Process hangs forever

[danslo]

With many contracts, we'll be stuck in a loop forever. Contract code example:

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

Contract::walkAndConnectNodes never finishes executing because it keeps recursively calling itself. Not quite sure yet why.

Calling printBlockReferences just before, results in the following:

(dest = 0x00000000, numrefs = 0x00000000, refs = {}, JUMPI: 0x00000055, Default: 0x0000000B )
(dest = 0x0000000B, numrefs = 0x00000001, refs = {0x00000000}, JUMPI: 0x00000148, Default: 0x0000003F )
(dest = 0x0000003F, numrefs = 0x00000001, refs = {0x0000000b}, JUMPI: 0x0000017E, Default: 0x0000004A )
(dest = 0x0000004A, numrefs = 0x00000001, refs = {0x0000003f}, JUMPI: 0x000001B4, Default: 0x00000055 )
(dest = 0x00000055, numrefs = 0x00000002, refs = {0x000000000x0000004a}, Default: 0x00000059 )
(dest = 0x00000059, numrefs = 0x00000001, refs = {0x00000055}, JUMPI: 0x0000013D, Default: 0x000000B4 )
(dest = 0x000000B4, numrefs = 0x00000001, refs = {0x00000059}, Default: 0x00000143 )
(dest = 0x0000013D, numrefs = 0x00000001, refs = {0x00000059}, Default: 0x00000143 )
(dest = 0x00000143, numrefs = 0x00000002, refs = {0x000000b40x0000013d}, Default: 0x00000144 )
(dest = 0x00000144, numrefs = 0x00000001, refs = {0x00000143}, Default: 0xDEADBABE )
(dest = 0x00000146, numrefs = 0x00000000, refs = {}, Default: 0x00000000 )
(dest = 0x00000148, numrefs = 0x00000001, refs = {0x0000000b}, JUMPI: 0x00000150, Default: 0x0000014F , hash = 0x66117276, str = func_66117276, )
(dest = 0x0000014F, numrefs = 0x00000001, refs = {0x00000148}, Default: 0x00000150 )
(dest = 0x00000150, numrefs = 0x00000002, refs = {0x000001480x0000014f}, Default: 0x00000225 )
(dest = 0x0000017C, numrefs = 0x00000000, refs = {}, Default: 0x00000000 )
(dest = 0x0000017E, numrefs = 0x00000001, refs = {0x0000003f}, JUMPI: 0x00000186, Default: 0x00000185 , hash = 0x82C90AC0, str = func_82c90ac0, )
(dest = 0x00000185, numrefs = 0x00000001, refs = {0x0000017e}, Default: 0x00000186 )
(dest = 0x00000186, numrefs = 0x00000002, refs = {0x0000017e0x00000185}, Default: 0x000002C8 )
(dest = 0x000001B2, numrefs = 0x00000000, refs = {}, Default: 0x00000000 )
(dest = 0x000001B4, numrefs = 0x00000001, refs = {0x0000004a}, Default: 0x0000036B , hash = 0xB76EA962, str = func_b76ea962, )
(dest = 0x00000223, numrefs = 0x00000000, refs = {}, Default: 0x00000000 )
(dest = 0x00000225, numrefs = 0x00000001, refs = {0x00000150}, JUMPI: 0x00000282, Default: 0x0000027D )
(dest = 0x0000027D, numrefs = 0x00000001, refs = {0x00000225}, Default: 0x00000282 )
(dest = 0x00000282, numrefs = 0x00000002, refs = {0x000002250x0000027d}, Default: 0x000002C4 )
(dest = 0x000002C4, numrefs = 0x00000001, refs = {0x00000282}, Default: 0x000002C5 )
(dest = 0x000002C5, numrefs = 0x00000001, refs = {0x000002c4}, Default: 0xDEADBABE )
(dest = 0x000002C8, numrefs = 0x00000001, refs = {0x00000186}, JUMPI: 0x00000325, Default: 0x00000320 )
(dest = 0x00000320, numrefs = 0x00000001, refs = {0x000002c8}, Default: 0x00000325 )
(dest = 0x00000325, numrefs = 0x00000002, refs = {0x000002c80x00000320}, Default: 0x00000367 )
(dest = 0x00000367, numrefs = 0x00000001, refs = {0x00000325}, Default: 0x00000368 )
(dest = 0x00000368, numrefs = 0x00000001, refs = {0x00000367}, Default: 0xDEADBABE )
(dest = 0x0000036B, numrefs = 0x00000001, refs = {0x000001b4}, JUMPI: 0x000003C8, Default: 0x000003C3 )
(dest = 0x000003C3, numrefs = 0x00000001, refs = {0x0000036b}, Default: 0x000003C8 )
(dest = 0x000003C8, numrefs = 0x00000002, refs = {0x0000036b0x000003c3}, JUMPI: 0x0000041D, Default: 0x000003F9 )
(dest = 0x000003F9, numrefs = 0x00000002, refs = {0x000003c80x00000407}, JUMPI: 0x0000041D, Default: 0x00000407 )
(dest = 0x00000407, numrefs = 0x00000001, refs = {0x000003f9}, Default: 0x000003F9 )
(dest = 0x0000041D, numrefs = 0x00000002, refs = {0x000003c80x000003f9}, JUMPI: 0x00000449, Default: 0x00000430 )
(dest = 0x00000430, numrefs = 0x00000001, refs = {0x0000041d}, Default: 0x00000449 )
(dest = 0x00000449, numrefs = 0x00000002, refs = {0x0000041d0x00000430}, JUMPI: 0x0000046E, Default: 0x00000469 )
(dest = 0x00000469, numrefs = 0x00000001, refs = {0x00000449}, Default: 0x0000046E )
(dest = 0x0000046E, numrefs = 0x00000002, refs = {0x000004490x00000469}, Default: 0x0000046F )
(dest = 0x0000046F, numrefs = 0x00000001, refs = {0x0000046e}, Default: 0x00000470 )
(dest = 0x00000470, numrefs = 0x00000001, refs = {0x0000046f}, Default: 0xDEADBABE )
(dest = 0xDEADBABE, numrefs = 0x00000004, refs = {0x000001440x000002c50x000003680x00000470}, Default: 0x00000000 )

