add a global may-we-JIT flag
The most interesting part of the CL is that we recheck gSkVMAllowJIT in
Program::eval() even though we've already checked it in the constructor.
This allows Viewer to toggle the JIT on and off without having to worry
about program caching. This is not something that you'd expect to come
up in practice if a program just sets gSkVMAllowJIT at the start of
main(); for real clients I think we can avoid all this with a simple
SkGraphics::allowJIT() that only lets clients opt-in, never back out.
I toyed with making '!' rotate through a tristate in Viewer, until I
realized that these really are independent bits: GMs like threshold_rt
that use both ordinary effects and SkVM-only effects demonstrate
different behavior and performance in all four modes. So '!' continues
to toggle SkVMBlitter, and now '@' toggles the JIT.
I've left the test program default settings unchanged, with the JIT
enabled unless --nojit is passed. Where we previously simplified the
command line by conflating --dylib with --skvm, we now conflate --dylib
with --jit.
Change-Id: If86bf524c657298c0846bcd33c706e3c3f91e788
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/308184
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
5 files changed