flat assembler
Message board for the users of flat assembler.

Index > Macroinstructions > bug in fastcall(64-bit) macro, incomplete addressing support

Author
Thread Post new topic Reply to topic
Madis731



Joined: 25 Sep 2003
Posts: 2140
Location: Estonia
Madis731
Code:
include 'win64a.inc'
use64
        fastcall blah,ecx,edx,r8,r9,dword[esp+40] ;Operand sizes do not match.
        fastcall blah,ecx,edx,r8,r9,[esp+40] ;Operand size not specified.
        fastcall blah,ecx,edx,r8,r9,dword[rsp+40] ;OK!
blah:
  ret
    


Seems that its using prefixes as hints, but in 64-bit mode 32-bit registers are not recommended (even forbidden on Intel compiler) and this tiny bit has been missed when writing these macros.

Shall I take the courage to fix this myself? It is not necessary that it worked, but it will give hard time to asmers coming from 32-bit world. Actually this bug surfaced with porting 32-bit code.

_________________
My updated idol Very Happy http://www.agner.org/optimize/


Last edited by Madis731 on 19 May 2009, 08:08; edited 1 time in total
Post 19 May 2009, 05:57
View user's profile Send private message Visit poster's website Yahoo Messenger MSN Messenger Reply with quote
MazeGen



Joined: 06 Oct 2003
Posts: 977
Location: Czechoslovakia
MazeGen
Madis731 wrote:
...but in 64-bit mode 32-bit registers are not recommended...

What does this mean exactly? I don't remember recommendation like this in the fastcall documentation.
Post 19 May 2009, 06:17
View user's profile Send private message Visit poster's website Reply with quote
Madis731



Joined: 25 Sep 2003
Posts: 2140
Location: Estonia
Madis731
Sorry, not the fastcall recommendation, but 64-bit addressing:
Code:
mov eax,[ebp+eax*4] ; is not recommended
mov eax,[rbp+rax*4] ; is recommended and even enforced i.e. Intel C-compiler in asm {} blocks.
    
Post 19 May 2009, 06:50
View user's profile Send private message Visit poster's website Yahoo Messenger MSN Messenger Reply with quote
revolution
When all else fails, read the source


Joined: 24 Aug 2004
Posts: 17667
Location: In your JS exploiting you and your system
revolution
That is like in Win32 doing this:
Code:
format PE GUI ...
...
MyString: "Hello cruel world!",13,10,0
...
mov ebx,MyString
mov al,[bx]
...    
Post 19 May 2009, 06:57
View user's profile Send private message Visit poster's website Reply with quote
Madis731



Joined: 25 Sep 2003
Posts: 2140
Location: Estonia
Madis731
Code:
;proc64.inc @ 144,1
-        else if opcode = 0FFh
+        else if opcode = 0FFh | opcode = 67h
    


Smile
Post 19 May 2009, 08:03
View user's profile Send private message Visit poster's website Yahoo Messenger MSN Messenger Reply with quote
asmfan



Joined: 11 Aug 2006
Posts: 392
Location: Russian
asmfan
Relatively this "simple" macro for win64 calling convention - the convention itself was made with respect to ease some obvious things like constant stack pointer moving which is absent in win64 CC but this macro revert us to x32 disadvantages. despite commitiong whole stack on entry equal to uneven max arg count of leaves-function *8 if playing with stack each time API's called. Suggest removing this macro definition till or if it will count args for leaf-func to balance stack once.
Post 24 Jun 2009, 08:23
View user's profile Send private message Reply with quote
Tomasz Grysztar



Joined: 16 Jun 2003
Posts: 7797
Location: Kraków, Poland
Tomasz Grysztar
asmfan wrote:
Relatively this "simple" macro for win64 calling convention - the convention itself was made with respect to ease some obvious things like constant stack pointer moving which is absent in win64 CC but this macro revert us to x32 disadvantages. despite commitiong whole stack on entry equal to uneven max arg count of leaves-function *8 if playing with stack each time API's called. Suggest removing this macro definition till or if it will count args for leaf-func to balance stack once.

Please read this thread: http://board.flatassembler.net/topic.php?t=4209
Perhaps you'd like to continue the discussion there.
Post 24 Jun 2009, 10:36
View user's profile Send private message Visit poster's website Reply with quote
Display posts from previous:
Post new topic Reply to topic

Jump to:  


< Last Thread | Next Thread >
Forum Rules:
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum


Copyright © 1999-2020, Tomasz Grysztar. Also on GitHub, YouTube, Twitter.

Website powered by rwasa.