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fc712eb7aa00aabcdafda54776038efdc486d570
clang-p2996/llvm/lib/CodeGen/GlobalISel/CallLowering.cpp
Matt Arsenault e7e7d371fd GlobalISel: Fix generic handling of single outgoing call arguments 
Simply call the argument handler like is done for the incoming
case. This will allow removal of hacks in the AMDGPU call lowering in
a future change.
2020-12-15 17:00:27 -05:00

547 lines
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//===-- lib/CodeGen/GlobalISel/CallLowering.cpp - Call lowering -----------===//
//
// 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
//
//===----------------------------------------------------------------------===//
///
/// \file
/// This file implements some simple delegations needed for call lowering.
///
//===----------------------------------------------------------------------===//
#include "llvm/CodeGen/Analysis.h"
#include "llvm/CodeGen/GlobalISel/CallLowering.h"
#include "llvm/CodeGen/GlobalISel/Utils.h"
#include "llvm/CodeGen/GlobalISel/MachineIRBuilder.h"
#include "llvm/CodeGen/MachineOperand.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/TargetLowering.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Module.h"
#include "llvm/Target/TargetMachine.h"
#define DEBUG_TYPE "call-lowering"
using namespace llvm;
void CallLowering::anchor() {}
/// Helper function which updates \p Flags when \p AttrFn returns true.
static void
addFlagsUsingAttrFn(ISD::ArgFlagsTy &Flags,
const std::function<bool(Attribute::AttrKind)> &AttrFn) {
if (AttrFn(Attribute::SExt))
Flags.setSExt();
if (AttrFn(Attribute::ZExt))
Flags.setZExt();
if (AttrFn(Attribute::InReg))
Flags.setInReg();
if (AttrFn(Attribute::StructRet))
Flags.setSRet();
if (AttrFn(Attribute::Nest))
Flags.setNest();
if (AttrFn(Attribute::ByVal))
Flags.setByVal();
if (AttrFn(Attribute::Preallocated))
Flags.setPreallocated();
if (AttrFn(Attribute::InAlloca))
Flags.setInAlloca();
if (AttrFn(Attribute::Returned))
Flags.setReturned();
if (AttrFn(Attribute::SwiftSelf))
Flags.setSwiftSelf();
if (AttrFn(Attribute::SwiftError))
Flags.setSwiftError();
}
ISD::ArgFlagsTy CallLowering::getAttributesForArgIdx(const CallBase &Call,
unsigned ArgIdx) const {
ISD::ArgFlagsTy Flags;
addFlagsUsingAttrFn(Flags, [&Call, &ArgIdx](Attribute::AttrKind Attr) {
return Call.paramHasAttr(ArgIdx, Attr);
});
return Flags;
}
void CallLowering::addArgFlagsFromAttributes(ISD::ArgFlagsTy &Flags,
const AttributeList &Attrs,
unsigned OpIdx) const {
addFlagsUsingAttrFn(Flags, [&Attrs, &OpIdx](Attribute::AttrKind Attr) {
return Attrs.hasAttribute(OpIdx, Attr);
});
}
bool CallLowering::lowerCall(MachineIRBuilder &MIRBuilder, const CallBase &CB,
ArrayRef<Register> ResRegs,
ArrayRef<ArrayRef<Register>> ArgRegs,
Register SwiftErrorVReg,
std::function<unsigned()> GetCalleeReg) const {
CallLoweringInfo Info;
const DataLayout &DL = MIRBuilder.getDataLayout();
MachineFunction &MF = MIRBuilder.getMF();
bool CanBeTailCalled = CB.isTailCall() &&
isInTailCallPosition(CB, MF.getTarget()) &&
(MF.getFunction()
.getFnAttribute("disable-tail-calls")
.getValueAsString() != "true");
// First step is to marshall all the function's parameters into the correct
// physregs and memory locations. Gather the sequence of argument types that
// we'll pass to the assigner function.
unsigned i = 0;
unsigned NumFixedArgs = CB.getFunctionType()->getNumParams();
for (auto &Arg : CB.args()) {
ArgInfo OrigArg{ArgRegs[i], Arg->getType(), getAttributesForArgIdx(CB, i),
i < NumFixedArgs};
setArgFlags(OrigArg, i + AttributeList::FirstArgIndex, DL, CB);
// If we have an explicit sret argument that is an Instruction, (i.e., it
// might point to function-local memory), we can't meaningfully tail-call.
if (OrigArg.Flags[0].isSRet() && isa<Instruction>(&Arg))
CanBeTailCalled = false;
Info.OrigArgs.push_back(OrigArg);
++i;
}
// Try looking through a bitcast from one function type to another.
