[AArch64] Add preserve_all calling convention.

[danielkiss]

Summary

Clang accepts preserve_all for AArch64 while it is missing form the backed.

Fixes #58145

[aaron.ballman]

Precommit CI found a relevant issue. Also, can you add release notes to Clang for the improvement?

Also, is there a reason to support preserve_all but not preserve_most given their relationship?

[danielkiss]

In D135652#3849147, @aaron.ballman wrote:

Precommit CI found a relevant issue. Also, can you add release notes to Clang for the improvement?

Fix and added.

Also, is there a reason to support preserve_all but not preserve_most given their relationship?

There is support for preserve_most already, works as expected.
https://godbolt.org/z/an1T6YGss

[danielkiss]

forgot to commit the test.

[aaron.ballman]

In D135652#3850283, @danielkiss wrote:

In D135652#3849147, @aaron.ballman wrote:

Also, is there a reason to support preserve_all but not preserve_most given their relationship?

There is support for preserve_most already, works as expected.
https://godbolt.org/z/an1T6YGss

Oh, well, that's all the more reason to support this work -- thank you for the fix! The Clang bits LGTM, but I'll leave it to LLVM folks to review that side of things.

[efriedma]

clang/include/clang/Basic/AttrDocs.td

5230

Please clarify which bits are actually getting preserved. It looks like it's the low 64 bits of each vector register?

[danielkiss]

To accommodate better to the vector ABI, AAPCS the vector parameter registers are not preserved by the callee but save the whole vector registers.

[efriedma]

clang/include/clang/Basic/AttrDocs.td

5230

Please clarify which bits are actually getting preserved. It looks like in the updated version, it's the low 128 bits of each vector register? (With SVE, that isn't necessarily the whole register.)

[danielkiss]

update docs.

[danielkiss]

clang/include/clang/Basic/AttrDocs.td

5230

Sorry missed it, now it hopefully completely clear.

[danielkiss]

ping

[efriedma]

LGTM

[danielkiss]

@efriedma Thanks!
Rebased.

clang/docs/ReleaseNotes.rst

- Clang supports flag output operands by which conditions in the NZCV could be outputs
   of inline assembly for AArch64. This change is more consistent with the behavior of
   GCC.
 
    .. code-block:: c
 
      // int a = foo(); int* b = bar();
      asm("ands %w[a], %w[a], #3" : [a] "+r"(a), "=@cceq"(*b));
 
+- Fix a crash when ``preserve_all`` calling convention is used on AArch64.
+  `Issue 58145 <https://github.com/llvm/llvm-project/issues/58145>`_
+
 Windows Support
 ^^^^^^^^^^^^^^^
 
 LoongArch Support
 ^^^^^^^^^^^^^^^^^
 
 - Patchable function entry (``-fpatchable-function-entry``) is now supported
   on LoongArch.

clang/include/clang/Basic/AttrDocs.td

 call in the caller. If the arguments are passed in callee-saved registers,
 then they will be preserved by the callee across the call. This doesn't
 apply for values returned in callee-saved registers.
 
 - On X86-64 the callee preserves all general purpose registers, except for
   R11. R11 can be used as a scratch register. Floating-point registers
   (XMMs/YMMs) are not preserved and need to be saved by the caller.
 
+- On AArch64 the callee preserve all general purpose registers, except X0-X8 and
+  X16-X18.
+
 The idea behind this convention is to support calls to runtime functions
 that have a hot path and a cold path. The hot path is usually a small piece
 of code that doesn't use many registers. The cold path might need to call out to
 another function and therefore only needs to preserve the caller-saved
 registers, which haven't already been saved by the caller. The
 ``preserve_most`` calling convention is very similar to the ``cold`` calling
 convention in terms of caller/callee-saved registers, but they are used for
 different types of function calls. ``coldcc`` is for function calls that are

 the arguments are passed in callee-saved registers, then they will be
 preserved by the callee across the call. This doesn't apply for values
 returned in callee-saved registers.
 
 - On X86-64 the callee preserves all general purpose registers, except for
   R11. R11 can be used as a scratch register. Furthermore it also preserves
   all floating-point registers (XMMs/YMMs).
 
+- On AArch64 the callee preserve all general purpose registers, except X0-X8 and
+  X16-X18. Furthermore it also preserves lower 128 bits of V8-V31 SIMD - floating
+  point registers.
+
 The idea behind this convention is to support calls to runtime functions
 that don't need to call out to any other functions.
 
 This calling convention, like the ``preserve_most`` calling convention, will be
 used by a future version of the Objective-C runtime and should be considered
 experimental at this time.
   }];
 }

llvm/docs/LangRef.rst

"``preserve_mostcc``" - The `PreserveMost` calling convention
     then they will be preserved by the callee across the call. This doesn't
     apply for values returned in callee-saved registers.
 
     - On X86-64 the callee preserves all general purpose registers, except for
       R11 and return registers, if any. R11 can be used as a scratch register.
       Floating-point registers (XMMs/YMMs) are not preserved and need to be
       saved by the caller.
 
+    - On AArch64 the callee preserve all general purpose registers, except X0-X8
+      and X16-X18.
+
     The idea behind this convention is to support calls to runtime functions
     that have a hot path and a cold path. The hot path is usually a small piece
     of code that doesn't use many registers. The cold path might need to call out to
     another function and therefore only needs to preserve the caller-saved
     registers, which haven't already been saved by the caller. The
     `PreserveMost` calling convention is very similar to the `cold` calling
     convention in terms of caller/callee-saved registers, but they are used for
     different types of function calls. `coldcc` is for function calls that are
"``preserve_allcc``" - The `PreserveAll` calling convention
     the arguments are passed in callee-saved registers, then they will be
     preserved by the callee across the call. This doesn't apply for values
     returned in callee-saved registers.
 
     - On X86-64 the callee preserves all general purpose registers, except for
       R11. R11 can be used as a scratch register. Furthermore it also preserves
       all floating-point registers (XMMs/YMMs).
 
+    - On AArch64 the callee preserve all general purpose registers, except X0-X8
+      and X16-X18. Furthermore it also preserves lower 128 bits of V8-V31 SIMD -
+      floating point registers.
+
     The idea behind this convention is to support calls to runtime functions
     that don't need to call out to any other functions.
 
