Re:Towards fearless SIMD, 7 years later
by dzaima on Monday March 31, 2025 @03:58PM
(#43539182)
> There are all kinds of bugs in these compilers all the time. I don’t think you can assert that.
That's a separate discussion; generally you need specific conditions in the source code to have compiler bugs affect your code (and for any given compiler bug it's much more likely for it to visibly break your program (i.e. be a clear release blocker) than quietly break on some specific user input; assuming you have appropriate testing).
I don't think I've ever even heard of any exploitable cases of spooky-bug-at-a-distance in Java, whereas such are commonplace for C projects.
Bad multi-threading in Java still won't produce spooky bugs at a distance - worst you may get is a long torn on a 32-bit boundary on 32-bit systems, or reordered reads/writes.
> I think clang should insert a ret at the end of the function.
......But UB means it's not required to do that... ...that's, like, the main thing the discussion is about. This isn't any form of issue or bug in clang to be fixed, it's intentionally chosen that that behavior is fine on UB.
That's a separate discussion; generally you need specific conditions in the source code to have compiler bugs affect your code (and for any given compiler bug it's much more likely for it to visibly break your program (i.e. be a clear release blocker) than quietly break on some specific user input; assuming you have appropriate testing).
I don't think I've ever even heard of any exploitable cases of spooky-bug-at-a-distance in Java, whereas such are commonplace for C projects.
Bad multi-threading in Java still won't produce spooky bugs at a distance - worst you may get is a long torn on a 32-bit boundary on 32-bit systems, or reordered reads/writes.
> I think clang should insert a ret at the end of the function.
......But UB means it's not required to do that... ...that's, like, the main thing the discussion is about. This isn't any form of issue or bug in clang to be fixed, it's intentionally chosen that that behavior is fine on UB.