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Easwaran Raman
116e08026c
Summary: Instead of using two separate callbacks to return the entry count and the relative block frequency, use a single callback to return callsite count. This would allow better supporting hybrid mode in the future as the count of callsite need not always be derived from entry count (as in sample PGO). Reviewers: davidxl Subscribers: mehdi_amini, steven_wu, dexonsmith, dang, llvm-commits Differential Revision: https://reviews.llvm.org/D56464 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@350755 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))
//===---------------------------------------------------------------------===//