GCC compiler question

General FreeBASIC programming questions.
UEZ
Posts: 336
Joined: May 05, 2017 19:59
Location: Germany

GCC compiler question

Postby UEZ » Mar 28, 2019 20:29

Can somebody explain me why this (the text starting at the red arrow) is compiled to the executable?

Image

Is this important to execute the program properly? If not, how can I tell the compiler not to add the text?

Screenshot is from Windows exe.

Thanks
Last edited by UEZ on Mar 29, 2019 12:34, edited 1 time in total.
marcov
Posts: 2762
Joined: Jun 16, 2005 9:45
Location: Eindhoven, NL
Contact:

Re: GCC compiler question

Postby marcov » Mar 28, 2019 20:44

Each compilation module (.o) has such identifier, and is either in a keep section, or referenced by something (debug info, is it stripped?)

Probably they all get tossed into the same section, so are in the same general part of the binary. Can be used that they are all sjlj and same version of mingw.

Might also be that these are weak or so on *nix, but don't get deduplicated on PE/windows.
dodicat
Posts: 5913
Joined: Jan 10, 2006 20:30
Location: Scotland

Re: GCC compiler question

Postby dodicat » Mar 29, 2019 11:18

UEZ
As an observation only:
I have also noticed the repeats of this string in the .exe file.
Even in the tiny shell64.exe from (shell "cmd" as the .bas file) gives me 24 repeats.
Larger .exe files (64 bit) give many more repeats.
The -gen gas equivalent string is "GCC: (i686-win32-sjlj-rev0, Built by MinGW-W64 project)"

Code: Select all





Function tally(somestring As String,partstring As String) As Integer
    Dim As Integer i,j,ln,lnp,count,num
    ln=Len(somestring)
    lnp=Len(partstring)
    count=0
    i=-1
    Do
        i+=1
        If somestring[i] <> partstring[0] Then Goto skip
        If somestring[i] = partstring[0] Then
            For j=0 To lnp-1
                If somestring[j+i]<>partstring[j] Then Goto skip
            Next j
        End If
        count+=1
        i=i+lnp-1
        skip:
    Loop Until i>=ln-1
    Return count
End Function

 #Include "file.bi"

Function loadfile(file as string) as String
   If FileExists(file)=0 Then Print file;" not found":Sleep:end
   var  f=freefile
    Open file For Binary Access Read As #f
    Dim As String text
    If Lof(f) > 0 Then
      text = String(Lof(f), 0)
      Get #f, , text
    End If
    Close #f
    return text
end Function

var L=loadfile("C:\Users\User\Desktop\shell64.exe")

print "File length ";len(L)
print "Repititions ";tally(L,"GCC: (x86_64-win32-sjlj-rev0, Built by MinGW-W64 project)")
sleep


 

I get

Code: Select all

File length  24064
Repititions  24

(Win 10)
with fb 1.06 official build.

The equivalent Pascal .exe file has this as the last few string entries
...
msvcrt.dll kernel32.dll oleaut32.dll user32.dll
but no repeat strings.

But is 42 kb (fb is 24 kb)
UEZ
Posts: 336
Joined: May 05, 2017 19:59
Location: Germany

Re: GCC compiler question

Postby UEZ » Mar 29, 2019 12:38

Apparently the length depends on the exe size. The larger the file the more repetitions exist.

Code: Select all

 #Include "file.bi"
 
Function tally(somestring As String,partstring As String) As Integer
    Dim As Integer i,j,ln,lnp,count,num
    ln=Len(somestring)
    lnp=Len(partstring)
    count=0
    i=-1
    Do
        i+=1
        If somestring[i] <> partstring[0] Then Goto skip
        If somestring[i] = partstring[0] Then
            For j=0 To lnp-1
                If somestring[j+i]<>partstring[j] Then Goto skip
            Next j
        End If
        count+=1
        i=i+lnp-1
        skip:
    Loop Until i>=ln-1
    Return count
End Function

Function loadfile(file As String) As String
   If Fileexists(file)=0 Then Print file;" Not found":Sleep:End
   Var  f=Freefile
    Open file For Binary Access Read As #f
    Dim As String text
    If Lof(f) > 0 Then
      text = String(Lof(f), 0)
      Get #f, , text
    End If
    Close #f
    Return text
End Function

Var L=loadfile("Test08.exe")
Dim As String s1 = "GCC: (i686-posix-sjlj-rev0, Built by MinGW-W64 project) 4.9.3", _
           s2 = "GCC: (i686-win32-sjlj-rev0, Built by MinGW-W64 project) 5.2.0"
Print "File length ";Len(L)
Print
Dim As Ulong l1 = tally(L, s1), l2 = tally(L, s2)
Print s1
Print "Repititions ";l1
Print
Print s2
Print "Repititions ";l2
Print
Print "Overall string length in bytes: " & Len(s1) * l1 + Len(s2) * l2
Print "Overall incl. 3 null chars between = " & Len(s1) * l1 + Len(s2) * l2 + (l1 + l2 - 1) * 24
Sleep


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