1 //===-- llvm/CallingConvLower.h - Calling Conventions -----------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file declares the CCState and CCValAssign classes, used for lowering
11 // and implementing calling conventions.
13 //===----------------------------------------------------------------------===//
15 #ifndef LLVM_CODEGEN_CALLINGCONVLOWER_H
16 #define LLVM_CODEGEN_CALLINGCONVLOWER_H
18 #include "llvm/ADT/SmallVector.h"
19 #include "llvm/CodeGen/MachineFrameInfo.h"
20 #include "llvm/CodeGen/MachineFunction.h"
21 #include "llvm/IR/CallingConv.h"
22 #include "llvm/Target/TargetCallingConv.h"
28 class TargetRegisterInfo;
30 /// CCValAssign - Represent assignment of one arg/retval to a location.
34 Full, // The value fills the full location.
35 SExt, // The value is sign extended in the location.
36 ZExt, // The value is zero extended in the location.
37 AExt, // The value is extended with undefined upper bits.
38 SExtUpper, // The value is in the upper bits of the location and should be
39 // sign extended when retrieved.
40 ZExtUpper, // The value is in the upper bits of the location and should be
41 // zero extended when retrieved.
42 AExtUpper, // The value is in the upper bits of the location and should be
43 // extended with undefined upper bits when retrieved.
44 BCvt, // The value is bit-converted in the location.
45 VExt, // The value is vector-widened in the location.
46 // FIXME: Not implemented yet. Code that uses AExt to mean
47 // vector-widen should be fixed to use VExt instead.
48 FPExt, // The floating-point value is fp-extended in the location.
49 Indirect // The location contains pointer to the value.
50 // TODO: a subset of the value is in the location.
54 /// ValNo - This is the value number begin assigned (e.g. an argument number).
57 /// Loc is either a stack offset or a register number.
60 /// isMem - True if this is a memory loc, false if it is a register loc.
63 /// isCustom - True if this arg/retval requires special handling.
64 unsigned isCustom : 1;
66 /// Information about how the value is assigned.
69 /// ValVT - The type of the value being assigned.
72 /// LocVT - The type of the location being assigned to.
76 static CCValAssign getReg(unsigned ValNo, MVT ValVT,
77 unsigned RegNo, MVT LocVT,
90 static CCValAssign getCustomReg(unsigned ValNo, MVT ValVT,
91 unsigned RegNo, MVT LocVT,
94 Ret = getReg(ValNo, ValVT, RegNo, LocVT, HTP);
99 static CCValAssign getMem(unsigned ValNo, MVT ValVT,
100 unsigned Offset, MVT LocVT,
106 Ret.isCustom = false;
113 static CCValAssign getCustomMem(unsigned ValNo, MVT ValVT,
114 unsigned Offset, MVT LocVT,
117 Ret = getMem(ValNo, ValVT, Offset, LocVT, HTP);
122 // There is no need to differentiate between a pending CCValAssign and other
123 // kinds, as they are stored in a different list.
124 static CCValAssign getPending(unsigned ValNo, MVT ValVT, MVT LocVT,
126 return getReg(ValNo, ValVT, 0, LocVT, HTP);
129 void convertToReg(unsigned RegNo) {
134 void convertToMem(unsigned Offset) {
139 unsigned getValNo() const { return ValNo; }
140 MVT getValVT() const { return ValVT; }
142 bool isRegLoc() const { return !isMem; }
143 bool isMemLoc() const { return isMem; }
145 bool needsCustom() const { return isCustom; }
147 unsigned getLocReg() const { assert(isRegLoc()); return Loc; }
148 unsigned getLocMemOffset() const { assert(isMemLoc()); return Loc; }
149 MVT getLocVT() const { return LocVT; }
151 LocInfo getLocInfo() const { return HTP; }
152 bool isExtInLoc() const {
153 return (HTP == AExt || HTP == SExt || HTP == ZExt);
156 bool isUpperBitsInLoc() const {
157 return HTP == AExtUpper || HTP == SExtUpper || HTP == ZExtUpper;
161 /// Describes a register that needs to be forwarded from the prologue to a
163 struct ForwardedRegister {
164 ForwardedRegister(unsigned VReg, MCPhysReg PReg, MVT VT)
165 : VReg(VReg), PReg(PReg), VT(VT) {}
171 /// CCAssignFn - This function assigns a location for Val, updating State to
172 /// reflect the change. It returns 'true' if it failed to handle Val.
