llvm/lib/Target/ARM/ARMCallingConv.td

//===-- ARMCallingConv.td - Calling Conventions for ARM ----*- tablegen -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
// This describes the calling conventions for ARM architecture.
//===----------------------------------------------------------------------===//

/// CCIfAlign - Match of the original alignment of the arg
class CCIfAlign<string Align, CCAction A>:
  CCIf<!strconcat("ArgFlags.getOrigAlign() == ", Align), A>;

//===----------------------------------------------------------------------===//
// ARM APCS Calling Convention
//===----------------------------------------------------------------------===//
def CC_ARM_APCS : CallingConv<[

  // Handles byval parameters.
  CCIfByVal<CCPassByVal<4, 4>>,
    
  CCIfType<[i1, i8, i16], CCPromoteToType<i32>>,

  // Handle all vector types as either f64 or v2f64.
  CCIfType<[v1i64, v2i32, v4i16, v8i8, v2f32], CCBitConvertToType<f64>>,
  CCIfType<[v2i64, v4i32, v8i16, v16i8, v4f32], CCBitConvertToType<v2f64>>,

  // f64 and v2f64 are passed in adjacent GPRs, possibly split onto the stack
  CCIfType<[f64, v2f64], CCCustom<"CC_ARM_APCS_Custom_f64">>,

  CCIfType<[f32], CCBitConvertToType<i32>>,
  CCIfType<[i32], CCAssignToReg<[R0, R1, R2, R3]>>,

  CCIfType<[i32], CCAssignToStack<4, 4>>,
  CCIfType<[f64], CCAssignToStack<8, 4>>,
  CCIfType<[v2f64], CCAssignToStack<16, 4>>
]>;

def RetCC_ARM_APCS : CallingConv<[
  CCIfType<[i1, i8, i16], CCPromoteToType<i32>>,
  CCIfType<[f32], CCBitConvertToType<i32>>,

  // Handle all vector types as either f64 or v2f64.
  CCIfType<[v1i64, v2i32, v4i16, v8i8, v2f32], CCBitConvertToType<f64>>,
  CCIfType<[v2i64, v4i32, v8i16, v16i8, v4f32], CCBitConvertToType<v2f64>>,

  CCIfType<[f64, v2f64], CCCustom<"RetCC_ARM_APCS_Custom_f64">>,

  CCIfType<[i32], CCAssignToReg<[R0, R1, R2, R3]>>,
  CCIfType<[i64], CCAssignToRegWithShadow<[R0, R2], [R1, R3]>>
]>;

//===----------------------------------------------------------------------===//
// ARM APCS Calling Convention for FastCC (when VFP2 or later is available)
//===----------------------------------------------------------------------===//
def FastCC_ARM_APCS : CallingConv<[
  // Handle all vector types as either f64 or v2f64.
  CCIfType<[v1i64, v2i32, v4i16, v8i8, v2f32], CCBitConvertToType<f64>>,
  CCIfType<[v2i64, v4i32, v8i16, v16i8, v4f32], CCBitConvertToType<v2f64>>,

  CCIfType<[v2f64], CCAssignToReg<[Q0, Q1, Q2, Q3]>>,
  CCIfType<[f64], CCAssignToReg<[D0, D1, D2, D3, D4, D5, D6, D7]>>,
  CCIfType<[f32], CCAssignToReg<[S0, S1, S2, S3, S4, S5, S6, S7, S8,
                                 S9, S10, S11, S12, S13, S14, S15]>>,

  // CPRCs may be allocated to co-processor registers or the stack – they
  // may never be allocated to core registers. 
  CCIfType<[f32], CCAssignToStackWithShadow<4, 4, [Q0, Q1, Q2, Q3]>>,
  CCIfType<[f64], CCAssignToStackWithShadow<8, 4, [Q0, Q1, Q2, Q3]>>,
  CCIfType<[v2f64], CCAssignToStackWithShadow<16, 4, [Q0, Q1, Q2, Q3]>>,

  CCDelegateTo<CC_ARM_APCS>
]>;

def RetFastCC_ARM_APCS : CallingConv<[
  // Handle all vector types as either f64 or v2f64.
  CCIfType<[v1i64, v2i32, v4i16, v8i8, v2f32], CCBitConvertToType<f64>>,
  CCIfType<[v2i64, v4i32, v8i16, v16i8, v4f32], CCBitConvertToType<v2f64>>,

