[PATCH] D40004: [XRay][compiler-rt][x86_64] Align the stack before and after calling handlers

[Dean Michael Berris via Phabricator via llvm-commits]

dberris created this revision.

This change fixes the XRay trampolines aside from the __xray_CustomEvent
trampoline to align the stack to 16-byte boundaries before calling the
handler. Before this change we've not been explicitly aligning the stack
to 16-byte boundaries, which makes it dangerous when calling handlers
that leave the stack in a state that isn't strictly 16-byte aligned
after calling the handlers.

We add a test that makes sure we can handle these cases appropriately
after the changes, and prevents us from regressing the state moving
forward.

Fixes http://llvm.org/PR35294.


https://reviews.llvm.org/D40004

Files:
  compiler-rt/lib/xray/xray_trampoline_x86_64.S
  compiler-rt/test/xray/TestCases/Linux/common-trampoline-alignment.cc

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