Was: Debug optimized code; Now: How many compiler bugs have you seen?

George Neuner <gneuner2@comcast.net> writes:


> Not to mention that the compiler itself is more likely to have
> strangely interacting bugs in its higher optimization levels.


People often mention this and having workied on compilers I've seen my
shared of bugs (from the inside). However, as a compiler customer I
can only recall two times in my career where I've actually encountered
a bug that was in the compiler and not in "my" code (the code I was
working on).


One case, was a case where a specific model of a machine had a special
hardware flaw and it wasn't patched over in the compiler I was using.
The other case was a simple blatant bug where the compiler simply
dropped the code for a line that said x = x * 2; (the work around was
to recoded it as x = x + x;).


However, beyond those two cases I've never (as a user) experienced a
real compiler bug. I've seen lots of cases where the compiler exposed
aliasing problems and places where the code was expecting things to be
order in specific ways not guaranteed by the standard, but only those
two bugs.


So, I wonder, how many of you have experienced real compiler bugs,
that you could verify was the compilers fault and not just "mysterious
behavior" that could be fixed by changing the optimizer/debugger
level?


Just curious,
-Chris


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Chris Clark Internet: christopher.f.clark@compiler-resources.com
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