ghc-7.6.3: crossmodule inline leads to buggy code (-O2)
The bug is found as a crash of gf-3.4 ('Grammatical Framework') package compiled with -O2. With some debugging I've come to roughly following minimal example:
This code compiles incorrectly:
import BuggyOpt() -- bug inducer!
import qualified Data.Map as Map
import Data.Array.IArray
{-# NOINLINE mkLin #-}
mkLin :: Array Int (Array Int Int) -> Map.Map (Array Int Int) Int -> Int -> (Map.Map (Array Int Int) Int, Int)
mkLin mseqs seqs seqid =
let seq_ = mseqs ! seqid
-- lookup/insert pair. exactly as in 'BuggyOpt' module
in case Map.lookup seq_ seqs of
Just seqid' -> (seqs,seqid')
Nothing -> let seqid'' = Map.size seqs
seqs' = Map.insert seq_ seqid'' seqs
in (seqs',seqid'')
And this works fine:
--import BuggyOpt() -- bug inducer!
import qualified Data.Map as Map
import Data.Array.IArray
{-# NOINLINE mkLin #-}
mkLin :: Array Int (Array Int Int) -> Map.Map (Array Int Int) Int -> Int -> (Map.Map (Array Int Int) Int, Int)
mkLin mseqs seqs seqid =
let seq_ = mseqs ! seqid
-- lookup/insert pair. exactly as in 'BuggyOpt' module
in case Map.lookup seq_ seqs of
Just seqid' -> (seqs,seqid')
Nothing -> let seqid'' = Map.size seqs
seqs' = Map.insert seq_ seqid'' seqs
in (seqs',seqid'')
Attached minimal test tarball and my results on it are:
[("Project name","The Glorious Glasgow Haskell Compilation System")
,("GCC extra via C opts"," -fwrapv")
,("C compiler command","x86_64-pc-linux-gnu-gcc")
,("C compiler flags"," -fno-stack-protector -Wl,--hash-size=31 -Wl,--reduce-memory-overheads")
,("ar command","/usr/bin/ar")
,("ar flags","q")
,("ar supports at file","YES")
,("touch command","touch")
,("dllwrap command","/bin/false")
,("windres command","/bin/false")
,("perl command","/usr/bin/perl")
,("target os","OSLinux")
,("target arch","ArchX86_64")
,("target word size","8")
,("target has GNU nonexec stack","True")
,("target has .ident directive","True")
,("target has subsections via symbols","False")
,("LLVM llc command","/usr/bin/llc")
,("LLVM opt command","/usr/bin/opt")
,("Project version","7.6.3")
,("Booter version","7.6.3")
,("Stage","2")
,("Build platform","x86_64-unknown-linux")
,("Host platform","x86_64-unknown-linux")
,("Target platform","x86_64-unknown-linux")
,("Have interpreter","YES")
,("Object splitting supported","YES")
,("Have native code generator","YES")
,("Support SMP","YES")
,("Unregisterised","NO")
,("Tables next to code","YES")
,("RTS ways","l debug thr thr_debug thr_l thr_p dyn debug_dyn thr_dyn thr_debug_dyn")
,("Leading underscore","NO")
,("Debug on","False")
,("LibDir","/usr/lib64/ghc-7.6.3")
,("Global Package DB","/usr/lib64/ghc-7.6.3/package.conf.d")
,("Gcc Linker flags","[\"-Wl,--hash-size=31\",\"-Wl,--reduce-memory-overheads\"]")
,("Ld Linker flags","[\"--hash-size=31\",\"--reduce-memory-overheads\"]")
]
RUN good
[1 of 2] Compiling Susp ( good/Susp.hs, good/Susp.o )
[2 of 2] Compiling Main ( good/main.hs, good/main.o )
Linking good/main ...
(fromList [(array (0,0) [(0,42)],0)],0)
RUN bad
[1 of 3] Compiling BuggyOpt ( bad/BuggyOpt.hs, bad/BuggyOpt.o )
[2 of 3] Compiling Susp ( bad/Susp.hs, bad/Susp.o )
[3 of 3] Compiling Main ( bad/main.hs, bad/main.o )
Linking bad/main ...
main: Error in array index; 0 not in range [0..0)
TEST FAILED in bad
What we see here is the test with useless import mysteriously fails:
main: Error in array index; 0 not in range [0..0)
while without import it works fine:
(fromList [(array (0,0) [(0,42)],0)],0)
The functions in both BuggyOpt and Susp modules contain suspiciously similar code:
case Map.lookup seq' seqs of
Just id' -> (seqs,id')
Nothing -> let last_seq = Map.size seqs
in (Map.insert seq' last_seq seqs, last_seq)
But in BuggyOpt ghc somehow deduces some arguments and applies that effect to (unrelated, but looking similar) Susp module.
Thanks!
Trac metadata
Trac field | Value |
---|---|
Version | 7.6.3 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | Compiler |
Test case | |
Differential revisions | |
BlockedBy | |
Related | |
Blocking | |
CC | |
Operating system | |
Architecture |