[llvm] [CodeGen] Ensure clearRegisterKills clears inside bundles. (PR #149177)

[Ricardo Jesus via llvm-commits]

https://github.com/rj-jesus created https://github.com/llvm/llvm-project/pull/149177

When clearing register kills, ensure we do so inside a bundle too. This came up in AArch64LdStOpt where we attempt to clear kill flags that affect the first store's register. If the kill happens in a bundle, we were only clearing it in the bundle operands, but not in the constituent instructions. This was leading to a verification error, for example: https://godbolt.org/z/WjhEWGcPW.

Fixes #149092.

>From dfa67db235787d763db1afa13023928e759a76dd Mon Sep 17 00:00:00 2001
From: Ricardo Jesus <rjj at nvidia.com>
Date: Wed, 16 Jul 2025 10:20:09 -0700
Subject: [PATCH] [CodeGen] Ensure clearRegisterKills works inside bundles.

---
 llvm/lib/CodeGen/MachineInstr.cpp             |  8 ++++----
 .../test/CodeGen/AArch64/sve-vls-ldst-opt.mir | 20 +++++++++++++++++++
 2 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/llvm/lib/CodeGen/MachineInstr.cpp b/llvm/lib/CodeGen/MachineInstr.cpp
index da3665b3b6a0b..a966add78a97e 100644
--- a/llvm/lib/CodeGen/MachineInstr.cpp
+++ b/llvm/lib/CodeGen/MachineInstr.cpp
@@ -2177,12 +2177,12 @@ void MachineInstr::clearRegisterKills(Register Reg,
                                       const TargetRegisterInfo *RegInfo) {
   if (!Reg.isPhysical())
     RegInfo = nullptr;
-  for (MachineOperand &MO : operands()) {
-    if (!MO.isReg() || !MO.isUse() || !MO.isKill())
+  for (MIBundleOperands O(*this); O.isValid(); ++O) {
+    if (!O->isReg() || !O->isUse() || !O->isKill())
       continue;
-    Register OpReg = MO.getReg();
+    Register OpReg = O->getReg();
     if ((RegInfo && RegInfo->regsOverlap(Reg, OpReg)) || Reg == OpReg)
-      MO.setIsKill(false);
+      O->setIsKill(false);
   }
 }
 
diff --git a/llvm/test/CodeGen/AArch64/sve-vls-ldst-opt.mir b/llvm/test/CodeGen/AArch64/sve-vls-ldst-opt.mir
index 49453bc178914..28c5220642ec5 100644
--- a/llvm/test/CodeGen/AArch64/sve-vls-ldst-opt.mir
+++ b/llvm/test/CodeGen/AArch64/sve-vls-ldst-opt.mir
@@ -72,3 +72,23 @@ body: |
 # CHECK: STURQi killed renamable $q1, renamable $x1, 16 :: (store (s128))
 # CHECK: STURQi killed renamable $q2, renamable $x1, 48 :: (store (s128))
 # CHECK: STR_ZXI killed renamable $z3, renamable $x1, 4 :: (store (<vscale x 1 x s128>))
+---
+name: clear-kill-in-bundle
+tracksRegLiveness: true
+body: |
+  bb.0:
+    liveins: $x0, $z0
+
+    STR_ZXI $z0, $x0, 0 :: (store (<vscale x 1 x s128>))
+    BUNDLE implicit-def $z1, implicit-def $q1, implicit killed $z0 {
+      $z1 = ADD_ZZZ_D $z0, killed $z0
+    }
+    STR_ZXI renamable $z1, $x0, 1 :: (store (<vscale x 1 x s128>))
+
+    RET_ReallyLR
+...
+# CHECK-LABEL: name: clear-kill-in-bundle
+# CHECK: BUNDLE implicit-def $z1, implicit-def $q1, implicit $z0 {
+# CHECK:   $z1 = ADD_ZZZ_D $z0, $z0
+# CHECK: }
+# CHECK: STPQi $q0, $q1, $x0, 0 :: (store (<vscale x 1 x s128>))