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https://github.com/c64scene-ar/llvm-6502.git
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3ef9cfef13
kicking in the big win of ConstantDataArray. As part of this, change the implementation of GetConstantStringInfo in ValueTracking to work with ConstantDataArray (and not ConstantArray) making it dramatically, amazingly, more efficient in the process and renaming it to getConstantStringInfo. This keeps around a GetConstantStringInfo entrypoint that (grossly) forwards to getConstantStringInfo and constructs the std::string required, but existing clients should move over to getConstantStringInfo instead. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@149351 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))
//===---------------------------------------------------------------------===//