     This calling convention, like the `PreserveMost` calling convention, will be
     used by a future version of the ObjectiveC runtime and should be considered
     experimental at this time.
 "``cxx_fast_tlscc``" - The `CXX_FAST_TLS` calling convention for access functions
     Clang generates an access function to access C++-style TLS. The access

llvm/docs/ReleaseNotes.rst

 Changes to Interprocedural Optimizations
 ----------------------------------------
 
 Changes to the AArch64 Backend
 ------------------------------
 
 * Added Assembly Support for the 2022 A-profile extensions FEAT_GCS (Guarded
   Control Stacks), FEAT_CHK (Check Feature Status), and FEAT_ATS1A.
+* Support for preserve_all calling convention is added.
 
 Changes to the AMDGPU Backend
 -----------------------------
 * More fine-grained synchronization around barriers for newer architectures
   (gfx90a+, gfx10+). The AMDGPU backend now omits previously automatically
   generated waitcnt instructions before barriers, allowing for more precise
   control. Users must now use memory fences to implement fine-grained
   synchronization strategies around barriers. Refer to `AMDGPU memory model

llvm/lib/Target/AArch64/AArch64CallingConvention.td

: CalleeSavedRegs<(add (sequence "W%u", 0, 30), WSP,
                            (sequence "S%u", 0, 31), (sequence "D%u", 0, 31),
                            (sequence "Q%u", 0, 31))>;
 
 def CSR_AArch64_NoRegs : CalleeSavedRegs<(add)>;
 
 def CSR_AArch64_RT_MostRegs :  CalleeSavedRegs<(add CSR_AArch64_AAPCS,
                                                 (sequence "X%u", 9, 15))>;
 
+def CSR_AArch64_RT_AllRegs :  CalleeSavedRegs<(add CSR_AArch64_RT_MostRegs,
+                                                (sequence "Q%u", 8, 31))>;
+
 def CSR_AArch64_StackProbe_Windows
     : CalleeSavedRegs<(add (sequence "X%u", 0, 15),
                            (sequence "X%u", 18, 28), FP, SP,
                            (sequence "Q%u", 0, 31))>;
 
 // Darwin variants of AAPCS.
 // Darwin puts the frame-record at the top of the callee-save area.
 def CSR_Darwin_AArch64_AAPCS : CalleeSavedRegs<(add LR, FP, X19, X20, X21, X22,

 
 // CSRs that are handled explicitly via copies.
 def CSR_Darwin_AArch64_CXX_TLS_ViaCopy
     : CalleeSavedRegs<(sub CSR_Darwin_AArch64_CXX_TLS, LR, FP)>;
 
 def CSR_Darwin_AArch64_RT_MostRegs
     : CalleeSavedRegs<(add CSR_Darwin_AArch64_AAPCS, (sequence "X%u", 9, 15))>;
 
+def CSR_Darwin_AArch64_RT_AllRegs
+    : CalleeSavedRegs<(add CSR_Darwin_AArch64_RT_MostRegs, (sequence "Q%u", 8, 31))>;
+
 // Variants of the standard calling conventions for shadow call stack.
 // These all preserve x18 in addition to any other registers.
 def CSR_AArch64_NoRegs_SCS
     : CalleeSavedRegs<(add CSR_AArch64_NoRegs, X18)>;
 def CSR_AArch64_AllRegs_SCS
     : CalleeSavedRegs<(add CSR_AArch64_AllRegs, X18)>;
 def CSR_AArch64_AAPCS_SwiftError_SCS
     : CalleeSavedRegs<(add CSR_AArch64_AAPCS_SwiftError, X18)>;
 def CSR_AArch64_RT_MostRegs_SCS
     : CalleeSavedRegs<(add CSR_AArch64_RT_MostRegs, X18)>;
+def CSR_AArch64_RT_AllRegs_SCS
+    : CalleeSavedRegs<(add CSR_AArch64_RT_AllRegs, X18)>;
 def CSR_AArch64_AAVPCS_SCS
     : CalleeSavedRegs<(add CSR_AArch64_AAVPCS, X18)>;
 def CSR_AArch64_SVE_AAPCS_SCS
     : CalleeSavedRegs<(add CSR_AArch64_SVE_AAPCS, X18)>;
 def CSR_AArch64_AAPCS_SCS
     : CalleeSavedRegs<(add CSR_AArch64_AAPCS, X18)>;

llvm/lib/Target/AArch64/AArch64FrameLowering.cpp

static void computeCalleeSaveRegisterPairs(
   AArch64FunctionInfo *AFI = MF.getInfo<AArch64FunctionInfo>();
   MachineFrameInfo &MFI = MF.getFrameInfo();
   CallingConv::ID CC = MF.getFunction().getCallingConv();
   unsigned Count = CSI.size();
   (void)CC;
   // MachO's compact unwind format relies on all registers being stored in
   // pairs.
   assert((!produceCompactUnwindFrame(MF) || CC == CallingConv::PreserveMost ||
-          CC == CallingConv::CXX_FAST_TLS || CC == CallingConv::Win64 ||
-          (Count & 1) == 0) &&
+          CC == CallingConv::PreserveAll || CC == CallingConv::CXX_FAST_TLS ||
+          CC == CallingConv::Win64 || (Count & 1) == 0) &&
          "Odd number of callee-saved regs to spill!");
   int ByteOffset = AFI->getCalleeSavedStackSize();
   int StackFillDir = -1;
   int RegInc = 1;
   unsigned FirstReg = 0;
   if (NeedsWinCFI) {
     // For WinCFI, fill the stack from the bottom up.
     ByteOffset = 0;
for (unsigned i = FirstReg; i < Count; i += RegInc) {
     // Windows AAPCS has FP and LR reversed.
     assert((!RPI.isPaired() || !NeedsFrameRecord || RPI.Reg1 != AArch64::FP ||
             RPI.Reg2 == AArch64::LR) &&
            "FrameRecord must be allocated together with LR");
 
     // MachO's compact unwind format relies on all registers being stored in
     // adjacent register pairs.
     assert((!produceCompactUnwindFrame(MF) || CC == CallingConv::PreserveMost ||
-            CC == CallingConv::CXX_FAST_TLS || CC == CallingConv::Win64 ||
+            CC == CallingConv::PreserveAll || CC == CallingConv::CXX_FAST_TLS ||
+            CC == CallingConv::Win64 ||
             (RPI.isPaired() &&
              ((RPI.Reg1 == AArch64::LR && RPI.Reg2 == AArch64::FP) ||
               RPI.Reg1 + 1 == RPI.Reg2))) &&
            "Callee-save registers not saved as adjacent register pair!");
 