  CCIfType<[v2f64], CCAssignToReg<[Q0, Q1, Q2, Q3]>>,
  CCIfType<[f64], CCAssignToReg<[D0, D1, D2, D3, D4, D5, D6, D7]>>,
  CCIfType<[f32], CCAssignToReg<[S0, S1, S2, S3, S4, S5, S6, S7, S8,
                                 S9, S10, S11, S12, S13, S14, S15]>>,
  CCDelegateTo<RetCC_ARM_APCS>
]>;

//===----------------------------------------------------------------------===//
// ARM APCS Calling Convention for GHC
//===----------------------------------------------------------------------===//

def CC_ARM_APCS_GHC : CallingConv<[
  // Handle all vector types as either f64 or v2f64.
  CCIfType<[v1i64, v2i32, v4i16, v8i8, v2f32], CCBitConvertToType<f64>>,
  CCIfType<[v2i64, v4i32, v8i16, v16i8, v4f32], CCBitConvertToType<v2f64>>,

  CCIfType<[v2f64], CCAssignToReg<[Q4, Q5]>>,
  CCIfType<[f64], CCAssignToReg<[D8, D9, D10, D11]>>,
  CCIfType<[f32], CCAssignToReg<[S16, S17, S18, S19, S20, S21, S22, S23]>>,

  // Promote i8/i16 arguments to i32.
  CCIfType<[i8, i16], CCPromoteToType<i32>>,

  // Pass in STG registers: Base, Sp, Hp, R1, R2, R3, R4, SpLim
  CCIfType<[i32], CCAssignToReg<[R4, R5, R6, R7, R8, R9, R10, R11]>>
]>;

//===----------------------------------------------------------------------===//
// ARM AAPCS (EABI) Calling Convention, common parts
//===----------------------------------------------------------------------===//

def CC_ARM_AAPCS_Common : CallingConv<[

  CCIfType<[i1, i8, i16], CCPromoteToType<i32>>,

  // i64/f64 is passed in even pairs of GPRs
  // i64 is 8-aligned i32 here, so we may need to eat R1 as a pad register
  // (and the same is true for f64 if VFP is not enabled)
  CCIfType<[i32], CCIfAlign<"8", CCAssignToRegWithShadow<[R0, R2], [R0, R1]>>>,
  CCIfType<[i32], CCIf<"ArgFlags.getOrigAlign() != 8",
                       CCAssignToReg<[R0, R1, R2, R3]>>>,

  CCIfType<[i32], CCIfAlign<"8", CCAssignToStackWithShadow<4, 8, [R0, R1, R2, R3]>>>,
  CCIfType<[i32], CCAssignToStackWithShadow<4, 4, [R0, R1, R2, R3]>>,
  CCIfType<[f32], CCAssignToStackWithShadow<4, 4, [Q0, Q1, Q2, Q3]>>,
  CCIfType<[f64], CCAssignToStackWithShadow<8, 8, [Q0, Q1, Q2, Q3]>>,
  CCIfType<[v2f64], CCAssignToStackWithShadow<16, 8, [Q0, Q1, Q2, Q3]>>
]>;

def RetCC_ARM_AAPCS_Common : CallingConv<[
  CCIfType<[i1, i8, i16], CCPromoteToType<i32>>,
  CCIfType<[i32], CCAssignToReg<[R0, R1, R2, R3]>>,
  CCIfType<[i64], CCAssignToRegWithShadow<[R0, R2], [R1, R3]>>
]>;

//===----------------------------------------------------------------------===//
// ARM AAPCS (EABI) Calling Convention
//===----------------------------------------------------------------------===//

def CC_ARM_AAPCS : CallingConv<[
  // Handles byval parameters.
  CCIfByVal<CCPassByVal<4, 4>>,

  // Handle all vector types as either f64 or v2f64.
  CCIfType<[v1i64, v2i32, v4i16, v8i8, v2f32], CCBitConvertToType<f64>>,
  CCIfType<[v2i64, v4i32, v8i16, v16i8, v4f32], CCBitConvertToType<v2f64>>,

  CCIfType<[f64, v2f64], CCCustom<"CC_ARM_AAPCS_Custom_f64">>,
  CCIfType<[f32], CCBitConvertToType<i32>>,
  CCDelegateTo<CC_ARM_AAPCS_Common>
]>;

def RetCC_ARM_AAPCS : CallingConv<[
  // Handle all vector types as either f64 or v2f64.
  CCIfType<[v1i64, v2i32, v4i16, v8i8, v2f32], CCBitConvertToType<f64>>,
  CCIfType<[v2i64, v4i32, v8i16, v16i8, v4f32], CCBitConvertToType<v2f64>>,

