[llvm-branch-commits] [llvm] release/22.x: [AArch64][SME] Disable tail calls in new ZA/ZT0 functions (#177152) (PR #177169)

[via llvm-branch-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-aarch64

Author: None (llvmbot)

<details>
<summary>Changes</summary>

Backport 10aca26ffffe6a9ee049f479ed7fee9e07421dad

Requested by: @<!-- -->MacDue

---
Full diff: https://github.com/llvm/llvm-project/pull/177169.diff


2 Files Affected:

- (modified) llvm/lib/Target/AArch64/AArch64ISelLowering.cpp (+2-1) 
- (added) llvm/test/CodeGen/AArch64/sme-new-za-zt0-no-tail-call.ll (+78) 


``````````diff
diff --git a/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp b/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
index 74ee8ff8ab5f5..093927049e9d1 100644
--- a/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
+++ b/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
@@ -9328,7 +9328,8 @@ bool AArch64TargetLowering::isEligibleForTailCallOptimization(
   if (CallAttrs.requiresSMChange() || CallAttrs.requiresLazySave() ||
       CallAttrs.requiresPreservingAllZAState() ||
       CallAttrs.requiresPreservingZT0() ||
-      CallAttrs.caller().hasStreamingBody())
+      CallAttrs.caller().hasStreamingBody() || CallAttrs.caller().isNewZA() ||
+      CallAttrs.caller().isNewZT0())
     return false;
 
   // Functions using the C or Fast calling convention that have an SVE signature
diff --git a/llvm/test/CodeGen/AArch64/sme-new-za-zt0-no-tail-call.ll b/llvm/test/CodeGen/AArch64/sme-new-za-zt0-no-tail-call.ll
new file mode 100644
index 0000000000000..3c76132556600
--- /dev/null
+++ b/llvm/test/CodeGen/AArch64/sme-new-za-zt0-no-tail-call.ll
@@ -0,0 +1,78 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 6
+; RUN: llc -mtriple=aarch64-linux-gnu -mattr=+sme2 -O3 -verify-machineinstrs < %s | FileCheck %s
+
+declare void @inout_za_zt0() "aarch64_inout_za" "aarch64_inout_zt0"
+
+define void @new_za_zt0() "aarch64_new_za" "aarch64_new_zt0" {
+; CHECK-LABEL: new_za_zt0:
+; CHECK:       // %bb.0: // %entry
+; CHECK-NEXT:    str x30, [sp, #-16]! // 8-byte Folded Spill
+; CHECK-NEXT:    .cfi_def_cfa_offset 16
+; CHECK-NEXT:    .cfi_offset w30, -16
+; CHECK-NEXT:    mrs x8, TPIDR2_EL0
+; CHECK-NEXT:    cbz x8, .LBB0_2
+; CHECK-NEXT:  // %bb.1: // %entry
+; CHECK-NEXT:    bl __arm_tpidr2_save
+; CHECK-NEXT:    msr TPIDR2_EL0, xzr
+; CHECK-NEXT:    zero {za}
+; CHECK-NEXT:    zero { zt0 }
+; CHECK-NEXT:  .LBB0_2: // %entry
+; CHECK-NEXT:    smstart za
+; CHECK-NEXT:    bl inout_za_zt0
+; CHECK-NEXT:    smstop za
+; CHECK-NEXT:    ldr x30, [sp], #16 // 8-byte Folded Reload
+; CHECK-NEXT:    ret
+entry:
+  tail call void @inout_za_zt0()
+  ret void
+}
+
+declare void @inout_za() "aarch64_inout_za"
+
+define void @new_za() "aarch64_new_za" {
+; CHECK-LABEL: new_za:
+; CHECK:       // %bb.0: // %entry
+; CHECK-NEXT:    str x30, [sp, #-16]! // 8-byte Folded Spill
+; CHECK-NEXT:    .cfi_def_cfa_offset 16
+; CHECK-NEXT:    .cfi_offset w30, -16
+; CHECK-NEXT:    mrs x8, TPIDR2_EL0
+; CHECK-NEXT:    cbz x8, .LBB1_2
+; CHECK-NEXT:  // %bb.1: // %entry
+; CHECK-NEXT:    bl __arm_tpidr2_save
+; CHECK-NEXT:    msr TPIDR2_EL0, xzr
+; CHECK-NEXT:    zero {za}
+; CHECK-NEXT:  .LBB1_2: // %entry
+; CHECK-NEXT:    smstart za
+; CHECK-NEXT:    bl inout_za
+; CHECK-NEXT:    smstop za
+; CHECK-NEXT:    ldr x30, [sp], #16 // 8-byte Folded Reload
+; CHECK-NEXT:    ret
+entry:
+  tail call void @inout_za()
+  ret void
+}
+
+declare void @inout_zt0() "aarch64_inout_zt0"
+
+define void @new_zt0() "aarch64_new_zt0" {
+; CHECK-LABEL: new_zt0:
+; CHECK:       // %bb.0: // %entry
+; CHECK-NEXT:    str x30, [sp, #-16]! // 8-byte Folded Spill
+; CHECK-NEXT:    .cfi_def_cfa_offset 16
+; CHECK-NEXT:    .cfi_offset w30, -16
+; CHECK-NEXT:    mrs x8, TPIDR2_EL0
+; CHECK-NEXT:    cbz x8, .LBB2_2
+; CHECK-NEXT:  // %bb.1: // %entry
+; CHECK-NEXT:    bl __arm_tpidr2_save
+; CHECK-NEXT:    msr TPIDR2_EL0, xzr
+; CHECK-NEXT:    zero { zt0 }
+; CHECK-NEXT:  .LBB2_2: // %entry
+; CHECK-NEXT:    smstart za
+; CHECK-NEXT:    bl inout_zt0
+; CHECK-NEXT:    smstop za
+; CHECK-NEXT:    ldr x30, [sp], #16 // 8-byte Folded Reload
+; CHECK-NEXT:    ret
+entry:
+  tail call void @inout_zt0()
+  ret void
+}

``````````

</details>


https://github.com/llvm/llvm-project/pull/177169