     RPI.FrameIdx = CSI[i].getFrameIdx();
     if (NeedsWinCFI &&
         RPI.isPaired()) // RPI.FrameIdx must be the lower index of the pair

llvm/lib/Target/AArch64/AArch64ISelLowering.cpp

default:
     report_fatal_error("Unsupported calling convention.");
   case CallingConv::WebKit_JS:
     return CC_AArch64_WebKit_JS;
   case CallingConv::GHC:
     return CC_AArch64_GHC;
   case CallingConv::C:
   case CallingConv::Fast:
   case CallingConv::PreserveMost:
+  case CallingConv::PreserveAll:
   case CallingConv::CXX_FAST_TLS:
   case CallingConv::Swift:
   case CallingConv::SwiftTail:
   case CallingConv::Tail:
     if (Subtarget->isTargetWindows() && IsVarArg) {
       if (Subtarget->isWindowsArm64EC())
         return CC_AArch64_Arm64EC_VarArg;
       return CC_AArch64_Win64_VarArg;

 }
 
 /// Return true if we might ever do TCO for calls with this calling convention.
 static bool mayTailCallThisCC(CallingConv::ID CC) {
   switch (CC) {
   case CallingConv::C:
   case CallingConv::AArch64_SVE_VectorCall:
   case CallingConv::PreserveMost:
+  case CallingConv::PreserveAll:
   case CallingConv::Swift:
   case CallingConv::SwiftTail:
   case CallingConv::Tail:
   case CallingConv::Fast:
     return true;
   default:
     return false;
   }

llvm/lib/Target/AArch64/AArch64RegisterInfo.cpp

if (MF->getSubtarget<AArch64Subtarget>().getTargetLowering()
           ->supportSwiftError() &&
       MF->getFunction().getAttributes().hasAttrSomewhere(
           Attribute::SwiftError))
     return CSR_AArch64_AAPCS_SwiftError_SaveList;
   if (MF->getFunction().getCallingConv() == CallingConv::SwiftTail)
     return CSR_AArch64_AAPCS_SwiftTail_SaveList;
   if (MF->getFunction().getCallingConv() == CallingConv::PreserveMost)
     return CSR_AArch64_RT_MostRegs_SaveList;
+  if (MF->getFunction().getCallingConv() == CallingConv::PreserveAll)
+    return CSR_AArch64_RT_AllRegs_SaveList;
   if (MF->getFunction().getCallingConv() == CallingConv::Win64)
     // This is for OSes other than Windows; Windows is a separate case further
     // above.
     return CSR_AArch64_AAPCS_X18_SaveList;
   if (MF->getInfo<AArch64FunctionInfo>()->isSVECC())
     return CSR_AArch64_SVE_AAPCS_SaveList;
   return CSR_AArch64_AAPCS_SaveList;
 }
if (MF->getSubtarget<AArch64Subtarget>().getTargetLowering()
           ->supportSwiftError() &&
       MF->getFunction().getAttributes().hasAttrSomewhere(
           Attribute::SwiftError))
     return CSR_Darwin_AArch64_AAPCS_SwiftError_SaveList;
   if (MF->getFunction().getCallingConv() == CallingConv::SwiftTail)
     return CSR_Darwin_AArch64_AAPCS_SwiftTail_SaveList;
   if (MF->getFunction().getCallingConv() == CallingConv::PreserveMost)
     return CSR_Darwin_AArch64_RT_MostRegs_SaveList;
+  if (MF->getFunction().getCallingConv() == CallingConv::PreserveAll)
+    return CSR_Darwin_AArch64_RT_AllRegs_SaveList;
   if (MF->getFunction().getCallingConv() == CallingConv::Win64)
     return CSR_Darwin_AArch64_AAPCS_Win64_SaveList;
   return CSR_Darwin_AArch64_AAPCS_SaveList;
 }
 
 const MCPhysReg *AArch64RegisterInfo::getCalleeSavedRegsViaCopy(
     const MachineFunction *MF) const {
   assert(MF && "Invalid MachineFunction pointer.");
if (MF.getSubtarget<AArch64Subtarget>()
           .getTargetLowering()
           ->supportSwiftError() &&
       MF.getFunction().getAttributes().hasAttrSomewhere(Attribute::SwiftError))
     return CSR_Darwin_AArch64_AAPCS_SwiftError_RegMask;
   if (CC == CallingConv::SwiftTail)
     return CSR_Darwin_AArch64_AAPCS_SwiftTail_RegMask;
   if (CC == CallingConv::PreserveMost)
     return CSR_Darwin_AArch64_RT_MostRegs_RegMask;
+  if (CC == CallingConv::PreserveAll)
+    return CSR_Darwin_AArch64_RT_AllRegs_RegMask;
   return CSR_Darwin_AArch64_AAPCS_RegMask;
 }
 
 const uint32_t *
 AArch64RegisterInfo::getCallPreservedMask(const MachineFunction &MF,
                                           CallingConv::ID CC) const {
   bool SCS = MF.getFunction().hasFnAttribute(Attribute::ShadowCallStack);
   if (CC == CallingConv::GHC)
AArch64RegisterInfo::getCallPreservedMask(const MachineFunction &MF,
   if (CC == CallingConv::SwiftTail) {
     if (SCS)
       report_fatal_error("ShadowCallStack attribute not supported with swifttail");
     return CSR_AArch64_AAPCS_SwiftTail_RegMask;
   }
   if (CC == CallingConv::PreserveMost)
     return SCS ? CSR_AArch64_RT_MostRegs_SCS_RegMask
                : CSR_AArch64_RT_MostRegs_RegMask;
+  else if (CC == CallingConv::PreserveAll)
+    return SCS ? CSR_AArch64_RT_AllRegs_SCS_RegMask
+               : CSR_AArch64_RT_AllRegs_RegMask;
+
   else
     return SCS ? CSR_AArch64_AAPCS_SCS_RegMask : CSR_AArch64_AAPCS_RegMask;
 }
 
 const uint32_t *AArch64RegisterInfo::getCustomEHPadPreservedMask(
     const MachineFunction &MF) const {
   if (MF.getSubtarget<AArch64Subtarget>().isTargetLinux())
     return CSR_AArch64_AAPCS_RegMask;
default:
     report_fatal_error("Unsupported calling convention.");
   case CallingConv::WebKit_JS:
     return HasReg(CC_AArch64_WebKit_JS_ArgRegs, Reg);
   case CallingConv::GHC:
     return HasReg(CC_AArch64_GHC_ArgRegs, Reg);
   case CallingConv::C:
   case CallingConv::Fast:
   case CallingConv::PreserveMost:
+  case CallingConv::PreserveAll:
   case CallingConv::CXX_FAST_TLS:
   case CallingConv::Swift:
   case CallingConv::SwiftTail:
   case CallingConv::Tail:
     if (STI.isTargetWindows() && IsVarArg)
       return HasReg(CC_AArch64_Win64_VarArg_ArgRegs, Reg);
     if (!STI.isTargetDarwin()) {
       switch (CC) {

llvm/lib/Target/AArch64/GISel/AArch64CallLowering.cpp

return (CC == CallingConv::Fast && GuaranteeTailCalls) ||
          CC == CallingConv::Tail || CC == CallingConv::SwiftTail;
 }
 
