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[AArch64][SME] Treat agnostic ZA invokes like private ZA callees #162684

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Oct 14, 2025
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[AArch64][SME] Treat agnostic ZA invokes like private ZA callees #162684

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Precommit tests
MacDue Oct 9, 2025
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[AArch64][SME] Treat agnostic ZA invokes like private ZA callees
MacDue Oct 9, 2025
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Remove incorrect comments
MacDue Oct 9, 2025
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6 changes: 6 additions & 0 deletions llvm/lib/Target/AArch64/Utils/AArch64SMEAttributes.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -130,6 +130,12 @@ SMECallAttrs::SMECallAttrs(const CallBase &CB, const AArch64TargetLowering *TLI)
if (auto *CalledFunction = CB.getCalledFunction())
CalledFn = SMEAttrs(*CalledFunction, TLI);

// An `invoke` of an agnostic ZA function may not return normally (it may
// resume in an exception block). In this case, it acts like a private ZA
// callee and may require a ZA save to be set up before it is called.
if (isa<InvokeInst>(CB))
CalledFn.set(SMEAttrs::ZA_State_Agnostic, /*Enable=*/false);

// FIXME: We probably should not allow SME attributes on direct calls but
// clang duplicates streaming mode attributes at each callsite.
assert((IsIndirect ||
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242 changes: 242 additions & 0 deletions llvm/test/CodeGen/AArch64/sme-za-exceptions.ll
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Expand Up @@ -732,6 +732,247 @@ exit:
ret void
}

; This example corresponds to:
;
; __arm_agnostic("sme_za_state") void try_catch_agnostic_za_invoke()
; {
; try {
; agnostic_za_call();
; } catch(...) {
; }
; }
;
; In this example we preserve all SME state enabled by PSTATE.ZA using
; `__arm_sme_save` before agnostic_za_call(). This is because on all normal
; returns from an agnostic ZA function ZA state should be preserved. That means
; we need to make sure ZA state is saved in case agnostic_za_call() throws, and
; we need to restore ZA state after unwinding to the catch block.

