20 May
2016
20 May
'16
7:36 p.m.
-spc (Wish the C standard committee had the balls to
say "2's
complement all the way, and a physical bit pattern of all 0s is a
NULL pointer" ... )
As far as I'm concerned, this is different only in degree from `Wish
the C standard committee had the balls to say "Everything is x86".'.
[3] Often to disasterous results. An agressive C
optimizer can
optimize the following right out:
if (x + 1 < x ) { ... }
Because "x+1" can *never* be less than
"x" (signed overflow?
What's that?)
More precisely, because signed overflow invokes undefined behaviour,
meaning that, for values of x where x+1 overflows, the program can
behave in any way whatever and still be within spec. Including, say,
skipping the stuff inside the { } block.
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