 /// Return true if we might ever do TCO for calls with this calling convention.
 static bool mayTailCallThisCC(CallingConv::ID CC) {
   switch (CC) {
   case CallingConv::C:
   case CallingConv::PreserveMost:
+  case CallingConv::PreserveAll:
   case CallingConv::Swift:
   case CallingConv::SwiftTail:
   case CallingConv::Tail:
   case CallingConv::Fast:
     return true;
   default:
     return false;
   }

llvm/lib/Target/ARM/ARMISelLowering.cpp

default:
     report_fatal_error("Unsupported calling convention");
   case CallingConv::ARM_AAPCS:
   case CallingConv::ARM_APCS:
   case CallingConv::GHC:
   case CallingConv::CFGuard_Check:
     return CC;
   case CallingConv::PreserveMost:
     return CallingConv::PreserveMost;
+  case CallingConv::PreserveAll:
+    return CallingConv::PreserveAll;
   case CallingConv::ARM_AAPCS_VFP:
   case CallingConv::Swift:
   case CallingConv::SwiftTail:
     return isVarArg ? CallingConv::ARM_AAPCS : CallingConv::ARM_AAPCS_VFP;
   case CallingConv::C:
   case CallingConv::Tail:
     if (!Subtarget->isAAPCS_ABI())
       return CallingConv::ARM_APCS;
CCAssignFn *ARMTargetLowering::CCAssignFnForNode(CallingConv::ID CC,
   case CallingConv::ARM_AAPCS_VFP:
     return (Return ? RetCC_ARM_AAPCS_VFP : CC_ARM_AAPCS_VFP);
   case CallingConv::Fast:
     return (Return ? RetFastCC_ARM_APCS : FastCC_ARM_APCS);
   case CallingConv::GHC:
     return (Return ? RetCC_ARM_APCS : CC_ARM_APCS_GHC);
   case CallingConv::PreserveMost:
     return (Return ? RetCC_ARM_AAPCS : CC_ARM_AAPCS);
+  case CallingConv::PreserveAll:
+    return (Return ? RetCC_ARM_AAPCS : CC_ARM_AAPCS);
   case CallingConv::CFGuard_Check:
     return (Return ? RetCC_ARM_AAPCS : CC_ARM_Win32_CFGuard_Check);
   }
 }
 
 SDValue ARMTargetLowering::MoveToHPR(const SDLoc &dl, SelectionDAG &DAG,
                                      MVT LocVT, MVT ValVT, SDValue Val) const {
   Val = DAG.getNode(ISD::BITCAST, dl, MVT::getIntegerVT(LocVT.getSizeInBits()),

llvm/test/CodeGen/AArch64/arm64-preserve-all.ll

+; RUN: llc -O0 --march=aarch64 -verify-machineinstrs --filetype=asm %s -o - 2>&1 | FileCheck %s
+; RUN: llc -O1 --march=aarch64 -verify-machineinstrs --filetype=asm %s -o - 2>&1 | FileCheck %s
+; RUN: llc -O2 --march=aarch64 -verify-machineinstrs --filetype=asm %s -o - 2>&1 | FileCheck %s
+target datalayout = "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128"
+target triple = "aarch64-unknown-linux-gnu"
+
+declare void @normal_cc()
+
+; Caller: preserve_allcc; callee: normalcc. Normally callee saved registers
+; x9~x15 need to be spilled. Since most of them will be spilled in pairs in
+; reverse order, we only check the odd number ones due to FileCheck not
+; matching the same line of assembly twice.
+; CHECK-LABEL: preserve_all
+; CHECK-DAG: {{st[rp]}} {{(q[0-9]+, )?q8(, x[0-9]+)?}}, [sp, #{{[-0-9]+}}]
+; CHECK-DAG: {{st[rp]}} {{(q[0-9]+, )?q10(, x[0-9]+)?}}, [sp, #{{[-0-9]+}}]
+; CHECK-DAG: {{st[rp]}} {{(q[0-9]+, )?q12(, x[0-9]+)?}}, [sp, #{{[-0-9]+}}]
+; CHECK-DAG: {{st[rp]}} {{(q[0-9]+, )?q14(, x[0-9]+)?}}, [sp, #{{[-0-9]+}}]
+; CHECK-DAG: {{st[rp]}} {{(q[0-9]+, )?q16(, x[0-9]+)?}}, [sp, #{{[-0-9]+}}]
+; CHECK-DAG: {{st[rp]}} {{(q[0-9]+, )?q18(, x[0-9]+)?}}, [sp, #{{[-0-9]+}}]
+; CHECK-DAG: {{st[rp]}} {{(q[0-9]+, )?q22(, x[0-9]+)?}}, [sp, #{{[-0-9]+}}]
+; CHECK-DAG: {{st[rp]}} {{(q[0-9]+, )?q24(, x[0-9]+)?}}, [sp, #{{[-0-9]+}}]
+; CHECK-DAG: {{st[rp]}} {{(q[0-9]+, )?q26(, x[0-9]+)?}}, [sp, #{{[-0-9]+}}]
+; CHECK-DAG: {{st[rp]}} {{(q[0-9]+, )?q28(, x[0-9]+)?}}, [sp, #{{[-0-9]+}}]
+; CHECK-DAG: {{st[rp]}} {{(q[0-9]+, )?q30(, x[0-9]+)?}}, [sp, #{{[-0-9]+}}]
+; CHECK-DAG: {{st[rp]}} {{(x[0-9]+, )?x9(, x[0-9]+)?}}, [sp, #{{[-0-9]+}}]
+; CHECK-DAG: {{st[rp]}} {{(x[0-9]+, )?x11(, x[0-9]+)?}}, [sp, #{{[-0-9]+}}]
+; CHECK-DAG: {{st[rp]}} {{(x[0-9]+, )?x13(, x[0-9]+)?}}, [sp, #{{[-0-9]+}}]
+; CHECK-DAG: {{st[rp]}} {{(x[0-9]+, )?x15(, x[0-9]+)?}}, [sp, #{{[-0-9]+}}]
+define preserve_allcc void @preserve_all() {
+  call void @normal_cc()
+  ret void
+}
+
+; Caller: normalcc; callee: preserve_allcc. x9/q9 does not need to be spilled.
+; The same holds for other x and q registers, but we only check x9 and q9.
+; CHECK-LABEL: normal_cc_caller
+; CHECK-NOT: stp {{x[0-9]+}}, x9, [sp, #{{[-0-9]+}}]
+; CHECK-NOT: stp x9, {{x[0-9]+}}, [sp, #{{[-0-9]+}}]
+; CHECK-NOT: str x9, [sp, {{#[-0-9]+}}]
+; CHECK-NOT: stp {{q[0-9]+}}, q9, [sp, #{{[-0-9]+}}]
+; CHECK-NOT: stp q9, {{q[0-9]+}}, [sp, #{{[-0-9]+}}]
+; CHECK-NOT: str q9, [sp, {{#[-0-9]+}}]
+define dso_local void @normal_cc_caller() {
+entry:
+  %v = alloca i32, align 4
+  call void asm sideeffect "mov x9, $0", "N,~{x9}"(i32 48879) #2
+  call void asm sideeffect "movi v9.2d, #0","~{v9}" () #2
+
+
+  call preserve_allcc void @preserve_all()
+  %0 = load i32, i32* %v, align 4
+  %1 = call i32 asm sideeffect "mov ${0:w}, w9", "=r,r"(i32 %0) #2
+  %2 = call i32 asm sideeffect "fneg v9.4s, v9.4s", "=r,~{v9}"() #2
+  store i32 %1, i32* %v, align 4
+  ret void
+}