// Commonly happens with calls to objc_msgSend().
const Value *CalleeV = CB.getCalledOperand()->stripPointerCasts();
if (const Function *F = dyn_cast<Function>(CalleeV))
Info.Callee = MachineOperand::CreateGA(F, 0);
else
Info.Callee = MachineOperand::CreateReg(GetCalleeReg(), false);
Info.OrigRet = ArgInfo{ResRegs, CB.getType(), ISD::ArgFlagsTy{}};
if (!Info.OrigRet.Ty->isVoidTy())
setArgFlags(Info.OrigRet, AttributeList::ReturnIndex, DL, CB);
Info.KnownCallees = CB.getMetadata(LLVMContext::MD_callees);
Info.CallConv = CB.getCallingConv();
Info.SwiftErrorVReg = SwiftErrorVReg;
Info.IsMustTailCall = CB.isMustTailCall();
Info.IsTailCall = CanBeTailCalled;
Info.IsVarArg = CB.getFunctionType()->isVarArg();
return lowerCall(MIRBuilder, Info);
}
template <typename FuncInfoTy>
void CallLowering::setArgFlags(CallLowering::ArgInfo &Arg, unsigned OpIdx,
const DataLayout &DL,
const FuncInfoTy &FuncInfo) const {
auto &Flags = Arg.Flags[0];
const AttributeList &Attrs = FuncInfo.getAttributes();
addArgFlagsFromAttributes(Flags, Attrs, OpIdx);
if (Flags.isByVal() || Flags.isInAlloca() || Flags.isPreallocated()) {
Type *ElementTy = cast<PointerType>(Arg.Ty)->getElementType();
auto Ty = Attrs.getAttribute(OpIdx, Attribute::ByVal).getValueAsType();
Flags.setByValSize(DL.getTypeAllocSize(Ty ? Ty : ElementTy));
// For ByVal, alignment should be passed from FE. BE will guess if
// this info is not there but there are cases it cannot get right.
Align FrameAlign;
if (auto ParamAlign = FuncInfo.getParamAlign(OpIdx - 2))
FrameAlign = *ParamAlign;
else
FrameAlign = Align(getTLI()->getByValTypeAlignment(ElementTy, DL));
Flags.setByValAlign(FrameAlign);
}
Flags.setOrigAlign(DL.getABITypeAlign(Arg.Ty));
}
template void
CallLowering::setArgFlags<Function>(CallLowering::ArgInfo &Arg, unsigned OpIdx,
const DataLayout &DL,
const Function &FuncInfo) const;
template void
CallLowering::setArgFlags<CallBase>(CallLowering::ArgInfo &Arg, unsigned OpIdx,
const DataLayout &DL,
const CallBase &FuncInfo) const;
Register CallLowering::packRegs(ArrayRef<Register> SrcRegs, Type *PackedTy,
MachineIRBuilder &MIRBuilder) const {
assert(SrcRegs.size() > 1 && "Nothing to pack");
const DataLayout &DL = MIRBuilder.getMF().getDataLayout();
MachineRegisterInfo *MRI = MIRBuilder.getMRI();
LLT PackedLLT = getLLTForType(*PackedTy, DL);
SmallVector<LLT, 8> LLTs;
SmallVector<uint64_t, 8> Offsets;
computeValueLLTs(DL, *PackedTy, LLTs, &Offsets);
assert(LLTs.size() == SrcRegs.size() && "Regs / types mismatch");
Register Dst = MRI->createGenericVirtualRegister(PackedLLT);
MIRBuilder.buildUndef(Dst);
for (unsigned i = 0; i < SrcRegs.size(); ++i) {
Register NewDst = MRI->createGenericVirtualRegister(PackedLLT);
MIRBuilder.buildInsert(NewDst, Dst, SrcRegs[i], Offsets[i]);
Dst = NewDst;
}
return Dst;
}
void CallLowering::unpackRegs(ArrayRef<Register> DstRegs, Register SrcReg,
Type *PackedTy,
MachineIRBuilder &MIRBuilder) const {
assert(DstRegs.size() > 1 && "Nothing to unpack");
const DataLayout &DL = MIRBuilder.getDataLayout();
SmallVector<LLT, 8> LLTs;
SmallVector<uint64_t, 8> Offsets;
computeValueLLTs(DL, *PackedTy, LLTs, &Offsets);
assert(LLTs.size() == DstRegs.size() && "Regs / types mismatch");
for (unsigned i = 0; i < DstRegs.size(); ++i)
MIRBuilder.buildExtract(DstRegs[i], SrcReg, Offsets[i]);
}
bool CallLowering::handleAssignments(MachineIRBuilder &MIRBuilder,
SmallVectorImpl<ArgInfo> &Args,
ValueHandler &Handler) const {
