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pervognsen/gist:d1c7b3a183aa6352164c

Created October 5, 2014 08:35
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In new(p) T(x) the C++ standard requires that placement new performs a null pointer check on p.
Unfortunately, this can add a pointless conditional to inner loops that use dynamic arrays implemented
in C++ via placement new. I don't expect the optimizer to perform a global analysis to conclude that p
can never be null, so I have to help it on its way. However, none of these three tricks convince Clang 3.5:
new(&*p) T(x);
(void) *p;
new(p) T(x);
if (!p) __builtin_unreachable();
new(p) T(x);
Does anyone have a better idea?
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