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//===-- CallingConvLower.cpp - Calling Conventions ------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file implements the CCState class, used for lowering and implementing
// calling conventions.
//
//===----------------------------------------------------------------------===//
#include "llvm/CodeGen/CallingConvLower.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/TargetLowering.h"
#include "llvm/CodeGen/TargetRegisterInfo.h"
#include "llvm/CodeGen/TargetSubtargetInfo.h"
#include "llvm/MC/MCRegisterInfo.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/SaveAndRestore.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
CCState::CCState(CallingConv::ID CC, bool IsVarArg, MachineFunction &MF,
SmallVectorImpl<CCValAssign> &Locs, LLVMContext &Context,
bool NegativeOffsets)
: CallingConv(CC), IsVarArg(IsVarArg), MF(MF),
TRI(*MF.getSubtarget().getRegisterInfo()), Locs(Locs), Context(Context),
NegativeOffsets(NegativeOffsets) {
// No stack is used.
StackSize = 0;
clearByValRegsInfo();
UsedRegs.resize((TRI.getNumRegs()+31)/32);
}
/// Allocate space on the stack large enough to pass an argument by value.
/// The size and alignment information of the argument is encoded in
/// its parameter attribute.
void CCState::HandleByVal(unsigned ValNo, MVT ValVT, MVT LocVT,
CCValAssign::LocInfo LocInfo, int MinSize,
Align MinAlign, ISD::ArgFlagsTy ArgFlags) {
Align Alignment = ArgFlags.getNonZeroByValAlign();
unsigned Size = ArgFlags.getByValSize();
if (MinSize > (int)Size)
Size = MinSize;
if (MinAlign > Alignment)
Alignment = MinAlign;
ensureMaxAlignment(Alignment);
MF.getSubtarget().getTargetLowering()->HandleByVal(this, Size, Alignment);
Size = unsigned(alignTo(Size, MinAlign));
uint64_t Offset = AllocateStack(Size, Alignment);
addLoc(CCValAssign::getMem(ValNo, ValVT, Offset, LocVT, LocInfo));
}
/// Mark a register and all of its aliases as allocated.
void CCState::MarkAllocated(MCPhysReg Reg) {
for (MCRegAliasIterator AI(Reg, &TRI, true); AI.isValid(); ++AI)
UsedRegs[*AI / 32] |= 1 << (*AI & 31);
}
void CCState::MarkUnallocated(MCPhysReg Reg) {
for (MCRegAliasIterator AI(Reg, &TRI, true); AI.isValid(); ++AI)
UsedRegs[*AI / 32] &= ~(1 << (*AI & 31));
}
bool CCState::IsShadowAllocatedReg(MCRegister Reg) const {
if (!isAllocated(Reg))
return false;
for (auto const &ValAssign : Locs)
if (ValAssign.isRegLoc() && TRI.regsOverlap(ValAssign.getLocReg(), Reg))
return false;
return true;
}
/// Analyze an array of argument values,
/// incorporating info about the formals into this state.
void
CCState::AnalyzeFormalArguments(const SmallVectorImpl<ISD::InputArg> &Ins,
CCAssignFn Fn) {
unsigned NumArgs = Ins.size();
for (unsigned i = 0; i != NumArgs; ++i) {
MVT ArgVT = Ins[i].VT;
ISD::ArgFlagsTy ArgFlags = Ins[i].Flags;
if (Fn(i, ArgVT, ArgVT, CCValAssign::Full, ArgFlags, *this))
report_fatal_error("unable to allocate function argument #" + Twine(i));
}
}
/// Analyze the return values of a function, returning true if the return can
/// be performed without sret-demotion and false otherwise.
bool CCState::CheckReturn(const SmallVectorImpl<ISD::OutputArg> &Outs,
CCAssignFn Fn) {
// Determine which register each value should be copied into.
for (unsigned i = 0, e = Outs.size(); i != e; ++i) {
MVT VT = Outs[i].VT;
ISD::ArgFlagsTy ArgFlags = Outs[i].Flags;
if (Fn(i, VT, VT, CCValAssign::Full, ArgFlags, *this))
return false;
}
return true;
}
/// Analyze the returned values of a return,
/// incorporating info about the result values into this state.
