Re: [GHC] #13916: Optimizations create run time seg faults

#13916: Optimizations create run time seg faults -------------------------------------+------------------------------------- Reporter: newthin | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.2 (CodeGen) | Resolution: | Keywords: optimization Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: Runtime crash | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by bgamari): Here is my analysis of `stg_takeMVarzh` for future reference, {{{ stg_takeMVarzh: // $rbx = mvar <+0>: mov (%rbx),%rax // $rax = info = GET_INFO(mvar) <+3>: cmpq $0x94f128,0x18(%rbx) // if (StgMVar_value(mvar) == stg_END_TSO_QUEUE_closure) <+11>: je 0x6ec277 // { jump; } (not taken) <+17>: mov %rbx,%rcx <+20>: mov 0x18(%rbx),%rdx // $rdx = val = StgMVar_value(mvar) <+24>: mov 0x8(%rbx),%rbx // $rbx = q = StgMVar_head(mvar) <+28>: cmp $0x94f128,%rbx // if (q == stg_END_TSO_QUEUE_closure) <+35>: je 0x6ec236 // { jump; } (not taken) <+41>: cmpq $0x6ed310,(%rbx) // if (StgHeader_info(q) == stg_IND_info) // ^ crashes here <+48>: je 0x6ec22d // { jump; } <+54>: cmpq $0x6ed938,(%rbx) // if (StgHeader_info(q) == stg_MSG_NULL_info) }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13916#comment:7 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler