#9741: Interpreter stack checks are not quite right -------------------------------------+------------------------------------- Reporter: simonpj | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.3 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Unknown | Type of failure: Blocked By: | None/Unknown Related Tickets: | Test Case: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- In my experimental branch, I'm getting this failure on `tests/ghci/should_run/ghcirun002`: {{{ <interactive>: internal error: ASSERTION FAILED: file rts/Interpreter.c, line 778 (GHC version 7.9.20141029 for x86_64_unknown_linux) }}} The ASSERTION failure means that I must have `-DDEBUG` in my RTS; I have no idea why. My `validate.mk` looks like this: {{{ GhcStage1HcOpts += -ticky -DDEBUG GhcStage2HcOpts += -ticky GhcLibHcOpts += -Wwarn -ticky SplitObjs = YES }}} That is mysterious but not the main point. Somehow we are getting a stack overflow in the interpreter. So I added this line to `Interpreter` on line 772: {{{ debugBelch ( "Interpreter Sp=%p SpLim=%p headroom = %ld\n\n", Sp, SpLim, Sp-SpLim ) ; }}} Sure enough, when running test `ghcirun002` on HEAD, I get this output {{{ Interpreter Sp=0x7f42649d0228 SpLim=0x7f42649d00c0 headroom = 45 Interpreter Sp=0x7f42649d0228 SpLim=0x7f42649d00c0 headroom = 45 Interpreter Sp=0x7f42649d0228 SpLim=0x7f42649d00c0 headroom = 45 Interpreter Sp=0x7f42649d0238 SpLim=0x7f42649d00c0 headroom = 47 Interpreter Sp=0x7f42649d0228 SpLim=0x7f42649d00c0 headroom = 45 Interpreter Sp=0x7f42649d0228 SpLim=0x7f42649d00c0 headroom = 45 Interpreter Sp=0x7f42649d0228 SpLim=0x7f42649d00c0 headroom = 45 Interpreter Sp=0x7f42649d0228 SpLim=0x7f42649d00c0 headroom = 45 Interpreter Sp=0x7f42649d0228 SpLim=0x7f42649d00c0 headroom = 45 Interpreter Sp=0x7f42649d0210 SpLim=0x7f42649d00c0 headroom = 42 Interpreter Sp=0x7f4264b40230 SpLim=0x7f4264b400c0 headroom = 46 Interpreter Sp=0x7f42649e1230 SpLim=0x7f42649e10c0 headroom = 46 Interpreter Sp=0x7f42649d9230 SpLim=0x7f42649d90c0 headroom = 46 Interpreter Sp=0x7f4264182230 SpLim=0x7f42641820c0 headroom = 46 Interpreter Sp=0x7f426417a230 SpLim=0x7f426417a0c0 headroom = 46 Interpreter Sp=0x7f4264172230 SpLim=0x7f42641720c0 headroom = 46 Interpreter Sp=0x7f426416a230 SpLim=0x7f426416a0c0 headroom = 46 Interpreter Sp=0x7f4264162230 SpLim=0x7f42641620c0 headroom = 46 Interpreter Sp=0x7f426415a230 SpLim=0x7f426415a0c0 headroom = 46 Interpreter Sp=0x7f4264152230 SpLim=0x7f42641520c0 headroom = 46 Interpreter Sp=0x7f426414a230 SpLim=0x7f426414a0c0 headroom = 46 Interpreter Sp=0x7f4264142230 