define void @try_catch_agnostic_za_invoke() "aarch64_za_state_agnostic" personality ptr @__gxx_personality_v0 {
; CHECK-LABEL: try_catch_agnostic_za_invoke:
; CHECK: .Lfunc_begin5:
; CHECK-NEXT: .cfi_startproc
; CHECK-NEXT: .cfi_personality 156, DW.ref.__gxx_personality_v0
; CHECK-NEXT: .cfi_lsda 28, .Lexception5
; CHECK-NEXT: // %bb.0: // %entry
; CHECK-NEXT: stp x29, x30, [sp, #-32]! // 16-byte Folded Spill
; CHECK-NEXT: str x19, [sp, #16] // 8-byte Folded Spill
; CHECK-NEXT: mov x29, sp
; CHECK-NEXT: .cfi_def_cfa w29, 32
; CHECK-NEXT: .cfi_offset w19, -16
; CHECK-NEXT: .cfi_offset w30, -24
; CHECK-NEXT: .cfi_offset w29, -32
; CHECK-NEXT: bl __arm_sme_state_size
; CHECK-NEXT: sub sp, sp, x0
; CHECK-NEXT: mov x19, sp
; CHECK-NEXT: .Ltmp15: // EH_LABEL
; CHECK-NEXT: mov x0, x19
; CHECK-NEXT: bl __arm_sme_save
; CHECK-NEXT: bl agnostic_za_call
; CHECK-NEXT: .Ltmp16: // EH_LABEL
; CHECK-NEXT: .LBB5_1: // %exit
; CHECK-NEXT: mov x0, x19
; CHECK-NEXT: bl __arm_sme_restore
; CHECK-NEXT: mov sp, x29
; CHECK-NEXT: ldr x19, [sp, #16] // 8-byte Folded Reload
; CHECK-NEXT: ldp x29, x30, [sp], #32 // 16-byte Folded Reload
; CHECK-NEXT: ret
; CHECK-NEXT: .LBB5_2: // %catch
; CHECK-NEXT: .Ltmp17: // EH_LABEL
; CHECK-NEXT: bl __cxa_begin_catch
; CHECK-NEXT: bl __cxa_end_catch
; CHECK-NEXT: b .LBB5_1
;
; CHECK-SDAG-LABEL: try_catch_agnostic_za_invoke:
; CHECK-SDAG: .Lfunc_begin5:
; CHECK-SDAG-NEXT: .cfi_startproc
; CHECK-SDAG-NEXT: .cfi_personality 156, DW.ref.__gxx_personality_v0
; CHECK-SDAG-NEXT: .cfi_lsda 28, .Lexception5
; CHECK-SDAG-NEXT: // %bb.0: // %entry
; CHECK-SDAG-NEXT: stp x29, x30, [sp, #-32]! // 16-byte Folded Spill
; CHECK-SDAG-NEXT: str x19, [sp, #16] // 8-byte Folded Spill
; CHECK-SDAG-NEXT: mov x29, sp
; CHECK-SDAG-NEXT: .cfi_def_cfa w29, 32
; CHECK-SDAG-NEXT: .cfi_offset w19, -16
; CHECK-SDAG-NEXT: .cfi_offset w30, -24
; CHECK-SDAG-NEXT: .cfi_offset w29, -32
; CHECK-SDAG-NEXT: bl __arm_sme_state_size
; CHECK-SDAG-NEXT: sub sp, sp, x0
; CHECK-SDAG-NEXT: mov x19, sp
; CHECK-SDAG-NEXT: .Ltmp15: // EH_LABEL
; CHECK-SDAG-NEXT: mov x0, x19
; CHECK-SDAG-NEXT: bl __arm_sme_save
; CHECK-SDAG-NEXT: bl agnostic_za_call
; CHECK-SDAG-NEXT: mov x0, x19
; CHECK-SDAG-NEXT: bl __arm_sme_restore
; CHECK-SDAG-NEXT: .Ltmp16: // EH_LABEL
; CHECK-SDAG-NEXT: .LBB5_1: // %exit
; CHECK-SDAG-NEXT: mov sp, x29
; CHECK-SDAG-NEXT: ldr x19, [sp, #16] // 8-byte Folded Reload
; CHECK-SDAG-NEXT: ldp x29, x30, [sp], #32 // 16-byte Folded Reload
; CHECK-SDAG-NEXT: ret
; CHECK-SDAG-NEXT: .LBB5_2: // %catch
; CHECK-SDAG-NEXT: .Ltmp17: // EH_LABEL
; CHECK-SDAG-NEXT: mov x1, x0
; CHECK-SDAG-NEXT: mov x0, x19
; CHECK-SDAG-NEXT: bl __arm_sme_restore
; CHECK-SDAG-NEXT: mov x0, x19
; CHECK-SDAG-NEXT: bl __arm_sme_save
; CHECK-SDAG-NEXT: mov x0, x1
; CHECK-SDAG-NEXT: bl __cxa_begin_catch
; CHECK-SDAG-NEXT: mov x0, x19
; CHECK-SDAG-NEXT: bl __arm_sme_restore
; CHECK-SDAG-NEXT: mov x0, x19
; CHECK-SDAG-NEXT: bl __arm_sme_save
; CHECK-SDAG-NEXT: bl __cxa_end_catch
; CHECK-SDAG-NEXT: mov x0, x19
; CHECK-SDAG-NEXT: bl __arm_sme_restore
; CHECK-SDAG-NEXT: b .LBB5_1
entry:
invoke void @agnostic_za_call()
to label %exit unwind label %catch

catch:
%eh_info = landingpad { ptr, i32 }
catch ptr null
%exception_ptr = extractvalue { ptr, i32 } %eh_info, 0
tail call ptr @__cxa_begin_catch(ptr %exception_ptr)
tail call void @__cxa_end_catch()
br label %exit

