ix mt'
where
(ix,mt') = addMetadata (ValMdDebugInfo di) mt
-- | A variant of 'addDebugInfo' that only inserts the 'DebugInfo' into the
-- 'mtEntries', not the 'mtNodes'. This has the effect of causing the
-- 'DebugInfo' /not/ to be added to any top-level metadata lists and instead
-- causing it to be printed inline wherever it occurs.
-- See @Note [Printing metadata inline]@.
addInlineDebugInfo :: DebugInfo' Int -> MetadataTable -> MetadataTable
addInlineDebugInfo di mt = mt { mtEntries = addValue tv (mtEntries mt) }
where
tv = Typed { typedType = PrimType Metadata
, typedValue = ValMd (ValMdDebugInfo di)
}
-- | Add a new node, that might be distinct.
addNode :: Bool -> [Maybe PValMd] -> MetadataTable -> MetadataTable
addNode isDistinct vals mt = nameNode False isDistinct ix mt'
where
(ix,mt') = addMetadata (ValMdNode vals) mt
addOldNode :: Bool -> [Typed PValue] -> MetadataTable -> MetadataTable
addOldNode fnLocal vals mt = nameNode fnLocal False ix mt'
where
(ix,mt') = addMetadata (ValMdNode [ Just (ValMdValue tv) | tv <- vals ]) mt
mdForwardRef :: [String] -> MetadataTable -> Int -> PValMd
mdForwardRef cxt mt ix = fromMaybe fallback nodeRef
where
nodeRef = reference `fmap` IntMap.lookup ix (mtNodes mt)
fallback = case forwardRef cxt ix (mtEntries mt) of
Typed { typedValue = ValMd md } -> md
tv -> ValMdValue tv
reference (False, _, r) = ValMdRef r
reference (_ , _, r) =
let explanation = "Illegal forward reference into function-local metadata."
in throw (BadValueRef callStack cxt explanation r)
mdForwardRefOrNull :: [String] -> MetadataTable -> Int -> Maybe PValMd
mdForwardRefOrNull cxt mt ix | ix > 0 = Just (mdForwardRef cxt mt (ix - 1))
| otherwise = Nothing
mdNodeRef :: HasCallStack
=> [String] -> MetadataTable -> Int -> Int
mdNodeRef cxt mt ix = maybe except prj (IntMap.lookup ix (mtNodes mt))
where explanation = "Bad forward reference into mtNodes"
except = throw (BadValueRef callStack cxt explanation ix)
prj (_, _, x) = x
mdString :: HasCallStack
=> [String] -> PartialMetadata -> Int -> String
mdString cxt partialMeta ix =
let explanation = "Null value when metadata string was expected"
in fromMaybe (throw (BadValueRef callStack cxt explanation ix))
(mdStringOrNull cxt partialMeta ix)
-- | This preferentially fetches the string from the strict string table
-- (@pmStrings@), but will return a forward reference when it can't find it there.
mdStringOrNull :: HasCallStack
=> [String]
-> PartialMetadata
-> Int
-> Maybe String
mdStringOrNull cxt partialMeta ix =
Map.lookup (ix - 1) (pmStrings partialMeta) <|>
case mdForwardRefOrNull cxt (pmEntries partialMeta) ix of
Nothing -> Nothing
Just (ValMdString str) -> Just str
Just _ ->
let explanation = "Non-string metadata when string was expected"
in throw (BadTypeRef callStack cxt explanation ix)
mdStringOrEmpty :: HasCallStack
=> [String]
-> PartialMetadata
-> Int
-> String
mdStringOrEmpty cxt partialMeta = fromMaybe "" . mdStringOrNull cxt partialMeta
mkMdRefTable :: MetadataTable -> MdRefTable
mkMdRefTable mt = IntMap.mapMaybe step (mtNodes mt)
where
step (fnLocal,_,ix) = do
guard (not fnLocal)
return ix
data PartialMetadata = PartialMetadata
{ pmEntries :: MetadataTable
, pmNamedEntries :: Map.Map String [Int]
, pmNextName :: Maybe String
, pmInstrAttachments :: InstrMdAttachments
, pmFnAttachments :: PFnMdAttachments
, pmGlobalAttachments:: PGlobalAttachments
, pmStrings :: Map Int String
-- ^ Forward references to metadata strings are never actually
-- forward references, string blocks (@METADATA_STRINGS@) always come first.
-- So references to them don't need to be inside the @MonadFix@ like
-- references into other 'pmEntries', allowing them to be strict.
--
-- See this comment:
-- - https://github.com/llvm-mirror/llvm/blob/release_40/lib/Bitcode/Reader/MetadataLoader.cpp#L913
-- - https://github.com/llvm-mirror/llvm/blob/release_60/lib/Bitcode/Reader/MetadataLoader.cpp#L1017
} deriving (Show)
emptyPartialMetadata ::
Int {- ^ globals seen so far -} ->
MdTable -> PartialMetadata
emptyPartialMetadata globals es = PartialMetadata
{ pmEntries = emptyMetadataTable globals es
, pmNamedEntries = Map.empty
, pmNextName = Nothing
, pmInstrAttachments = Map.empty
, pmFnAttachments = Map.empty
, pmGlobalAttachments = Map.empty
, pmStrings = Map.empty
}
updateMetadataTable :: (MetadataTable -> MetadataTable)
-> (PartialMetadata -> PartialMetadata)
updateMetadataTable f pm = pm { pmEntries = f (pmEntries pm) }
addGlobalAttachments ::
Symbol {- ^ name of the global to attach to ^ -} ->
(Map.Map KindMd PValMd) {- ^ metadata references to attach ^ -} ->
(PartialMetadata -> PartialMetadata)
addGlobalAttachments sym mds pm =
pm { pmGlobalAttachments = Map.insert sym mds (pmGlobalAttachments pm)
}
setNextName :: String -> PartialMetadata -> PartialMetadata
setNextName name pm = pm { pmNextName = Just name }
addFnAttachment :: PFnMdAttachments -> PartialMetadata -> PartialMetadata
addFnAttachment att pm =
-- left-biased union, since the parser overwrites metadata as it encounters it
pm { pmFnAttachments = Map.union att (pmFnAttachments pm) }
addInstrAttachment :: Int -> [(KindMd,PValMd)]
-> PartialMetadata -> PartialMetadata
addInstrAttachment instr md pm =
pm { pmInstrAttachments = Map.insert instr md (pmInstrAttachments pm) }
nameMetadata :: [Int] -> PartialMetadata -> Parse PartialMetadata
nameMetadata val pm = case pmNextName pm of
Just name -> return $! pm
{ pmNextName = Nothing
, pmNamedEntries = Map.insert name val (pmNamedEntries pm)
}
Nothing -> fail "Expected a metadata name"
-- De-duplicating ---------------------------------------------------------------
-- | This function generically traverses the given unnamed metadata values.