SpLim=0x7f42641420c0 headroom = 46 Interpreter Sp=0x7f426413a230 SpLim=0x7f426413a0c0 headroom = 46 Interpreter Sp=0x7f4264132230 SpLim=0x7f42641320c0 headroom = 46 Interpreter Sp=0x7f42649d0238 SpLim=0x7f42649d00c0 headroom = 47 Interpreter Sp=0x7f4264a1e238 SpLim=0x7f4264a1e0c0 headroom = 47 Interpreter Sp=0x7f4264a16238 SpLim=0x7f4264a160c0 headroom = 47 Interpreter Sp=0x7f4264a0e238 SpLim=0x7f4264a0e0c0 headroom = 47 Interpreter Sp=0x7f4264a06238 SpLim=0x7f4264a060c0 headroom = 47 Interpreter Sp=0x7f4257ff8238 SpLim=0x7f4257ff80c0 headroom = 47 Interpreter Sp=0x7f4257ff0238 SpLim=0x7f4257ff00c0 headroom = 47 Interpreter Sp=0x7f4257fe8238 SpLim=0x7f4257fe80c0 headroom = 47 Interpreter Sp=0x7f4257fe0238 SpLim=0x7f4257fe00c0 headroom = 47 Interpreter Sp=0x7f4257fd8238 SpLim=0x7f4257fd80c0 headroom = 47 Interpreter Sp=0x7f4257fd0238 SpLim=0x7f4257fd00c0 headroom = 47 Interpreter Sp=0x7f4257fc8238 SpLim=0x7f4257fc80c0 headroom = 47 Interpreter Sp=0x7f4257fc0238 SpLim=0x7f4257fc00c0 headroom = 47 Interpreter Sp=0x7f4257fb8238 SpLim=0x7f4257fb80c0 headroom = 47 Interpreter Sp=0x7f4257fb0238 SpLim=0x7f4257fb00c0 headroom = 47 Interpreter Sp=0x7f42641f8238 SpLim=0x7f42641f80c0 headroom = 47 Interpreter Sp=0x7f42641f0238 SpLim=0x7f42641f00c0 headroom = 47 Interpreter Sp=0x7f42644f8238 SpLim=0x7f42644f80c0 headroom = 47 Interpreter Sp=0x7f42644ef238 SpLim=0x7f42644ef0c0 headroom = 47 Interpreter Sp=0x7f42644e7238 SpLim=0x7f42644e70c0 headroom = 47 Interpreter Sp=0x7f42644de238 SpLim=0x7f42644de0c0 headroom = 47 Interpreter Sp=0x7f42644d6238 SpLim=0x7f42644d60c0 headroom = 47 Interpreter Sp=0x7f42644ce238 SpLim=0x7f42644ce0c0 headroom = 47 Interpreter Sp=0x7f42644c5238 SpLim=0x7f42644c50c0 headroom = 47 Interpreter Sp=0x7f42644bd238 SpLim=0x7f42644bd0c0 headroom = 47 Interpreter Sp=0x7f42644b4238 SpLim=0x7f42644b40c0 headroom = 47 Interpreter Sp=0x7f42644ac238 SpLim=0x7f42644ac0c0 headroom = 47 Interpreter Sp=0x7f42644a4238 SpLim=0x7f42644a40c0 headroom = 47 Interpreter Sp=0x7f426449b238 SpLim=0x7f426449b0c0 headroom = 47 Interpreter Sp=0x7f4264493238 SpLim=0x7f42644930c0 headroom = 47 Interpreter Sp=0x7f426448a238 SpLim=0x7f426448a0c0 headroom = 47 Interpreter Sp=0x7f4264482238 SpLim=0x7f42644820c0 headroom = 47 Interpreter Sp=0x7f426447a238 SpLim=0x7f426447a0c0 headroom = 47 Interpreter Sp=0x7f426454e238 SpLim=0x7f426454e0c0 headroom = 47 Interpreter Sp=0x7f42641e8238 SpLim=0x7f42641e80c0 headroom = 47 Interpreter Sp=0x7f426417c238 SpLim=0x7f426417c0c0 headroom = 47 Interpreter Sp=0x7f4264174238 SpLim=0x7f42641740c0 headroom = 47 Interpreter Sp=0x7f426416c238 