[llvm] Consistently respect naked fn attribute in TargetFrameLowering::hasFP().

Some targets (e.g. PPC and Hexagon) already did this. I think it's best to do
this consistently so that frontend authors don't run into inconsistent results
when they emit naked functions. For example, in Zig, we had to change our emit
code to also set frame-pointer=none to get reliable results across targets.

Author: alexrp

llvm/lib/Target/AArch64/AArch64FrameLowering.cpp

@@ -478,6 +478,11 @@ bool AArch64FrameLowering::canUseRedZone(const MachineFunction &MF) const {
 /// hasFP - Return true if the specified function should have a dedicated frame
 /// pointer register.
 bool AArch64FrameLowering::hasFP(const MachineFunction &MF) const {
+  // Naked functions have no stack frame pushed, so we don't have a frame
+  // pointer.
+  if (MF.getFunction().hasFnAttribute(Attribute::Naked))
+    return false;
+
   const MachineFrameInfo &MFI = MF.getFrameInfo();
   const TargetRegisterInfo *RegInfo = MF.getSubtarget().getRegisterInfo();
 

llvm/lib/Target/ARC/ARCFrameLowering.cpp

@@ -488,6 +488,11 @@ MachineBasicBlock::iterator ARCFrameLowering::eliminateCallFramePseudoInstr(
 }
 
 bool ARCFrameLowering::hasFP(const MachineFunction &MF) const {
+  // Naked functions have no stack frame pushed, so we don't have a frame
+  // pointer.
+  if (MF.getFunction().hasFnAttribute(Attribute::Naked))
+    return false;
+
   const TargetRegisterInfo *RegInfo = MF.getSubtarget().getRegisterInfo();
   bool HasFP = MF.getTarget().Options.DisableFramePointerElim(MF) ||
                MF.getFrameInfo().hasVarSizedObjects() ||

llvm/lib/Target/ARM/ARMFrameLowering.cpp

@@ -200,6 +200,11 @@ bool ARMFrameLowering::enableCalleeSaveSkip(const MachineFunction &MF) const {
 /// pointer register.  This is true if the function has variable sized allocas
 /// or if frame pointer elimination is disabled.
 bool ARMFrameLowering::hasFP(const MachineFunction &MF) const {
+  // Naked functions have no stack frame pushed, so we don't have a frame
+  // pointer.
+  if (MF.getFunction().hasFnAttribute(Attribute::Naked))
+    return false;
+
   const TargetRegisterInfo *RegInfo = MF.getSubtarget().getRegisterInfo();
   const MachineFrameInfo &MFI = MF.getFrameInfo();
 

llvm/lib/Target/AVR/AVRFrameLowering.cpp

@@ -233,6 +233,11 @@ void AVRFrameLowering::emitEpilogue(MachineFunction &MF,
 // Notice that strictly this is not a frame pointer because it contains SP after
 // frame allocation instead of having the original SP in function entry.
 bool AVRFrameLowering::hasFP(const MachineFunction &MF) const {
+  // Naked functions have no stack frame pushed, so we don't have a frame
+  // pointer.
+  if (MF.getFunction().hasFnAttribute(Attribute::Naked))
+    return false;
+
   const AVRMachineFunctionInfo *FuncInfo = MF.getInfo<AVRMachineFunctionInfo>();
 
   return (FuncInfo->getHasSpills() || FuncInfo->getHasAllocas() ||

llvm/lib/Target/CSKY/CSKYFrameLowering.cpp

@@ -34,6 +34,11 @@ static Register getFPReg(const CSKYSubtarget &STI) { return CSKY::R8; }
 static Register getBPReg(const CSKYSubtarget &STI) { return CSKY::R7; }
 
 bool CSKYFrameLowering::hasFP(const MachineFunction &MF) const {
+  // Naked functions have no stack frame pushed, so we don't have a frame
+  // pointer.
+  if (MF.getFunction().hasFnAttribute(Attribute::Naked))
+    return false;
+
   const TargetRegisterInfo *RegInfo = MF.getSubtarget().getRegisterInfo();
 
   const MachineFrameInfo &MFI = MF.getFrameInfo();

llvm/lib/Target/LoongArch/LoongArchFrameLowering.cpp

@@ -32,6 +32,11 @@ using namespace llvm;
 // disabled, if it needs dynamic stack realignment, if the function has
 // variable sized allocas, or if the frame address is taken.
 bool LoongArchFrameLowering::hasFP(const MachineFunction &MF) const {
+  // Naked functions have no stack frame pushed, so we don't have a frame
+  // pointer.
+  if (MF.getFunction().hasFnAttribute(Attribute::Naked))
+    return false;
+
   const TargetRegisterInfo *RegInfo = MF.getSubtarget().getRegisterInfo();
 
   const MachineFrameInfo &MFI = MF.getFrameInfo();

llvm/lib/Target/M68k/M68kFrameLowering.cpp

@@ -41,6 +41,11 @@ M68kFrameLowering::M68kFrameLowering(const M68kSubtarget &STI, Align Alignment)
 }
 
 bool M68kFrameLowering::hasFP(const MachineFunction &MF) const {
+  // Naked functions have no stack frame pushed, so we don't have a frame
+  // pointer.
+  if (MF.getFunction().hasFnAttribute(Attribute::Naked))
+    return false;
+
   const MachineFrameInfo &MFI = MF.getFrameInfo();
   const TargetRegisterInfo *TRI = STI.getRegisterInfo();
 

llvm/lib/Target/MSP430/MSP430FrameLowering.cpp

@@ -31,6 +31,11 @@ MSP430FrameLowering::MSP430FrameLowering(const MSP430Subtarget &STI)
       STI(STI), TII(*STI.getInstrInfo()), TRI(STI.getRegisterInfo()) {}
 
 bool MSP430FrameLowering::hasFP(const MachineFunction &MF) const {
+  // Naked functions have no stack frame pushed, so we don't have a frame
+  // pointer.
+  if (MF.getFunction().hasFnAttribute(Attribute::Naked))
+    return false;
+
   const MachineFrameInfo &MFI = MF.getFrameInfo();
 
   return (MF.getTarget().Options.DisableFramePointerElim(MF) ||

llvm/lib/Target/Mips/MipsFrameLowering.cpp

@@ -91,6 +91,11 @@ const MipsFrameLowering *MipsFrameLowering::create(const MipsSubtarget &ST) {
 // if it needs dynamic stack realignment, if frame pointer elimination is
 // disabled, or if the frame address is taken.
 bool MipsFrameLowering::hasFP(const MachineFunction &MF) const {
+  // Naked functions have no stack frame pushed, so we don't have a frame
+  // pointer.
+  if (MF.getFunction().hasFnAttribute(Attribute::Naked))
+    return false;
+
   const MachineFrameInfo &MFI = MF.getFrameInfo();
   const TargetRegisterInfo *TRI = STI.getRegisterInfo();
 

llvm/lib/Target/RISCV/RISCVFrameLowering.cpp

@@ -310,6 +310,11 @@ static Register getMaxPushPopReg(const MachineFunction &MF,
 // disabled, if it needs dynamic stack realignment, if the function has
 // variable sized allocas, or if the frame address is taken.
 bool RISCVFrameLowering::hasFP(const MachineFunction &MF) const {
+  // Naked functions have no stack frame pushed, so we don't have a frame
+  // pointer.
+  if (MF.getFunction().hasFnAttribute(Attribute::Naked))
+    return false;
+
   const TargetRegisterInfo *RegInfo = MF.getSubtarget().getRegisterInfo();
 
   const MachineFrameInfo &MFI = MF.getFrameInfo();