-- When it encounters one with a 'PValMd' inside of it, it looks up that
-- value in the list. If found, it replaces the value with a reference to it.
--
-- Such de-duplication is necessary because the @fallback@ of
-- 'mdForwardRefOrNull' is often called when it is in fact unnecessary, just
-- because the appropriate references aren't available yet.
--
-- This function is concise at the cost of efficiency: In the worst case, every
-- metadata node contains a reference to every other metadata node, and the
-- cost is O(n^2*log(n)) where
-- * n^2 comes from looking at every 'PValMd' inside every 'PartialUnnamedMd'
-- * log(n) is the cost of looking them up in a 'Map'.
dedupMetadata :: Seq PartialUnnamedMd -> Seq PartialUnnamedMd
dedupMetadata pumd = helper (mkPartialUnnamedMdMap pumd) <$> pumd
where helper pumdMap pum =
let pumdMap' = Map.delete (pumValues pum) pumdMap -- don't self-reference
in pum { pumValues = maybeTransform pumdMap' (pumValues pum) }
-- | We avoid erroneously recursing into ValMdValues and exit early on
-- a few other constructors de-duplication wouldn't affect.
maybeTransform :: Map PValMd Int -> PValMd -> PValMd
maybeTransform pumdMap v@(ValMdNode _) = transform (trans pumdMap) v
maybeTransform pumdMap v@(ValMdLoc _) = transform (trans pumdMap) v
maybeTransform pumdMap v@(ValMdDebugInfo _) = transform (trans pumdMap) v
maybeTransform _ v = v
trans :: Map PValMd Int -> PValMd -> PValMd
trans pumdMap v = case Map.lookup v pumdMap of
Just idex -> ValMdRef idex
Nothing -> v
mkPartialUnnamedMdMap :: Seq PartialUnnamedMd -> Map PValMd Int
mkPartialUnnamedMdMap =
foldl' (\mp part -> Map.insert (pumValues part) (pumIndex part) mp) Map.empty
-- Finalizing ---------------------------------------------------------------
namedEntries :: PartialMetadata -> Seq NamedMd
namedEntries = Seq.fromList
. map (uncurry NamedMd)
. Map.toList
. pmNamedEntries
data PartialUnnamedMd = PartialUnnamedMd
{ pumIndex :: Int
, pumValues :: PValMd
, pumDistinct :: Bool
} deriving (Data, Eq, Ord, Generic, Show, Typeable)
finalizePartialUnnamedMd :: PartialUnnamedMd -> Finalize UnnamedMd
finalizePartialUnnamedMd pum = mkUnnamedMd `fmap` finalizePValMd (pumValues pum)
where
mkUnnamedMd v = UnnamedMd
{ umIndex = pumIndex pum
, umValues = v
, umDistinct = pumDistinct pum
}
finalizePValMd :: PValMd -> Finalize ValMd
finalizePValMd = relabel requireBbEntryName
-- | Partition unnamed entries into global and function local unnamed entries.
unnamedEntries :: PartialMetadata -> (Seq PartialUnnamedMd, Seq PartialUnnamedMd)
unnamedEntries pm = bimap Seq.fromList Seq.fromList (partitionEithers (mapMaybe resolveNode (IntMap.toList (mtNodes mt))))
where
mt = pmEntries pm
-- TODO: is this silently eating errors with metadata that's not in the
-- value table (when the lookupValueTableAbs fails)?
resolveNode :: (Int, (Bool, Bool, Int))
-> Maybe (Either PartialUnnamedMd PartialUnnamedMd)
resolveNode (ref,(fnLocal,d,ix)) =
((if fnLocal then Right else Left) <$> lookupNode ref d ix)
lookupNode :: Int -> Bool -> Int -> Maybe PartialUnnamedMd
lookupNode ref d ix = do
tv <- lookupValueTableAbs ref (mtEntries mt)
case tv of
Typed { typedValue = ValMd v } ->
pure $! PartialUnnamedMd
{ pumIndex = ix
, pumValues = v
, pumDistinct = d
}
_ -> error "Impossible: Only ValMds are stored in mtEntries"
type InstrMdAttachments = Map.Map Int [(KindMd,PValMd)]
type PKindMd = Int
type PFnMdAttachments = Map.Map PKindMd PValMd
type PGlobalAttachments = Map.Map Symbol (Map.Map KindMd PValMd)
type ParsedMetadata =
( Seq NamedMd
, (Seq PartialUnnamedMd, Seq PartialUnnamedMd)
, InstrMdAttachments
, PFnMdAttachments
, PGlobalAttachments
)
parsedMetadata :: PartialMetadata -> ParsedMetadata
parsedMetadata pm =
( namedEntries pm
, unnamedEntries pm
, pmInstrAttachments pm
, pmFnAttachments pm
, pmGlobalAttachments pm
)
-- Metadata Parsing ------------------------------------------------------------
parseMetadataBlock ::
Int {- ^ globals seen so far -} ->
ValueTable -> [Entry] -> Parse ParsedMetadata
parseMetadataBlock globals vt es = label "METADATA_BLOCK" $ do
ms <- getMdTable
let pm0 = emptyPartialMetadata globals ms
rec pm <- foldM (parseMetadataEntry vt (pmEntries pm)) pm0 es
let entries = pmEntries pm
setMdTable (mtEntries entries)
setMdRefs (mkMdRefTable entries)
return (parsedMetadata pm)
-- | Parse an entry in the metadata block.
