[llvm] e0c49c0 - AArch64/GlobalISel: Mark the LR def of the Mach-O TLS call dead (#227234)

[via llvm-commits]

Author: Matt Arsenault
Date: 2026-09-29T12:19:26+02:00
New Revision: e0c49c0739807c8c75d38148babfa338d1e07f6a

URL: https://github.com/llvm/llvm-project/commit/e0c49c0739807c8c75d38148babfa338d1e07f6a
DIFF: https://github.com/llvm/llvm-project/commit/e0c49c0739807c8c75d38148babfa338d1e07f6a.diff

LOG: AArch64/GlobalISel: Mark the LR def of the Mach-O TLS call dead (#227234)

The ordinary call path already does this, and the SelectionDAG emitter
marks unused implicit physreg defs dead for free. Without it the dead
flag needs to be reinferred later.

Co-authored-by: Claude Opus 5 <noreply at anthropic.com>

Added: 
    llvm/test/CodeGen/AArch64/GlobalISel/select-tls-macho.ll

Modified: 
    llvm/lib/Target/AArch64/GISel/AArch64InstructionSelector.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Target/AArch64/GISel/AArch64InstructionSelector.cpp b/llvm/lib/Target/AArch64/GISel/AArch64InstructionSelector.cpp
index 309dbd0def387..22c0e3a3a462d 100644
--- a/llvm/lib/Target/AArch64/GISel/AArch64InstructionSelector.cpp
+++ b/llvm/lib/Target/AArch64/GISel/AArch64InstructionSelector.cpp
@@ -3920,6 +3920,7 @@ bool AArch64InstructionSelector::selectTLSGlobalValueMachO(
   }
 
   MIB.buildInstr(Opcode, {}, {Load})
+      .setOperandDead(1) // implicit-def $lr
       .addUse(AArch64::X0, RegState::Implicit)
       .addDef(AArch64::X0, RegState::Implicit)
       .addRegMask(TRI.getTLSCallPreservedMask());

diff  --git a/llvm/test/CodeGen/AArch64/GlobalISel/select-tls-macho.ll b/llvm/test/CodeGen/AArch64/GlobalISel/select-tls-macho.ll
new file mode 100644
index 0000000000000..0586ac29f4105
--- /dev/null
+++ b/llvm/test/CodeGen/AArch64/GlobalISel/select-tls-macho.ll
@@ -0,0 +1,30 @@
+; NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py UTC_ARGS: --version 6
+; RUN: llc -mtriple=arm64-apple-macosx -global-isel -O0 -stop-after=instruction-select < %s | FileCheck %s
+
+ at tls_var = external thread_local global i32
+
+define ptr @tls_addr() {
+  ; CHECK-LABEL: name: tls_addr
+  ; CHECK: bb.1 (%ir-block.0):
+  ; CHECK-NEXT:   [[LOADgot:%[0-9]+]]:gpr64common = LOADgot target-flags(aarch64-tls) @tls_var
+  ; CHECK-NEXT:   [[LDRXui:%[0-9]+]]:gpr64common = LDRXui [[LOADgot]], 0
+  ; CHECK-NEXT:   $x0 = COPY [[LOADgot]]
+  ; CHECK-NEXT:   BLR [[LDRXui]], csr_darwin_aarch64_tls, implicit-def dead $lr, implicit $sp, implicit $x0, implicit-def $x0
+  ; CHECK-NEXT:   [[COPY:%[0-9]+]]:gpr64 = COPY $x0
+  ; CHECK-NEXT:   $x0 = COPY [[COPY]]
+  ; CHECK-NEXT:   RET_ReallyLR implicit $x0
+  ret ptr @tls_var
+}
+
+define ptr @tls_addr_ptrauth() "ptrauth-calls" {
+  ; CHECK-LABEL: name: tls_addr_ptrauth
+  ; CHECK: bb.1 (%ir-block.0):
+  ; CHECK-NEXT:   [[LOADgot:%[0-9]+]]:gpr64common = LOADgot target-flags(aarch64-tls) @tls_var
+  ; CHECK-NEXT:   [[LDRXui:%[0-9]+]]:gpr64common = LDRXui [[LOADgot]], 0
+  ; CHECK-NEXT:   $x0 = COPY [[LOADgot]]
+  ; CHECK-NEXT:   BLRAAZ [[LDRXui]], csr_darwin_aarch64_tls, implicit-def dead $lr, implicit $sp, implicit $x0, implicit-def $x0
+  ; CHECK-NEXT:   [[COPY:%[0-9]+]]:gpr64 = COPY $x0
+  ; CHECK-NEXT:   $x0 = COPY [[COPY]]
+  ; CHECK-NEXT:   RET_ReallyLR implicit $x0
+  ret ptr @tls_var
+}