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//===-- SparcCallingConv.td - Calling Conventions Sparc ----*- 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 the Sparc architectures.
//
//===----------------------------------------------------------------------===//
//===----------------------------------------------------------------------===//
// SPARC v8 32-bit.
//===----------------------------------------------------------------------===//
def CC_Sparc32 : CallingConv<[
// Custom assign SRet to [sp+64].
CCIfSRet<CCCustom<"CC_Sparc_Assign_SRet">>,
// i32 f32 arguments get passed in integer registers if there is space.
CCIfType<[i32, f32], CCAssignToReg<[I0, I1, I2, I3, I4, I5]>>,
// f64 arguments are split and passed through registers or through stack.
CCIfType<[f64], CCCustom<"CC_Sparc_Assign_f64">>,
// Alternatively, they are assigned to the stack in 4-byte aligned units.
CCAssignToStack<4, 4>
]>;
def RetCC_Sparc32 : CallingConv<[
CCIfType<[i32], CCAssignToReg<[I0, I1, I2, I3, I4, I5]>>,
CCIfType<[f32], CCAssignToReg<[F0, F1, F2, F3]>>,
CCIfType<[f64], CCAssignToReg<[D0, D1]>>
]>;
//===----------------------------------------------------------------------===//
// SPARC v9 64-bit.
//===----------------------------------------------------------------------===//
//
// The 64-bit ABI conceptually assigns all function arguments to a parameter
// array starting at [%fp+BIAS+128] in the callee's stack frame. All arguments
// occupy a multiple of 8 bytes in the array. Integer arguments are extended to
// 64 bits by the caller. Floats are right-aligned in their 8-byte slot, the
// first 4 bytes in the slot are undefined.
//
// The integer registers %i0 to %i5 shadow the first 48 bytes of the parameter
// array at fixed offsets. Integer arguments are promoted to registers when
// possible.
//
// The floating point registers %f0 to %f31 shadow the first 128 bytes of the
// parameter array at fixed offsets. Float and double parameters are promoted
// to these registers when possible.
//
// Structs up to 16 bytes in size are passed by value. They are right-aligned
// in one or two 8-byte slots in the parameter array. Struct members are
// promoted to both floating point and integer registers when possible. A
// struct containing two floats would thus be passed in %f0 and %f1, while two
// float function arguments would occupy 8 bytes each, and be passed in %f1 and
// %f3.
//
// When a struct { int, float } is passed by value, the int goes in the high
// bits of an integer register while the float goes in a floating point
// register.
//
// The difference is encoded in LLVM IR using the inreg atttribute on function
// arguments:
//
// C: void f(float, float);
// IR: declare void f(float %f1, float %f3)
//
// C: void f(struct { float f0, f1; });
// IR: declare void f(float inreg %f0, float inreg %f1)
//
// C: void f(int, float);
// IR: declare void f(int signext %i0, float %f3)
//
// C: void f(struct { int i0high; float f1; });
// IR: declare void f(i32 inreg %i0high, float inreg %f1)
//
// Two ints in a struct are simply coerced to i64:
//
// C: void f(struct { int i0high, i0low; });
// IR: declare void f(i64 %i0.coerced)
//
// The frontend and backend divide the task of producing ABI compliant code for
// C functions. The C frontend will:
//
// - Annotate integer arguments with zeroext or signext attributes.
//
// - Split structs into one or two 64-bit sized chunks, or 32-bit chunks with
// inreg attributes.
//
// - Pass structs larger than 16 bytes indirectly with an explicit pointer
// argument. The byval attribute is not used.
//
// The backend will:
//
// - Assign all arguments to 64-bit aligned stack slots, 32-bits for inreg.
//
// - Promote to integer or floating point registers depending on type.
//
// Function return values are passed exactly like function arguments, except a
// struct up to 32 bytes in size can be returned in registers.
// Function arguments AND return values.
def CC_Sparc64 : CallingConv<[
// The frontend uses the inreg flag to indicate i32 and float arguments from
// structs. These arguments are not promoted to 64 bits, but they can still
// be assigned to integer and float registers.
CCIfInReg<CCIfType<[i32, f32], CCCustom<"CC_Sparc64_Half">>>,
// All integers are promoted to i64 by the caller.
CCIfType<[i32], CCPromoteToType<i64>>,
// Custom assignment is required because stack space is reserved for all
// arguments whether they are passed in registers or not.
CCCustom<"CC_Sparc64_Full">
]>;
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