--
-- XXX this currently relies on the constant block having been parsed already.
-- Though most bitcode examples I've seen are ordered this way, it would be nice
-- to not have to rely on it.
--
-- Based on the function 'parseOneMetadata' in the LLVM source.
parseMetadataEntry :: ValueTable -> MetadataTable -> PartialMetadata -> Entry
-> Parse PartialMetadata
parseMetadataEntry vt mt pm (fromEntry -> Just r) =
let -- The assert* functions below check if a metadata record size matches
-- what is expected, and if not, emit a warning.
--
-- In the past, we made these fatal errors instead of warnings, but we
-- downgraded them to a warning due to how frequently LLVM adds new
-- metadata record fields. Moreover, it is usually not a serious problem
-- for downstream users that llvm-pretty-bc-parser lacks newer metadata
-- fields, since they usually do not affect the semantics of the overall
-- LLVM bitcode.
assertRecordSizeBetween lb ub = do
cxt <- getContext
let len = length (recordFields r)
when (len < lb || ub < len) $
addParseWarning $
InvalidMetadataRecordSize len (MetadataRecordSizeBetween lb ub) cxt
assertRecordSizeIn ns = do
cxt <- getContext
let len = length (recordFields r)
when (not (len `elem` ns)) $
addParseWarning $
InvalidMetadataRecordSize len (MetadataRecordSizeIn ns) cxt
assertRecordSizeAtLeast lb = do
cxt <- getContext
let len = length (recordFields r)
when (len < lb) $
addParseWarning $
InvalidMetadataRecordSize len (MetadataRecordSizeAtLeast lb) cxt
-- Helper for a common pattern which appears below in the parsing
ron n = do ctx <- getContext
mdForwardRefOrNull ctx mt <$> parseField r n numeric
-- Note: the parsing cases below use a Monadic coding style, as opposed to an
-- Applicative style (as was originally used) for performance reasons:
-- Applicative record construction has quadratic size and corresponding
-- performance impacts (the initial conversion from Applicative to Monadic
-- saved 11s when parsing a 22MB bitcode file).
--
-- Additionally, this module uses RecordWildcards... a pragma that is not
-- normally advisable but which does work to good effect in this situation to
-- simplify the following and remove boilerplate intermediary assignments.
in case recordCode r of
-- [values]
1 -> label "METADATA_STRING" $ do
str <- fmap UTF8.decode (parseFields r 0 char) `mplus` parseField r 0 string
return $! addString str pm
-- [type num, value num]
2 -> label "METADATA_VALUE" $ do
assertRecordSizeIn [2]
let field = parseField r
ty <- getType =<< field 0 numeric
when (ty == PrimType Metadata || ty == PrimType Void)
(fail "invalid record")
cxt <- getContext
ix <- field 1 numeric
let tv = forwardRef cxt ix vt
return $! updateMetadataTable (addMdValue tv) pm
-- [n x md num]
3 -> label "METADATA_NODE" (parseMetadataNode False mt r pm)
-- [values]
4 -> label "METADATA_NAME" $ do
name <- fmap UTF8.decode (parseFields r 0 char) `mplus` parseField r 0 cstring
return $! setNextName name pm
-- [n x md num]
5 -> label "METADATA_DISTINCT_NODE" (parseMetadataNode True mt r pm)
-- [n x [id, name]]
6 -> label "METADATA_KIND" $ do
kind <- parseField r 0 numeric
name <- UTF8.decode <$> parseFields r 1 char
addKind kind name
return pm
-- [distinct, line, col, scope, inlined-at?]
7 -> label "METADATA_LOCATION" $ do
-- TODO: broken in 3.7+; needs to be a DILocation rather than an
-- MDLocation, but there appears to be no difference in the
-- bitcode. /sigh/
assertRecordSizeIn [5, 6]
let field = parseField r
cxt <- getContext
isDistinct <- field 0 nonzero
dlLine <- field 1 numeric
dlCol <- field 2 numeric
dlScope <- mdForwardRef cxt mt <$> field 3 numeric
dlIA <- mdForwardRefOrNull cxt mt <$> field 4 numeric
dlImplicit <- if length (recordFields r) <= 5
then pure False
else parseField r 5 nonzero
let loc = DebugLoc {..}
return $! updateMetadataTable (addLoc isDistinct loc) pm
-- [n x (type num, value num)]
8 -> label "METADATA_OLD_NODE" (parseMetadataOldNode False vt mt r pm)
-- [n x (type num, value num)]
9 -> label "METADATA_OLD_FN_NODE" (parseMetadataOldNode True vt mt r pm)
-- [n x mdnodes]
10 -> label "METADATA_NAMED_NODE" $ do
mdIds <- parseFields r 0 numeric
cxt <- getContext
let ids = map (mdNodeRef cxt mt) mdIds
nameMetadata ids pm
-- [m x [value, [n x [id, mdnode]]]
11 -> label "METADATA_ATTACHMENT" $ do
let recordSize = length (recordFields r)
when (recordSize == 0)
(fail "Invalid record")
if recordSize `mod` 2 == 0
then label "function attachment" $ do
att <- Map.fromList <$> parseAttachment r 0
return $! addFnAttachment att pm
else label "instruction attachment" $ do
inst <- parseField r 0 numeric
patt <- parseAttachment r 1
att <- mapM (\(k,md) -> (,md) <$> getKind k) patt
return $! addInstrAttachment inst att pm
12 -> label "METADATA_GENERIC_DEBUG" $ do
--isDistinct <- parseField r 0 numeric
--tag <- parseField r 1 numeric
--version <- parseField r 2 numeric
--header <- parseField r 3 string
-- TODO: parse all remaining fields
fail "not yet implemented"
13 -> label "METADATA_SUBRANGE" $ do
assertRecordSizeIn [3, 5]
field0 <- parseField r 0 unsigned
let isDistinct = field0 .&. 0 == 1
-- The format field determines what set of fields are contained in this
-- record and what their types are (see
-- https://github.com/llvm/llvm-project/blob/bbe8cd13/llvm/lib/Bitcode/Reader/MetadataLoader.cpp#L1437-L1444).
