July 2015 - ghc-tickets

Re: [GHC] #5954: Performance regression 7.0 -> 7.2 (still in 7.4)
by GHC 02 Jul '15

02 Jul '15

#5954: Performance regression 7.0 -> 7.2 (still in 7.4) -------------------------------------+------------------------------------- Reporter: simonmar | Owner: simonpj Type: bug | Status: new Priority: normal | Milestone: 7.12.1 Component: Compiler | Version: 7.4.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Runtime | Unknown/Multiple performance bug | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Revisions: -------------------------------------+------------------------------------- Comment (by George): Replying to [comment:11 carter]: > is this bug still going on in head? No reply to this so changing status to infoneeded -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/5954#comment:15> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8363: Order matters for unused import warnings when reexporting identifiers
by GHC 02 Jul '15

02 Jul '15

#8363: Order matters for unused import warnings when reexporting identifiers ------------------------------------+------------------------------------- Reporter: bergmark | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.7 Keywords: | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ------------------------------------+------------------------------------- Import order seem to change whether unused import warnings trigger when a module re-exports an identifier, with another module importing it and another module exporting the same identifier. Reproduction: {{{ module Foo ( (<$>) , g ) where import Control.Applicative g :: Int g = 1 }}} {{{ module Main where import Control.Applicative import Foo main :: IO () main = print =<< ((+2) <$> return g) }}} {{{ $ ghc -fwarn-unused-imports Main.hs [1 of 2] Compiling Foo ( Foo.hs, Foo.o ) [2 of 2] Compiling Main ( Main.hs, Main.o ) Linking Main ... }}} If Main is not using `g` then this gives a warning that the import of `Foo` is redundant. If we switch the order of the imports we do get the warning: {{{ module Main where import Foo import Control.Applicative main :: IO () main = print =<< ((+2) <$> return g) }}} {{{ > ghc -fwarn-unused-imports Main.hs [1 of 2] Compiling Foo ( Foo.hs, Foo.o ) [2 of 2] Compiling Main ( Main.hs, Main.o ) Main.hs:4:1: Warning: The import of `Control.Applicative' is redundant except perhaps to import instances from `Control.Applicative' To import instances alone, use: import Control.Applicative() Linking Main ... }}} I expected both versions of Main to produce the same warning. Tested on GHC 7.7.20130824 and 7.4.2. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8363> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #5071: GHCi crashes on large alloca/allocaBytes requests
by GHC 02 Jul '15

02 Jul '15

#5071: GHCi crashes on large alloca/allocaBytes requests -------------------------------------+------------------------------------- Reporter: guest | Owner: Type: bug | Status: new Priority: normal | Milestone: ⊥ Component: Compiler | Version: 7.0.3 Resolution: | Keywords: report- Operating System: Unknown/Multiple | impact Type of failure: None/Unknown | Architecture: Blocked By: | Unknown/Multiple Related Tickets: | Test Case: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- Changes (by thomie): * keywords: => report-impact Comment: Quoting [comment:4 comment:4]: > I think we made a mistake in the standard here. In fact, by changing `alloca` to raise an exception I think we'll be ''fixing'' a lot of broken code! -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/5071#comment:12> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #4092: Floating point manipulation : ulp and coerce IEEE-754 Double# into Word64#
by GHC 02 Jul '15

