mirror of
https://github.com/yuzu-emu/unicorn.git
synced 2024-12-22 19:05:32 +00:00
accel/tcg: Add URL of clang bug to comment about our workaround
In cpu_exec() we have a longstanding workaround for compilers which do not correctly implement the part of the sigsetjmp()/siglongjmp() spec which requires that local variables which are not changed between the setjmp and the longjmp retain their value. I recently ran across the upstream clang bug report for this; add a link to it to the comment describing the workaround, and generally expand the comment, so that we have a reasonable chance in future of understanding why it's there and determining when we can remove it, assuming clang eventually fixes the bug. Remove the /* buggy compiler */ comments on the #else and #endif: they don't add anything to understanding and are somewhat misleading since they're sandwiching the code path for *non*-buggy compilers. Backports e6a41a045c298538d303cd8fe8d7ae29a0c066ad
This commit is contained in:
parent
93b0428f48
commit
2c926832bb
|
@ -551,18 +551,30 @@ int cpu_exec(struct uc_struct *uc, CPUState *cpu)
|
|||
/* prepare setjmp context for exception handling */
|
||||
if (sigsetjmp(cpu->jmp_env, 0) != 0) {
|
||||
#if defined(__clang__)
|
||||
/* Some compilers wrongly smash all local variables after
|
||||
* siglongjmp. There were bug reports for gcc 4.5.0 and clang.
|
||||
/*
|
||||
* Some compilers wrongly smash all local variables after
|
||||
* siglongjmp (the spec requires that only non-volatile locals
|
||||
* which are changed between the sigsetjmp and siglongjmp are
|
||||
* permitted to be trashed). There were bug reports for gcc
|
||||
* 4.5.0 and clang. The bug is fixed in all versions of gcc
|
||||
* that we support, but is still unfixed in clang:
|
||||
* https://bugs.llvm.org/show_bug.cgi?id=21183
|
||||
*
|
||||
* Reload essential local variables here for those compilers.
|
||||
* Newer versions of gcc would complain about this code (-Wclobbered). */
|
||||
* Newer versions of gcc would complain about this code (-Wclobbered),
|
||||
* so we only perform the workaround for clang.
|
||||
*/
|
||||
cpu = uc->current_cpu;
|
||||
env = cpu->env_ptr;
|
||||
cc = CPU_GET_CLASS(uc, cpu);
|
||||
#else /* buggy compiler */
|
||||
/* Assert that the compiler does not smash local variables. */
|
||||
#else
|
||||
/*
|
||||
* Non-buggy compilers preserve these locals; assert that
|
||||
* they have the correct value.
|
||||
*/
|
||||
g_assert(cpu == uc->current_cpu);
|
||||
g_assert(cc == CPU_GET_CLASS(uc, cpu));
|
||||
#endif /* buggy compiler */
|
||||
#endif
|
||||
// Unicorn: commented out
|
||||
//tb_lock_reset();
|
||||
}
|
||||
|
|
Loading…
Reference in a new issue