let format = field0 `shiftR` 1
let asValMdInt64 x = Just $ ValMdValue
$ Typed { typedType = PrimType $ Integer 64
, typedValue = ValInteger x
}
diNode <- case format of
2 -> do disrCount <- ron 1
disrLowerBound <- ron 2
disrUpperBound <- ron 3
disrStride <- ron 4
return $ DISubrange {..}
1 -> do disrCount <- ron 1
disrLowerBound <- ron 2
let disrUpperBound = Nothing
let disrStride = Nothing
return $ DISubrange {..}
0 -> do disrCount <- asValMdInt64 <$> parseField r 1 numeric
disrLowerBound <- asValMdInt64 . fromIntegral <$> parseField r 2 signedInt64
let disrUpperBound = Nothing
let disrStride = Nothing
return $ DISubrange {..}
_ -> fail $ "Unknown format: " <> show format
return $! updateMetadataTable
(addDebugInfo isDistinct (DebugInfoSubrange diNode)) pm
-- [isBigInt|isUnsigned|distinct, value, name]
14 -> label "METADATA_ENUMERATOR" $ do
assertRecordSizeAtLeast 3
ctx <- getContext
flags <- parseField r 0 numeric
let isDistinct = testBit (flags :: Int) 0
isUnsigned = testBit (flags :: Int) 1
isBigInt = testBit (flags :: Int) 2
name <- mdString ctx pm <$> parseField r 2 numeric
value <-
if isBigInt
-- LLVM 12 or later
then parseWideInteger r 3
-- Pre-LLVM 12
else toInteger <$> parseField r 1 signedInt64
let diEnum = DebugInfoEnumerator name value isUnsigned
return $! updateMetadataTable (addDebugInfo isDistinct diEnum) pm
15 -> label "METADATA_BASIC_TYPE" $ do
assertRecordSizeIn [6, 7]
ctx <- getContext
isDistinct <- parseField r 0 nonzero
dibtTag <- parseField r 1 numeric
dibtName <- mdString ctx pm <$> parseField r 2 numeric
dibtSize <- parseField r 3 numeric
dibtAlign <- parseField r 4 numeric
dibtEncoding <- parseField r 5 numeric
dibtFlags <- if length (recordFields r) <= 6
then pure Nothing
else Just <$> parseField r 6 numeric
let dibt = DIBasicType {..}
return $! updateMetadataTable
(addDebugInfo isDistinct (DebugInfoBasicType dibt)) pm
-- [distinct, filename, directory]
16 -> label "METADATA_FILE" $ do
assertRecordSizeIn [3, 5]
ctx <- getContext
isDistinct <- parseField r 0 nonzero
difFilename <- mdStringOrEmpty ctx pm <$> parseField r 1 numeric
difDirectory <- mdStringOrEmpty ctx pm <$> parseField r 2 numeric
let diFile = DIFile {..}
return $! updateMetadataTable
(addDebugInfo isDistinct (DebugInfoFile diFile)) pm
17 -> label "METADATA_DERIVED_TYPE" $ do
-- While upstream LLVM currently imposes a maximum of 14 records per
-- entry, we raise this to 15 for the sake of parsing Apple LLVM.
-- See Note [Apple LLVM].
assertRecordSizeBetween 12 15
ctx <- getContext
isDistinct <- parseField r 0 nonzero
didtTag <- parseField r 1 numeric
didtName <- mdStringOrNull ctx pm <$> parseField r 2 numeric
didtFile <- ron 3
didtLine <- parseField r 4 numeric
didtScope <- ron 5
didtBaseType <- ron 6
didtSize <- parseField r 7 numeric
didtAlign <- parseField r 8 numeric
didtOffset <- parseField r 9 numeric
didtFlags <- parseField r 10 numeric
didtExtraData <- ron 11
didtDwarfAddressSpace <-
if length (recordFields r) <= 12
then pure Nothing -- field not present
else do v <- parseField r 12 numeric
-- dwarf address space is encoded in bitcode as +1; a value of
-- zero means there is no dwarf address space present:
-- https://github.com/llvm/llvm-project/blob/bbe8cd1/llvm/lib/Bitcode/Reader/MetadataLoader.cpp#L1544-L1548
-- The AST representation is the actual address space, or Nothing
-- if there is no address space (indistinguishable from "field
-- not present" for LLVM 4 and earlier).