  CCIfType<[f64, v2f64], CCCustom<"RetCC_ARM_AAPCS_Custom_f64">>,
  CCIfType<[f32], CCBitConvertToType<i32>>,
  CCDelegateTo<RetCC_ARM_AAPCS_Common>
]>;

//===----------------------------------------------------------------------===//
// ARM AAPCS-VFP (EABI) Calling Convention
// Also used for FastCC (when VFP2 or later is available)
//===----------------------------------------------------------------------===//

def CC_ARM_AAPCS_VFP : CallingConv<[
  // Handles byval parameters.
  CCIfByVal<CCPassByVal<4, 4>>,

  // Handle all vector types as either f64 or v2f64.
  CCIfType<[v1i64, v2i32, v4i16, v8i8, v2f32], CCBitConvertToType<f64>>,
  CCIfType<[v2i64, v4i32, v8i16, v16i8, v4f32], CCBitConvertToType<v2f64>>,

  CCIfType<[v2f64], CCAssignToReg<[Q0, Q1, Q2, Q3]>>,
  CCIfType<[f64], CCAssignToReg<[D0, D1, D2, D3, D4, D5, D6, D7]>>,
  CCIfType<[f32], CCAssignToReg<[S0, S1, S2, S3, S4, S5, S6, S7, S8,
                                 S9, S10, S11, S12, S13, S14, S15]>>,
  CCDelegateTo<CC_ARM_AAPCS_Common>
]>;

def RetCC_ARM_AAPCS_VFP : CallingConv<[
  // Handle all vector types as either f64 or v2f64.
  CCIfType<[v1i64, v2i32, v4i16, v8i8, v2f32], CCBitConvertToType<f64>>,
  CCIfType<[v2i64, v4i32, v8i16, v16i8, v4f32], CCBitConvertToType<v2f64>>,

  CCIfType<[v2f64], CCAssignToReg<[Q0, Q1, Q2, Q3]>>,
  CCIfType<[f64], CCAssignToReg<[D0, D1, D2, D3, D4, D5, D6, D7]>>,
  CCIfType<[f32], CCAssignToReg<[S0, S1, S2, S3, S4, S5, S6, S7, S8,
                                 S9, S10, S11, S12, S13, S14, S15]>>,
  CCDelegateTo<RetCC_ARM_AAPCS_Common>
]>;

//===----------------------------------------------------------------------===//
// Callee-saved register lists.
//===----------------------------------------------------------------------===//

def CSR_NoRegs : CalleeSavedRegs<(add)>;

def CSR_AAPCS : CalleeSavedRegs<(add LR, R11, R10, R9, R8, R7, R6, R5, R4,
                                     (sequence "D%u", 15, 8))>;

// Constructors and destructors return 'this' in the ARM C++ ABI; since 'this'
// and the pointer return value are both passed in R0 in these cases, this can
// be partially modelled by treating R0 as a callee-saved register
// Only the resulting RegMask is used; the SaveList is ignored
def CSR_AAPCS_ThisReturn : CalleeSavedRegs<(add LR, R11, R10, R9, R8, R7, R6,
                                            R5, R4, (sequence "D%u", 15, 8),
                                            R0)>;

// iOS ABI deviates from ARM standard ABI. R9 is not a callee-saved register.
// Also save R7-R4 first to match the stack frame fixed spill areas.
def CSR_iOS : CalleeSavedRegs<(add LR, R7, R6, R5, R4, (sub CSR_AAPCS, R9))>;

def CSR_iOS_ThisReturn : CalleeSavedRegs<(add LR, R7, R6, R5, R4,
                                         (sub CSR_AAPCS_ThisReturn, R9))>;

// The "interrupt" attribute is used to generate code that is acceptable in
// exception-handlers of various kinds. It makes us use a different return
// instruction (handled elsewhere) and affects which registers we must return to
// our "caller" in the same state as we receive them.

// For most interrupts, all registers except SP and LR are shared with
// user-space. We mark LR to be saved anyway, since this is what the ARM backend
// generally does rather than tracking its liveness as a normal register.
def CSR_GenericInt : CalleeSavedRegs<(add LR, (sequence "R%u", 12, 0))>;

// The fast interrupt handlers have more private state and get their own copies
// of R8-R12, in addition to SP and LR. As before, mark LR for saving too.

// FIXME: we mark R11 as callee-saved since it's often the frame-pointer, and
// current frame lowering expects to encounter it while processing callee-saved
// registers.
def CSR_FIQ : CalleeSavedRegs<(add LR, R11, (sequence "R%u", 7, 0))>;