[llvm] [AArch64] Drop flags from BSP pseudos (PR #151856)

[David Green via llvm-commits]

https://github.com/davemgreen created https://github.com/llvm/llvm-project/pull/151856

This prevents cases where some of the operands match from hitting verifier errorswith kill flags. These nodes should have been removed eariler in most cases.

>From 0135db5edb6ee5e64393f3c4c5a358263adade3e Mon Sep 17 00:00:00 2001
From: David Green <david.green at arm.com>
Date: Sun, 3 Aug 2025 09:01:13 +0100
Subject: [PATCH] [AArch64] Drop flags from BSP pseudos

This prevents cases where some of the operands match from hitting verifier
errorswith kill flags. These nodes should have been removed eariler in most
cases.
---
 .../AArch64/AArch64ExpandPseudoInsts.cpp      |  6 +++--
 .../test/CodeGen/AArch64/bsp_implicit_ops.mir | 22 ++++++++++++++++++-
 2 files changed, 25 insertions(+), 3 deletions(-)

diff --git a/llvm/lib/Target/AArch64/AArch64ExpandPseudoInsts.cpp b/llvm/lib/Target/AArch64/AArch64ExpandPseudoInsts.cpp
index 201bfe0a443d6..77fcad634776d 100644
--- a/llvm/lib/Target/AArch64/AArch64ExpandPseudoInsts.cpp
+++ b/llvm/lib/Target/AArch64/AArch64ExpandPseudoInsts.cpp
@@ -1242,8 +1242,10 @@ bool AArch64ExpandPseudo::expandMI(MachineBasicBlock &MBB,
             .addReg(DstReg,
                     RegState::Define |
                         getRenamableRegState(MI.getOperand(0).isRenamable()))
-            .add(MI.getOperand(1))
-            .add(MI.getOperand(1));
+            .addReg(MI.getOperand(1).getReg(),
+                    getRenamableRegState(MI.getOperand(1).isRenamable()))
+            .addReg(MI.getOperand(1).getReg(),
+                    getRenamableRegState(MI.getOperand(1).isRenamable()));
         auto I2 =
             BuildMI(MBB, MBBI, MI.getDebugLoc(),
                     TII->get(Opcode == AArch64::BSPv8i8 ? AArch64::BSLv8i8
diff --git a/llvm/test/CodeGen/AArch64/bsp_implicit_ops.mir b/llvm/test/CodeGen/AArch64/bsp_implicit_ops.mir
index 23ac67cac6416..7ba363d46a1ff 100644
--- a/llvm/test/CodeGen/AArch64/bsp_implicit_ops.mir
+++ b/llvm/test/CodeGen/AArch64/bsp_implicit_ops.mir
@@ -13,7 +13,7 @@ body:             |
     ; CHECK-LABEL: name: BSL_COPY
     ; CHECK: liveins: $q20, $q21, $q22, $q23, $q6, $q1, $q7
     ; CHECK-NEXT: {{  $}}
-    ; CHECK-NEXT: renamable $q2 = ORRv16i8 killed renamable $q20, killed renamable $q20
+    ; CHECK-NEXT: renamable $q2 = ORRv16i8 renamable $q20, renamable $q20
     ; CHECK-NEXT: renamable $q2 = BSLv16i8 killed renamable $q2, renamable $q21, renamable $q6, implicit killed $q21_q22_q23, implicit killed $q0_q1_q2_q3, implicit-def $q0_q1_q2_q3
     ; CHECK-NEXT: $q22 = ORRv16i8 $q0, killed $q0
     ; CHECK-NEXT: $q23 = ORRv16i8 $q1, killed $q1
@@ -96,3 +96,23 @@ body:             |
     $q25 = ORRv16i8 $q3, killed $q3
     RET_ReallyLR implicit $q22
 ...
+---
+name:            DoubleOp
+tracksRegLiveness: true
+body:             |
+  bb.0.entry:
+    liveins: $q2
+
+    ; CHECK-LABEL: name: DoubleOp
+    ; CHECK: liveins: $q2
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: renamable $q0 = MOVIv8i16 1, 0
+    ; CHECK-NEXT: renamable $q1 = ORRv16i8 renamable $q2, renamable $q2
+    ; CHECK-NEXT: renamable $q1 = BSLv16i8 killed renamable $q1, renamable $q2, renamable $q0
+    ; CHECK-NEXT: renamable $q0 = SQADDv8i16 killed renamable $q1, killed renamable $q0
+    ; CHECK-NEXT: RET undef $lr, implicit $q0
+    renamable $q0 = MOVIv8i16 1, 0
+    renamable $q1 = BSPv16i8 killed renamable $q2, renamable $q2, renamable $q0
+    renamable $q0 = SQADDv8i16 killed renamable $q1, killed renamable $q0
+    RET_ReallyLR implicit $q0
+...