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cleaned up g_proc_exit, optimized generated code and also added some comments about possible ABI variations. the changes also fix two tests on my system related to cdecl procedures
git-svn-id: trunk@26918 -
This commit is contained in:
Károly Balogh
parent
65fe978b71
commit
8730b1bf45
@ -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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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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{ 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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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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{ 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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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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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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{ 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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{ 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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