MachineFunction &MF = MIRBuilder.getMF();
const Function &F = MF.getFunction();
SmallVector<CCValAssign, 16> ArgLocs;
CCState CCInfo(F.getCallingConv(), F.isVarArg(), MF, ArgLocs, F.getContext());
return handleAssignments(CCInfo, ArgLocs, MIRBuilder, Args, Handler);
}
bool CallLowering::handleAssignments(CCState &CCInfo,
SmallVectorImpl<CCValAssign> &ArgLocs,
MachineIRBuilder &MIRBuilder,
SmallVectorImpl<ArgInfo> &Args,
ValueHandler &Handler) const {
MachineFunction &MF = MIRBuilder.getMF();
const Function &F = MF.getFunction();
const DataLayout &DL = F.getParent()->getDataLayout();
unsigned NumArgs = Args.size();
for (unsigned i = 0; i != NumArgs; ++i) {
EVT CurVT = EVT::getEVT(Args[i].Ty);
if (CurVT.isSimple() &&
!Handler.assignArg(i, CurVT.getSimpleVT(), CurVT.getSimpleVT(),
CCValAssign::Full, Args[i], Args[i].Flags[0],
CCInfo))
continue;
MVT NewVT = TLI->getRegisterTypeForCallingConv(
F.getContext(), F.getCallingConv(), EVT(CurVT));
// If we need to split the type over multiple regs, check it's a scenario
// we currently support.
unsigned NumParts = TLI->getNumRegistersForCallingConv(
F.getContext(), F.getCallingConv(), CurVT);
if (NumParts == 1) {
// Try to use the register type if we couldn't assign the VT.
if (Handler.assignArg(i, NewVT, NewVT, CCValAssign::Full, Args[i],
Args[i].Flags[0], CCInfo))
return false;
continue;
}
assert(NumParts > 1);
// For now only handle exact splits.
if (NewVT.getSizeInBits() * NumParts != CurVT.getSizeInBits())
return false;
// For incoming arguments (physregs to vregs), we could have values in
// physregs (or memlocs) which we want to extract and copy to vregs.
// During this, we might have to deal with the LLT being split across
// multiple regs, so we have to record this information for later.
//
// If we have outgoing args, then we have the opposite case. We have a
// vreg with an LLT which we want to assign to a physical location, and
// we might have to record that the value has to be split later.
if (Handler.isIncomingArgumentHandler()) {
// We're handling an incoming arg which is split over multiple regs.
// E.g. passing an s128 on AArch64.
ISD::ArgFlagsTy OrigFlags = Args[i].Flags[0];
Args[i].OrigRegs.push_back(Args[i].Regs[0]);
Args[i].Regs.clear();
Args[i].Flags.clear();
LLT NewLLT = getLLTForMVT(NewVT);
// For each split register, create and assign a vreg that will store
// the incoming component of the larger value. These will later be
// merged to form the final vreg.
for (unsigned Part = 0; Part < NumParts; ++Part) {
Register Reg =
MIRBuilder.getMRI()->createGenericVirtualRegister(NewLLT);
ISD::ArgFlagsTy Flags = OrigFlags;
if (Part == 0) {
Flags.setSplit();
} else {
Flags.setOrigAlign(Align(1));
if (Part == NumParts - 1)
Flags.setSplitEnd();
}
Args[i].Regs.push_back(Reg);
Args[i].Flags.push_back(Flags);
if (Handler.assignArg(i, NewVT, NewVT, CCValAssign::Full, Args[i],
Args[i].Flags[Part], CCInfo)) {
// Still couldn't assign this smaller part type for some reason.
return false;
}
}
} else {
// This type is passed via multiple registers in the calling convention.
// We need to extract the individual parts.
Register LargeReg = Args[i].Regs[0];
LLT SmallTy = LLT::scalar(NewVT.getSizeInBits());
auto Unmerge = MIRBuilder.buildUnmerge(SmallTy, LargeReg);
assert(Unmerge->getNumOperands() == NumParts + 1);
ISD::ArgFlagsTy OrigFlags = Args[i].Flags[0];
// We're going to replace the regs and flags with the split ones.
