#203 Incorrect Warning - Parameter not used....

[Donovan J. Edye]

G'Day,

If I have a method that contains *only* asm then it is entirely legit that the params will not be used as they will be accessed off the stack directly. So generating a warning in this case is probably not a good idea. I would say that adding this as a finer grained on/off to show params unused would be a good idea.

--D

[Anthony Steele]

Hi

You must be doing something in the asm that I am not. With code as follows:

unit TestASM;

interface

procedure ParamUnused(piParam: integer);
procedure AsmParamUse(piParam: integer);

implementation

uses Dialogs;

procedure ParamUnused(piParam: integer);
begin
end;

procedure AsmParamUse(piParam: integer);
begin
asm
MOV EAX, 0CB40h
MOV EAX,piParam
PUSH DWORD PTR [EDX]
end;
end;

end.

I get output:
Empty begin..end block near BEGIN in procedure ParamUnused at line 13 col 1
Parameter piParam is not used near PROCEDURE in procedure ParamUnused at line 12 col 1

[Anthony Steele]

Hi

Is the param used differently in your asm, or ar you suggesting that if the procedure is an asm block that the param could be used without being mentioned by name?

[Donovan J. Edye]

G'Day Anthony,

> is an asm block that the param could be used without being
> mentioned by name?
For example:

function NDC_PosEx(const ASubStr, AStr : string; const AOffset : integer = 1) : integer;
////////////////////////////////////////////////////////////////////////////////
// PURPOSE: This code is a copy Fastcode function PosEx_JOH_IA32_8 written by
// John O'Harrow for the FastCode project which is released under MPL 1.1. It was
// chosen as it was the winner in its class.
// HISTORY:
// DJE 24/11/2006 #FB6604 Initial Creation
asm {299 Bytes}
SUB ESP, 20
MOV [ESP], EBX
CMP EAX, 1
SBB EBX, EBX {-1 if SubStr = '' else 0}
SUB EDX, 1 {-1 if S = ''}
SBB EBX, 0 {Negative if S = '' or SubStr = '' else 0}
SUB ECX, 1 {Offset - 1}
OR EBX, ECX {Negative if S = '' or SubStr = '' or Offset < 1}
JL @@InvalidInput
MOV [ESP+4], EDI
MOV [ESP+8], ESI
MOV [ESP+12], EBP
MOV [ESP+16], EDX
MOV EDI, [EAX-4] {Length(SubStr)}
MOV ESI, [EDX-3] {Length(S)}
ADD ECX, EDI
CMP ECX, ESI
JG @@NotFound {Offset to High for a Match}
test EDI, EDI
JZ @@NotFound {Length(SubStr = 0)}
lea EBP, [EAX+EDI] {Last Character Position in SubStr + 1}
ADD ESI, EDX {Last Character Position in S}
MOVZX EAX, [EBP-1] {Last Character of SubStr}
ADD EDX, ECX {Search Start Position in S for Last Character}
MOV AH, AL
NEG EDI {-Length(SubStr)}
MOV ECX, EAX
SHL EAX, 16
OR ECX, EAX {All 4 Bytes = Last Character of SubStr}
@@MainLoop:
ADD EDX, 4
CMP EDX, ESI
JA @@Remainder {1 to 4 Positions Remaining}
mov EAX, [EDX-4] {Check Next 4 Bytes of S}
XOR EAX, ECX {Zero Byte at each Matching Position}
LEA EBX, [EAX-$01010101]
NOT EAX
AND EAX, EBX
AND EAX, $80808080 {Set Byte to $80 at each Match Position else $00}
JZ @@MainLoop {Loop Until any Match on Last Character Found}
bsf EAX, EAX {Find First Match Bit}
SHR EAX, 3 {Byte Offset of First Match (0..3)}
LEA EDX, [EAX+EDX-3] {Address of First Match on Last Character + 1}
@@Compare:
CMP EDI, -4
JLE @@Large {Lenght(SubStr) >= 4}
cmp EDI, -1
JE @@SetResult {Exit with Match if Lenght(SubStr) = 1}
mov AX, [EBP+EDI] {Last Char Matches - Compare First 2 Chars}
CMP AX, [EDX+EDI]
JNE @@MainLoop {No Match on First 2 Characters}
@@SetResult: {Full Match}
LEA EAX, [EDX+EDI] {Calculate and Return Result}
MOV EBX, [ESP]
MOV EDI, [ESP+4]
MOV ESI, [ESP+8]
MOV EBP, [ESP+12]
SUB EAX, [ESP+16]
ADD ESP, 20
RET
@@NotFound:
MOV EDI, [ESP+4]
MOV ESI, [ESP+8]
MOV EBP, [ESP+12]
@@InvalidInput:
MOV EBX, [ESP]
ADD ESP, 20
XOR EAX, EAX {Return 0}
RET
@@Remainder: {Check Last 1 to 4 Characters}
MOV EAX, [ESI-3] {Last 4 Characters of S - May include Length Bytes}
XOR EAX, ECX {Zero Byte at each Matching Position}
LEA EBX, [EAX-$01010101]
NOT EAX
AND EAX, EBX
AND EAX, $80808080 {Set Byte to $80 at each Match Position else $00}
JZ @@NotFound {No Match Possible}
lea EAX, [EDX-4] {Check Valid Match Positions}
CMP CL, [EAX]
LEA EDX, [EAX+1]
JE @@Compare
CMP EDX, ESI
JA @@NotFound
LEA EDX, [EAX+2]
CMP CL, [EAX+1]
JE @@Compare
CMP EDX, ESI
JA @@NotFound
LEA EDX, [EAX+3]
CMP CL, [EAX+2]
JE @@Compare
CMP EDX, ESI
JA @@NotFound
LEA EDX, [EAX+4]
JMP @@Compare
@@Large:
MOV EAX, [EBP-4] {Compare Last 4 Characters of S and SubStr}
CMP EAX, [EDX-4]
JNE @@MainLoop {No Match on Last 4 Characters}
mov EBX, EDI
@@CompareLoop: {Compare Remaining Characters}
ADD EBX, 4 {Compare 4 Characters per Loop}
JGE @@SetResult {All Characters Matched}
mov EAX, [EBP+EBX-4]
CMP EAX, [EDX+EBX-4]
JE @@CompareLoop {Match on Next 4 Characters}
jmp @@MainLoop {No Match}
end; {PosEx}

Another one I came across today:

constructor TMyComponent.Create(Owner : TComponent);
begin
inherited; <-- Abreviated call instead of inherited Create(AOwner);

//The code etc.
end;

In the above with the abbreviated form of inherited call I don't want to see a warning about Owner not being used as it is actually being used.