[AArch64] Make sure we don't emit packed unwind for .seh_save_any_reg_p

[efriedma]

Summary

Obvious oversight in implementation in D135417.

[mstorsjo]

LGTM

In many similar switches, we've got a default: llvm_unreachable("Unsupported ARM64 unwind code"); - I wonder if we should have that here too, or at least default: return false;?

[efriedma]

Looking a bit more closely, it looks like the following opcodes don't show up in the switch:

UOP_AllocLarge
UOP_AddFP
UOP_TrapFrame
UOP_Context
UOP_ClearUnwoundToCall

Not sure if this actually leads to issues in practice, but I'll follow up to address.

[mstorsjo]

In D138955#3961548, @efriedma wrote:

Looking a bit more closely, it looks like the following opcodes don't show up in the switch:

UOP_AllocLarge
UOP_AddFP
UOP_TrapFrame
UOP_Context
UOP_ClearUnwoundToCall

Not sure if this actually leads to issues in practice, but I'll follow up to address.

Ok, so then we can't make it an unreachable unless we add those as well. In that case, I guess default: return false; would be simplest/safest?

llvm/lib/MC/MCWin64EH.cpp

case Win64EH::UOP_SaveFPLR:
       Location = FrameRecord;
       FPLRPair = true;
       break;
     case Win64EH::UOP_SetFP:
       if (Location != FrameRecord)
         return false;
       Location = End;
       break;
+    case Win64EH::UOP_SaveAnyRegI:
+    case Win64EH::UOP_SaveAnyRegIP:
+    case Win64EH::UOP_SaveAnyRegD:
+    case Win64EH::UOP_SaveAnyRegDP:
+    case Win64EH::UOP_SaveAnyRegQ:
+    case Win64EH::UOP_SaveAnyRegQP:
+    case Win64EH::UOP_SaveAnyRegIX:
+    case Win64EH::UOP_SaveAnyRegIPX:
+    case Win64EH::UOP_SaveAnyRegDX:
+    case Win64EH::UOP_SaveAnyRegDPX:
+    case Win64EH::UOP_SaveAnyRegQX:
+    case Win64EH::UOP_SaveAnyRegQPX:
+      // These are never canonical; they don't show up with the usual Arm64
+      // calling convention.
+      return false;
     }
   }
   if (RegI > 10 || RegF > 8)
     return false;
   if (StandaloneLR && FPLRPair)
     return false;
   if (FPLRPair && Location != End)
     return false;

llvm/test/MC/AArch64/seh-packed-unwind.s

 // CHECK-NEXT:     ExceptionRecord:
 // CHECK-NEXT:     ExceptionData {
 // CHECK:            EpiloguePacked: Yes
 // CHECK:        RuntimeFunction {
 // CHECK-NEXT:     Function: nonpacked15
 // CHECK-NEXT:     ExceptionRecord:
 // CHECK-NEXT:     ExceptionData {
 // CHECK:            EpiloguePacked: Yes
+// CHECK:        RuntimeFunction {
+// CHECK-NEXT:     Function: nonpacked16
+// CHECK-NEXT:     ExceptionRecord:
+// CHECK-NEXT:     ExceptionData {
+// CHECK:            EpiloguePacked: Yes
+
 
     .text
 func1:
     .seh_proc func1
     stp x19, x20, [sp, #-144]!
     .seh_save_r19r20_x 144
     stp x21, x22, [sp, #16]
     .seh_save_regp x21, 16
nonpacked15:
     .seh_save_lrpair x21, 16
     ldp x19, x20, [sp], #32
     .seh_save_r19r20_x 32
     autibsp
     .seh_pac_sign_lr
     .seh_endepilogue
     ret
     .seh_endproc
+
+nonpacked16:
+    .seh_proc nonpacked16
+    // Make sure we correctly analyze .seh_save_any_reg_p
+    stp     x29, x30, [sp, #-176]!
+    .seh_save_fplr_x        176
+    stp     q6, q7, [sp, #16]
+    .seh_save_any_reg_p     q6, 16
+    stp     q8, q9, [sp, #48]
+    .seh_save_any_reg_p     q8, 48
+    stp     q10, q11, [sp, #80]
+    .seh_save_any_reg_p     q10, 80
+    stp     q12, q13, [sp, #112]
+    .seh_save_any_reg_p     q12, 112
+    stp     q14, q15, [sp, #144]
+    .seh_save_any_reg_p     q14, 144
+    mov     x29, sp
+    .seh_set_fp
+    .seh_endprologue
+    nop
+    .seh_startepilogue
+    ldp     q14, q15, [sp, #144]
+    .seh_save_any_reg_p     q14, 144
+    ldp     q12, q13, [sp, #112]
+    .seh_save_any_reg_p     q12, 112
+    ldp     q10, q11, [sp, #80]
+    .seh_save_any_reg_p     q10, 80
+    ldp     q8, q9, [sp, #48]
+    .seh_save_any_reg_p     q8, 48
+    ldp     q6, q7, [sp, #16]
+    .seh_save_any_reg_p     q6, 16
+    ldp     x29, x30, [sp], #176
+    .seh_save_fplr_x        176
+    .seh_endepilogue
+    br      x9
+    .seh_endproc