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 18 def 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 30 def 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. 107 def 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 ]>; 120 121 def 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. 131 def 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. 137 def RTCSR : CalleeSavedRegs<(add)> { 138 let OtherPreserved = (add I6, I7); 139 } 140
