[llvm-commits] [asan] Use getTypeAllocSize instead of getTypeStoreSize

[Evgeniy Stepanov]

Hi,

as Eli correctly pointed out in
http://llvm.org/bugs/show_bug.cgi?id=12047, it is not a good idea to
set up stack allocation redzones based on
TargetData::getTypeStoreSize. One case when this produces undesired
results is an optimization in InstCombine pass
(PromoteCastOfAllocation), which can replace  alloca(T) with
alloca(S), where S has the same AllocSize, but a smaller StoreSize.
Another case is memcpy(long double => long double), where ASan will
poison bytes 10-15 of a stack-allocated long double (StoreSize  10,
AllocSize 16, sizeof(long double) = 16).

This patch replaces getTypeStoreSize with getTypeAllocSize in
AddressSanitizer instrumentation for stack allocations. Another patch
adds a test.
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