The first problem was that, on x86, we failed to properly keep track
of whether to expect the return address to be on the stack or not when
unwinding through a frame. We were relying on a "stackLimit" pointer
to tell us whether we were looking at the most recently-called frame
by comparing it with the stack pointer for that frame. That was
inaccurate in the case of a thread executing at the beginning of a
method before a new frame is allocated, in which case the most recent
two frames share a stack pointer, confusing the unwinder. The
solution involves keeping track of how many frames we've looked at
while walking the stack.
The other problem was that compareIpToMethodBounds assumed every
method was followed by at least one byte of padding before the next
method started. That assumption was usually valid because we were
storing the size following method code prior to the code itself.
However, the last method of an AOT-compiled code image is not followed
by any such method header and may instead be followed directly by
native code with no intervening padding. In that case, we risk
interpreting that native code as part of the preceding method, with
potentially bizarre results.
The reason for the compareIpToMethodBounds assumption was that methods
which throw exceptions as their last instruction generate a
non-returning call, which nonetheless push a return address on the
stack which points past the end of the method, and the unwinder needs
to know that return address belongs to that method. A better solution
is to add an extra trap instruction to the end of such methods, which
is what this patch does.
For some reason, Cygwin's MinGW-W64 compilers end up pulling in our
version of process.h from unistd.h. That doesn't really make sense --
it should use the one from the sysroot, but we can work around it by
just not including unistd.h, since it's not needed on Windows anyway.
This clarifies the need to include both openjdk.pro and vm.pro when
building with OpenJDK and ProGuard. It also makes
-dontusemixedcaseclassnames the default in the ProGuard command and
gives different names to the C++ files used in the embedding and
bootimage examples to avoid confusion.
OpenJDK is huge, so building a bootimage out of the whole thing (as
opposed to an app shrunk using ProGuard) requires a lot of space.
Note that we still can't handle this on ARM or PowerPC due to a
limitation in the compiler, but we don't expect people to ship
binaries with the entire OpenJDK class library anyway, so it shouldn't
be a problem in practice.
If we don't initialize that at our first opportunity, it's possible
we'll run out of memory later and exit silently instead of printing
the error and returning a nonzero exit code.
