danielkiss updated this revision to Diff 266595.
danielkiss marked an inline comment as done.
danielkiss retitled this revision from "[AArch64] __builtin_extract_return_addr
for PAuth." to "[AArch64] __builtin_return_address for PAuth.".
danielkiss edited the summary of this revision.
danielkiss added a comment.
Changing the implementation from __builtin_extract_return_addr to
__builtin_return_address.
Stripping PAC in __builtin_return_address is a better solution, because:
- we should not expose PAC bits to the user because it could be passed around
and that would be an ABI break.
- __builtin_extract_return_addr has a pair, the __builtin_frob_return_addr
which won't be supported with PAC.
I'm thinking of adding a warning if __builtin_frob_return_addr is used with PAC
on.
Same change will be proposed from gcc too.
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D75044/new/
https://reviews.llvm.org/D75044
Files:
llvm/include/llvm/CodeGen/ISDOpcodes.h
llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
llvm/test/CodeGen/AArch64/aarch64-signedreturnaddress.ll
Index: llvm/test/CodeGen/AArch64/aarch64-signedreturnaddress.ll
===================================================================
--- /dev/null
+++ llvm/test/CodeGen/AArch64/aarch64-signedreturnaddress.ll
@@ -0,0 +1,28 @@
+; RUN: llc < %s -mtriple=arm64-eabi -asm-verbose=false -mattr=v8.2a | FileCheck %s
+; RUN: llc < %s -mtriple=arm64-eabi -asm-verbose=false -mattr=v8.3a | FileCheck %s --check-prefix=CHECKV83
+
+; Armv8.3-A Pointer Authetication requires a special intsruction to strip the
+; pointer authentication code from the pointer.
+; The XPACLRI instruction assembles to a hint-space instruction before Armv8.3-A
+; therefore this instruction can be safely used for any pre Armv8.3-A architectures.
+; On Armv8.3-A and onwards XPACI is available so use that instead.
+
+define i8* @era0() nounwind readnone #0 {
+entry:
+; CHECK-LABEL: era0:
+; CHECK: hint #25
+; CHECK-NEXT: str x30, [sp, #-16]!
+; CHECK-NEXT: hint #7
+; CHECK-NEXT: mov x0, x30
+; CHECK-NEXT: ldr x30, [sp], #16
+; CHECK-NEXT: hint #29
+; CHECK-NEXT: ret
+; CHECKV83: paciasp
+; CHECKV83-NEXT: xpaci x0
+; CHECKV83-NEXT: retaa
+ %0 = tail call i8* @llvm.returnaddress(i32 0)
+ ret i8* %0
+}
+attributes #0 = { "sign-return-address"="all" }
+
+declare i8* @llvm.returnaddress(i32) nounwind readnone
Index: llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
===================================================================
--- llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
+++ llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
@@ -6093,17 +6093,39 @@
EVT VT = Op.getValueType();
SDLoc DL(Op);
unsigned Depth = cast<ConstantSDNode>(Op.getOperand(0))->getZExtValue();
+ SDValue ReturnAddress;
if (Depth) {
SDValue FrameAddr = LowerFRAMEADDR(Op, DAG);
SDValue Offset = DAG.getConstant(8, DL, getPointerTy(DAG.getDataLayout()));
- return DAG.getLoad(VT, DL, DAG.getEntryNode(),
- DAG.getNode(ISD::ADD, DL, VT, FrameAddr, Offset),
- MachinePointerInfo());
+ ReturnAddress = DAG.getLoad(
+ VT, DL, DAG.getEntryNode(),
+ DAG.getNode(ISD::ADD, DL, VT, FrameAddr, Offset), MachinePointerInfo());
+ } else {
+ // Return LR, which contains the return address. Mark it an implicit
+ // live-in.
+ unsigned Reg = MF.addLiveIn(AArch64::LR, &AArch64::GPR64RegClass);
+ ReturnAddress = DAG.getCopyFromReg(DAG.getEntryNode(), DL, Reg, VT);
+ }
+
+ if (!MF.getFunction().hasFnAttribute("sign-return-address"))
+ return ReturnAddress;
+
+ // The XPACLRI instruction assembles to a hint-space instruction before
+ // Armv8.3-A therefore this instruction can be safely used for any pre
+ // Armv8.3-A architectures. On Armv8.3-A and onwards XPACI is available so use
+ // that instead.
+ if (Subtarget->hasV8_3aOps()) {
+ SDValue Reg =
+ DAG.getCopyToReg(DAG.getEntryNode(), DL, AArch64::X0, ReturnAddress);
+ SDNode *St = DAG.getMachineNode(AArch64::XPACI, DL, VT, Reg);
+ return SDValue(St, 0);
+ } else {
+ // XPACLRI operates on LR therefore we must move the operand accordingly.
+ SDValue Reg =
+ DAG.getCopyToReg(DAG.getEntryNode(), DL, AArch64::LR, ReturnAddress);
+ SDNode *St = DAG.getMachineNode(AArch64::XPACLRI, DL, VT, Reg);
+ return SDValue(St, 0);
}
-
- // Return LR, which contains the return address. Mark it an implicit live-in.
- unsigned Reg = MF.addLiveIn(AArch64::LR, &AArch64::GPR64RegClass);
- return DAG.getCopyFromReg(DAG.getEntryNode(), DL, Reg, VT);
}
/// LowerShiftRightParts - Lower SRA_PARTS, which returns two
Index: llvm/include/llvm/CodeGen/ISDOpcodes.h
===================================================================
--- llvm/include/llvm/CodeGen/ISDOpcodes.h
+++ llvm/include/llvm/CodeGen/ISDOpcodes.h
@@ -85,7 +85,16 @@
/// the parent's frame or return address, and so on.
FRAMEADDR,
RETURNADDR,
+
+ /// ADDROFRETURNADDR - Represents the llvm.addressofreturnaddress intrinsic.
+ /// This node takes no operand, returns a target-specific pointer to the
+ /// place in the stack frame where the return address of the current
+ /// function is stored.
ADDROFRETURNADDR,
+
+ /// SPONENTRY - Represents the llvm.sponentry intrinsic. Takes no argument
+ /// and returns the stack pointer value at the entry of the current
+ /// function calling this intrinsic.
SPONENTRY,
/// LOCAL_RECOVER - Represents the llvm.localrecover intrinsic.
_______________________________________________
cfe-commits mailing list
cfe-commits@lists.llvm.org
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
