llvm-6502/lib/CodeGen/CallingConvLower.cpp
Reid Kleckner 34b7fde802 Make musttail more robust for vector types on x86
Previously I tried to plug musttail into the existing vararg lowering
code. That turned out to be a mistake, because non-vararg calls use
significantly different register lowering, even on x86. For example, AVX
vectors are usually passed in registers to normal functions and memory
to vararg functions.  Now musttail uses a completely separate lowering.

Hopefully this can be used as the basis for non-x86 perfect forwarding.

Reviewers: majnemer

Differential Revision: http://reviews.llvm.org/D6156

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@224745 91177308-0d34-0410-b5e6-96231b3b80d8
2014-12-22 23:58:37 +00:00

237 lines
8.7 KiB
C++

//===-- CallingConvLower.cpp - Calling Conventions ------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// 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/MachineRegisterInfo.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/SaveAndRestore.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetLowering.h"
#include "llvm/Target/TargetRegisterInfo.h"
#include "llvm/Target/TargetSubtargetInfo.h"
using namespace llvm;
CCState::CCState(CallingConv::ID CC, bool isVarArg, MachineFunction &mf,
SmallVectorImpl<CCValAssign> &locs, LLVMContext &C)
: CallingConv(CC), IsVarArg(isVarArg), MF(mf),
TRI(*MF.getSubtarget().getRegisterInfo()), Locs(locs), Context(C),
CallOrPrologue(Unknown) {
// No stack is used.
StackOffset = 0;
clearByValRegsInfo();
UsedRegs.resize((TRI.getNumRegs()+31)/32);
}
// HandleByVal - 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, int MinAlign,
ISD::ArgFlagsTy ArgFlags) {
unsigned Align = ArgFlags.getByValAlign();
unsigned Size = ArgFlags.getByValSize();
if (MinSize > (int)Size)
Size = MinSize;
if (MinAlign > (int)Align)
Align = MinAlign;
MF.getFrameInfo()->ensureMaxAlignment(Align);
MF.getSubtarget().getTargetLowering()->HandleByVal(this, Size, Align);
Size = unsigned(RoundUpToAlignment(Size, MinAlign));
unsigned Offset = AllocateStack(Size, Align);
addLoc(CCValAssign::getMem(ValNo, ValVT, Offset, LocVT, LocInfo));
}
/// MarkAllocated - Mark a register and all of its aliases as allocated.
void CCState::MarkAllocated(unsigned Reg) {
for (MCRegAliasIterator AI(Reg, &TRI, true); AI.isValid(); ++AI)
UsedRegs[*AI/32] |= 1 << (*AI&31);
}
/// AnalyzeFormalArguments - 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)) {
#ifndef NDEBUG
dbgs() << "Formal argument #" << i << " has unhandled type "
<< EVT(ArgVT).getEVTString() << '\n';
#endif
llvm_unreachable(nullptr);
}
}
}
/// CheckReturn - 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;
}
/// AnalyzeReturn - 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)) {
#ifndef NDEBUG
dbgs() << "Return operand #" << i << " has unhandled type "
<< EVT(VT).getEVTString() << '\n';
#endif
llvm_unreachable(nullptr);
}
}
}
/// AnalyzeCallOperands - 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 "
<< EVT(ArgVT).getEVTString() << '\n';
#endif
llvm_unreachable(nullptr);
}
}
}
/// AnalyzeCallOperands - 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 "
<< EVT(ArgVT).getEVTString() << '\n';
#endif
llvm_unreachable(nullptr);
}
}
}
/// AnalyzeCallResult - 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 "
<< EVT(VT).getEVTString() << '\n';
#endif
llvm_unreachable(nullptr);
}
}
}
/// AnalyzeCallResult - Same as above except it's specialized for calls which
/// 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 "
<< EVT(VT).getEVTString() << '\n';
#endif
llvm_unreachable(nullptr);
}
}
void CCState::getRemainingRegParmsForType(SmallVectorImpl<MCPhysReg> &Regs,
MVT VT, CCAssignFn Fn) {
unsigned SavedStackOffset = StackOffset;
unsigned NumLocs = Locs.size();
// Allocate something of this value type repeatedly with just the inreg flag
// set until we get assigned a location in memory.
ISD::ArgFlagsTy Flags;
Flags.setInReg();
bool HaveRegParm = true;
while (HaveRegParm) {
if (Fn(0, VT, VT, CCValAssign::Full, Flags, *this)) {
#ifndef NDEBUG
dbgs() << "Call has unhandled type " << EVT(VT).getEVTString()
<< " while computing remaining regparms\n";
#endif
llvm_unreachable(nullptr);
}
HaveRegParm = Locs.back().isRegLoc();
}
// 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.
StackOffset = SavedStackOffset;
Locs.resize(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<bool> SavedVarArg(IsVarArg, false);
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) {
unsigned VReg = MF.addLiveIn(PReg, RC);
Forwards.push_back(ForwardedRegister(VReg, PReg, RegVT));
}
}
}