llvm/test/CodeGen/AArch64/preserve.ll

+
+; RUN: llc -enable-ipra -print-regusage -o /dev/null 2>&1 < %s | FileCheck %s
+
+target triple = "aarch64-unknown-unknown"
+declare void @bar1()
+define preserve_mostcc void @baz() #0 {
+; CHECK: baz Clobbered Registers: $ffr $fpcr $nzcv $sp $vg $wsp $za $b0 $b1 $b2 $b3 $b4 $b5 $b6 $b7 $b16 $b17 $b18 $b19 $b20 $b21 $b22 $b23 $b24 $b25 $b26 $b27 $b28 $b29 $b30 $b31 $d0 $d1 $d2 $d3 $d4 $d5 $d6 $d7 $d16 $d17 $d18 $d19 $d20 $d21 $d22 $d23 $d24 $d25 $d26 $d27 $d28 $d29 $d30 $d31 $h0 $h1 $h2 $h3 $h4 $h5 $h6 $h7 $h16 $h17 $h18 $h19 $h20 $h21 $h22 $h23 $h24 $h25 $h26 $h27 $h28 $h29 $h30 $h31 $p0 $p1 $p2 $p3 $p4 $p5 $p6 $p7 $p8 $p9 $p10 $p11 $p12 $p13 $p14 $p15 $q0 $q1 $q2 $q3 $q4 $q5 $q6 $q7 $q8 $q9 $q10 $q11 $q12 $q13 $q14 $q15 $q16 $q17 $q18 $q19 $q20 $q21 $q22 $q23 $q24 $q25 $q26 $q27 $q28 $q29 $q30 $q31 $s0 $s1 $s2 $s3 $s4 $s5 $s6 $s7 $s16 $s17 $s18 $s19 $s20 $s21 $s22 $s23 $s24 $s25 $s26 $s27 $s28 $s29 $s30 $s31 $w0 $w1 $w2 $w3 $w4 $w5 $w6 $w7 $w8 $w16 $w17 $w18 $x0 $x1 $x2 $x3 $x4 $x5 $x6 $x7 $x8 $x16 $x17 $x18 $z0 $z1 $z2 $z3 $z4 $z5 $z6 $z7 $z8 $z9 $z10 $z11 $z12 $z13 $z14 $z15 $z16 $z17 $z18 $z19 $z20 $z21 $z22 $z23 $z24 $z25 $z26 $z27 $z28 $z29 $z30 $z31 $zab0 $zad0 $zad1 $zad2 $zad3 $zad4 $zad5 $zad6 $zad7 $zah0 $zah1 $zaq0 $zaq1 $zaq2 $zaq3 $zaq4 $zaq5 $zaq6 $zaq7 $zaq8 $zaq9 $zaq10 $zaq11 $zaq12 $zaq13 $zaq14 $zaq15 $zas0 $zas1 $zas2 $zas3 $zt0 $z0_hi $z1_hi $z2_hi $z3_hi $z4_hi $z5_hi $z6_hi $z7_hi $z8_hi $z9_hi $z10_hi $z11_hi $z12_hi $z13_hi $z14_hi $z15_hi $z16_hi $z17_hi $z18_hi $z19_hi $z20_hi $z21_hi $z22_hi $z23_hi $z24_hi $z25_hi $z26_hi $z27_hi $z28_hi $z29_hi $z30_hi $z31_hi $d0_d1 $d1_d2 $d2_d3 $d3_d4 $d4_d5 $d5_d6 $d6_d7 $d7_d8 $d15_d16 $d16_d17 $d17_d18 $d18_d19 $d19_d20 $d20_d21 $d21_d22 $d22_d23 $d23_d24 $d24_d25 $d25_d26 $d26_d27 $d27_d28 $d28_d29 $d29_d30 $d30_d31 $d31_d0 $d0_d1_d2_d3 $d1_d2_d3_d4 $d2_d3_d4_d5 $d3_d4_d5_d6 $d4_d5_d6_d7 $d5_d6_d7_d8 $d6_d7_d8_d9 $d7_d8_d9_d10 $d13_d14_d15_d16 $d14_d15_d16_d17 $d15_d16_d17_d18 $d16_d17_d18_d19 $d17_d18_d19_d20 $d18_d19_d20_d21 $d19_d20_d21_d22 $d20_d21_d22_d23 $d21_d22_d23_d24 $d22_d23_d24_d25 $d23_d24_d25_d26 $d24_d25_d26_d27 $d25_d26_d27_d28 $d26_d27_d28_d29 $d27_d28_d29_d30 $d28_d29_d30_d31 $d29_d30_d31_d0 $d30_d31_d0_d1 $d31_d0_d1_d2 $d0_d1_d2 $d1_d2_d3 $d2_d3_d4 $d3_d4_d5 $d4_d5_d6 $d5_d6_d7 $d6_d7_d8 $d7_d8_d9 $d14_d15_d16 $d15_d16_d17 $d16_d17_d18 $d17_d18_d19 $d18_d19_d20 $d19_d20_d21 $d20_d21_d22 $d21_d22_d23 $d22_d23_d24 $d23_d24_d25 $d24_d25_d26 $d25_d26_d27 $d26_d27_d28 $d27_d28_d29 $d28_d29_d30 $d29_d30_d31 $d30_d31_d0 $d31_d0_d1 $p0_p1 $p1_p2 $p2_p3 $p3_p4 $p4_p5 $p5_p6 $p6_p7 $p7_p8 $p8_p9 $p9_p10 $p10_p11 $p11_p12 $p12_p13 $p13_p14 $p14_p15 $p15_p0 $q0_q1 $q1_q2 $q2_q3 $q3_q4 $q4_q5 $q5_q6 $q6_q7 $q7_q8 $q8_q9 $q9_q10 $q10_q11 $q11_q12 $q12_q13 $q13_q14 $q14_q15 $q15_q16 $q16_q17 $q17_q18 $q18_q19 $q19_q20 $q20_q21 $q21_q22 $q22_q23 $q23_q24 $q24_q25 $q25_q26 $q26_q27 $q27_q28 $q28_q29 $q29_q30 $q30_q31 $q31_q0 $q0_q1_q2_q3 $q1_q2_q3_q4 $q2_q3_q4_q5 $q3_q4_q5_q6 $q4_q5_q6_q7 $q5_q6_q7_q8 $q6_q7_q8_q9 $q7_q8_q9_q10 $q8_q9_q10_q11 $q9_q10_q11_q12 $q10_q11_q12_q13 $q11_q12_q13_q14 $q12_q13_q14_q15 $q13_q14_q15_q16 $q14_q15_q16_q17 $q15_q16_q17_q18 $q16_q17_q18_q19 $q17_q18_q19_q20 $q18_q19_q20_q21 $q19_q20_q21_q22 $q20_q21_q22_q23 $q21_q22_q23_q24 $q22_q23_q24_q25 $q23_q24_q25_q26 $q24_q25_q26_q27 $q25_q26_q27_q28 $q26_q27_q28_q29 $q27_q28_q29_q30 $q28_q29_q30_q31 $q29_q30_q31_q0 $q30_q31_q0_q1 $q31_q0_q1_q2 $q0_q1_q2 $q1_q2_q3 $q2_q3_q4 $q3_q4_q5 $q4_q5_q6 $q5_q6_q7 $q6_q7_q8 $q7_q8_q9 $q8_q9_q10 $q9_q10_q11 $q10_q11_q12 $q11_q12_q13 $q12_q13_q14 $q13_q14_q15 $q14_q15_q16 $q15_q16_q17 $q16_q17_q18 $q17_q18_q19 $q18_q19_q20 $q19_q20_q21 $q20_q21_q22 $q21_q22_q23 $q22_q23_q24 $q23_q24_q25 $q24_q25_q26 $q25_q26_q27 $q26_q27_q28 $q27_q28_q29 $q28_q29_q30 $q29_q30_q31 $q30_q31_q0 $q31_q0_q1 $x0_x1_x2_x3_x4_x5_x6_x7 $x2_x3_x4_x5_x6_x7_x8_x9 $x4_x5_x6_x7_x8_x9_x10_x11 $x6_x7_x8_x9_x10_x11_x12_x13 $x8_x9_x10_x11_x12_x13_x14_x15 $x10_x11_x12_x13_x14_x15_x16_x17 $x12_x13_x14_x15_x16_x17_x18_x19 $x14_x15_x16_x17_x18_x19_x20_x21 $x16_x17_x18_x19_x20_x21_x22_x23 $x18_x19_x20_x21_x22_x23_x24_x25 $w30_wzr $w0_w1 $w2_w3 $w4_w5 $w6_w7 $w8_w9 $w10_w11 $w12_w13 $w14_w15 $w16_w17 $w18_w19 $lr_xzr $x0_x1 $x2_x3 $x4_x5 $x6_x7 $x8_x9 $x10_x11 $x12_x13 $x14_x15 $x16_x17 $x18_x19 $z0_z1 $z1_z2 $z2_z3 $z3_z4 $z4_z5 $z5_z6 $z6_z7 $z7_z8 $z8_z9 $z9_z10 $z10_z11 $z11_z12 $z12_z13 $z13_z14 $z14_z15 $z15_z16 $z16_z17 $z17_z18 $z18_z19 $z19_z20 $z20_z21 $z21_z22 $z22_z23 $z23_z24 $z24_z25 $z25_z26 $z26_z27 $z27_z28 $z28_z29 $z29_z30 $z30_z31 $z31_z0 $z0_z1_z2_z3 $z1_z2_z3_z4 $z2_z3_z4_z5 $z3_z4_z5_z6 $z4_z5_z6_z7 $z5_z6_z7_z8 $z6_z7_z8_z9 $z7_z8_z9_z10 $z8_z9_z10_z11 $z9_z10_z11_z12 $z10_z11_z12_z13 $z11_z12_z13_z14 $z12_z13_z14_z15 $z13_z14_z15_z16 $z14_z15_z16_z17 $z15_z16_z17_z18 $z16_z17_z18_z19 $z17_z18_z19_z20 $z18_z19_z20_z21 $z19_z20_z21_z22 $z20_z21_z22_z23 $z21_z22_z23_z24 $z22_z23_z24_z25 $z23_z24_z25_z26 $z24_z25_z26_z27 $z25_z26_z27_z28 $z26_z27_z28_z29 $z27_z28_z29_z30 $z28_z29_z30_z31 $z29_z30_z31_z0 $z30_z31_z0_z1 $z31_z0_z1_z2 $z0_z1_z2 $z1_z2_z3 $z2_z3_z4 $z3_z4_z5 $z4_z5_z6 $z5_z6_z7 $z6_z7_z8 $z7_z8_z9 $z8_z9_z10 $z9_z10_z11 $z10_z11_z12 $z11_z12_z13 $z12_z13_z14 $z13_z14_z15 $z14_z15_z16 $z15_z16_z17 $z16_z17_z18 $z17_z18_z19 $z18_z19_z20 $z19_z20_z21 $z20_z21_z22 $z21_z22_z23 $z22_z23_z24 $z23_z24_z25 $z24_z25_z26 $z25_z26_z27 $z26_z27_z28 $z27_z28_z29 $z28_z29_z30 $z29_z30_z31 $z30_z31_z0 $z31_z0_z1 $z16_z24 $z17_z25 $z18_z26 $z19_z27 $z20_z28 $z21_z29 $z22_z30 $z23_z31 $z0_z8 $z1_z9 $z2_z10 $z3_z11 $z4_z12 $z5_z13 $z6_z14 $z7_z15 $z16_z20_z24_z28 $z17_z21_z25_z29 $z18_z22_z26_z30 $z19_z23_z27_z31 $z0_z4_z8_z12 $z1_z5_z9_z13 $z2_z6_z10_z14 $z3_z7_z11_z15
+  call void @bar1()
+  call void @bar2()
+  ret void
+}
+define preserve_allcc void @foo() #0 {
