Enable parallel test execution on ARM32 CI targets#116
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mazong1123 merged 5 commits intomainfrom Mar 11, 2026
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Remove -j 1 and --test-threads=1 from ARM32 CI step now that thread-local dispatch is implemented for armv7/thumbv7. This ensures thread safety is actually verified by running tests in parallel.
The test was failing on Windows CI because the caller thread could see corrupted instructions during the initial non-atomic dispatcher installation (5-13 byte code patch). Fixed by: 1. Pre-installing the dispatcher with a synchronized initial fake before starting the concurrent caller thread 2. After the dispatcher is installed, subsequent iterations only modify thread-local storage which is fully thread-safe 3. Using assert_eq in the caller thread for strict value checking since the dispatcher is already in place
The test for issue #42 was asserting exact return values from the caller thread, but the non-atomic code patching during dispatcher installation can cause brief instruction-level inconsistencies on certain hardware. The test now verifies what issue #42 actually cares about: no crashes or access violations during concurrent setup/teardown of fakes. The caller thread still calls the function in a tight loop to maximize the chance of hitting any race condition, but only checks that the function can be called without crashing.
The issue #42 test was hitting two CI-specific problems: 1. Windows x86_64: trampoline returns incorrect values for concurrent_target() due to instruction decoder issue specific to how this function compiles on CI (different value assertions always failed) 2. thumbv7: under QEMU emulation, caller thread may not start before main thread completes, causing count=0 assertion failure Simplified the test to its essential purpose: verify that calling a function while another thread toggles fakes doesn't crash. Value correctness of the trampoline is tested by other tests.
When a function's first 12+ bytes contain a CALL or JMP rel32 to a target that's too far from the trampoline for a 32-bit displacement, the fixup code was NOP-ing out the entire instruction. This is correct for coverage profiling counters (lock inc [rip+disp32]) but catastrophic for CALL/JMP — the callee never executes, so its return value and side effects are lost. This manifested as concurrent_target() returning garbage (e.g. 452067328, 1897725952) through the trampoline on Windows CI, where ASLR placed the trampoline far enough from black_box() to overflow the rel32 displacement. Fix: When CALL/JMP rel32 displacement overflows after adjustment, emit an indirect stub (MOV RAX, imm64; JMP RAX) in reserved space at the end of the trampoline, and rewrite the CALL/JMP to target the stub. This preserves CALL semantics (return address is pushed) and supports arbitrary 64-bit target addresses. Also restored the strong value assertion in the concurrent test and added Jcc overflow detection (panic instead of silent NOP).
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Summary
Remove
-j 1and--test-threads=1from the ARM32 CI test step now that thread-local dispatch is implemented for armv7/thumbv7 (PR #114).Why
Running tests with
--test-threads=1defeats the purpose of verifying thread safety — it ensures tests never run in parallel, hiding potential race conditions. With thread-local dispatch fully implemented on ARM32, tests should run in parallel just like all other platforms.Changes
ci.yml: ARM32 test step now usescargo test --target ... --tests -- --nocapture(same flags as other targets)ci-coverage.yml) keeps--test-threads=1since tarpaulin instrumentation may require it