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@@ -1670,65 +1670,57 @@ unit cgcpu;
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end;
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end;
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-{ procedure tcg68k.g_restore_frame_pointer(list : TAsmList);
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- var
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- r:Tregister;
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- begin
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- r:=NR_FRAME_POINTER_REG;
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- list.concat(taicpu.op_reg(A_UNLK,S_NO,r));
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- end;
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-}
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-
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procedure tcg68k.g_proc_exit(list : TAsmList; parasize: longint; nostackframe: boolean);
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var
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r,hregister : TRegister;
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- localsize: tcgint;
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spr : TRegister;
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fpr : TRegister;
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ref : TReference;
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begin
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if not nostackframe then
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begin
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- localsize := current_procinfo.calc_stackframe_size;
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list.concat(taicpu.op_reg(A_UNLK,S_NO,NR_FRAME_POINTER_REG));
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parasize := parasize - target_info.first_parm_offset; { i'm still not 100% confident that this is
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correct here, but at least it looks less
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hacky, and makes some sense (KB) }
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- if (parasize<>0) then
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+
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+ { if parasize is less than zero here, we probably have a cdecl function.
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+ According to the info here: http://www.makestuff.eu/wordpress/gcc-68000-abi/
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+ 68k GCC uses two different methods to free the stack, depending if the target
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+ architecture supports RTD or not, and one does callee side, the other does
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+ caller side free, which looks like a PITA to support. We have to figure this
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+ out later. More info welcomed. (KB) }
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+
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+ if (parasize > 0) then
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begin
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- { only 68020+ supports RTD, so this needs another code path
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- for 68000 and Coldfire (KB) }
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-{ TODO: 68020+ only code generation, without fallback}
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if current_settings.cputype=cpu_mc68020 then
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list.concat(taicpu.op_const(A_RTD,S_NO,parasize))
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else
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begin
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-
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{ We must pull the PC Counter from the stack, before }
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{ restoring the stack pointer, otherwise the PC would }
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{ point to nowhere! }
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- { save the PC counter (pop it from the stack) }
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- { use A0 for this which is defined as a scratch }
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- { register }
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+ { Instead of doing a slow copy of the return address while trying }
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+ { to feed it to the RTS instruction, load the PC to A0 (scratch reg) }
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+ { then free up the stack allocated for paras, then use a JMP (A0) to }
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+ { return to the caller with the paras freed. (KB) }
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+
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hregister:=NR_A0;
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cg.a_reg_alloc(list,hregister);
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reference_reset_base(ref,NR_STACK_POINTER_REG,0,4);
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ref.direction:=dir_inc;
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list.concat(taicpu.op_ref_reg(A_MOVE,S_L,ref,hregister));
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- { can we do a quick addition ... }
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+
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r:=NR_SP;
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+ { can we do a quick addition ... }
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if (parasize > 0) and (parasize < 9) then
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list.concat(taicpu.op_const_reg(A_ADDQ,S_L,parasize,r))
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else { nope ... }
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list.concat(taicpu.op_const_reg(A_ADD,S_L,parasize,r));
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- { restore the PC counter (push it on the stack) }
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- reference_reset_base(ref,NR_STACK_POINTER_REG,0,4);
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- ref.direction:=dir_dec;
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- cg.a_reg_alloc(list,hregister);
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- list.concat(taicpu.op_reg_ref(A_MOVE,S_L,hregister,ref));
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- list.concat(taicpu.op_none(A_RTS,S_NO));
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+ reference_reset_base(ref,hregister,0,4);
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+ list.concat(taicpu.op_ref(A_JMP,S_NO,ref));
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end;
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end
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else
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@@ -1739,9 +1731,9 @@ unit cgcpu;
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list.concat(taicpu.op_none(A_RTS,S_NO));
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end;
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-// writeln('g_proc_exit');
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{ Routines with the poclearstack flag set use only a ret.
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- also routines with parasize=0 }
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+ also routines with parasize=0 }
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+ { TODO: figure out if these are still relevant to us (KB) }
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(*
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if current_procinfo.procdef.proccalloption in clearstack_pocalls then
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begin
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@@ -1756,40 +1748,6 @@ unit cgcpu;
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list.concat(taicpu.op_none(A_RTS,S_NO));
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end
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else
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- begin
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- { return with immediate size possible here
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- signed!
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- RTD is not supported on the coldfire }
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- if (current_settings.cputype=cpu_MC68020) and (parasize<$7FFF) then
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- list.concat(taicpu.op_const(A_RTD,S_NO,parasize))
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- { manually restore the stack }
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- else
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- begin
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- { We must pull the PC Counter from the stack, before }
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- { restoring the stack pointer, otherwise the PC would }
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- { point to nowhere! }
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-
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- { save the PC counter (pop it from the stack) }
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- hregister:=NR_A3;
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- cg.a_reg_alloc(list,hregister);
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- reference_reset_base(ref,NR_STACK_POINTER_REG,0);
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- ref.direction:=dir_inc;
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- list.concat(taicpu.op_ref_reg(A_MOVE,S_L,ref,hregister));
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- { can we do a quick addition ... }
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- r:=NR_SP;
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- if (parasize > 0) and (parasize < 9) then
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- list.concat(taicpu.op_const_reg(A_ADDQ,S_L,parasize,r))
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- else { nope ... }
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- list.concat(taicpu.op_const_reg(A_ADD,S_L,parasize,r));
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-
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- { restore the PC counter (push it on the stack) }
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- reference_reset_base(ref,NR_STACK_POINTER_REG,0);
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- ref.direction:=dir_dec;
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- cg.a_reg_alloc(list,hregister);
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- list.concat(taicpu.op_reg_ref(A_MOVE,S_L,hregister,ref));
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- list.concat(taicpu.op_none(A_RTS,S_NO));
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- end;
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- end;
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*)
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end;
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Károly Balogh