SpLim=0x7f426416c0c0 headroom = 47 Interpreter Sp=0x7f4264164238 SpLim=0x7f42641640c0 headroom = 47 Interpreter Sp=0x7f426415c238 SpLim=0x7f426415c0c0 headroom = 47 Interpreter Sp=0x7f4264154238 SpLim=0x7f42641540c0 headroom = 47 Interpreter Sp=0x7f426414c238 SpLim=0x7f426414c0c0 headroom = 47 Interpreter Sp=0x7f42643e0238 SpLim=0x7f42643e00c0 headroom = 47 Interpreter Sp=0x7f42643d8238 SpLim=0x7f42643d80c0 headroom = 47 Interpreter Sp=0x7f42643d0238 SpLim=0x7f42643d00c0 headroom = 47 Interpreter Sp=0x7f42643c8238 SpLim=0x7f42643c80c0 headroom = 47 Interpreter Sp=0x7f42643c0238 SpLim=0x7f42643c00c0 headroom = 47 Interpreter Sp=0x7f42643b8238 SpLim=0x7f42643b80c0 headroom = 47 Interpreter Sp=0x7f42643e0238 SpLim=0x7f42643e00c0 headroom = 47 Interpreter Sp=0x7f4264154138 SpLim=0x7f42641540c0 headroom = 15 Interpreter Sp=0x7f42641541d0 SpLim=0x7f42641540c0 headroom = 34 Interpreter Sp=0x7f426415c230 SpLim=0x7f426415c0c0 headroom = 46 Interpreter Sp=0x7f4264164130 SpLim=0x7f42641640c0 headroom = 14 Interpreter Sp=0x7f42641641c8 SpLim=0x7f42641640c0 headroom = 33 Interpreter Sp=0x7f426447a0e0 SpLim=0x7f426447a0c0 headroom = 4 Interpreter Sp=0x7f426447a178 SpLim=0x7f426447a0c0 headroom = 23 Interpreter Sp=0x7f426447a210 SpLim=0x7f426447a0c0 headroom = 42 Interpreter Sp=0x7f4264482138 SpLim=0x7f42644820c0 headroom = 15 Interpreter Sp=0x7f42644821d0 SpLim=0x7f42644820c0 headroom = 34 Interpreter Sp=0x7f426448a228 SpLim=0x7f426448a0c0 headroom = 45 Interpreter Sp=0x7f4264493238 SpLim=0x7f42644930c0 headroom = 47 Interpreter Sp=0x7f426449b130 SpLim=0x7f426449b0c0 headroom = 14 Interpreter Sp=0x7f426449b1c8 SpLim=0x7f426449b0c0 headroom = 33 Interpreter Sp=0x7f42644ac0d0 SpLim=0x7f42644ac0c0 headroom = 2 Interpreter Sp=0x7f42644ac168 SpLim=0x7f42644ac0c0 headroom = 21 Interpreter Sp=0x7f42644ac200 SpLim=0x7f42644ac0c0 headroom = 40 Interpreter Sp=0x7f42644b4230 SpLim=0x7f42644b40c0 headroom = 46 Interpreter Sp=0x7f42644bd108 SpLim=0x7f42644bd0c0 headroom = 9 Interpreter Sp=0x7f42644bd1a0 SpLim=0x7f42644bd0c0 headroom = 28 Interpreter Sp=0x7f42644bd238 SpLim=0x7f42644bd0c0 headroom = 47 Interpreter Sp=0x7f42644ce140 SpLim=0x7f42644ce0c0 headroom = 16 Interpreter Sp=0x7f42644ce1d8 SpLim=0x7f42644ce0c0 headroom = 35 Interpreter Sp=0x7f42644d6218 SpLim=0x7f42644d60c0 headroom = 43 Interpreter Sp=0x7f42644de0e0 SpLim=0x7f42644de0c0 headroom = 4 Interpreter Sp=0x7f42644de178 SpLim=0x7f42644de0c0 headroom = 23 Interpreter Sp=0x7f42644de210 SpLim=0x7f42644de0c0 headroom = 42 Interpreter Sp=0x7f42644e70c0 SpLim=0x7f42644e70c0 headroom = 0 Interpreter