[pull] master from JuliaLang:master #2126
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Replace all uses of `ptrdiff_t slide` and `int64_t slide` with
`uint64_t`. If a JITted object is ever assigned an address in the upper
half of the address space on a platform with `sizeof(char *) = 4`, which
is quite common on 32-bit Linux, the following can happen:
In JITDebugInfoRegistry::registerJITObject, `SectionAddr -
SectionLoadAddr` is computed in uint64_t (ok), then cast to ptrdiff_t
(two's complement of the uint64_t version mod 2^32). This is apparently
implementation-defined behaviour rather than undefined.
Say SectionAddr = 0x1000UL, SectionLoadAddr = 0xe93b2000UL and size_t
pointer = 0xe93b20abU.
```
(ptrdiff_t)(SectionAddr - SectionLoadAddr)
== (ptrdiff_t)0xffffffff16c4f000
== 382005248
```
jl_DI_for_fptr implicitly converts the ptrdiff_t to int64_t:
```
(int64_t)382005248 == 382005248L
```
lookup_pointer adds `size_t pointer` to `int64_t slide`. Both are
converted to int64_t because it can represent every size_t:
```
(int64_t)0xe93b20abU + 382005248L == 3912966315L + 382005248L
== 4294971563L
```
This is converted back to uint64_t by makeAddress, resulting in an
address other than the 0x10ab we expected:
```
(uint64_t)4294971563L == 0x1000010abUL
```
It is easier to use uint64_t everywhere we need a difference, since they
avoid the problem of losing upper bits after sign extension and avoid
weird UB from signed overflow.
Cherry-picked from #60031.
[1] https://buildkite.com/julialang/julia-master/builds/52196/steps/canvas?sid=019a9d6f-14a6-4ffc-be19-f2f835d1e719
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