+; CHECK: foo Clobbered Registers: $ffr $fpcr $nzcv $sp $vg $wsp $za $b0 $b1 $b2 $b3 $b4 $b5 $b6 $b7 $d0 $d1 $d2 $d3 $d4 $d5 $d6 $d7 $h0 $h1 $h2 $h3 $h4 $h5 $h6 $h7 $p0 $p1 $p2 $p3 $p4 $p5 $p6 $p7 $p8 $p9 $p10 $p11 $p12 $p13 $p14 $p15 $q0 $q1 $q2 $q3 $q4 $q5 $q6 $q7 $s0 $s1 $s2 $s3 $s4 $s5 $s6 $s7 $w0 $w1 $w2 $w3 $w4 $w5 $w6 $w7 $w8 $w16 $w17 $w18 $x0 $x1 $x2 $x3 $x4 $x5 $x6 $x7 $x8 $x16 $x17 $x18 $z0 $z1 $z2 $z3 $z4 $z5 $z6 $z7 $z8 $z9 $z10 $z11 $z12 $z13 $z14 $z15 $z16 $z17 $z18 $z19 $z20 $z21 $z22 $z23 $z24 $z25 $z26 $z27 $z28 $z29 $z30 $z31 $zab0 $zad0 $zad1 $zad2 $zad3 $zad4 $zad5 $zad6 $zad7 $zah0 $zah1 $zaq0 $zaq1 $zaq2 $zaq3 $zaq4 $zaq5 $zaq6 $zaq7 $zaq8 $zaq9 $zaq10 $zaq11 $zaq12 $zaq13 $zaq14 $zaq15 $zas0 $zas1 $zas2 $zas3 $zt0 $z0_hi $z1_hi $z2_hi $z3_hi $z4_hi $z5_hi $z6_hi $z7_hi $z8_hi $z9_hi $z10_hi $z11_hi $z12_hi $z13_hi $z14_hi $z15_hi $z16_hi $z17_hi $z18_hi $z19_hi $z20_hi $z21_hi $z22_hi $z23_hi $z24_hi $z25_hi $z26_hi $z27_hi $z28_hi $z29_hi $z30_hi $z31_hi $d0_d1 $d1_d2 $d2_d3 $d3_d4 $d4_d5 $d5_d6 $d6_d7 $d7_d8 $d15_d16 $d16_d17 $d17_d18 $d18_d19 $d19_d20 $d20_d21 $d21_d22 $d22_d23 $d23_d24 $d24_d25 $d25_d26 $d26_d27 $d27_d28 $d28_d29 $d29_d30 $d30_d31 $d31_d0 $d0_d1_d2_d3 $d1_d2_d3_d4 $d2_d3_d4_d5 $d3_d4_d5_d6 $d4_d5_d6_d7 $d5_d6_d7_d8 $d6_d7_d8_d9 $d7_d8_d9_d10 $d13_d14_d15_d16 $d14_d15_d16_d17 $d15_d16_d17_d18 $d16_d17_d18_d19 $d17_d18_d19_d20 $d18_d19_d20_d21 $d19_d20_d21_d22 $d20_d21_d22_d23 $d21_d22_d23_d24 $d22_d23_d24_d25 $d23_d24_d25_d26 $d24_d25_d26_d27 $d25_d26_d27_d28 $d26_d27_d28_d29 $d27_d28_d29_d30 $d28_d29_d30_d31 $d29_d30_d31_d0 $d30_d31_d0_d1 $d31_d0_d1_d2 $d0_d1_d2 $d1_d2_d3 $d2_d3_d4 $d3_d4_d5 $d4_d5_d6 $d5_d6_d7 $d6_d7_d8 $d7_d8_d9 $d14_d15_d16 $d15_d16_d17 $d16_d17_d18 $d17_d18_d19 $d18_d19_d20 $d19_d20_d21 $d20_d21_d22 $d21_d22_d23 $d22_d23_d24 $d23_d24_d25 $d24_d25_d26 $d25_d26_d27 $d26_d27_d28 $d27_d28_d29 $d28_d29_d30 $d29_d30_d31 $d30_d31_d0 $d31_d0_d1 $p0_p1 $p1_p2 $p2_p3 $p3_p4 $p4_p5 $p5_p6 $p6_p7 $p7_p8 $p8_p9 $p9_p10 $p10_p11 $p11_p12 $p12_p13 $p13_p14 $p14_p15 $p15_p0 $q0_q1 $q1_q2 $q2_q3 $q3_q4 $q4_q5 $q5_q6 $q6_q7 $q7_q8 $q8_q9 $q9_q10 $q10_q11 $q11_q12 $q12_q13 $q13_q14 $q14_q15 $q15_q16 $q16_q17 $q17_q18 $q18_q19 $q19_q20 $q20_q21 $q21_q22 $q22_q23 $q23_q24 $q24_q25 $q25_q26 $q26_q27 $q27_q28 $q28_q29 $q29_q30 $q30_q31 $q31_q0 $q0_q1_q2_q3 $q1_q2_q3_q4 $q2_q3_q4_q5 $q3_q4_q5_q6 $q4_q5_q6_q7 $q5_q6_q7_q8 $q6_q7_q8_q9 $q7_q8_q9_q10 $q8_q9_q10_q11 $q9_q10_q11_q12 $q10_q11_q12_q13 $q11_q12_q13_q14 $q12_q13_q14_q15 $q13_q14_q15_q16 $q14_q15_q16_q17 $q15_q16_q17_q18 $q16_q17_q18_q19 $q17_q18_q19_q20 $q18_q19_q20_q21 $q19_q20_q21_q22 $q20_q21_q22_q23 $q21_q22_q23_q24 $q22_q23_q24_q25 $q23_q24_q25_q26 $q24_q25_q26_q27 $q25_q26_q27_q28 $q26_q27_q28_q29 $q27_q28_q29_q30 $q28_q29_q30_q31 $q29_q30_q31_q0 $q30_q31_q0_q1 $q31_q0_q1_q2 $q0_q1_q2 $q1_q2_q3 $q2_q3_q4 $q3_q4_q5 $q4_q5_q6 $q5_q6_q7 $q6_q7_q8 $q7_q8_q9 $q8_q9_q10 $q9_q10_q11 $q10_q11_q12 $q11_q12_q13 $q12_q13_q14 $q13_q14_q15 $q14_q15_q16 $q15_q16_q17 $q16_q17_q18 $q17_q18_q19 $q18_q19_q20 $q19_q20_q21 $q20_q21_q22 $q21_q22_q23 $q22_q23_q24 $q23_q24_q25 $q24_q25_q26 $q25_q26_q27 $q26_q27_q28 $q27_q28_q29 $q28_q29_q30 $q29_q30_q31 $q30_q31_q0 $q31_q0_q1 $x0_x1_x2_x3_x4_x5_x6_x7 $x2_x3_x4_x5_x6_x7_x8_x9 $x4_x5_x6_x7_x8_x9_x10_x11 $x6_x7_x8_x9_x10_x11_x12_x13 $x8_x9_x10_x11_x12_x13_x14_x15 $x10_x11_x12_x13_x14_x15_x16_x17 $x12_x13_x14_x15_x16_x17_x18_x19 $x14_x15_x16_x17_x18_x19_x20_x21 $x16_x17_x18_x19_x20_x21_x22_x23 $x18_x19_x20_x21_x22_x23_x24_x25 $w30_wzr $w0_w1 $w2_w3 $w4_w5 $w6_w7 $w8_w9 $w10_w11 $w12_w13 $w14_w15 $w16_w17 $w18_w19 $lr_xzr $x0_x1 $x2_x3 $x4_x5 $x6_x7 $x8_x9 $x10_x11 $x12_x13 $x14_x15 $x16_x17 $x18_x19 $z0_z1 $z1_z2 $z2_z3 $z3_z4 $z4_z5 $z5_z6 $z6_z7 $z7_z8 $z8_z9 $z9_z10 $z10_z11 $z11_z12 $z12_z13 $z13_z14 $z14_z15 $z15_z16 $z16_z17 $z17_z18 $z18_z19 $z19_z20 $z20_z21 $z21_z22 $z22_z23 $z23_z24 $z24_z25 $z25_z26 $z26_z27 $z27_z28 $z28_z29 $z29_z30 $z30_z31 $z31_z0 $z0_z1_z2_z3 $z1_z2_z3_z4 $z2_z3_z4_z5 $z3_z4_z5_z6 $z4_z5_z6_z7 $z5_z6_z7_z8 $z6_z7_z8_z9 $z7_z8_z9_z10 $z8_z9_z10_z11 $z9_z10_z11_z12 $z10_z11_z12_z13 $z11_z12_z13_z14 $z12_z13_z14_z15 $z13_z14_z15_z16 $z14_z15_z16_z17 $z15_z16_z17_z18 $z16_z17_z18_z19 $z17_z18_z19_z20 $z18_z19_z20_z21 $z19_z20_z21_z22 $z20_z21_z22_z23 $z21_z22_z23_z24 $z22_z23_z24_z25 $z23_z24_z25_z26 $z24_z25_z26_z27 $z25_z26_z27_z28 $z26_z27_z28_z29 $z27_z28_z29_z30 $z28_z29_z30_z31 $z29_z30_z31_z0 $z30_z31_z0_z1 $z31_z0_z1_z2 $z0_z1_z2 $z1_z2_z3 $z2_z3_z4 $z3_z4_z5 $z4_z5_z6 $z5_z6_z7 $z6_z7_z8 $z7_z8_z9 $z8_z9_z10 $z9_z10_z11 $z10_z11_z12 $z11_z12_z13 $z12_z13_z14 $z13_z14_z15 $z14_z15_z16 $z15_z16_z17 $z16_z17_z18 $z17_z18_z19 $z18_z19_z20 $z19_z20_z21 $z20_z21_z22 $z21_z22_z23 $z22_z23_z24 $z23_z24_z25 $z24_z25_z26 $z25_z26_z27 $z26_z27_z28 $z27_z28_z29 $z28_z29_z30 $z29_z30_z31 $z30_z31_z0 $z31_z0_z1 $z16_z24 $z17_z25 $z18_z26 $z19_z27 $z20_z28 $z21_z29 $z22_z30 $z23_z31 $z0_z8 $z1_z9 $z2_z10 $z3_z11 $z4_z12 $z5_z13 $z6_z14 $z7_z15 $z16_z20_z24_z28 $z17_z21_z25_z29 $z18_z22_z26_z30 $z19_z23_z27_z31 $z0_z4_z8_z12 $z1_z5_z9_z13 $z2_z6_z10_z14 $z3_z7_z11_z15
+  call void @bar1()
+  call void @bar2()
+  ret void
+}
+declare void @bar2()
+
[e-mail] = appending global [2 x ptr] [ptr @foo, ptr @baz]
+
+attributes #0 = {nounwind}

llvm/test/CodeGen/AArch64/tailcall-ccmismatch2.ll

+; RUN: llc -o - %s | FileCheck %s
+; RUN: llc -global-isel -verify-machineinstrs -o - %s | FileCheck %s
+target triple="aarch64--"
+
+declare void @somefunc()
+define preserve_allcc void @test_ccmismatch_notail() {
+; Ensure that no tail call is used here, as the called function somefunc does
+; not preserve enough registers for preserve_allcc.
+; CHECK-LABEL: test_ccmismatch_notail:
+; CHECK-NOT: b somefunc
+; CHECK: bl somefunc
+  tail call void @somefunc()
+  ret void
+}
+
+declare preserve_allcc void @some_preserve_all_func()
+define void @test_ccmismatch_tail() {
+; We can perform a tail call here, because some_preserve_all_func preserves
+; all registers necessary for test_ccmismatch_tail.
+; CHECK-LABEL: test_ccmismatch_tail:
+; CHECK-NOT: bl some_preserve_all_func
+; CHECK: b some_preserve_all_func
+  tail call preserve_allcc void @some_preserve_all_func()
+  ret void
+}