if v == 0
then return Nothing
else return $ Just $ v - 1
didtAnnotations <- if length (recordFields r) <= 13
then pure Nothing
else ron 13
let didt = DIDerivedType {..}
return $! updateMetadataTable
(addDebugInfo isDistinct (DebugInfoDerivedType didt)) pm
18 -> label "METADATA_COMPOSITE_TYPE" $ do
assertRecordSizeBetween 16 22
ctx <- getContext
isDistinct <- parseField r 0 nonzero
dictTag <- parseField r 1 numeric
dictName <- mdStringOrNull ctx pm <$> parseField r 2 numeric
dictFile <- ron 3
dictLine <- parseField r 4 numeric
dictScope <- ron 5
dictBaseType <- ron 6
dictSize <- parseField r 7 numeric
dictAlign <- parseField r 8 numeric
dictOffset <- parseField r 9 numeric
dictFlags <- parseField r 10 numeric
dictElements <- ron 11
dictRuntimeLang <- parseField r 12 numeric
dictVTableHolder <- ron 13
dictTemplateParams <- ron 14
dictIdentifier <- mdStringOrNull ctx pm <$> parseField r 15 numeric
dictDiscriminator <- if length (recordFields r) <= 16
then pure Nothing
else ron 16
dictDataLocation <- if length (recordFields r) <= 17
then pure Nothing
else ron 17
dictAssociated <- if length (recordFields r) <= 18
then pure Nothing
else ron 18
dictAllocated <- if length (recordFields r) <= 19
then pure Nothing
else ron 19
dictRank <- if length (recordFields r) <= 20
then pure Nothing
else ron 20
dictAnnotations <- if length (recordFields r) <= 21
then pure Nothing
else ron 21
let dict = DICompositeType {..}
return $! updateMetadataTable
(addDebugInfo isDistinct (DebugInfoCompositeType dict)) pm
19 -> label "METADATA_SUBROUTINE_TYPE" $ do
assertRecordSizeBetween 3 4
isDistinct <- parseField r 0 nonzero
distFlags <- parseField r 1 numeric
distTypeArray <- ron 2
let dist = DISubroutineType {..}
return $! updateMetadataTable
(addDebugInfo isDistinct (DebugInfoSubroutineType dist)) pm
20 -> label "METADATA_COMPILE_UNIT" $ do
assertRecordSizeBetween 14 22
let recordSize = length (recordFields r)
ctx <- getContext
isDistinct <- parseField r 0 nonzero
dicuLanguage <- parseField r 1 numeric
dicuFile <- ron 2
dicuProducer <- mdStringOrNull ctx pm <$> parseField r 3 numeric
dicuIsOptimized <- parseField r 4 nonzero
dicuFlags <- mdStringOrNull ctx pm <$> parseField r 5 numeric
dicuRuntimeVersion <- parseField r 6 numeric
dicuSplitDebugFilename <- mdStringOrNull ctx pm <$> parseField r 7 numeric
dicuEmissionKind <- parseField r 8 numeric
dicuEnums <- ron 9
dicuRetainedTypes <- ron 10
dicuSubprograms <- ron 11
dicuGlobals <- ron 12
dicuImports <- ron 13
dicuMacros <- if recordSize <= 15
then pure Nothing
else ron 15
dicuDWOId <- if recordSize <= 14
then pure 0
else parseField r 14 numeric
dicuSplitDebugInlining <- if recordSize <= 16
then pure True
else parseField r 16 nonzero
dicuDebugInfoForProf <- if recordSize <= 17
then pure False
else parseField r 17 nonzero
dicuNameTableKind <- if recordSize <= 18
then pure 0
else parseField r 18 numeric
dicuRangesBaseAddress <- if recordSize <= 19
then pure False
else parseField r 19 nonzero
dicuSysRoot <- if recordSize <= 20
then pure Nothing
else mdStringOrNull ctx pm <$> parseField r 20 numeric
dicuSDK <- if recordSize <= 21
then pure Nothing
else mdStringOrNull ctx pm <$> parseField r 21 numeric
let dicu = DICompileUnit {..}
return $! updateMetadataTable
(addDebugInfo isDistinct (DebugInfoCompileUnit dicu)) pm
21 -> label "METADATA_SUBPROGRAM" $ do
-- this one is a bit funky:
-- https://github.com/llvm/llvm-project/blob/release/10.x/llvm/lib/Bitcode/Reader/MetadataLoader.cpp#L1486
assertRecordSizeBetween 18 21
-- A "version" is encoded in the high-order bits of the isDistinct field.
version <- parseField r 0 numeric
let hasSPFlags = (version .&. (0x4 :: Word64)) /= 0;
(diFlags0, spFlags0) <-
if hasSPFlags then
(,) <$> parseField r 11 numeric <*> parseField r 9 numeric
else
(,) <$> parseField r (11 + 2) numeric <*> pure 0
let diFlagMainSubprogram = bit 21 :: Word32
hasOldMainSubprogramFlag = (diFlags0 .&. diFlagMainSubprogram) /= 0
-- CF https://github.com/llvm/llvm-project/blob/release/10.x/llvm/include/llvm/IR/DebugInfoFlags.def
spFlagIsLocal = bit 2
spFlagIsDefinition = bit 3
spFlagIsOptimized = bit 4
spFlagIsMain = bit 8
dispFlags :: Word32
dispFlags
| hasOldMainSubprogramFlag = diFlags0 .&. complement diFlagMainSubprogram
| otherwise = diFlags0
spFlags :: Word32
spFlags
| hasOldMainSubprogramFlag = spFlags0 .|. spFlagIsMain
| otherwise = spFlags0
-- TODO, isMain isn't exposed via DISubprogram
(dispIsLocal, dispIsDefinition, dispIsOptimized, dispVirtuality, _isMain) <-
if hasSPFlags then
let spIsLocal = spFlags .&. spFlagIsLocal /= 0
spIsDefinition = spFlags .&. spFlagIsDefinition /= 0
spIsOptimized = spFlags .&. spFlagIsOptimized /= 0
spIsMain = spFlags .&. spFlagIsMain /= 0
spVirtuality :: Word8
spVirtuality = fromIntegral (spFlags .&. 0x3)
in return (spIsLocal, spIsDefinition, spIsOptimized, spVirtuality, spIsMain)
else
do spIsLocal <- parseField r 7 nonzero
spIsDefinition <- parseField r 8 nonzero
spIsOptimized <- parseField r 14 nonzero
spVirtuality <- parseField r 11 numeric
return (spIsLocal, spIsDefinition, spIsOptimized, spVirtuality, hasOldMainSubprogramFlag)
let recordSize = length (recordFields r)
isDistinct = (version .&. 0x1 /= 0) || (spFlags .&. spFlagIsDefinition /= 0)
hasUnit = version .&. 0x2 /= 0
offsetA
| not hasSPFlags = 2
| otherwise = 0
offsetB
| not hasSPFlags && recordSize >= 19 = 3
| not hasSPFlags = 2
| otherwise = 0
-- this doesn't seem to be used in our parser...
