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3990b121cf
I asked Devang to do back on Sep 27. Instead of going through the MetadataContext class with methods like getMD() and getMDs(), just ask the instruction directly for its metadata with getMetadata() and getAllMetadata(). This includes a variety of other fixes and improvements: previously all Value*'s were bloated because the HasMetadata bit was thrown into value, adding a 9th bit to a byte. Now this is properly sunk down to the Instruction class (the only place where it makes sense) and it will be folded away somewhere soon. This also fixes some confusion in getMDs and its clients about whether the returned list is indexed by the MDID or densely packed. This is now returned sorted and densely packed and the comments make this clear. This introduces a number of fixme's which I'll follow up on. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@92235 91177308-0d34-0410-b5e6-96231b3b80d8
Analysis Opportunities:
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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.
//===---------------------------------------------------------------------===//