The `enforcenoraises` pragma prevents generation of exception checking
code for atomic... functions when compiling with Microsoft Visual C++ as
backend.
Fixes#25445
Without this change, the following test program:
```nim
import std/sysatomics
var x: ptr uint64 = cast[ptr uint64](uint64(0))
var y: ptr uint64 = cast[ptr uint64](uint64(42))
let z = atomicExchangeN(addr x, y, ATOMIC_ACQ_REL)
let a = atomicCompareExchangeN(addr x, addr y, y, true, ATOMIC_ACQ_REL, ATOMIC_ACQ_REL)
var v = 42
atomicStoreN(addr v, 43, ATOMIC_ACQ_REL)
let w = atomicLoadN(addr v, ATOMIC_ACQ_REL)
```
... generates this C code when compiling with `--cc:vcc`:
```c
N_LIB_PRIVATE N_NIMCALL(void, NimMainModule)(void) {
{
NU64* T1_;
NIM_BOOL T2_;
NI T3_;
NIM_BOOL* nimErr_;
nimfr_("testexcept", "/tmp/testexcept.nim");
nimErr_ = nimErrorFlag();
nimlf_(7, "/tmp/testexcept.nim");T1_ = ((NU64*) 0);
T1_ = atomicExchangeN__testexcept_u4((&x__testexcept_u2), y__testexcept_u3, ((int) 4));
if (NIM_UNLIKELY((*nimErr_))) {
goto BeforeRet_;
}
z__testexcept_u32 = T1_;
nimln_(9);T2_ = ((NIM_BOOL) 0);
T2_ = atomicCompareExchangeN__testexcept_u33((&x__testexcept_u2), (&y__testexcept_u3), y__testexcept_u3, NIM_TRUE, ((int) 4), ((int) 4));
if (NIM_UNLIKELY((*nimErr_))) {
goto BeforeRet_;
}
a__testexcept_u45 = T2_;
nimln_(12);atomicStoreN__testexcept_u47(((&v__testexcept_u46)), ((NI) 43));
if (NIM_UNLIKELY((*nimErr_))) {
goto BeforeRet_;
}
nimln_(13);T3_ = ((NI) 0);
T3_ = atomicLoadN__testexcept_u53(((&v__testexcept_u46)));
if (NIM_UNLIKELY((*nimErr_))) {
goto BeforeRet_;
}
w__testexcept_u59 = T3_;
BeforeRet_: ;
nimTestErrorFlag();
popFrame();
}
}
```
Note the repeated checks for `*nimErr_`.
With this PR applied, the checks vanish:
```c
N_LIB_PRIVATE N_NIMCALL(void, NimMainModule)(void) {
{
nimfr_("testexcept", "/tmp/testexcept.nim");
nimlf_(7, "/tmp/testexcept.nim");z__testexcept_u32 = atomicExchangeN__testexcept_u4((&x__testexcept_u2), y__testexcept_u3, ((int) 4));
nimln_(9);a__testexcept_u45 = atomicCompareExchangeN__testexcept_u33((&x__testexcept_u2), (&y__testexcept_u3), y__testexcept_u3, NIM_TRUE, ((int) 4), ((int) 4));
nimln_(12);atomicStoreN__testexcept_u47(((&v__testexcept_u46)), ((NI) 43));
nimln_(13);w__testexcept_u59 = atomicLoadN__testexcept_u53(((&v__testexcept_u46)));
nimTestErrorFlag();
popFrame();
}
}
```
For reference, with gcc as backend the generated code looks as follows:
```c
N_LIB_PRIVATE N_NIMCALL(void, NimMainModule)(void) {
{
nimfr_("testexcept", "/tmp/testexcept.nim");
nimlf_(7, "/tmp/testexcept.nim");z__testexcept_u9 = __atomic_exchange_n((&x__testexcept_u2), y__testexcept_u3, __ATOMIC_ACQ_REL);
nimln_(9);a__testexcept_u18 = __atomic_compare_exchange_n((&x__testexcept_u2), (&y__testexcept_u3), y__testexcept_u3, NIM_TRUE, __ATOMIC_ACQ_REL, __ATOMIC_ACQ_REL);
nimln_(12);__atomic_store_n(((&v__testexcept_u19)), ((NI) 43), __ATOMIC_ACQ_REL);
nimln_(13);w__testexcept_u29 = __atomic_load_n(((&v__testexcept_u19)), __ATOMIC_ACQ_REL);
nimTestErrorFlag();
popFrame();
}
}
```
With this PR the program from #25445 yields the correct output `Error:
unhandled exception: index 4 not in 0 .. 3 [IndexDefect]` instead of
crashing with a SIGSEGV.
PS: Unfortunately, I did not find out how to run the tests with MSVC.
`./koch tests --cc:vcc` doesn't use MSVC.
`InterlockedCompareExchange64 `(winnt.h) is used instead of gcc atomics
when compiling with MSVC on Windows, but the function signatures are
`InterlockedCompareExchange64(ptr int64, int64, int64)` and
`InterlockedCompareExchange32(ptr int32, int32, int32)` as opposed to
`(ptr T, ptr T, T)` for `__atomic_compare_exchange_n`.
Passing a pointer to the expected value (parameter two) instead of the
value itself causes the comparison to unconditionally fail, with stalls
in threaded code using atomic comparisons.
Fix the function signature for MSVC.
Signed-off-by: Ryan Walklin <ryan@testtoast.com>
* Fix: make nintendoswitch someGcc, remove symlink support for nintendoswitch, add getAppFilename for nintendoswitch
* Fix: use getApplHeuristic on nintendoswitch