173 typedef bool CCAssignFn(unsigned ValNo, MVT ValVT,
174 MVT LocVT, CCValAssign::LocInfo LocInfo,
175 ISD::ArgFlagsTy ArgFlags, CCState &State);
177 /// CCCustomFn - This function assigns a location for Val, possibly updating
178 /// all args to reflect changes and indicates if it handled it. It must set
179 /// isCustom if it handles the arg and returns true.
180 typedef bool CCCustomFn(unsigned &ValNo, MVT &ValVT,
181 MVT &LocVT, CCValAssign::LocInfo &LocInfo,
182 ISD::ArgFlagsTy &ArgFlags, CCState &State);
184 /// ParmContext - This enum tracks whether calling convention lowering is in
185 /// the context of prologue or call generation. Not all backends make use of
186 /// this information.
187 typedef enum { Unknown, Prologue, Call } ParmContext;
189 /// CCState - This class holds information needed while lowering arguments and
190 /// return values. It captures which registers are already assigned and which
191 /// stack slots are used. It provides accessors to allocate these values.
194 CallingConv::ID CallingConv;
197 const TargetRegisterInfo &TRI;
198 SmallVectorImpl<CCValAssign> &Locs;
199 LLVMContext &Context;
201 unsigned StackOffset;
202 SmallVector<uint32_t, 16> UsedRegs;
203 SmallVector<CCValAssign, 4> PendingLocs;
205 // ByValInfo and SmallVector<ByValInfo, 4> ByValRegs:
207 // Vector of ByValInfo instances (ByValRegs) is introduced for byval registers
209 // Or, in another words it tracks byval parameters that are stored in
210 // general purpose registers.
212 // For 4 byte stack alignment,
213 // instance index means byval parameter number in formal
214 // arguments set. Assume, we have some "struct_type" with size = 4 bytes,
215 // then, for function "foo":
217 // i32 foo(i32 %p, %struct_type* %r, i32 %s, %struct_type* %t)
219 // ByValRegs[0] describes how "%r" is stored (Begin == r1, End == r2)
220 // ByValRegs[1] describes how "%t" is stored (Begin == r3, End == r4).
222 // In case of 8 bytes stack alignment,
223 // ByValRegs may also contain information about wasted registers.
224 // In function shown above, r3 would be wasted according to AAPCS rules.
225 // And in that case ByValRegs[1].Waste would be "true".
226 // ByValRegs vector size still would be 2,
227 // while "%t" goes to the stack: it wouldn't be described in ByValRegs.
229 // Supposed use-case for this collection:
230 // 1. Initially ByValRegs is empty, InRegsParamsProcessed is 0.
231 // 2. HandleByVal fillups ByValRegs.
232 // 3. Argument analysis (LowerFormatArguments, for example). After
233 // some byval argument was analyzed, InRegsParamsProcessed is increased.
235 ByValInfo(unsigned B, unsigned E, bool IsWaste = false) :
236 Begin(B), End(E), Waste(IsWaste) {}
237 // First register allocated for current parameter.
240 // First after last register allocated for current parameter.
243 // Means that current range of registers doesn't belong to any
244 // parameters. It was wasted due to stack alignment rules.
245 // For more information see:
246 // AAPCS, 5.5 Parameter Passing, Stage C, C.3.
249 SmallVector<ByValInfo, 4 > ByValRegs;
251 // InRegsParamsProcessed - shows how many instances of ByValRegs was proceed
252 // during argument analysis.
253 unsigned InRegsParamsProcessed;
256 ParmContext CallOrPrologue;
259 CCState(CallingConv::ID CC, bool isVarArg, MachineFunction &MF,
260 SmallVectorImpl<CCValAssign> &locs, LLVMContext &C);
262 void addLoc(const CCValAssign &V) {
266 LLVMContext &getContext() const { return Context; }
267 MachineFunction &getMachineFunction() const { return MF; }
268 CallingConv::ID getCallingConv() const { return CallingConv; }
269 bool isVarArg() const { return IsVarArg; }
271 unsigned getNextStackOffset() const { return StackOffset; }
273 /// isAllocated - Return true if the specified register (or an alias) is
275 bool isAllocated(unsigned Reg) const {
276 return UsedRegs[Reg/32] & (1 << (Reg&31));
279 /// AnalyzeFormalArguments - Analyze an array of argument values,
280 /// incorporating info about the formals into this state.
