WebAssembly/wasi-libc

main in a library regression

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#485 opened on Mar 16, 2024

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help wanted

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Description

recent wasi-libc is broken if you put main in a library.

test case: https://github.com/yamt/garbage/tree/d422b1073125b3fc8f843ce4b12280ab3982fb84/c/main_in_lib

spacetanuki% ./build-native.sh
spacetanuki% ./a.out
this is foo
spacetanuki% WASI_SDK=/opt/wasi-sdk-20.0 ./build-wasi.sh
spacetanuki% toywasm --wasi a.out
this is foo
spacetanuki% WASI_SDK=/opt/wasi-sdk-21.0 ./build-wasi.sh
spacetanuki% toywasm --wasi a.out                       
Error: [trap] unreachable executed (4): unreachable at 0001a5
frame[  2] funcpc 0001a5 (<unknown>:undefined_weak:main) callerpc 0022de
  param [0] = 00000001
  param [1] = 00010b30
frame[  1] funcpc 00226c (<unknown>:__main_void) callerpc 0001df
  local [0] = 00010b00
  local [1] = 00010b30
  local [2] = 00010b20
frame[  0] funcpc 0001ab (<unknown>:_start)
  local [0] = 00000000
2024-03-16 14:47:15 (1710568035.864123000): [117042600] instance_execute_func failed with -1
2024-03-16 14:47:15 (1710568035.864618000): [117042600] invoke failed with -1
spacetanuki%

i guess this is a regression caused by https://github.com/WebAssembly/wasi-libc/pull/429

Contributor guide

Research direction
Inspect the failing test case and trace the regression caused by PR #429. Investigate how the linker handles 'main' in a library and why it leads to an unreachable error.
Tech stack
cwasm
Domain
backend
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
CWebAssemblywasi libc
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60