[Git][ghc/ghc][wip/T17609] nativeGen: Deduplicate DWARF strings
Ben Gamari
gitlab at gitlab.haskell.org
Thu Apr 30 16:02:17 UTC 2020
Ben Gamari pushed to branch wip/T17609 at Glasgow Haskell Compiler / GHC
Commits:
a78ef103 by Ben Gamari at 2020-04-30T12:02:11-04:00
nativeGen: Deduplicate DWARF strings
As noted in #17609, we previously made no attempt to deduplicate
strings. This resulted in unnecessarily long compile times and large
object files. Fix this.
Fixes #17609.
- - - - -
3 changed files:
- compiler/GHC/CmmToAsm/Dwarf.hs
- compiler/GHC/CmmToAsm/Dwarf/Constants.hs
- compiler/GHC/CmmToAsm/Dwarf/Types.hs
Changes:
=====================================
compiler/GHC/CmmToAsm/Dwarf.hs
=====================================
@@ -10,9 +10,10 @@ import Config ( cProjectName, cProjectVersion )
import GHC.Core ( Tickish(..) )
import GHC.Cmm.DebugBlock
import GHC.Driver.Session
-import GHC.Types.Module
import Outputable
import GHC.Platform
+import GHC.Types.Module
+import GHC.Types.SrcLoc
import GHC.Types.Unique
import GHC.Types.Unique.Supply
@@ -47,11 +48,12 @@ dwarfGen df modLoc us blocks = do
compPath <- getCurrentDirectory
let lowLabel = dblCLabel $ head procs
highLabel = mkAsmTempEndLabel $ dblCLabel $ last procs
+ producer = dwarfStringFromString $ cProjectName ++ " " ++ cProjectVersion
dwarfUnit = DwarfCompileUnit
{ dwChildren = map (procToDwarf df) (map stripBlocks procs)
- , dwName = fromMaybe "" (ml_hs_file modLoc)
- , dwCompDir = addTrailingPathSeparator compPath
- , dwProducer = cProjectName ++ " " ++ cProjectVersion
+ , dwName = dwarfStringFromString $ fromMaybe "" (ml_hs_file modLoc)
+ , dwCompDir = dwarfStringFromString $ addTrailingPathSeparator compPath
+ , dwProducer = producer
, dwLowLabel = lowLabel
, dwHighLabel = highLabel
, dwLineLabel = dwarfLineLabel
@@ -77,6 +79,9 @@ dwarfGen df modLoc us blocks = do
, compileUnitFooter unitU
]
+ -- .debug_str section: Strings
+ let stringsSct = dwarfStringsSection (dwarfInfoStrings dwarfUnit)
+
-- .debug_line section: Generated mainly by the assembler, but we
-- need to label it
let lineSct = dwarfLineSection platform $$
@@ -93,7 +98,7 @@ dwarfGen df modLoc us blocks = do
| otherwise = [DwarfARange lowLabel highLabel]
let aranges = dwarfARangesSection platform $$ pprDwarfARanges platform aranges' unitU
- return (infoSct $$ abbrevSct $$ lineSct $$ frameSct $$ aranges, us'')
+ return (infoSct $$ stringsSct $$ abbrevSct $$ lineSct $$ frameSct $$ aranges, us'')
-- | Build an address range entry for one proc.
-- With split sections, each proc needs its own entry, since they may get
@@ -178,7 +183,7 @@ parent, B.
procToDwarf :: DynFlags -> DebugBlock -> DwarfInfo
procToDwarf df prc
= DwarfSubprogram { dwChildren = map blockToDwarf (dblBlocks prc)
- , dwName = case dblSourceTick prc of
+ , dwName = dwarfStringFromString $ case dblSourceTick prc of
Just s at SourceNote{} -> sourceName s
_otherwise -> showSDocDump df $ ppr $ dblLabel prc
, dwLabel = dblCLabel prc
@@ -209,7 +214,13 @@ blockToDwarf blk
| otherwise = Nothing -- block was optimized out
tickToDwarf :: Tickish () -> [DwarfInfo]
-tickToDwarf (SourceNote ss _) = [DwarfSrcNote ss]
+tickToDwarf (SourceNote ss _) =
+ [DwarfSrcNote { dwSpanFile = dwarfStringFromFastString (srcSpanFile ss)
+ , dwSpanStartLine = srcSpanStartLine ss
+ , dwSpanStartCol = srcSpanStartCol ss
+ , dwSpanEndLine = srcSpanEndLine ss
+ , dwSpanEndCol = srcSpanEndCol ss
+ }]
tickToDwarf _ = []
-- | Generates the data for the debug frame section, which encodes the
=====================================
compiler/GHC/CmmToAsm/Dwarf/Constants.hs
=====================================
@@ -86,12 +86,14 @@ dW_CHILDREN_no, dW_CHILDREN_yes :: Word8
dW_CHILDREN_no = 0
dW_CHILDREN_yes = 1
-dW_FORM_addr, dW_FORM_data2, dW_FORM_data4, dW_FORM_string, dW_FORM_flag,
+dW_FORM_addr, dW_FORM_data2, dW_FORM_data4,
+ dW_FORM_strp,dW_FORM_string, dW_FORM_flag,
dW_FORM_block1, dW_FORM_ref4, dW_FORM_ref_addr, dW_FORM_flag_present :: Word
dW_FORM_addr = 0x01
dW_FORM_data2 = 0x05
dW_FORM_data4 = 0x06
dW_FORM_string = 0x08
+dW_FORM_strp = 0x0e
dW_FORM_flag = 0x0c
dW_FORM_block1 = 0x0a
dW_FORM_ref_addr = 0x10
=====================================
compiler/GHC/CmmToAsm/Dwarf/Types.hs
=====================================
@@ -1,8 +1,16 @@
+{-# LANGUAGE RecordWildCards #-}
+
module GHC.CmmToAsm.Dwarf.Types
( -- * Dwarf information
DwarfInfo(..)
, pprDwarfInfo
, pprAbbrevDecls
+ , dwarfInfoStrings
+ -- * Dwarf Strings section
+ , DwarfString
+ , dwarfStringsSection
+ , dwarfStringFromString
+ , dwarfStringFromFastString
-- * Dwarf address range table
, DwarfARange(..)
, pprDwarfARanges
@@ -27,18 +35,14 @@ import GhcPrelude
import GHC.Cmm.DebugBlock
import GHC.Cmm.CLabel
import GHC.Cmm.Expr ( GlobalReg(..) )
-import Encoding
import FastString
import Outputable
import GHC.Platform
import GHC.Types.Unique
import GHC.Platform.Reg
-import GHC.Types.SrcLoc
-import Util
import GHC.CmmToAsm.Dwarf.Constants
-import qualified Data.ByteString as BS
import qualified Control.Monad.Trans.State.Strict as S
import Control.Monad (zipWithM, join)
import Data.Bits
@@ -48,18 +52,46 @@ import Data.Char
import GHC.Platform.Regs
+-- | A string in the DWARF @.debug_str@ section.
+newtype DwarfString = DwarfString FastString
+
+dwarfStringFromString :: String -> DwarfString
+dwarfStringFromString = dwarfStringFromFastString . fsLit
+
+dwarfStringFromFastString :: FastString -> DwarfString
+dwarfStringFromFastString = DwarfString
+
+dwarfStringSymbol :: DwarfString -> SDoc
+dwarfStringSymbol (DwarfString fs) =
+ text "_dbgfs_" <> ppr (getUnique fs)
+
+debugStrSection :: SDoc
+debugStrSection = text ".debug_str"
+
+pprDwarfString :: Platform -> DwarfString -> SDoc
+pprDwarfString plat s =
+ sectionOffset plat (dwarfStringSymbol s) debugStrSection
+
+dwarfStringsSection :: [DwarfString] -> SDoc
+dwarfStringsSection xs =
+ text ".section" <+> debugStrSection $$ hcat (map string xs)
+ where
+ string :: DwarfString -> SDoc
+ string dstr@(DwarfString fstr) =
+ dwarfStringSymbol dstr <> colon $$ pprFastString fstr
+
-- | Individual dwarf records. Each one will be encoded as an entry in
-- the @.debug_info@ section.
data DwarfInfo
= DwarfCompileUnit { dwChildren :: [DwarfInfo]
- , dwName :: String
- , dwProducer :: String
- , dwCompDir :: String
+ , dwName :: DwarfString
+ , dwProducer :: DwarfString
+ , dwCompDir :: DwarfString
, dwLowLabel :: CLabel
, dwHighLabel :: CLabel
, dwLineLabel :: PtrString }
| DwarfSubprogram { dwChildren :: [DwarfInfo]
- , dwName :: String
+ , dwName :: DwarfString
, dwLabel :: CLabel
, dwParent :: Maybe CLabel
-- ^ label of DIE belonging to the parent tick
@@ -68,9 +100,23 @@ data DwarfInfo
, dwLabel :: CLabel
, dwMarker :: Maybe CLabel
}
- | DwarfSrcNote { dwSrcSpan :: RealSrcSpan
+ | DwarfSrcNote { dwSpanFile :: !DwarfString
+ , dwSpanStartLine :: !Int
+ , dwSpanStartCol :: !Int
+ , dwSpanEndLine :: !Int
+ , dwSpanEndCol :: !Int
}
+-- | 'DwarfStrings' mentioned by the given 'DwarfInfo'.