--hasFn
-- | not hasSPFlags && recordSize >= 19 = not hasUnit
-- | otherwise = False
hasThisAdjustment
| not hasSPFlags = recordSize >= 20
| otherwise = True
hasThrownTypes
| not hasSPFlags = recordSize >= 21
| otherwise = True
hasAnnotations
| not hasSPFlags = False
| otherwise = recordSize >= 19
-- Some additional sanity checking
when (not hasSPFlags && hasUnit)
(assertRecordSizeBetween 19 21)
when (hasSPFlags && not hasUnit)
(fail "DISubprogram record has subprogram flags, but does not have unit. Invalid record.")
ctx <- getContext
-- Forward references that depend on the 'version'
let optFwdRef b n =
if b
then mdForwardRefOrNull ctx mt <$> parseField r n numeric
else pure Nothing
dispScope <- ron 1
dispName <- mdStringOrNull ctx pm <$> parseField r 2 numeric
dispLinkageName <- mdStringOrNull ctx pm <$> parseField r 3 numeric
dispFile <- ron 4
dispLine <- parseField r 5 numeric
dispType <- ron 6
dispScopeLine <- parseField r (7 + offsetA) numeric
dispContainingType <- ron (8 + offsetA)
dispVirtualIndex <- parseField r (10 + offsetA) numeric
dispThisAdjustment <- if hasThisAdjustment
then parseField r (16 + offsetB) numeric
else return 0
dispUnit <- optFwdRef hasUnit (12 + offsetB)
dispTemplateParams <- ron (13 + offsetB)
dispDeclaration <- ron (14 + offsetB)
dispRetainedNodes <- ron (15 + offsetB)
dispThrownTypes <- optFwdRef hasThrownTypes (17 + offsetB)
dispAnnotations <- optFwdRef hasAnnotations (18 + offsetB)
let disp = DISubprogram {..}
-- TODO: in the LLVM parser, it then goes into the metadata table
-- and updates function entries to point to subprograms. Is that
-- neccessary for us?
return $! updateMetadataTable
(addDebugInfo isDistinct (DebugInfoSubprogram disp)) pm
22 -> label "METADATA_LEXICAL_BLOCK" $ do
assertRecordSizeIn [5]
isDistinct <- parseField r 0 nonzero
dilbScope <- ron 1
dilbFile <- ron 2
dilbLine <- parseField r 3 numeric
dilbColumn <- parseField r 4 numeric
let dilb = DILexicalBlock {..}
return $! updateMetadataTable
(addDebugInfo isDistinct (DebugInfoLexicalBlock dilb)) pm
23 -> label "METADATA_LEXICAL_BLOCK_FILE" $ do
assertRecordSizeIn [4]
cxt <- getContext
isDistinct <- parseField r 0 nonzero
dilbfScope <- mdForwardRef cxt mt <$> parseField r 1 numeric
dilbfFile <- ron 2
dilbfDiscriminator <- parseField r 3 numeric
let dilbf = DILexicalBlockFile {..}
return $! updateMetadataTable
(addDebugInfo isDistinct (DebugInfoLexicalBlockFile dilbf)) pm
24 -> label "METADATA_NAMESPACE" $ do
assertRecordSizeIn [3, 5]
let isNew = length (recordFields r) == 3
let nameIdx = if isNew then 2 else 3
cxt <- getContext
isDistinct <- parseField r 0 nonzero
dinsName <- mdStringOrNull cxt pm <$> parseField r nameIdx numeric
dinsScope <- mdForwardRef cxt mt <$> parseField r 1 numeric
dinsFile <- if isNew
then return (ValMdString "")
else mdForwardRef cxt mt <$> parseField r 2 numeric
dinsLine <- if isNew then return 0 else parseField r 4 numeric
let dins = DINameSpace {..}
return $! updateMetadataTable
(addDebugInfo isDistinct (DebugInfoNameSpace dins)) pm
25 -> label "METADATA_TEMPLATE_TYPE" $ do
assertRecordSizeIn [3, 4]
let hasIsDefault = length (recordFields r) == 4
cxt <- getContext
isDistinct <- parseField r 0 nonzero
dittpName <- mdStringOrNull cxt pm <$> parseField r 1 numeric
dittpType <- ron 2
dittpIsDefault <- if hasIsDefault
then Just <$> parseField r 3 boolean
else pure Nothing
let dittp = DITemplateTypeParameter {..}
return $! updateMetadataTable
(addDebugInfo isDistinct (DebugInfoTemplateTypeParameter dittp)) pm
26 -> label "METADATA_TEMPLATE_VALUE" $ do
assertRecordSizeIn [5, 6]
let hasIsDefault = length (recordFields r) == 6
cxt <- getContext
isDistinct <- parseField r 0 nonzero
ditvpTag <- parseField r 1 numeric
ditvpName <- mdStringOrNull cxt pm <$> parseField r 2 numeric
ditvpType <- ron 3
ditvpIsDefault <- if hasIsDefault
then Just <$> parseField r 4 boolean
else pure Nothing
ditvpValue <- mdForwardRef cxt mt <$> parseField r (if hasIsDefault then 5 else 4) numeric
let ditvp = DITemplateValueParameter {..}
return $! updateMetadataTable
(addDebugInfo isDistinct (DebugInfoTemplateValueParameter ditvp)) pm
27 -> label "METADATA_GLOBAL_VAR" $ do
assertRecordSizeBetween 11 13
ctx <- getContext
field0 <- parseField r 0 numeric
let isDistinct = testBit field0 0
_version = shiftR field0 1 :: Int
digvScope <- ron 1
digvName <- mdStringOrNull ctx pm <$> parseField r 2 numeric
digvLinkageName <- mdStringOrNull ctx pm <$> parseField r 3 numeric
digvFile <- ron 4
digvLine <- parseField r 5 numeric
digvType <- ron 6
digvIsLocal <- parseField r 7 nonzero
digvIsDefinition <- parseField r 8 nonzero
digvVariable <- ron 9
digvDeclaration <- ron 10
digvAlignment <- if length (recordFields r) > 11
then Just <$> parseField r 11 numeric
else pure Nothing
digvAnnotations <- if length (recordFields r) > 12
then ron 12
else pure Nothing
let digv = DIGlobalVariable {..}
return $! updateMetadataTable
(addDebugInfo isDistinct (DebugInfoGlobalVariable digv)) pm
28 -> label "METADATA_LOCAL_VAR" $ do
-- this one is a bit funky:
-- https://github.com/llvm-mirror/llvm/blob/release_38/lib/Bitcode/Reader/BitcodeReader.cpp#L2308
assertRecordSizeBetween 8 10
ctx <- getContext
field0 <- parseField r 0 numeric
let isDistinct = testBit (field0 :: Word32) 0
hasAlignment = testBit (field0 :: Word32) 1
hasTag | not hasAlignment && length (recordFields r) > 8 = 1
| otherwise = 0
adj i = i + hasTag
dilvScope <- mdForwardRefOrNull ("dilvScope":ctx) mt
<$> parseField r (adj 1) numeric
dilvName <- mdStringOrNull ("dilvName" :ctx) pm
<$> parseField r (adj 2) numeric
dilvFile <- mdForwardRefOrNull ("dilvFile" :ctx) mt
<$> parseField r (adj 3) numeric
dilvLine <- parseField r (adj 4) numeric
dilvType <- mdForwardRefOrNull ("dilvType" :ctx) mt
<$> parseField r (adj 5) numeric
dilvArg <- parseField r (adj 6) numeric
dilvFlags <- parseField r (adj 7) numeric
dilvAlignment <-
if hasAlignment
then do n <- parseField r 8 numeric
when ((n :: Word64) > fromIntegral (maxBound :: Word32))
(fail "Alignment value is too large")
return $ Just (fromIntegral n :: Word32)
else return Nothing
dilvAnnotations <- if hasAlignment && length (recordFields r) > 9
then ron 9
else pure Nothing
let dilv = DILocalVariable {..}
return $! updateMetadataTable
(addDebugInfo isDistinct (DebugInfoLocalVariable dilv)) pm
29 -> label "METADATA_EXPRESSION" $ do
{-
Although DIExpressions store an `isDistinct` field in LLVM bitcode, it is
never used in practice. This is because DIExpressions are always printed
inline in definitions, and since the `distinct` keyword is only printed in
top-level metadata lists, there is no way for `distinct` to be printed
before a DIExpression. See also Note [Printing metadata inline].
