[Python-Dev] ANSI strict aliasing and Python

[Andrew MacIntyre]

On Fri, 18 Jul 2003, Tim Peters wrote:

> Has anyone tried running Python compiled without no-strict-aliasing?  If so,
> how bad was it?

I've never used no-strict-aliasing with gcc on the EMX port.  With gcc
2.8.1 and 2.95.2 -O3, I've not seen failures that appear to be bad code;
with gcc 3.2.1 I see 3 tests (test_codeccallbacks, test_format &
test_unicode) that seem to have repeatable failures that are sensitive to
optimisation level (-O3 = fail, -O2 = pass) which may be bad code.  I'll
try -no-stict-aliasing when I get back digging into this.

BTW, the following sequence of tests causes a core dump from an assertion
failure in test_enumerate on EMX which I haven't been able to replicate on
FreeBSD :-(

test_importhooks
test_re
test_glob
test_parser
test_enumerate

I haven't played with all possible permutations, but skipping any one of
the precursor tests doesn't exhibit the assertion failure, which is:

Assertion failed: gc->gc.gc_refs != 0, file ../../Modules/gcmodule.c, line
231

I also encountered a hang in test_poll on FreeBSD 5.1 (gcc 3.2.2), which I
suspect is more likely to be a problem with FreeBSD 5.1's library code
(thread codebase instability) than Python.  I ran about a dozen full -r
runs on FreeBSD 4.8 (gcc 2.95.4) with no sign of anything being amiss
(which doesn't mean it isn't, just not readily tripped over).

More digging clearly indicated on both EMX issues...

--
Andrew I MacIntyre                     "These thoughts are mine alone..."
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