Sp=0x7f42644e7158 SpLim=0x7f42644e70c0 headroom = 19 Interpreter Sp=0x7f42644e71f0 SpLim=0x7f42644e70c0 headroom = 38 Interpreter Sp=0x7f42644ef230 SpLim=0x7f42644ef0c0 headroom = 46 Interpreter Sp=0x7f42644f8190 SpLim=0x7f42644f80c0 headroom = 26 Interpreter Sp=0x7f42644f8228 SpLim=0x7f42644f80c0 headroom = 45 Interpreter Sp=0x7f42641f00d8 SpLim=0x7f42641f00c0 headroom = 3 Interpreter Sp=0x7f42641f0170 SpLim=0x7f42641f00c0 headroom = 22 Interpreter Sp=0x7f42641f0208 SpLim=0x7f42641f00c0 headroom = 41 Interpreter Sp=0x7f4257fb8210 SpLim=0x7f4257fb80c0 headroom = 42 Interpreter Sp=0x7f4257fb80f0 SpLim=0x7f4257fb80c0 headroom = 6 Interpreter Sp=0x7f4257fb8188 SpLim=0x7f4257fb80c0 headroom = 25 Interpreter Sp=0x7f4257fb8220 SpLim=0x7f4257fb80c0 headroom = 44 Interpreter Sp=0x7f4257fc00d0 SpLim=0x7f4257fc00c0 headroom = 2 Interpreter Sp=0x7f4257fc0168 SpLim=0x7f4257fc00c0 headroom = 21 Interpreter Sp=0x7f4257fc0200 SpLim=0x7f4257fc00c0 headroom = 40 Interpreter Sp=0x7f4257fc80b0 SpLim=0x7f4257fc80c0 headroom = -2 <---- NB Interpreter Sp=0x7f4257fc8148 SpLim=0x7f4257fc80c0 headroom = 17 Interpreter Sp=0x7f4257fc81e0 SpLim=0x7f4257fc80c0 headroom = 36 Interpreter Sp=0x7f4257fd0228 SpLim=0x7f4257fd00c0 headroom = 45 Interpreter Sp=0x7f4257fe0228 SpLim=0x7f4257fe00c0 headroom = 45 Interpreter Sp=0x7f4257fe8140 SpLim=0x7f4257fe80c0 headroom = 16 Interpreter Sp=0x7f4257fe81d8 SpLim=0x7f4257fe80c0 headroom = 35 Interpreter Sp=0x7f4257ff0120 SpLim=0x7f4257ff00c0 headroom = 12 Interpreter Sp=0x7f4257ff01b8 SpLim=0x7f4257ff00c0 headroom = 31 Interpreter Sp=0x7f4257ff8100 SpLim=0x7f4257ff80c0 headroom = 8 Interpreter Sp=0x7f4257ff8198 SpLim=0x7f4257ff80c0 headroom = 27 Interpreter Sp=0x7f4257ff8230 SpLim=0x7f4257ff80c0 headroom = 46 Interpreter Sp=0x7f4264a060e0 SpLim=0x7f4264a060c0 headroom = 4 Interpreter Sp=0x7f4264a06178 SpLim=0x7f4264a060c0 headroom = 23 Interpreter Sp=0x7f4264a06210 SpLim=0x7f4264a060c0 headroom = 42 Interpreter Sp=0x7f4264a0e0c0 SpLim=0x7f4264a0e0c0 headroom = 0 Interpreter Sp=0x7f4264a0e158 SpLim=0x7f4264a0e0c0 headroom = 19 Interpreter Sp=0x7f4264a0e1f0 SpLim=0x7f4264a0e0c0 headroom = 38 Interpreter Sp=0x7f4264a16138 SpLim=0x7f4264a160c0 headroom = 15 Interpreter Sp=0x7f4264a161d0 SpLim=0x7f4264a160c0 headroom = 34 Interpreter Sp=0x7f4264a1e118 SpLim=0x7f4264a1e0c0 headroom = 11 }}} So yes, we get into a situation in which we have negative headroom. Presumably if the ASSERT is off, we simply don't notice. But it's clearly wrong. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9741 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler