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31 lines
1006 B
31 lines
1006 B
4 months ago
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Analysis Opportunities:
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//===---------------------------------------------------------------------===//
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In test/Transforms/LoopStrengthReduce/quadradic-exit-value.ll, the
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ScalarEvolution expression for %r is this:
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{1,+,3,+,2}<loop>
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Outside the loop, this could be evaluated simply as (%n * %n), however
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ScalarEvolution currently evaluates it as
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(-2 + (2 * (trunc i65 (((zext i64 (-2 + %n) to i65) * (zext i64 (-1 + %n) to i65)) /u 2) to i64)) + (3 * %n))
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In addition to being much more complicated, it involves i65 arithmetic,
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which is very inefficient when expanded into code.
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//===---------------------------------------------------------------------===//
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In formatValue in test/CodeGen/X86/lsr-delayed-fold.ll,
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ScalarEvolution is forming this expression:
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((trunc i64 (-1 * %arg5) to i32) + (trunc i64 %arg5 to i32) + (-1 * (trunc i64 undef to i32)))
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This could be folded to
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(-1 * (trunc i64 undef to i32))
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//===---------------------------------------------------------------------===//
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