void CCState::AnalyzeReturn(const SmallVectorImpl<ISD::OutputArg> &Outs,
CCAssignFn Fn) {
// Determine which register each value should be copied into.
for (unsigned i = 0, e = Outs.size(); i != e; ++i) {
MVT VT = Outs[i].VT;
ISD::ArgFlagsTy ArgFlags = Outs[i].Flags;
if (Fn(i, VT, VT, CCValAssign::Full, ArgFlags, *this))
report_fatal_error("unable to allocate function return #" + Twine(i));
}
}
/// Analyze the outgoing arguments to a call,
/// incorporating info about the passed values into this state.
void CCState::AnalyzeCallOperands(const SmallVectorImpl<ISD::OutputArg> &Outs,
CCAssignFn Fn) {
unsigned NumOps = Outs.size();
for (unsigned i = 0; i != NumOps; ++i) {
MVT ArgVT = Outs[i].VT;
ISD::ArgFlagsTy ArgFlags = Outs[i].Flags;
if (Fn(i, ArgVT, ArgVT, CCValAssign::Full, ArgFlags, *this)) {
#ifndef NDEBUG
dbgs() << "Call operand #" << i << " has unhandled type "
<< ArgVT << '\n';
#endif
llvm_unreachable(nullptr);
}
}
}
/// Same as above except it takes vectors of types and argument flags.
void CCState::AnalyzeCallOperands(SmallVectorImpl<MVT> &ArgVTs,
SmallVectorImpl<ISD::ArgFlagsTy> &Flags,
CCAssignFn Fn) {
unsigned NumOps = ArgVTs.size();
for (unsigned i = 0; i != NumOps; ++i) {
MVT ArgVT = ArgVTs[i];
ISD::ArgFlagsTy ArgFlags = Flags[i];
if (Fn(i, ArgVT, ArgVT, CCValAssign::Full, ArgFlags, *this)) {
#ifndef NDEBUG
dbgs() << "Call operand #" << i << " has unhandled type "
<< ArgVT << '\n';
#endif
llvm_unreachable(nullptr);
}
}
}
/// Analyze the return values of a call, incorporating info about the passed
/// values into this state.
void CCState::AnalyzeCallResult(const SmallVectorImpl<ISD::InputArg> &Ins,
CCAssignFn Fn) {
for (unsigned i = 0, e = Ins.size(); i != e; ++i) {
MVT VT = Ins[i].VT;
ISD::ArgFlagsTy Flags = Ins[i].Flags;
if (Fn(i, VT, VT, CCValAssign::Full, Flags, *this)) {
#ifndef NDEBUG
dbgs() << "Call result #" << i << " has unhandled type "
<< VT << '\n';
#endif
llvm_unreachable(nullptr);
}
}
}
/// Same as above except it's specialized for calls that produce a single value.
void CCState::AnalyzeCallResult(MVT VT, CCAssignFn Fn) {
if (Fn(0, VT, VT, CCValAssign::Full, ISD::ArgFlagsTy(), *this)) {
#ifndef NDEBUG
dbgs() << "Call result has unhandled type "
<< VT << '\n';
#endif
llvm_unreachable(nullptr);
}
}
void CCState::ensureMaxAlignment(Align Alignment) {
if (!AnalyzingMustTailForwardedRegs)
MF.getFrameInfo().ensureMaxAlignment(Alignment);
}
static bool isValueTypeInRegForCC(CallingConv::ID CC, MVT VT) {
if (VT.isVector())
return true; // Assume -msse-regparm might be in effect.
if (!VT.isInteger())
return false;
return (CC == CallingConv::X86_VectorCall || CC == CallingConv::X86_FastCall);
}
void CCState::getRemainingRegParmsForType(SmallVectorImpl<MCPhysReg> &Regs,
MVT VT, CCAssignFn Fn) {
uint64_t SavedStackSize = StackSize;
Align SavedMaxStackArgAlign = MaxStackArgAlign;
unsigned NumLocs = Locs.size();
// Set the 'inreg' flag if it is used for this calling convention.
