This check now runs at function finalization time, before constant
propagation has occurred; this affected the "DeadIfStatement" test.
Our detection isn't smart enough to realize that a loop will run zero
times, so it treats `for` and `while` loops as always running at least
once. This isn't strictly correct, but it actually mirrors how the CFG
implementation works anyway. The only downside is that we would not flag
code like `for (i=0; i<0; ++i) { return x; }` as an error.
Change-Id: I5e43a6ee3a3993045559f0fb0646d36112543a94
Bug: skia:11377
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/379056
Commit-Queue: John Stiles <johnstiles@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
Rather than have the inliner own this responsibility, the function
finalizer now detects if a function is supposed to return a value but
never actually does. This will allow us to detect this error case even
if the inliner is disabled. The inliner should no longer encounter
functions that claim to return a value but don't, so it will now assert
if one is encountered. (The inliner still has the logic to handle this
case gracefully, just in case.)
The check is currently very simple and doesn't analyze the structure of
the function, so it won't report cases where some paths return a value
and others don't, e.g. this will pass the test:
int func() { if (something()) return 123; }
(This is good enough to resolve the inliner issue, though, as it only
occurred in functions with no value-returns at all.)
Change-Id: I21f13daffe66c8f2e72932b320ee268ba9207bfa
Bug: oss-fuzz:31469, oss-fuzz:31525, skia:11377
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/377196
Reviewed-by: Ethan Nicholas <ethannicholas@google.com>
Commit-Queue: John Stiles <johnstiles@google.com>
In http://review.skia.org/375776, an optimization was added to the
Inliner, causing it to skip generation of unnecessary temporary
variables. The fuzzer immediately discovered a flaw in this logic: the
"unnecessary" variable was actually used in the rare case that a
function failed to actually return a value. The inliner didn't detect
this case. Of course, this isn't a valid program either, so now we
report the error and cleanly fail.
Change-Id: I1f201cfd33f45cace3be93765a4e214e43a46e69
Bug: oss-fuzz:31469, oss-fuzz:31525
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/377101
Reviewed-by: Ethan Nicholas <ethannicholas@google.com>
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