-}
-- isDistinct <- parseField r 0 nonzero
diExpr <- DebugInfoExpression . DIExpression <$> parseFields r 1 numeric
return $! updateMetadataTable (addInlineDebugInfo diExpr) pm
30 -> label "METADATA_OBJC_PROPERTY" $ do
-- TODO
fail "not yet implemented"
31 -> label "METADATA_IMPORTED_ENTITY" $ do
assertRecordSizeIn [6, 7]
cxt <- getContext
isDistinct <- parseField r 0 nonzero
diieTag <- parseField r 1 numeric
diieScope <- ron 2
diieEntity <- ron 3
diieFile <- if length (recordFields r) >= 7
then ron 6
else pure Nothing
diieLine <- parseField r 4 numeric
diieName <- mdStringOrNull cxt pm <$> parseField r 5 numeric
let diie = DIImportedEntity {..}
return $! updateMetadataTable
(addDebugInfo isDistinct (DebugInfoImportedEntity diie)) pm
32 -> label "METADATA_MODULE" $ do
-- cxt <- getContext
-- isDistinct <- parseField r 0 numeric
-- mdForwardRefOrNull cxt mt <$> parseField r 1 numeric
-- parseField r 2 string
-- parseField r 3 string
-- parseField r 4 string
-- parseField r 5 string
-- TODO
fail "not yet implemented"
33 -> label "METADATA_MACRO" $ do
-- isDistinct <- parseField r 0 numeric
-- parseField r 1 numeric
-- parseField r 2 numeric
-- parseField r 3 string
-- parseField r 4 string
-- TODO
fail "not yet implemented"
34 -> label "METADATA_MACRO_FILE" $ do
-- cxt <- getContext
-- isDistinct <- parseField r 0 numeric
-- parseField r 1 numeric
-- parseField r 2 numeric
-- mdForwardRefOrNull cxt mt <$> parseField r 3 numeric
-- mdForwardRefOrNull cxt mt <$> parseField r 4 numeric
-- TODO
fail "not yet implemented"
35 -> label "METADATA_STRINGS" $ do
assertRecordSizeIn [3]
count <- parseField r 0 numeric
offset <- parseField r 1 numeric
bs <- parseField r 2 fieldBlob
when (count == 0)
(fail "Invalid record: metadata strings with no strings")
when (offset > S.length bs)
(fail "Invalid record: metadata strings corrupt offset")
let (bsLengths, bsStrings) = S.splitAt offset bs
lengths <- either fail return $ parseMetadataStringLengths count bsLengths
when (sum lengths > S.length bsStrings)
(fail "Invalid record: metadata strings truncated")
let strings = snd (mapAccumL f bsStrings lengths)
where f s i = case S.splitAt i s of
(str, rest) -> (rest, Char8.unpack str)
return $! addStrings strings pm
-- [ valueid, n x [id, mdnode] ]
36 -> label "METADATA_GLOBAL_DECL_ATTACHMENT" $ do
-- the record will always be of odd length
when (mod (length (recordFields r)) 2 == 0)
(fail "Invalid record")
valueId <- parseField r 0 numeric
sym <- case lookupValueTableAbs valueId vt of
Just (Typed { typedValue = ValSymbol sym }) -> return sym
_ -> fail "Non-global referenced"
refs <- parseGlobalObjectAttachment mt r
return $! addGlobalAttachments sym refs pm
37 -> label "METADATA_GLOBAL_VAR_EXPR" $ do
assertRecordSizeIn [3]
isDistinct <- parseField r 0 nonzero
digveVariable <- ron 1
digveExpression <- ron 2
let digve = DIGlobalVariableExpression {..}
return $! updateMetadataTable
(addDebugInfo isDistinct (DebugInfoGlobalVariableExpression digve)) pm
38 -> label "METADATA_INDEX_OFFSET" $ do
assertRecordSizeIn [2]
a <- parseField r 0 numeric
b <- parseField r 1 numeric
let _offset = a + (b `shiftL` 32) :: Word64
-- TODO: is it OK to skip this if we always parse everything?
return pm
-- In the llvm source, this node is processed when the INDEX_OFFSET record is
-- found.
