[PATCH] D63360: hwasan: Use the lower 8 bits of the ring buffer entry address as the base stack tag.

[Peter Collingbourne via Phabricator via llvm-commits]

pcc created this revision.
pcc added a reviewer: eugenis.
Herald added subscribers: Sanitizers, hiraditya, kubamracek, srhines.
Herald added projects: Sanitizers, LLVM.

This saves roughly 32 bytes of instructions per function with stack objects
and causes us to preserve enough information that we can recover the original
tags of all stack variables.

Now that stack tags are deterministic (and can never be zero), we no longer
need to pass -hwasan-generate-tags-with-calls during check-hwasan. This also
means that the new stack tag generation mechanism is exercised by check-hwasan.

Depends on D63119 <https://reviews.llvm.org/D63119>


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D63360

Files:
  compiler-rt/test/hwasan/lit.cfg
  llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp
  llvm/test/Instrumentation/HWAddressSanitizer/alloca.ll
  llvm/test/Instrumentation/HWAddressSanitizer/dbg-declare-tag-offset.ll
  llvm/test/Instrumentation/HWAddressSanitizer/kernel-alloca.ll
  llvm/test/Instrumentation/HWAddressSanitizer/prologue.ll

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