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8f32e5f0d6
Summary: Initially, these intrinsics seemed like part of a family of "frame" related intrinsics, but now I think that's more confusing than helpful. Initially, the LangRef specified that this would create a new kind of allocation that would be allocated at a fixed offset from the frame pointer (EBP/RBP). We ended up dropping that design, and leaving the stack frame layout alone. These intrinsics are really about sharing local stack allocations, not frame pointers. I intend to go further and add an `llvm.localaddress()` intrinsic that returns whatever register (EBP, ESI, ESP, RBX) is being used to address locals, which should not be confused with the frame pointer. Naming suggestions at this point are welcome, I'm happy to re-run sed. Reviewers: majnemer, nicholas Subscribers: llvm-commits Differential Revision: http://reviews.llvm.org/D11011 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@241633 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))
//===---------------------------------------------------------------------===//