The compiler does not recognize HACKY_CALL as a call
(we intentionally hide it from the compiler so that it can
compile non-leaf functions as leaf functions).
To compensate for that hacky call thunk saves and restores
all caller-saved registers. However, it saves only
general-purposes registers and does not save XMM registers.
This is a latent bug that was masked up until a recent "NFC" commit
d736002e90 ("tsan: move memory access functions to a separate file"),
which allowed more inlining and exposed the 10-year bug.
Save and restore caller-saved XMM registers (all) as well.
Currently the bug manifests as e.g. frexp interceptor messes the
return value and the added test fails with:
i=8177 y=0.000000 exp=4
Reviewed By: melver
Differential Revision: https://reviews.llvm.org/D113742
Dmitry Vyukov