[all-commits] [llvm/llvm-project] addd07: [AIX][PowerPC][PGO] Generate .ref for some PGO sec...

[w2yehia via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: addd0733250af38da0ff5503d65250156a9c179a
      https://github.com/llvm/llvm-project/commit/addd0733250af38da0ff5503d65250156a9c179a
  Author: Wael Yehia <wyehia at ca.ibm.com>
  Date:   2022-02-05 (Sat, 05 Feb 2022)

  Changed paths:
    M llvm/include/llvm/MC/MCContext.h
    M llvm/include/llvm/MC/MCStreamer.h
    M llvm/include/llvm/MC/MCXCOFFStreamer.h
    M llvm/lib/MC/MCAsmStreamer.cpp
    M llvm/lib/MC/MCContext.cpp
    M llvm/lib/MC/MCStreamer.cpp
    M llvm/lib/Target/PowerPC/PPCAsmPrinter.cpp
    A llvm/test/CodeGen/PowerPC/pgo-ref-directive.ll

  Log Message:
  -----------
  [AIX][PowerPC][PGO] Generate .ref for some PGO sections

For PGO on AIX, when we switch to the linux-style PGO variable access
(via _start and _stop labels), we need the compiler to generate a .ref
assembly for each of the three csects:

 -   __llvm_prf_data[RW]
 -   __llvm_prf_names[RO]
 -   __llvm_prf_vnds[RW]

We insert the .ref inside the __llvm_prf_cnts[RW] csect so that if it's
live then the 3 csects are live.

For example, for a testcase with at least one function definition, when
compiled with -fprofile-generate we should generate:

        .csect __llvm_prf_cnts[RW],3
        .ref __llvm_prf_data[RW]   <<============ needs to be inserted
        .ref __llvm_prf_names[RO]  <<===========

the __llvm_prf_vnds is not always present, so we reference it only when
it's present.

Reviewed By: sfertile, daltenty

Differential Revision: https://reviews.llvm.org/D116607