[all-commits] [llvm/llvm-project] 0c1381: [llc] Use -filetype=null to disable MIR printing

[Jay Foad via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 0c1381d79567f58655561bd39f5efb1d468c930a
      https://github.com/llvm/llvm-project/commit/0c1381d79567f58655561bd39f5efb1d468c930a
  Author: Jay Foad <jay.foad at amd.com>
  Date:   2020-10-16 (Fri, 16 Oct 2020)

  Changed paths:
    M llvm/lib/CodeGen/LLVMTargetMachine.cpp
    A llvm/test/tools/llc/filetype-null-stop-after.ll

  Log Message:
  -----------
  [llc] Use -filetype=null to disable MIR printing

If you use -stop-after or similar options, llc will normally print MIR.
This patch checks for -filetype=null as a special case to disable MIR
printing. As the comment says, "The Null output is intended for use for
performance analysis ...", and I found this useful for timing a subset
of the passes that llc runs without the significant overhead of printing
MIR just to send it to /dev/null.

Differential Revision: https://reviews.llvm.org/D89476