1//===-- SparcCallingConv.td - Calling Conventions Sparc ----*- tablegen -*-===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This describes the calling conventions for the Sparc architectures. 11// 12//===----------------------------------------------------------------------===// 13 14//===----------------------------------------------------------------------===// 15// SPARC v8 32-bit. 16//===----------------------------------------------------------------------===// 17 18def CC_Sparc32 : CallingConv<[ 19 // Custom assign SRet to [sp+64]. 20 CCIfSRet<CCCustom<"CC_Sparc_Assign_SRet">>, 21 // i32 f32 arguments get passed in integer registers if there is space. 22 CCIfType<[i32, f32], CCAssignToReg<[I0, I1, I2, I3, I4, I5]>>, 23 // f64 arguments are split and passed through registers or through stack. 24 CCIfType<[f64], CCCustom<"CC_Sparc_Assign_f64">>, 25 26 // Alternatively, they are assigned to the stack in 4-byte aligned units. 27 CCAssignToStack<4, 4> 28]>; 29 30def RetCC_Sparc32 : CallingConv<[ 31 CCIfType<[i32], CCAssignToReg<[I0, I1, I2, I3, I4, I5]>>, 32 CCIfType<[f32], CCAssignToReg<[F0, F1, F2, F3]>>, 33 CCIfType<[f64], CCAssignToReg<[D0, D1]>> 34]>; 35 36 37//===----------------------------------------------------------------------===// 38// SPARC v9 64-bit. 39//===----------------------------------------------------------------------===// 40// 41// The 64-bit ABI conceptually assigns all function arguments to a parameter 42// array starting at [%fp+BIAS+128] in the callee's stack frame. All arguments 43// occupy a multiple of 8 bytes in the array. Integer arguments are extended to 44// 64 bits by the caller. Floats are right-aligned in their 8-byte slot, the 45// first 4 bytes in the slot are undefined. 46// 47// The integer registers %i0 to %i5 shadow the first 48 bytes of the parameter 48// array at fixed offsets. Integer arguments are promoted to registers when 49// possible. 50// 51// The floating point registers %f0 to %f31 shadow the first 128 bytes of the 52// parameter array at fixed offsets. Float and double parameters are promoted 53// to these registers when possible. 54// 55// Structs up to 16 bytes in size are passed by value. They are right-aligned 56// in one or two 8-byte slots in the parameter array. Struct members are 57// promoted to both floating point and integer registers when possible. A 58// struct containing two floats would thus be passed in %f0 and %f1, while two 59// float function arguments would occupy 8 bytes each, and be passed in %f1 and 60// %f3. 61// 62// When a struct { int, float } is passed by value, the int goes in the high 63// bits of an integer register while the float goes in a floating point 64// register. 65// 66// The difference is encoded in LLVM IR using the inreg atttribute on function 67// arguments: 68// 69// C: void f(float, float); 70// IR: declare void f(float %f1, float %f3) 71// 72// C: void f(struct { float f0, f1; }); 73// IR: declare void f(float inreg %f0, float inreg %f1) 74// 75// C: void f(int, float); 76// IR: declare void f(int signext %i0, float %f3) 77// 78// C: void f(struct { int i0high; float f1; }); 79// IR: declare void f(i32 inreg %i0high, float inreg %f1) 80// 81// Two ints in a struct are simply coerced to i64: 82// 83// C: void f(struct { int i0high, i0low; }); 84// IR: declare void f(i64 %i0.coerced) 85// 86// The frontend and backend divide the task of producing ABI compliant code for 87// C functions. The C frontend will: 88// 89// - Annotate integer arguments with zeroext or signext attributes. 90// 91// - Split structs into one or two 64-bit sized chunks, or 32-bit chunks with 92// inreg attributes. 93// 94// - Pass structs larger than 16 bytes indirectly with an explicit pointer 95// argument. The byval attribute is not used. 96// 97// The backend will: 98// 99// - Assign all arguments to 64-bit aligned stack slots, 32-bits for inreg. 100// 101// - Promote to integer or floating point registers depending on type. 102// 103// Function return values are passed exactly like function arguments, except a 104// struct up to 32 bytes in size can be returned in registers. 105 106// Function arguments AND most return values. 107def CC_Sparc64 : CallingConv<[ 108 // The frontend uses the inreg flag to indicate i32 and float arguments from 109 // structs. These arguments are not promoted to 64 bits, but they can still 110 // be assigned to integer and float registers. 111 CCIfInReg<CCIfType<[i32, f32], CCCustom<"CC_Sparc64_Half">>>, 112 113 // All integers are promoted to i64 by the caller. 114 CCIfType<[i32], CCPromoteToType<i64>>, 115 116 // Custom assignment is required because stack space is reserved for all 117 // arguments whether they are passed in registers or not. 118 CCCustom<"CC_Sparc64_Full"> 119]>; 120 121def RetCC_Sparc64 : CallingConv<[ 122 // A single f32 return value always goes in %f0. The ABI doesn't specify what 123 // happens to multiple f32 return values outside a struct. 124 CCIfType<[f32], CCCustom<"CC_Sparc64_Half">>, 125 126 // Otherwise, return values are passed exactly like arguments. 127 CCDelegateTo<CC_Sparc64> 128]>; 129 130// Callee-saved registers are handled by the register window mechanism. 131def CSR : CalleeSavedRegs<(add)> { 132 let OtherPreserved = (add (sequence "I%u", 0, 7), 133 (sequence "L%u", 0, 7)); 134} 135 136// Callee-saved registers for calls with ReturnsTwice attribute. 137def RTCSR : CalleeSavedRegs<(add)> { 138 let OtherPreserved = (add I6, I7); 139} 140