02 Jul '15

#4092: Floating point manipulation : ulp and coerce IEEE-754 Double# into Word64# -------------------------------------+------------------------------------- Reporter: malosh | Owner: Type: feature request | Status: new Priority: normal | Milestone: 7.12.1 Component: Compiler | Version: 6.12.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: None/Unknown | Unknown/Multiple Blocked By: | Test Case: Related Tickets: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- Comment (by duncan): In the meantime, in the absence of primops, this is the best I can manage. I suggest we add this or similar to GHC.Float: {{{ {-# INLINE castWord2Float #-} castWord2Float :: Word32 -> Float castWord2Float (W32# w#) = F# (castWord2Float# w#) {-# NOINLINE castWord2Float# #-} castWord2Float# :: Word# -> Float# castWord2Float# w# = case newByteArray# 4# realWorld# of (# s', mba# #) -> case writeWord32Array# mba# 0# w# s' of s'' -> case readFloatArray# mba# 0# s'' of (# _, f# #) -> f# {-# INLINE castWord2Double #-} castWord2Double :: Word64 -> Double castWord2Double (W64# w#) = D# (castWord2Double# w#) {-# NOINLINE castWord2Double# #-} castWord2Double# :: Word# -> Double# castWord2Double# w# = case newByteArray# 8# realWorld# of (# s', mba# #) -> case writeWord64Array# mba# 0# w# s' of s'' -> case readDoubleArray# mba# 0# s'' of (# _, f# #) -> f# }}} This is similar to the "cast STUArray" method, but avoids the extra call and closure allocation due to the `runSTRep`. For the "cast STUArray" method, see: http://hackage.haskell.org/package/reinterpret-cast-0.1.0/docs/src/Data- ReinterpretCast-Internal-ImplArray.html The `NOINLINE` means that the use of `realWorld#` should be ok, despite `newByteArray# 8# realWorld#` being a constant. It'll need a very similar impl for 32bit systems that need the Word64# type. Compare the CMM of the above: {{{ castWord2Double#_entry() // [R2] { info_tbl: [(c2Qn, label: castWord2Double#_info rep:HeapRep static { Fun {arity: 1 fun_type: ArgSpec 4} })] stack_info: arg_space: 8 updfr_space: Just 8 } {offset c2Qn: Hp = Hp + 24; if (Hp > HpLim) goto c2Qr; else goto c2Qq; c2Qr: HpAlloc = 24; R2 = R2; R1 = castWord2Double#_closure; call (stg_gc_fun)(R2, R1) args: 8, res: 0, upd: 8; c2Qq: I64[Hp - 16] = stg_ARR_WORDS_info; I64[Hp - 8] = 8; _s2Q9::P64 = Hp - 16; I64[_s2Q9::P64 + 16] = R2; D1 = F64[_s2Q9::P64 + 16]; call (P64[Sp])(D1) args: 8, res: 0, upd: 8; } } }}} with the version that uses runST / runSTRep {{{ sat_s2QX_entry() // [R1] { info_tbl: [(c2Rd, label: sat_s2QX_info rep:HeapRep 1 nonptrs { Fun {arity: 1 fun_type: ArgSpec 3} })] stack_info: arg_space: 8 updfr_space: Just 8 } {offset c2Rd: Hp = Hp + 40; if (Hp > HpLim) goto c2Rj; else goto c2Ri; c2Rj: HpAlloc = 40; R1 = R1; call (stg_gc_fun)(R1) args: 8, res: 0, upd: 8; c2Ri: _s2QN::I64 = I64[R1 + 7]; I64[Hp - 32] = stg_ARR_WORDS_info; I64[Hp - 24] = 8; _s2QR::P64 = Hp - 32; I64[_s2QR::P64 + 16] = _s2QN::I64; _s2QV::F64 = F64[_s2QR::P64 + 16]; I64[Hp - 8] = D#_con_info; F64[Hp] = _s2QV::F64; R1 = Hp - 7; call (P64[Sp])(R1) args: 8, res: 0, upd: 8; } }, castWord2Double#_entry() // [R2] { info_tbl: [(c2Rk, label: castWord2Double#_info rep:HeapRep static { Fun {arity: 1 fun_type: ArgSpec 4} })] stack_info: arg_space: 8 updfr_space: Just 8 } {offset c2Rk: Hp = Hp + 16; if (Hp > HpLim) goto c2Ro; else goto c2Rn; c2Ro: HpAlloc = 16; R2 = R2; R1 = castWord2Double#_closure; call (stg_gc_fun)(R2, R1) args: 8, res: 0, upd: 8; c2Rn: I64[Hp - 8] = sat_s2QX_info; I64[Hp] = R2; R2 = Hp - 7; call runSTRep_info(R2) args: 8, res: 0, upd: 8; } } }}} The runSTRep version involves allocating a `sat_s2QX` closure and calling `runSTRep` to call that closure. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/4092#comment:20> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #1388: Newbie help features
by GHC 02 Jul '15

