#9059: Excessive space usage while generating code for fractional literals with big exponents ------------------------------------+------------------------------------- Reporter: basvandijk | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.2 Keywords: | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ------------------------------------+------------------------------------- Generating (byte-)code for fractional literals with big exponents causes excessive space usage: {{{ $ ghci -ddump-bcos GHCi, version 7.6.3: http://www.haskell.org/ghc/ :? for help Loading package ghc-prim ... linking ... done. Loading package integer-gmp ... linking ... done. Loading package base ... linking ... done. Prelude> let r=1e1000 :: Rational ==================== Proto-BCOs ==================== ProtoBCO ExprTopLevel_E0#0 []: let sat_so4 = ... in ... bitmap: 0 [] ALLOC_AP 0 PUSH_BCO ProtoBCO sat_so4#0 []: let sat_snX = ... in ... bitmap: 0 [] PUSH_UBX (1) 1 PACK GHC.Integer.Type.S# 1 ALLOC_AP 0 PUSH_BCO ProtoBCO sat_snY#0 []: let sat_siH = ... in ... bitmap: 0 [] STKCHECK 544 PUSH_UBX (1) 30 PACK GHC.Types.I# 1 PUSH_G GHC.Types.[] PUSH_L 1 PACK : 2 PUSH_UBX (1) 953884573 PACK GHC.Types.I# 1 PUSH_LL 1 0 PACK : 2 PUSH_UBX (1) 1777164331 PACK GHC.Types.I# 1 PUSH_LL 1 0 PACK : 2 PUSH_UBX (1) 1665817172 PACK GHC.Types.I# 1 PUSH_LL 1 0 PACK : 2 PUSH_UBX (1) 1937337765 PACK GHC.Types.I# 1 PUSH_LL 1 0 PACK : 2 PUSH_UBX (1) 799142572 PACK GHC.Types.I# 1 PUSH_LL 1 0 PACK : 2 PUSH_UBX (1) 1439062260 PACK GHC.Types.I# 1 PUSH_LL 1 0 PACK : 2 PUSH_UBX (1) 1049546550 PACK GHC.Types.I# 1 PUSH_LL 1 0 PACK : 2 PUSH_UBX (1) 580758741 PACK GHC.Types.I# 1 PUSH_LL 1 0 PACK : 2 PUSH_UBX (1) 139570364 PACK GHC.Types.I# 1 PUSH_LL 1 0 PACK : 2 ... }}} Increasing the exponent to say a 1000000 will quickly fill up the memory of my machine. A similar problem occurs while compiling: !BigExponentBug.hs: {{{ module BigExponentBug (r) where r = 1e100 :: Rational }}} {{{ ghc --make BigExponentBug.hs -ddump-simpl [1 of 1] Compiling BigExponentBug ( BigExponentBug.hs, BigExponentBug.o ) ==================== Tidy Core ==================== Result size of Tidy Core = {terms: 9, types: 5, coercions: 0} BigExponentBug.r :: GHC.Real.Rational [GblId] BigExponentBug.r = GHC.Real.fromRational @ GHC.Real.Rational (GHC.Real.$fFractionalRatio @ GHC.Integer.Type.Integer (GHC.Real.$fNumRatio @ GHC.Integer.Type.Integer GHC.Real.$fIntegralInteger) GHC.Real.$fIntegralInteger) (GHC.Real.:% @ GHC.Integer.Type.Integer (__integer 10000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000) (__integer 1)) }}} Again increasing the exponent to 1000000 quickly invokes the OOM killer on my machine. P.S. This bug was discovered while fixing a [https://github.com/bos/aeson/issues/198 related bug] in `aeson`. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9059 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler