llvm-6502/lib/Target/ARM/ARMCallingConv.td
Evan Cheng 9f5baa3c7e Tweak ARM fastcc by adopting these two AAPCS rules:
* CPRCs may be allocated to co-processor registers or the stack – they may never be allocated to core registers
* When a CPRC is allocated to the stack, all other VFP registers should be marked as unavailable

The difference is only noticeable in rare cases where there are a large number of floating point arguments (e.g.
7 doubles + additional float, double arguments). Although it's probably still better to avoid vmov as it can cause
stalls in some older ARM cores. The other, more subtle benefit, is to minimize difference between the various
calling conventions.

rdar://16039676


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@201193 91177308-0d34-0410-b5e6-96231b3b80d8
2014-02-11 23:49:31 +00:00

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//===-- 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))>;