39 -> label "METADATA_INDEX" $ do
-- TODO: is it OK to skip this if we always parse everything?
return pm
40 -> label "METADATA_LABEL" $ do
assertRecordSizeIn [5]
cxt <- getContext
isDistinct <- parseField r 0 nonzero
dilScope <- ron 1
dilName <- mdString cxt pm <$> parseField r 2 numeric
dilFile <- ron 3
dilLine <- parseField r 4 numeric
let dil = DILabel {..}
return $! updateMetadataTable
(addDebugInfo isDistinct (DebugInfoLabel dil)) pm
41 -> label "METADATA_STRING_TYPE" $ do
notImplemented
-- Codes 42 and 43 are reserved for Fortran array–specific debug info, see
-- https://github.com/llvm/llvm-project/blob/4681f6111e655057f5015564a9bf3705f87495bf/llvm/include/llvm/Bitcode/LLVMBitCodes.h#L348-L349
44 -> label "METADATA_COMMON_BLOCK" $ do
notImplemented
45 -> label "METADATA_GENERIC_SUBRANGE" $ do
notImplemented
46 -> label "METADATA_ARG_LIST" $ do
cxt <- getContext
dial <- DIArgList
<$> (map (mdForwardRef cxt mt) <$> parseFields r 0 numeric)
return $! updateMetadataTable
(addInlineDebugInfo (DebugInfoArgList dial)) pm
code -> fail ("unknown record code: " ++ show code)
parseMetadataEntry _ _ pm (abbrevDef -> Just _) =
return pm
parseMetadataEntry _ _ _ r =
fail ("unexpected metadata entry: " ++ show r)
parseAttachment :: Record -> Int -> Parse [(PKindMd,PValMd)]
parseAttachment r l = loop (length (recordFields r) - 1) []
where
loop n acc | n < l = return acc
| otherwise = do
kind <- parseField r (n - 1) numeric
md <- getMetadata =<< parseField r n numeric
loop (n - 2) ((kind,typedValue md) : acc)
-- | This is a named version of the metadata list that can show up at the end of
-- a global declaration. It will be of the form @!dbg !2 [!dbg !n, ...]@.
parseGlobalObjectAttachment :: MetadataTable -> Record -> Parse (Map.Map KindMd PValMd)
parseGlobalObjectAttachment mt r = label "parseGlobalObjectAttachment" $
do cxt <- getContext
go cxt Map.empty 1
where
len = length (recordFields r)
go cxt acc n | n < len =
do kind <- getKind =<< parseField r n numeric
i <- parseField r (n + 1) numeric
go cxt (Map.insert kind (mdForwardRef cxt mt i) acc) (n + 2)
go _ acc _ =
return acc
-- | Parse a metadata node.
parseMetadataNode :: Bool -> MetadataTable -> Record -> PartialMetadata
-> Parse PartialMetadata
parseMetadataNode isDistinct mt r pm = do
ixs <- parseFields r 0 numeric
cxt <- getContext
let lkp = mdForwardRefOrNull cxt mt
return $! updateMetadataTable (addNode isDistinct (map lkp ixs)) pm
-- | Parse out a metadata node in the old format.
parseMetadataOldNode :: Bool -> ValueTable -> MetadataTable -> Record
-> PartialMetadata -> Parse PartialMetadata
parseMetadataOldNode fnLocal vt mt r pm = do
values <- loop =<< parseFields r 0 numeric
return $! updateMetadataTable (addOldNode fnLocal values) pm
where
loop fs = case fs of
tyId:valId:rest -> do
cxt <- getContext
ty <- getType' tyId
val <- case ty of
PrimType Metadata -> return $ Typed (PrimType Metadata)
(ValMd (mdForwardRef cxt mt valId))
-- XXX need to check for a void type here
_ -> return (forwardRef cxt valId vt)
vals <- loop rest
return (val:vals)
[] -> return []
_ -> fail "Malformed metadata node"
parseMetadataKindEntry :: Record -> Parse ()
parseMetadataKindEntry r = do
kind <- parseField r 0 numeric
name <- parseFields r 1 char
addKind kind (UTF8.decode name)
{-
Note [Apple LLVM]
~~~~~~~~~~~~~~~~~
Apple maintains a fork of LLVM, whose source code can be found at
https://github.com/apple/llvm-project. The version of Clang that is shipped
with Xcode, and thereby the de facto default Clang version on macOS, is based
on this LLVM fork. To distinguish between the two LLVM codebases, we will refer
to "upstream LLVM" and "Apple LLVM" throughout this Note.
One of the more noticeable differences between upstream and Apple LLVM is that
Apple LLVM uses a slightly different bitcode format. In particular, Apple LLVM
has support for pointer authentication
(https://lists.llvm.org/pipermail/llvm-dev/2019-October/136091.html), which
requires adding an extra record to the METADATA_DERIVED_TYPE entry that is not
present in upstream LLVM. This impacts llvm-pretty-bc-parser, as we currently
check that the number of records does not exceed a certain maximum, but this
maximum is different depending on whether we parse upstream or Apple LLVM
bitcode.
For now, we work around this issue by raising the maximum number of
METADATA_DERIVED_TYPE records by one to accommodate Apple LLVM, but we do not
actually parse any information related to pointer authentication. This should
work provided that Apple LLVM continues to encode pointer authentication–related
metadata in the same part of METADATA_DERIVED_TYPE in future releases. If this
assumption does not hold true in the future, we will likely need a more
sophisticated solution that involves parsing the bitcode differently depending
on what Apple LLVM version was used to produce a bitcode file.
Note [Printing metadata inline]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
There are some forms of metadata that we should always print inline and never
create entries for in top-level metadata lists (named or otherwise). Currently,
these forms of metadata are:
* DIExpression
* DIArgList
This list is taken from the LLVM source code here:
https://github.com/llvm/llvm-project/blob/65600cb2a7e940babf6c493503b9d3fd19f8cb06/llvm/lib/IR/AsmWriter.cpp#L1242-L1245
Implementation-wise, this is accomplished by using `addInlineDebugInfo`. Unlike
`addDebugInfo`, this inserts the metadata field into a separate `mtEntries` map
that is not used to populate top-level metadata lists when pretty-printing an
LLVM module.
-}