[llvm-dev] Reducing the number of ptrtoint/inttoptrs that are generated by LLVM
David Chisnall via llvm-dev
llvm-dev at lists.llvm.org
Tue Jan 15 03:59:20 PST 2019
On 14/01/2019 20:55, Juneyoung Lee via llvm-dev wrote:
> Correctness of psub is guaranteed by the specification of pointer
> subtraction of C/C++.
> When two pointers are subtracted, both shall point to elements of the
> same array object, or one past the last element of the array object
As with many things in the C and C++ specifications, this has very
little relationship to real-world code. The biggest example I've seen
that violates this rule is the way that the FreeBSD kernel implements
per-CPU storage, but in a fairly ad-hoc analysis of existing C/C++ code
we found quite a few cases where subtraction occurred between objects.
More information about the llvm-dev