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b48a18903a
captured. This allows the tracker to look at the specific use, which may be especially interesting for function calls. Use this to fix 'nocapture' deduction in FunctionAttrs. The existing one does not iterate until a fixpoint and does not guarantee that it produces the same result regardless of iteration order. The new implementation builds up a graph of how arguments are passed from function to function, and uses a bottom-up walk on the argument-SCCs to assign nocapture. This gets us nocapture more often, and does so rather efficiently and independent of iteration order. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@147327 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))
//===---------------------------------------------------------------------===//