+dwarfInfoStrings :: DwarfInfo -> [DwarfString]
+dwarfInfoStrings dwinfo =
+ case dwinfo of
+ DwarfCompileUnit {..} -> [dwName, dwProducer, dwCompDir] ++ foldMap dwarfInfoStrings dwChildren
+ DwarfSubprogram {..} -> [dwName] ++ foldMap dwarfInfoStrings dwChildren
+ DwarfBlock {..} -> foldMap dwarfInfoStrings dwChildren
+ DwarfSrcNote {..} -> [dwSpanFile]
+
+
-- | Abbreviation codes used for encoding above records in the
-- @.debug_info@ section.
data DwarfAbbrev
@@ -133,7 +179,7 @@ pprAbbrevDecls platform haveDebugLine =
, (dW_AT_high_pc, dW_FORM_addr)
] $$
mkAbbrev DwAbbrGhcSrcNote dW_TAG_ghc_src_note dW_CHILDREN_no
- [ (dW_AT_ghc_span_file, dW_FORM_string)
+ [ (dW_AT_ghc_span_file, dW_FORM_strp)
, (dW_AT_ghc_span_start_line, dW_FORM_data4)
, (dW_AT_ghc_span_start_col, dW_FORM_data2)
, (dW_AT_ghc_span_end_line, dW_FORM_data4)
@@ -163,10 +209,10 @@ pprDwarfInfoOpen :: Platform -> Bool -> DwarfInfo -> SDoc
pprDwarfInfoOpen platform haveSrc (DwarfCompileUnit _ name producer compDir lowLabel
highLabel lineLbl) =
pprAbbrev DwAbbrCompileUnit
- $$ pprString name
- $$ pprString producer
+ $$ pprDwarfString platform name
+ $$ pprDwarfString platform producer
$$ pprData4 dW_LANG_Haskell
- $$ pprString compDir
+ $$ pprDwarfString platform compDir
$$ pprWord platform (ppr lowLabel)
$$ pprWord platform (ppr highLabel)
$$ if haveSrc
@@ -176,7 +222,7 @@ pprDwarfInfoOpen platform _ (DwarfSubprogram _ name label
parent) = sdocWithDynFlags $ \df ->
ppr (mkAsmTempDieLabel label) <> colon
$$ pprAbbrev abbrev
- $$ pprString name
+ $$ pprDwarfString platform name
$$ pprString (renderWithStyle (initSDocContext df (mkCodeStyle CStyle)) (ppr label))
$$ pprFlag (externallyVisibleCLabel label)
$$ pprWord platform (ppr label)
@@ -199,13 +245,13 @@ pprDwarfInfoOpen platform _ (DwarfBlock _ label (Just marker)) = sdocWithDynFlag
$$ pprString (renderWithStyle (initSDocContext df (mkCodeStyle CStyle)) (ppr label))
$$ pprWord platform (ppr marker)
$$ pprWord platform (ppr $ mkAsmTempEndLabel marker)
-pprDwarfInfoOpen _ _ (DwarfSrcNote ss) =
+pprDwarfInfoOpen platform _ (DwarfSrcNote {..}) =
pprAbbrev DwAbbrGhcSrcNote
- $$ pprString' (ftext $ srcSpanFile ss)
- $$ pprData4 (fromIntegral $ srcSpanStartLine ss)
- $$ pprHalf (fromIntegral $ srcSpanStartCol ss)
- $$ pprData4 (fromIntegral $ srcSpanEndLine ss)
- $$ pprHalf (fromIntegral $ srcSpanEndCol ss)
+ $$ pprDwarfString platform dwSpanFile
+ $$ pprData4 (fromIntegral dwSpanStartLine)
+ $$ pprHalf (fromIntegral dwSpanStartCol)
+ $$ pprData4 (fromIntegral dwSpanEndLine)
+ $$ pprHalf (fromIntegral dwSpanEndCol)
-- | Close a DWARF info record with children
pprDwarfInfoClose :: SDoc
@@ -573,13 +619,13 @@ pprLEBInt x | x >= -64 && x < 64
pprString' :: SDoc -> SDoc
pprString' str = text "\t.asciz \"" <> str <> char '"'
+-- | Generate a string constant. We take care to escape the string.
+pprFastString :: FastString -> SDoc
+pprFastString = pprString' . hcat . map escapeChar . unpackFS
+
-- | Generate a string constant. We take care to escape the string.
pprString :: String -> SDoc
-pprString str
- = pprString' $ hcat $ map escapeChar $
- if str `lengthIs` utf8EncodedLength str
- then str
- else map (chr . fromIntegral) $ BS.unpack $ bytesFS $ mkFastString str
+pprString = pprFastString . mkFastString
-- | Escape a single non-unicode character
escapeChar :: Char -> SDoc
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/a78ef103f9c95f28929082f4fa402c684445b81f
--
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/a78ef103f9c95f28929082f4fa402c684445b81f
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