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7c52c97a22
add a new Region::block_iterator which actually iterates over the basic blocks of the region. The old iterator, now call 'block_node_iterator' iterates over RegionNodes which contain a single basic block. This works well with the GraphTraits-based iterator design, however most users actually want an iterator over the BasicBlocks inside these RegionNodes. Now the 'block_iterator' is a wrapper which exposes exactly this interface. Internally it uses the block_node_iterator to walk all nodes which are single basic blocks, but transparently unwraps the basic block to make user code simpler. While this patch is a bit of a wash, most of the updates are to internal users, not external users of the RegionInfo. I have an accompanying patch to Polly that is a strict simplification of every user of this interface, and I'm working on a pass that also wants the same simplified interface. This patch alone should have no functional impact. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@156202 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))
//===---------------------------------------------------------------------===//