tree c1b354fe601a83369bc7c79d48d2620196210c59
parent 5ad50864a5cb57f95e812e46084030e027e1c46b
author Amanieu d'Antras <amanieu@gmail.com> 1592031468 +0100
committer Copybara-Service <copybara-worker@google.com> 1598638630 -0700

[libunwind][RISCV] Track PC separately from RA

Summary:
This allows unwinding to work across signal handler frames where the IP of the previous frame is not the same as the current value of the RA register. This is particularly useful for acquiring backtraces from signal handlers.

I kept the size of the context structure the same to avoid ABI breakage; the PC is stored in the previously unused slot for register 0.

Reviewers: #libunwind, mhorne, lenary, luismarques, arichardson, compnerd

Reviewed By: #libunwind, mhorne, lenary, compnerd

Subscribers: kamleshbhalui, jrtc27, bsdjhb, arichardson, compnerd, simoncook, kito-cheng, shiva0217, rogfer01, rkruppe, psnobl, benna, Jim, s.egerton, sameer.abuasal, evandro, llvm-commits, libcxx-commits

Tags: #libunwind, #llvm

Differential Revision: https://reviews.llvm.org/D78931

GitOrigin-RevId: 0c1a135adae530b88f68c9425fb85bd8fb9152ca