This reverts commit a212d8da94d08e229aa8d65283e4b116310bba10, and follow
on fixes 0cd6763fa93159b84d70a5bb602c24996acaafaa,
e9ff53d42feac7fc157718523275619a8106f2f3, and
37c6a25e9ab230e5e21fa34e246d9fec55275df0.
After re-reading the documentation for hash_combine, I don't think this
is the appropriate hash function to use for computing the hash to use as
a stack id in the metadata, since it is not guaranteed to produce stable
values across executions. I have not hit this problem, but plan to
switch to using an MD5 hash. I am hitting an issue with one of the bots
(https://lab.llvm.org/buildbot/#/builders/171/builds/20732)
where the values produced are only the lower 32 bits of the expected
hash values, however, which I assume is related to the implementation of
hash_combine and hash_code.
I believe I fixed all of the other bot failures with the follow on fixes,
which I'll merge into the new version before reapplying.
Analysis Opportunities:
//===---------------------------------------------------------------------===//
In test/Transforms/LoopStrengthReduce/quadradic-exit-value.ll, the
ScalarEvolution expression for %r is this:
{1,+,3,+,2}<loop>
Outside the loop, this could be evaluated simply as (%n * %n), however
ScalarEvolution currently evaluates it as
(-2 + (2 * (trunc i65 (((zext i64 (-2 + %n) to i65) * (zext i64 (-1 + %n) to i65)) /u 2) to i64)) + (3 * %n))
In addition to being much more complicated, it involves i65 arithmetic,
which is very inefficient when expanded into code.
//===---------------------------------------------------------------------===//
In formatValue in test/CodeGen/X86/lsr-delayed-fold.ll,
ScalarEvolution is forming this expression:
((trunc i64 (-1 * %arg5) to i32) + (trunc i64 %arg5 to i32) + (-1 * (trunc i64 undef to i32)))
This could be folded to
(-1 * (trunc i64 undef to i32))
//===---------------------------------------------------------------------===//
794b7ea960