Args[i].Regs.clear();
Args[i].Flags.clear();
for (unsigned PartIdx = 0; PartIdx < NumParts; ++PartIdx) {
ISD::ArgFlagsTy Flags = OrigFlags;
if (PartIdx == 0) {
Flags.setSplit();
} else {
Flags.setOrigAlign(Align(1));
if (PartIdx == NumParts - 1)
Flags.setSplitEnd();
}
Args[i].Regs.push_back(Unmerge.getReg(PartIdx));
Args[i].Flags.push_back(Flags);
if (Handler.assignArg(i, NewVT, NewVT, CCValAssign::Full,
Args[i], Args[i].Flags[PartIdx], CCInfo))
return false;
}
}
}
for (unsigned i = 0, e = Args.size(), j = 0; i != e; ++i, ++j) {
assert(j < ArgLocs.size() && "Skipped too many arg locs");
CCValAssign &VA = ArgLocs[j];
assert(VA.getValNo() == i && "Location doesn't correspond to current arg");
if (VA.needsCustom()) {
unsigned NumArgRegs =
Handler.assignCustomValue(Args[i], makeArrayRef(ArgLocs).slice(j));
if (!NumArgRegs)
return false;
j += NumArgRegs;
continue;
}
// FIXME: Pack registers if we have more than one.
Register ArgReg = Args[i].Regs[0];
EVT OrigVT = EVT::getEVT(Args[i].Ty);
EVT VAVT = VA.getValVT();
const LLT OrigTy = getLLTForType(*Args[i].Ty, DL);
// Expected to be multiple regs for a single incoming arg.
// There should be Regs.size() ArgLocs per argument.
unsigned NumArgRegs = Args[i].Regs.size();
assert((j + (NumArgRegs - 1)) < ArgLocs.size() &&
"Too many regs for number of args");
for (unsigned Part = 0; Part < NumArgRegs; ++Part) {
// There should be Regs.size() ArgLocs per argument.
VA = ArgLocs[j + Part];
if (VA.isMemLoc()) {
// Don't currently support loading/storing a type that needs to be split
// to the stack. Should be easy, just not implemented yet.
if (NumArgRegs > 1) {
LLVM_DEBUG(
dbgs()
<< "Load/store a split arg to/from the stack not implemented yet\n");
return false;
}
// FIXME: Use correct address space for pointer size
EVT LocVT = VA.getValVT();
unsigned MemSize = LocVT == MVT::iPTR ? DL.getPointerSize()
: LocVT.getStoreSize();
unsigned Offset = VA.getLocMemOffset();
MachinePointerInfo MPO;
Register StackAddr = Handler.getStackAddress(MemSize, Offset, MPO);
Handler.assignValueToAddress(Args[i], StackAddr,
MemSize, MPO, VA);
continue;
}
assert(VA.isRegLoc() && "custom loc should have been handled already");
// GlobalISel does not currently work for scalable vectors.
if (OrigVT.getFixedSizeInBits() >= VAVT.getFixedSizeInBits() ||
!Handler.isIncomingArgumentHandler()) {
// This is an argument that might have been split. There should be
// Regs.size() ArgLocs per argument.
// Insert the argument copies. If VAVT < OrigVT, we'll insert the merge
// to the original register after handling all of the parts.
Handler.assignValueToReg(Args[i].Regs[Part], VA.getLocReg(), VA);
continue;
}
// This ArgLoc covers multiple pieces, so we need to split it.
const LLT VATy(VAVT.getSimpleVT());
Register NewReg =
MIRBuilder.getMRI()->createGenericVirtualRegister(VATy);
Handler.assignValueToReg(NewReg, VA.getLocReg(), VA);
// If it's a vector type, we either need to truncate the elements
// or do an unmerge to get the lower block of elements.
if (VATy.isVector() &&
VATy.getNumElements() > OrigVT.getVectorNumElements()) {
// Just handle the case where the VA type is 2 * original type.
if (VATy.getNumElements() != OrigVT.getVectorNumElements() * 2) {
LLVM_DEBUG(dbgs()
<< "Incoming promoted vector arg has too many elts");
return false;
}
auto Unmerge = MIRBuilder.buildUnmerge({OrigTy, OrigTy}, {NewReg});
MIRBuilder.buildCopy(ArgReg, Unmerge.getReg(0));
} else {
MIRBuilder.buildTrunc(ArgReg, {NewReg}).getReg(0);
}
}
// Now that all pieces have been handled, re-pack any arguments into any
// wider, original registers.
if (Handler.isIncomingArgumentHandler()) {
if (VAVT.getFixedSizeInBits() < OrigVT.getFixedSizeInBits()) {
assert(NumArgRegs >= 2);
// Merge the split registers into the expected larger result vreg
// of the original call.
