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[Arm64EC] Preserve X9 for indirect calls. #167782

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[Arm64EC] Preserve X9 for indirect calls. #167782

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19 changes: 16 additions & 3 deletions llvm/lib/Target/AArch64/AArch64Arm64ECCallLowering.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -662,12 +662,15 @@ Function *AArch64Arm64ECCallLowering::buildGuestExitThunk(Function *F) {
Function *Thunk = buildExitThunk(F->getFunctionType(), F->getAttributes());
CallInst *GuardCheck = B.CreateCall(
GuardFnType, GuardCheckLoad, {F, Thunk});
Value *GuardCheckDest = B.CreateExtractValue(GuardCheck, 0);
Value *GuardFinalDest = B.CreateExtractValue(GuardCheck, 1);

// Ensure that the first argument is passed in the correct register.
GuardCheck->setCallingConv(CallingConv::CFGuard_Check);

SmallVector<Value *> Args(llvm::make_pointer_range(GuestExit->args()));
CallInst *Call = B.CreateCall(Arm64Ty, GuardCheck, Args);
OperandBundleDef OB("cfguardtarget", GuardFinalDest);
CallInst *Call = B.CreateCall(Arm64Ty, GuardCheckDest, Args, OB);
Call->setTailCallKind(llvm::CallInst::TCK_MustTail);

if (Call->getType()->isVoidTy())
Expand Down Expand Up @@ -767,11 +770,21 @@ void AArch64Arm64ECCallLowering::lowerCall(CallBase *CB) {
CallInst *GuardCheck =
B.CreateCall(GuardFnType, GuardCheckLoad, {CalledOperand, Thunk},
Bundles);
Value *GuardCheckDest = B.CreateExtractValue(GuardCheck, 0);
Value *GuardFinalDest = B.CreateExtractValue(GuardCheck, 1);

// Ensure that the first argument is passed in the correct register.
GuardCheck->setCallingConv(CallingConv::CFGuard_Check);

CB->setCalledOperand(GuardCheck);
// Update the call: set the callee, and add a bundle with the final
// destination,
CB->setCalledOperand(GuardCheckDest);
OperandBundleDef OB("cfguardtarget", GuardFinalDest);
auto *NewCall = CallBase::addOperandBundle(CB, LLVMContext::OB_cfguardtarget,
OB, CB->getIterator());
NewCall->copyMetadata(*CB);
CB->replaceAllUsesWith(NewCall);
CB->eraseFromParent();
}

bool AArch64Arm64ECCallLowering::runOnModule(Module &Mod) {
Expand All @@ -789,7 +802,7 @@ bool AArch64Arm64ECCallLowering::runOnModule(Module &Mod) {
I64Ty = Type::getInt64Ty(M->getContext());
VoidTy = Type::getVoidTy(M->getContext());

GuardFnType = FunctionType::get(PtrTy, {PtrTy, PtrTy}, false);
GuardFnType = FunctionType::get(StructType::get(PtrTy, PtrTy), {PtrTy, PtrTy}, false);
DispatchFnType = FunctionType::get(PtrTy, {PtrTy, PtrTy, PtrTy}, false);
GuardFnCFGlobal = M->getOrInsertGlobal("__os_arm64x_check_icall_cfg", PtrTy);
GuardFnGlobal = M->getOrInsertGlobal("__os_arm64x_check_icall", PtrTy);
Expand Down
13 changes: 11 additions & 2 deletions llvm/lib/Target/AArch64/AArch64CallingConvention.td
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Expand Up @@ -162,7 +162,13 @@ def RetCC_AArch64_AAPCS : CallingConv<[
]>;

let Entry = 1 in
def CC_AArch64_Win64PCS : CallingConv<AArch64_Common>;
def CC_AArch64_Win64PCS : CallingConv<!listconcat(
[
// 'CFGuardTarget' is used for Arm64EC; it passes its parameter in X9.
CCIfCFGuardTarget<CCAssignToReg<[X9]>>
],
AArch64_Common)
>;

// Vararg functions on windows pass floats in integer registers
let Entry = 1 in
Expand All @@ -177,6 +183,9 @@ def CC_AArch64_Win64_VarArg : CallingConv<[
// a stack layout compatible with the x64 calling convention.
let Entry = 1 in
def CC_AArch64_Arm64EC_VarArg : CallingConv<[
// 'CFGuardTarget' is used for Arm64EC; it passes its parameter in X9.
CCIfCFGuardTarget<CCAssignToReg<[X9]>>,

CCIfNest<CCAssignToReg<[X15]>>,

// Convert small floating-point values to integer.
Expand Down Expand Up @@ -345,7 +354,7 @@ def CC_AArch64_Arm64EC_CFGuard_Check : CallingConv<[

let Entry = 1 in
def RetCC_AArch64_Arm64EC_CFGuard_Check : CallingConv<[
CCIfType<[i64], CCAssignToReg<[X11]>>
CCIfType<[i64], CCAssignToReg<[X11, X9]>>
]>;


Expand Down
50 changes: 50 additions & 0 deletions llvm/test/CodeGen/AArch64/arm64ec-indirect-call.ll
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@@ -0,0 +1,50 @@
; RUN: llc -mtriple=arm64ec-pc-windows-msvc < %s | FileCheck %s

define void @simple(ptr %g) {
; CHECK-LABEL: "#simple":
; CHECK: str x30, [sp, #-16]!
; CHECK-NEXT: .seh_save_reg_x x30, 16
; CHECK-NEXT: .seh_endprologue
; CHECK-NEXT: adrp x8, __os_arm64x_check_icall
; CHECK-NEXT: adrp x10, $iexit_thunk$cdecl$v$v
; CHECK-NEXT: add x10, x10, :lo12:$iexit_thunk$cdecl$v$v
; CHECK-NEXT: ldr x8, [x8, :lo12:__os_arm64x_check_icall]
; CHECK-NEXT: mov x11, x0
; CHECK-NEXT: blr x8
; CHECK-NEXT: blr x11
; CHECK-NEXT: .seh_startepilogue
; CHECK-NEXT: ldr x30, [sp], #16
; CHECK-NEXT: .seh_save_reg_x x30, 16
; CHECK-NEXT: .seh_endepilogue
; CHECK-NEXT: ret

entry:
call void %g()
ret void
}

; Make sure the check for the security cookie doesn't use x9.
define void @stackguard(ptr %g) sspreq {
; CHECK-LABEL: "#stackguard":
; CHECK: adrp x8, __os_arm64x_check_icall
; CHECK-NEXT: ldr x8, [x8, :lo12:__os_arm64x_check_icall]
; CHECK-NEXT: blr x8
; CHECK-NEXT: adrp x8, __security_cookie
; CHECK-NEXT: ldr x10, [sp, #8]
; CHECK-NEXT: ldr x8, [x8, :lo12:__security_cookie]
; CHECK-NEXT: cmp x8, x10
; CHECK-NEXT: b.ne .LBB1_2
; CHECK-NEXT: // %bb.1:
; CHECK-NEXT: fmov d0, #1.00000000
; CHECK-NEXT: .seh_startepilogue
; CHECK-NEXT: ldr x30, [sp, #16]
; CHECK-NEXT: .seh_save_reg x30, 16
; CHECK-NEXT: add sp, sp, #32
; CHECK-NEXT: .seh_stackalloc 32
; CHECK-NEXT: .seh_endepilogue
; CHECK-NEXT: br x11

entry:
%call = tail call double %g(double noundef 1.000000e+00)
ret void
}
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