Which ends up in a loop between nodes 0x000003C8 -> 0x0000041D -> 0x00000449 -> 0x0000041D -> 0x000003C8 -> etc. So there's circular referencing going on, but I haven't been able to wrap my head around it yet.

After running it for a couple of iterations, this is the pattern that emerges:

CURRENT: 0000041D - NEXT: 0000046F - JUMPI: 00000000
CURRENT: 0000041D - NEXT: 00000470 - JUMPI: 00000000
CURRENT: 0000041D - NEXT: 00000223 - JUMPI: 00000000
CURRENT: 0000041D - NEXT: 00000000 - JUMPI: 00000000
CURRENT: 000003C8 - NEXT: 000003F9 - JUMPI: 00000000
CURRENT: 000003C8 - NEXT: 00000407 - JUMPI: 0000041D
CURRENT: 0000041D - NEXT: 00000430 - JUMPI: 00000449 <--\
CURRENT: 00000449 - NEXT: 00000469 - JUMPI: 0000046E	|
CURRENT: 0000046E - NEXT: 0000046F - JUMPI: 00000000	|
CURRENT: 0000046E - NEXT: 00000470 - JUMPI: 00000000	|
CURRENT: 0000046E - NEXT: 00000223 - JUMPI: 00000000	|
CURRENT: 0000046E - NEXT: 00000000 - JUMPI: 00000000	|
CURRENT: 00000449 - NEXT: 0000046E - JUMPI: 00000000	|
CURRENT: 00000449 - NEXT: 0000046F - JUMPI: 00000000	|
CURRENT: 00000449 - NEXT: 00000470 - JUMPI: 00000000	|
CURRENT: 00000449 - NEXT: 00000223 - JUMPI: 00000000	|
CURRENT: 00000449 - NEXT: 00000000 - JUMPI: 00000000	|
CURRENT: 0000041D - NEXT: 00000449 - JUMPI: 00000000	|
CURRENT: 0000041D - NEXT: 00000469 - JUMPI: 0000046E	|
CURRENT: 0000046E - NEXT: 0000046F - JUMPI: 00000000	|
CURRENT: 0000046E - NEXT: 00000470 - JUMPI: 00000000	|
CURRENT: 0000046E - NEXT: 00000223 - JUMPI: 00000000	|
CURRENT: 0000046E - NEXT: 00000000 - JUMPI: 00000000	|
CURRENT: 0000041D - NEXT: 0000046E - JUMPI: 00000000	|
CURRENT: 0000041D - NEXT: 0000046F - JUMPI: 00000000	|
CURRENT: 0000041D - NEXT: 00000470 - JUMPI: 00000000	|
CURRENT: 0000041D - NEXT: 00000223 - JUMPI: 00000000	|
CURRENT: 0000041D - NEXT: 00000000 - JUMPI: 00000000	|
CURRENT: 000003C8 - NEXT: 000003F9 - JUMPI: 00000000	|
CURRENT: 000003C8 - NEXT: 00000407 - JUMPI: 0000041D ---/
CURRENT: 0000041D - NEXT: 00000430 - JUMPI: 00000449
CURRENT: 00000449 - NEXT: 00000469 - JUMPI: 0000046E
CURRENT: 0000046E - NEXT: 0000046F - JUMPI: 00000000
CURRENT: 0000046E - NEXT: 00000470 - JUMPI: 00000000
CURRENT: 0000046E - NEXT: 00000223 - JUMPI: 00000000
CURRENT: 0000046E - NEXT: 00000000 - JUMPI: 00000000

[danslo]

@msuiche I'm happy to debug this further, but you probably have a better idea of what's going on given the information above. Let me know how/where I can help :)

[danslo]

On further examination, it's not due to recursion. But a simple circular reference between 0x407 and 0x3F9. Both their dstDefault's point to eachother. Not sure what it means :)

[msuiche]

Fixed by c7ac851

[danslo]

Cool, that fixes the infinite loop while resolving basic blocks, but now get's stuck in an infinite loop complaining about executeInstruction: NOT_IMPLEMENTED: REVERT, for the same bytecode.

[ytrezq]

@msuiche it seems there’s regression as I’m have the exact same problem but with different code #50.