exit:
ret void
}

; This is the same `try_catch_agnostic_za_invoke`, but shows a lazy save would
; also need to be committed in a shared-ZA function calling an agnostic-ZA function.
define void @try_catch_inout_za_agnostic_za_callee() "aarch64_inout_za" personality ptr @__gxx_personality_v0 {
; CHECK-LABEL: try_catch_inout_za_agnostic_za_callee:
; CHECK: .Lfunc_begin6:
; CHECK-NEXT: .cfi_startproc
; CHECK-NEXT: .cfi_personality 156, DW.ref.__gxx_personality_v0
; CHECK-NEXT: .cfi_lsda 28, .Lexception6
; CHECK-NEXT: // %bb.0: // %entry
; CHECK-NEXT: stp x29, x30, [sp, #-16]! // 16-byte Folded Spill
; CHECK-NEXT: mov x29, sp
; CHECK-NEXT: sub sp, sp, #16
; CHECK-NEXT: .cfi_def_cfa w29, 16
; CHECK-NEXT: .cfi_offset w30, -8
; CHECK-NEXT: .cfi_offset w29, -16
; CHECK-NEXT: rdsvl x8, #1
; CHECK-NEXT: mov x9, sp
; CHECK-NEXT: msub x9, x8, x8, x9
; CHECK-NEXT: mov sp, x9
; CHECK-NEXT: stp x9, x8, [x29, #-16]
; CHECK-NEXT: .Ltmp18: // EH_LABEL
; CHECK-NEXT: sub x8, x29, #16
; CHECK-NEXT: msr TPIDR2_EL0, x8
; CHECK-NEXT: bl agnostic_za_call
; CHECK-NEXT: .Ltmp19: // EH_LABEL
; CHECK-NEXT: .LBB6_1: // %exit
; CHECK-NEXT: smstart za
; CHECK-NEXT: mrs x8, TPIDR2_EL0
; CHECK-NEXT: sub x0, x29, #16
; CHECK-NEXT: cbnz x8, .LBB6_3
; CHECK-NEXT: // %bb.2: // %exit
; CHECK-NEXT: bl __arm_tpidr2_restore
; CHECK-NEXT: .LBB6_3: // %exit
; CHECK-NEXT: msr TPIDR2_EL0, xzr
; CHECK-NEXT: mov sp, x29
; CHECK-NEXT: ldp x29, x30, [sp], #16 // 16-byte Folded Reload
; CHECK-NEXT: ret
; CHECK-NEXT: .LBB6_4: // %catch
; CHECK-NEXT: .Ltmp20: // EH_LABEL
; CHECK-NEXT: bl __cxa_begin_catch
; CHECK-NEXT: bl __cxa_end_catch
; CHECK-NEXT: b .LBB6_1
;
; CHECK-SDAG-LABEL: try_catch_inout_za_agnostic_za_callee:
; CHECK-SDAG: .Lfunc_begin6:
; CHECK-SDAG-NEXT: .cfi_startproc
; CHECK-SDAG-NEXT: .cfi_personality 156, DW.ref.__gxx_personality_v0
; CHECK-SDAG-NEXT: .cfi_lsda 28, .Lexception6
; CHECK-SDAG-NEXT: // %bb.0: // %entry
; CHECK-SDAG-NEXT: stp x29, x30, [sp, #-32]! // 16-byte Folded Spill
; CHECK-SDAG-NEXT: str x19, [sp, #16] // 8-byte Folded Spill
; CHECK-SDAG-NEXT: mov x29, sp
; CHECK-SDAG-NEXT: sub sp, sp, #16
; CHECK-SDAG-NEXT: .cfi_def_cfa w29, 32
; CHECK-SDAG-NEXT: .cfi_offset w19, -16
; CHECK-SDAG-NEXT: .cfi_offset w30, -24
; CHECK-SDAG-NEXT: .cfi_offset w29, -32
; CHECK-SDAG-NEXT: rdsvl x8, #1
; CHECK-SDAG-NEXT: mov x9, sp
; CHECK-SDAG-NEXT: msub x9, x8, x8, x9
; CHECK-SDAG-NEXT: mov sp, x9
; CHECK-SDAG-NEXT: stp x9, x8, [x29, #-16]
; CHECK-SDAG-NEXT: .Ltmp18: // EH_LABEL
; CHECK-SDAG-NEXT: sub x19, x29, #16
; CHECK-SDAG-NEXT: msr TPIDR2_EL0, x19
; CHECK-SDAG-NEXT: bl agnostic_za_call
; CHECK-SDAG-NEXT: smstart za
; CHECK-SDAG-NEXT: mrs x8, TPIDR2_EL0
; CHECK-SDAG-NEXT: sub x0, x29, #16
; CHECK-SDAG-NEXT: cbnz x8, .LBB6_2
; CHECK-SDAG-NEXT: // %bb.1: // %entry
; CHECK-SDAG-NEXT: bl __arm_tpidr2_restore
; CHECK-SDAG-NEXT: .LBB6_2: // %entry
; CHECK-SDAG-NEXT: msr TPIDR2_EL0, xzr
; CHECK-SDAG-NEXT: .Ltmp19: // EH_LABEL
; CHECK-SDAG-NEXT: .LBB6_3: // %exit
; CHECK-SDAG-NEXT: mov sp, x29
; CHECK-SDAG-NEXT: ldr x19, [sp, #16] // 8-byte Folded Reload
; CHECK-SDAG-NEXT: ldp x29, x30, [sp], #32 // 16-byte Folded Reload
; CHECK-SDAG-NEXT: ret
; CHECK-SDAG-NEXT: .LBB6_4: // %catch
; CHECK-SDAG-NEXT: .Ltmp20: // EH_LABEL
; CHECK-SDAG-NEXT: mov x1, x0
; CHECK-SDAG-NEXT: smstart za
; CHECK-SDAG-NEXT: mrs x8, TPIDR2_EL0
; CHECK-SDAG-NEXT: sub x0, x29, #16
; CHECK-SDAG-NEXT: cbnz x8, .LBB6_6
; CHECK-SDAG-NEXT: // %bb.5: // %catch
; CHECK-SDAG-NEXT: bl __arm_tpidr2_restore
; CHECK-SDAG-NEXT: .LBB6_6: // %catch
; CHECK-SDAG-NEXT: mov x0, x1
; CHECK-SDAG-NEXT: msr TPIDR2_EL0, xzr
; CHECK-SDAG-NEXT: msr TPIDR2_EL0, x19
; CHECK-SDAG-NEXT: bl __cxa_begin_catch
; CHECK-SDAG-NEXT: smstart za
; CHECK-SDAG-NEXT: mrs x8, TPIDR2_EL0
; CHECK-SDAG-NEXT: sub x0, x29, #16
; CHECK-SDAG-NEXT: cbnz x8, .LBB6_8
; CHECK-SDAG-NEXT: // %bb.7: // %catch
; CHECK-SDAG-NEXT: bl __arm_tpidr2_restore
; CHECK-SDAG-NEXT: .LBB6_8: // %catch
; CHECK-SDAG-NEXT: msr TPIDR2_EL0, xzr
; CHECK-SDAG-NEXT: msr TPIDR2_EL0, x19
; CHECK-SDAG-NEXT: bl __cxa_end_catch
; CHECK-SDAG-NEXT: smstart za
; CHECK-SDAG-NEXT: mrs x8, TPIDR2_EL0
; CHECK-SDAG-NEXT: sub x0, x29, #16
; CHECK-SDAG-NEXT: cbnz x8, .LBB6_10
; CHECK-SDAG-NEXT: // %bb.9: // %catch
; CHECK-SDAG-NEXT: bl __arm_tpidr2_restore
; CHECK-SDAG-NEXT: .LBB6_10: // %catch
; CHECK-SDAG-NEXT: msr TPIDR2_EL0, xzr
; CHECK-SDAG-NEXT: b .LBB6_3
entry:
invoke void @agnostic_za_call()
to label %exit unwind label %catch

catch:
%eh_info = landingpad { ptr, i32 }
catch ptr null
%exception_ptr = extractvalue { ptr, i32 } %eh_info, 0
tail call ptr @__cxa_begin_catch(ptr %exception_ptr)
tail call void @__cxa_end_catch()
br label %exit

exit:
ret void
}

declare ptr @__cxa_allocate_exception(i64)
declare void @__cxa_throw(ptr, ptr, ptr)
declare ptr @__cxa_begin_catch(ptr)
Expand All @@ -742,3 +983,4 @@ declare void @may_throw()
declare void @shared_za_call() "aarch64_inout_za"
declare void @noexcept_shared_za_call() "aarch64_inout_za"
declare void @shared_zt0_call() "aarch64_inout_zt0"
declare void @agnostic_za_call() "aarch64_za_state_agnostic"