02 Jul '15

#1388: Newbie help features -------------------------------------+------------------------------------- Reporter: guest | Owner: Type: feature request | Status: new Priority: low | Milestone: ⊥ Component: GHCi | Version: 6.6.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: None/Unknown | Unknown/Multiple Blocked By: | Test Case: Related Tickets: #4929 | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- Changes (by thomie): * cc: bgamari (added) * related: => #4929 Comment: Support for top-level declarations was added in #4929. With 1ff7f09b3abedb2a6daf384b55ad3d0134f0d174, `f = 1` now prints: {{{ + parse error on input ‘=’ + Perhaps you need a 'let' in a 'do' block? + e.g. 'let x = 5' instead of 'x = 5' }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/1388#comment:8> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8222: CTYPE pragma on newtype is ignored
by GHC 01 Jul '15

01 Jul '15

#8222: CTYPE pragma on newtype is ignored --------------------------+------------------------------------------------ Reporter: akio | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: | Version: 7.6.3 Compiler | Operating System: Linux Keywords: | Type of failure: Incorrect result at runtime Architecture: x86_64 | Test Case: (amd64) | Blocking: Difficulty: | Unknown | Blocked By: | Related Tickets: | --------------------------+------------------------------------------------ User's guide includes an example where a CTYPE pragma is used for a newtype. {{{ newtype {-# CTYPE "useconds_t" #-} T = ... }}} However, in the following program, the CTYPE pragma seems to be ignored: {{{ {-# LANGUAGE CApiFFI #-} import Foreign.Ptr foreign import capi unsafe "sys/socket.h CMSG_DATA" c_CMSG_DATA :: Ptr Cmsg -> Ptr a newtype {-# CTYPE "sys/socket.h" "struct cmsghdr" #-} Cmsg = Cmsg () main = return () }}} Save this as {{{capi.hs}}}, then compile it like: {{{ ghc capi.hs -fforce-recomp -keep-tmp-files -tmpdir . }}} Then GHC creates a C file: {{{ #define IN_STG_CODE 0 #include "Rts.h" #include "Stg.h" #ifdef __cplusplus extern "C" { #endif #include <sys/socket.h> void* ghczuwrapperZC0ZCmainZCMainZCCMSGzuDATA(void* a1) {return CMSG_DATA(a1);} #ifdef __cplusplus } #endif }}} The argument type of the wrapper function is {{{void *}}}, but it should be {{{struct cmsghdr *}}}. If I replace {{{newtype}}} with {{{data}}} in capi.hs, the wrapper function gets the correct type. I can see this problem in HEAD and in 7.6.3. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8222> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #3490: Relax superclass restrictions
by GHC 01 Jul '15

01 Jul '15

#3490: Relax superclass restrictions -------------------------------------+------------------------------------- Reporter: simonpj | Owner: Type: feature request | DevarshDesai Priority: normal | Status: new Component: Compiler | Milestone: ⊥ Resolution: | Version: 6.10.4 Operating System: Unknown/Multiple | Keywords: Type of failure: None/Unknown | Architecture: Blocked By: | Unknown/Multiple Related Tickets: | Test Case: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- Changes (by DevarshDesai): * owner: => DevarshDesai * failure: => None/Unknown -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/3490#comment:5> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #3541: Allow local foreign imports
by GHC 01 Jul '15

01 Jul '15

#3541: Allow local foreign imports -------------------------------------+------------------------------------- Reporter: mokus | Owner: Type: feature request | DevarshDesai Priority: normal | Status: new Component: Compiler (FFI) | Milestone: ⊥ Resolution: | Version: 6.12.2 Operating System: Unknown/Multiple | Keywords: newcomer Type of failure: None/Unknown | Architecture: Blocked By: | Unknown/Multiple Related Tickets: | Test Case: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- Changes (by DevarshDesai): * owner: => DevarshDesai * version: 6.10.4 => 6.12.2 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/3541#comment:5> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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