281 void AnalyzeFormalArguments(const SmallVectorImpl<ISD::InputArg> &Ins,
284 /// AnalyzeReturn - Analyze the returned values of a return,
285 /// incorporating info about the result values into this state.
286 void AnalyzeReturn(const SmallVectorImpl<ISD::OutputArg> &Outs,
289 /// CheckReturn - Analyze the return values of a function, returning
290 /// true if the return can be performed without sret-demotion, and
292 bool CheckReturn(const SmallVectorImpl<ISD::OutputArg> &ArgsFlags,
295 /// AnalyzeCallOperands - Analyze the outgoing arguments to a call,
296 /// incorporating info about the passed values into this state.
297 void AnalyzeCallOperands(const SmallVectorImpl<ISD::OutputArg> &Outs,
300 /// AnalyzeCallOperands - Same as above except it takes vectors of types
301 /// and argument flags.
302 void AnalyzeCallOperands(SmallVectorImpl<MVT> &ArgVTs,
303 SmallVectorImpl<ISD::ArgFlagsTy> &Flags,
306 /// AnalyzeCallResult - Analyze the return values of a call,
307 /// incorporating info about the passed values into this state.
308 void AnalyzeCallResult(const SmallVectorImpl<ISD::InputArg> &Ins,
311 /// AnalyzeCallResult - Same as above except it's specialized for calls which
312 /// produce a single value.
313 void AnalyzeCallResult(MVT VT, CCAssignFn Fn);
315 /// getFirstUnallocated - Return the index of the first unallocated register
316 /// in the set, or Regs.size() if they are all allocated.
317 unsigned getFirstUnallocated(ArrayRef<MCPhysReg> Regs) const {
318 for (unsigned i = 0; i < Regs.size(); ++i)
319 if (!isAllocated(Regs[i]))
324 /// AllocateReg - Attempt to allocate one register. If it is not available,
325 /// return zero. Otherwise, return the register, marking it and any aliases
327 unsigned AllocateReg(unsigned Reg) {
328 if (isAllocated(Reg)) return 0;
333 /// Version of AllocateReg with extra register to be shadowed.
334 unsigned AllocateReg(unsigned Reg, unsigned ShadowReg) {
335 if (isAllocated(Reg)) return 0;
337 MarkAllocated(ShadowReg);
341 /// AllocateReg - Attempt to allocate one of the specified registers. If none
342 /// are available, return zero. Otherwise, return the first one available,
343 /// marking it and any aliases as allocated.
344 unsigned AllocateReg(ArrayRef<MCPhysReg> Regs) {
345 unsigned FirstUnalloc = getFirstUnallocated(Regs);
346 if (FirstUnalloc == Regs.size())
347 return 0; // Didn't find the reg.
349 // Mark the register and any aliases as allocated.
350 unsigned Reg = Regs[FirstUnalloc];
355 /// AllocateRegBlock - Attempt to allocate a block of RegsRequired consecutive
356 /// registers. If this is not possible, return zero. Otherwise, return the first
357 /// register of the block that were allocated, marking the entire block as allocated.
358 unsigned AllocateRegBlock(ArrayRef<uint16_t> Regs, unsigned RegsRequired) {
359 if (RegsRequired > Regs.size())
362 for (unsigned StartIdx = 0; StartIdx <= Regs.size() - RegsRequired;
364 bool BlockAvailable = true;
365 // Check for already-allocated regs in this block
366 for (unsigned BlockIdx = 0; BlockIdx < RegsRequired; ++BlockIdx) {
367 if (isAllocated(Regs[StartIdx + BlockIdx])) {
368 BlockAvailable = false;
372 if (BlockAvailable) {
373 // Mark the entire block as allocated
374 for (unsigned BlockIdx = 0; BlockIdx < RegsRequired; ++BlockIdx) {
375 MarkAllocated(Regs[StartIdx + BlockIdx]);
377 return Regs[StartIdx];
380 // No block was available
384 /// Version of AllocateReg with list of registers to be shadowed.
385 unsigned AllocateReg(ArrayRef<MCPhysReg> Regs, const MCPhysReg *ShadowRegs) {
386 unsigned FirstUnalloc = getFirstUnallocated(Regs);
387 if (FirstUnalloc == Regs.size())
388 return 0; // Didn't find the reg.