MIRBuilder.buildMerge(Args[i].OrigRegs[0], Args[i].Regs);
}
}
j += NumArgRegs - 1;
}
return true;
}
bool CallLowering::analyzeArgInfo(CCState &CCState,
SmallVectorImpl<ArgInfo> &Args,
CCAssignFn &AssignFnFixed,
CCAssignFn &AssignFnVarArg) const {
for (unsigned i = 0, e = Args.size(); i < e; ++i) {
MVT VT = MVT::getVT(Args[i].Ty);
CCAssignFn &Fn = Args[i].IsFixed ? AssignFnFixed : AssignFnVarArg;
if (Fn(i, VT, VT, CCValAssign::Full, Args[i].Flags[0], CCState)) {
// Bail out on anything we can't handle.
LLVM_DEBUG(dbgs() << "Cannot analyze " << EVT(VT).getEVTString()
<< " (arg number = " << i << "\n");
return false;
}
}
return true;
}
bool CallLowering::resultsCompatible(CallLoweringInfo &Info,
MachineFunction &MF,
SmallVectorImpl<ArgInfo> &InArgs,
CCAssignFn &CalleeAssignFnFixed,
CCAssignFn &CalleeAssignFnVarArg,
CCAssignFn &CallerAssignFnFixed,
CCAssignFn &CallerAssignFnVarArg) const {
const Function &F = MF.getFunction();
CallingConv::ID CalleeCC = Info.CallConv;
CallingConv::ID CallerCC = F.getCallingConv();
if (CallerCC == CalleeCC)
return true;
SmallVector<CCValAssign, 16> ArgLocs1;
CCState CCInfo1(CalleeCC, false, MF, ArgLocs1, F.getContext());
if (!analyzeArgInfo(CCInfo1, InArgs, CalleeAssignFnFixed,
CalleeAssignFnVarArg))
return false;
SmallVector<CCValAssign, 16> ArgLocs2;
CCState CCInfo2(CallerCC, false, MF, ArgLocs2, F.getContext());
if (!analyzeArgInfo(CCInfo2, InArgs, CallerAssignFnFixed,
CalleeAssignFnVarArg))
return false;
// We need the argument locations to match up exactly. If there's more in
// one than the other, then we are done.
if (ArgLocs1.size() != ArgLocs2.size())
return false;
// Make sure that each location is passed in exactly the same way.
for (unsigned i = 0, e = ArgLocs1.size(); i < e; ++i) {
const CCValAssign &Loc1 = ArgLocs1[i];
const CCValAssign &Loc2 = ArgLocs2[i];
// We need both of them to be the same. So if one is a register and one
// isn't, we're done.
if (Loc1.isRegLoc() != Loc2.isRegLoc())
return false;
if (Loc1.isRegLoc()) {
// If they don't have the same register location, we're done.
if (Loc1.getLocReg() != Loc2.getLocReg())
return false;
// They matched, so we can move to the next ArgLoc.
continue;
}
// Loc1 wasn't a RegLoc, so they both must be MemLocs. Check if they match.
if (Loc1.getLocMemOffset() != Loc2.getLocMemOffset())
return false;
}
return true;
}
Register CallLowering::ValueHandler::extendRegister(Register ValReg,
CCValAssign &VA,
unsigned MaxSizeBits) {
LLT LocTy{VA.getLocVT()};
LLT ValTy = MRI.getType(ValReg);
if (LocTy.getSizeInBits() == ValTy.getSizeInBits())
return ValReg;
if (LocTy.isScalar() && MaxSizeBits && MaxSizeBits < LocTy.getSizeInBits()) {
if (MaxSizeBits <= ValTy.getSizeInBits())
return ValReg;
LocTy = LLT::scalar(MaxSizeBits);
}
switch (VA.getLocInfo()) {
default: break;
case CCValAssign::Full:
case CCValAssign::BCvt:
// FIXME: bitconverting between vector types may or may not be a
// nop in big-endian situations.
return ValReg;
case CCValAssign::AExt: {
auto MIB = MIRBuilder.buildAnyExt(LocTy, ValReg);
return MIB.getReg(0);
}
case CCValAssign::SExt: {
Register NewReg = MRI.createGenericVirtualRegister(LocTy);
MIRBuilder.buildSExt(NewReg, ValReg);
return NewReg;
}
case CCValAssign::ZExt: {
Register NewReg = MRI.createGenericVirtualRegister(LocTy);
MIRBuilder.buildZExt(NewReg, ValReg);
return NewReg;
}
}
llvm_unreachable("unable to extend register");
}
void CallLowering::ValueHandler::anchor() {}
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