[all-commits] [llvm/llvm-project] 78a18d: [VP] vp intrinsics are not speculatable

[Simon Moll via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 78a18d2b54e7e8e0e2c1d1cb33d015d7f69b8cc7
      https://github.com/llvm/llvm-project/commit/78a18d2b54e7e8e0e2c1d1cb33d015d7f69b8cc7
  Author: Simon Moll <simon.moll at emea.nec.com>
  Date:   2022-05-30 (Mon, 30 May 2022)

  Changed paths:
    M llvm/include/llvm/Analysis/ValueTracking.h
    M llvm/include/llvm/IR/Intrinsics.td
    M llvm/lib/Analysis/ValueTracking.cpp
    M llvm/lib/CodeGen/ExpandVectorPredication.cpp

  Log Message:
  -----------
  [VP] vp intrinsics are not speculatable

VP intrinsics show UB if the %evl parameter is out of bounds - they must
not carry the speculatable attribute.  The out-of-bounds UB disappears
when the %evl parameter is expanded into the mask or expansion replaces
the entire VP intrinsic with non-VP code.

This patch
- Removes the speculatable attribute on all VP intrinsics.
- Generalizes the isSafeToSpeculativelyExecute function to let VP
  expansion know whether the VP intrinsic replacement will be
  speculatable.  VP expansion may only discard %evl where this is the
  case.

Reviewed By: frasercrmck

Differential Revision: https://reviews.llvm.org/D125296