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Re: changing "configure" to default to "gcc -g -O2 -fwrapv ..."
Ian Lance Taylor <iant@google.com> writes:
| Gabriel Dos Reis <gdr@integrable-solutions.net> writes:
|
| > for this specific function (vrp_int_const_binop), I'm issuing a
| > warning inside the else-if branch that tests for the overflowed
| > result. I'm unclear why that is a false positive since the result is
| > known to overflow. Could you elaborate?
|
| Within VRP, calculations are made on ranges. The upper and lower
| limits of those ranges need not actually appear in the program. If
| you warn whenever vrp_int_const_binop produces an overflow, you will
| get an enormous number of false positives.
Thanks for this explanation.
| I have a patch which issues warnings whenever gcc assumes that signed
| overflow is undefined, except in loop IV calculations. I'm tweaking
| it to see whether it is possible to bootstrap gcc with this patch. It
| currently builds libcpp with no warnings, but falls over on this code
| in decDivideOp in decNumber.c in libdecnumber:
OK, I see; since today is a bit special I may not be able to get back
to you as quickly as I would like.
-- Gaby