390 // Mark the register and any aliases as allocated.
391 unsigned Reg = Regs[FirstUnalloc], ShadowReg = ShadowRegs[FirstUnalloc];
393 MarkAllocated(ShadowReg);
397 /// AllocateStack - Allocate a chunk of stack space with the specified size
399 unsigned AllocateStack(unsigned Size, unsigned Align) {
400 assert(Align && ((Align - 1) & Align) == 0); // Align is power of 2.
401 StackOffset = ((StackOffset + Align - 1) & ~(Align - 1));
402 unsigned Result = StackOffset;
404 MF.getFrameInfo()->ensureMaxAlignment(Align);
408 /// Version of AllocateStack with extra register to be shadowed.
409 unsigned AllocateStack(unsigned Size, unsigned Align, unsigned ShadowReg) {
410 MarkAllocated(ShadowReg);
411 return AllocateStack(Size, Align);
414 /// Version of AllocateStack with list of extra registers to be shadowed.
415 /// Note that, unlike AllocateReg, this shadows ALL of the shadow registers.
416 unsigned AllocateStack(unsigned Size, unsigned Align,
417 ArrayRef<MCPhysReg> ShadowRegs) {
418 for (unsigned i = 0; i < ShadowRegs.size(); ++i)
419 MarkAllocated(ShadowRegs[i]);
420 return AllocateStack(Size, Align);
423 // HandleByVal - Allocate a stack slot large enough to pass an argument by
424 // value. The size and alignment information of the argument is encoded in its
425 // parameter attribute.
426 void HandleByVal(unsigned ValNo, MVT ValVT,
427 MVT LocVT, CCValAssign::LocInfo LocInfo,
428 int MinSize, int MinAlign, ISD::ArgFlagsTy ArgFlags);
430 // Returns count of byval arguments that are to be stored (even partly)
432 unsigned getInRegsParamsCount() const { return ByValRegs.size(); }
434 // Returns count of byval in-regs arguments proceed.
435 unsigned getInRegsParamsProcessed() const { return InRegsParamsProcessed; }
437 // Get information about N-th byval parameter that is stored in registers.
438 // Here "ByValParamIndex" is N.
439 void getInRegsParamInfo(unsigned InRegsParamRecordIndex,
440 unsigned& BeginReg, unsigned& EndReg) const {
441 assert(InRegsParamRecordIndex < ByValRegs.size() &&
442 "Wrong ByVal parameter index");
444 const ByValInfo& info = ByValRegs[InRegsParamRecordIndex];
445 BeginReg = info.Begin;
449 // Add information about parameter that is kept in registers.
450 void addInRegsParamInfo(unsigned RegBegin, unsigned RegEnd) {
451 ByValRegs.push_back(ByValInfo(RegBegin, RegEnd));
454 // Goes either to next byval parameter (excluding "waste" record), or
455 // to the end of collection.
456 // Returns false, if end is reached.
457 bool nextInRegsParam() {
458 unsigned e = ByValRegs.size();
459 if (InRegsParamsProcessed < e)
460 ++InRegsParamsProcessed;
461 return InRegsParamsProcessed < e;
464 // Clear byval registers tracking info.
465 void clearByValRegsInfo() {
466 InRegsParamsProcessed = 0;
470 // Rewind byval registers tracking info.
471 void rewindByValRegsInfo() {
472 InRegsParamsProcessed = 0;
475 ParmContext getCallOrPrologue() const { return CallOrPrologue; }
477 // Get list of pending assignments
478 SmallVectorImpl<llvm::CCValAssign> &getPendingLocs() {
482 /// Compute the remaining unused register parameters that would be used for
483 /// the given value type. This is useful when varargs are passed in the
484 /// registers that normal prototyped parameters would be passed in, or for
485 /// implementing perfect forwarding.
486 void getRemainingRegParmsForType(SmallVectorImpl<MCPhysReg> &Regs, MVT VT,
489 /// Compute the set of registers that need to be preserved and forwarded to
490 /// any musttail calls.
491 void analyzeMustTailForwardedRegisters(
492 SmallVectorImpl<ForwardedRegister> &Forwards, ArrayRef<MVT> RegParmTypes,
496 /// MarkAllocated - Mark a register and all of its aliases as allocated.
497 void MarkAllocated(unsigned Reg);
502 } // end namespace llvm