[all-commits] [llvm/llvm-project] a50419: [X86] Emit a reg-reg copy for fast isel of vector ...

[topperc via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: a5041987eddc21d37345d055cb7a51b3eb5ee698
      https://github.com/llvm/llvm-project/commit/a5041987eddc21d37345d055cb7a51b3eb5ee698
  Author: Craig Topper <craig.topper at intel.com>
  Date:   2020-06-24 (Wed, 24 Jun 2020)

  Changed paths:
    M llvm/lib/Target/X86/X86FastISel.cpp
    A llvm/test/CodeGen/X86/fast-isel-bitcast-crash.ll

  Log Message:
  -----------
  [X86] Emit a reg-reg copy for fast isel of vector bitcasts.

Previously we just updated a map and moved on. But it possible
we cached known bits information with the vreg that can be used by
another basic block. If the other basic block has a different view
of the VT these known bits won't make sense.

By emitting a copy we ensure we have different vregs before and
after the bitcast. This prevents the known bits from being used
with the wrong type.

Differential Revision: https://reviews.llvm.org/D82517