[llvm] Revert "[InitUndef] handleSubReg should skip artificial subregs. (#116248)" (PR #117365)

[Vitaly Buka via llvm-commits]

https://github.com/vitalybuka created https://github.com/llvm/llvm-project/pull/117365

Maybe not needed but to avoid conflicts with #117307
Without revert of this one, but reverting #117307, the
regenerated init-undef.mir became empty.

This reverts commit be15fd5085680cc5ed9ec4f4f2258b504cdd55db.


>From 0d670f8260a713f60235654118b27a054a548f5d Mon Sep 17 00:00:00 2001
From: Vitaly Buka <vitalybuka at google.com>
Date: Fri, 22 Nov 2024 11:24:13 -0800
Subject: [PATCH] =?UTF-8?q?[=F0=9D=98=80=F0=9D=97=BD=F0=9D=97=BF]=20initia?=
 =?UTF-8?q?l=20version?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Created using spr 1.3.4
---
 llvm/lib/CodeGen/InitUndef.cpp           | 8 --------
 llvm/test/CodeGen/AArch64/init-undef.mir | 3 +--
 2 files changed, 1 insertion(+), 10 deletions(-)

diff --git a/llvm/lib/CodeGen/InitUndef.cpp b/llvm/lib/CodeGen/InitUndef.cpp
index d8b3190f31003e..d4ac131a32a959 100644
--- a/llvm/lib/CodeGen/InitUndef.cpp
+++ b/llvm/lib/CodeGen/InitUndef.cpp
@@ -164,14 +164,6 @@ bool InitUndef::handleSubReg(MachineFunction &MF, MachineInstr &MI,
     TRI->getCoveringSubRegIndexes(*MRI, TargetRegClass, NeedDef,
                                   SubRegIndexNeedInsert);
 
-    // It's not possible to create the INIT_UNDEF when there is no register
-    // class associated for the subreg. This may happen for artificial subregs
-    // that are not directly addressable.
-    if (any_of(SubRegIndexNeedInsert, [&](unsigned Ind) -> bool {
-          return !TRI->getSubRegisterClass(TargetRegClass, Ind);
-        }))
-      continue;
-
     Register LatestReg = Reg;
     for (auto ind : SubRegIndexNeedInsert) {
       Changed = true;
diff --git a/llvm/test/CodeGen/AArch64/init-undef.mir b/llvm/test/CodeGen/AArch64/init-undef.mir
index c9d23006d35234..7935c09d7df5ec 100644
--- a/llvm/test/CodeGen/AArch64/init-undef.mir
+++ b/llvm/test/CodeGen/AArch64/init-undef.mir
@@ -1,6 +1,5 @@
 # NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py UTC_ARGS: --version 5
-# RUN: llc -mtriple=aarch64-- -aarch64-enable-subreg-liveness-tracking=false -run-pass=init-undef -o - %s | FileCheck %s
-# RUN: llc -mtriple=aarch64-- -aarch64-enable-subreg-liveness-tracking=true -run-pass=init-undef -o - %s | FileCheck %s
+# RUN: llc -mtriple=aarch64-- -run-pass=init-undef -o - %s | FileCheck %s
 
 ---
 name:            test_stxp_undef