ISD::ArgFlagsTy Flags;
if (isValueTypeInRegForCC(CallingConv, VT))
Flags.setInReg();
// Allocate something of this value type repeatedly until we get assigned a
// location in memory.
bool HaveRegParm;
do {
if (Fn(0, VT, VT, CCValAssign::Full, Flags, *this)) {
#ifndef NDEBUG
dbgs() << "Call has unhandled type " << VT
<< " while computing remaining regparms\n";
#endif
llvm_unreachable(nullptr);
}
HaveRegParm = Locs.back().isRegLoc();
} while (HaveRegParm);
// Copy all the registers from the value locations we added.
assert(NumLocs < Locs.size() && "CC assignment failed to add location");
for (unsigned I = NumLocs, E = Locs.size(); I != E; ++I)
if (Locs[I].isRegLoc())
Regs.push_back(MCPhysReg(Locs[I].getLocReg()));
// Clear the assigned values and stack memory. We leave the registers marked
// as allocated so that future queries don't return the same registers, i.e.
// when i64 and f64 are both passed in GPRs.
StackSize = SavedStackSize;
MaxStackArgAlign = SavedMaxStackArgAlign;
Locs.truncate(NumLocs);
}
void CCState::analyzeMustTailForwardedRegisters(
SmallVectorImpl<ForwardedRegister> &Forwards, ArrayRef<MVT> RegParmTypes,
CCAssignFn Fn) {
// Oftentimes calling conventions will not user register parameters for
// variadic functions, so we need to assume we're not variadic so that we get
// all the registers that might be used in a non-variadic call.
SaveAndRestore SavedVarArg(IsVarArg, false);
SaveAndRestore SavedMustTail(AnalyzingMustTailForwardedRegs, true);
for (MVT RegVT : RegParmTypes) {
SmallVector<MCPhysReg, 8> RemainingRegs;
getRemainingRegParmsForType(RemainingRegs, RegVT, Fn);
const TargetLowering *TL = MF.getSubtarget().getTargetLowering();
const TargetRegisterClass *RC = TL->getRegClassFor(RegVT);
for (MCPhysReg PReg : RemainingRegs) {
Register VReg = MF.addLiveIn(PReg, RC);
Forwards.push_back(ForwardedRegister(VReg, PReg, RegVT));
}
}
}
bool CCState::resultsCompatible(CallingConv::ID CalleeCC,
CallingConv::ID CallerCC, MachineFunction &MF,
LLVMContext &C,
const SmallVectorImpl<ISD::InputArg> &Ins,
CCAssignFn CalleeFn, CCAssignFn CallerFn) {
if (CalleeCC == CallerCC)
return true;
SmallVector<CCValAssign, 4> RVLocs1;
CCState CCInfo1(CalleeCC, false, MF, RVLocs1, C);
CCInfo1.AnalyzeCallResult(Ins, CalleeFn);
SmallVector<CCValAssign, 4> RVLocs2;
CCState CCInfo2(CallerCC, false, MF, RVLocs2, C);
CCInfo2.AnalyzeCallResult(Ins, CallerFn);
auto AreCompatible = [](const CCValAssign &Loc1, const CCValAssign &Loc2) {
assert(!Loc1.isPendingLoc() && !Loc2.isPendingLoc() &&
"The location must have been decided by now");
// Must fill the same part of their locations.
if (Loc1.getLocInfo() != Loc2.getLocInfo())
return false;
// Must both be in the same registers, or both in memory at the same offset.
if (Loc1.isRegLoc() && Loc2.isRegLoc())
return Loc1.getLocReg() == Loc2.getLocReg();
if (Loc1.isMemLoc() && Loc2.isMemLoc())
return Loc1.getLocMemOffset() == Loc2.getLocMemOffset();
llvm_unreachable("Unknown location kind");
};
return std::equal(RVLocs1.begin(), RVLocs1.end(), RVLocs2.begin(),
RVLocs2.end(), AreCompatible);
}
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