[WIP][clang][Fuchsia] Support HWASan for Fuchsia

[leonardchan]

Summary

This tracks all the compiler/llvm changes needed for building Fuchsia with the HWASan variant.

[pcc]

How does Zircon handle tagged addresses in syscalls? Are they handled equivalently to Linux's tagged address ABI?

[leonardchan]

Locally I'm able to build and run the bringup.arm64 config (that is launch the shell and run some commands).

[leonardchan]

In D91466#2395297, @pcc wrote:

How does Zircon handle tagged addresses in syscalls? Are they handled equivalently to Linux's tagged address ABI?

Woops, accidentally let this slide. I'm guessing you saw this in the Fuchsia patch, but I believe we haven't made a final decision yet on how syscalls will handle tagged pointers.

[phosek]

clang/lib/Driver/ToolChains/Fuchsia.cpp

100–101 ↗

(On Diff #317118)

Nit: can you move this above TSan so it's alphabetically sorted?

222 ↗

(On Diff #317118)

222–229 ↗

(On Diff #317118)

Can you move this above relative-vtables so we keep all sanitizers together?

225 ↗

(On Diff #317118)

compiler-rt/lib/hwasan/hwasan_fuchsia.cpp

123–125

I don't think this applies to Fuchsia.

compiler-rt/lib/hwasan/hwasan_poisoning.cpp

22

It might be better to move this function to a per-platform file rather than conditionally compiling the entire body.

[phosek]

@leonardchan would it be possible to break up this patch into multiple changes:

• Clang driver
• Cache file
• hwasan_new_delete.cpp
• HWAddressSanitizer.cpp
• sanitizer_platform_limits_fuchsia.h
• sanitizer_symbolizer_markup.cpp
• the rest

[leonardchan]

Rebase against submitted changes.