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dd5d86d992
infrastructure. This was essentially work toward PGO based on a design that had several flaws, partially dating from a time when LLVM had a different architecture, and with an effort to modernize it abandoned without being completed. Since then, it has bitrotted for several years further. The result is nearly unusable, and isn't helping any of the modern PGO efforts. Instead, it is getting in the way, adding confusion about PGO in LLVM and distracting everyone with maintenance on essentially dead code. Removing it paves the way for modern efforts around PGO. Among other effects, this removes the last of the runtime libraries from LLVM. Those are being developed in the separate 'compiler-rt' project now, with somewhat different licensing specifically more approriate for runtimes. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@191835 91177308-0d34-0410-b5e6-96231b3b80d8
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))
//===---------------------------------------------------------------------===//