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Re: [Tinycc-devel] [BUG] The main function parameter is missing.


From: Edward Gynt
Subject: Re: [Tinycc-devel] [BUG] The main function parameter is missing.
Date: Fri, 7 Jun 2024 15:03:35 +0200

I am having trouble reproducing your issue. My .exe files output the correct information. The "C file" code you mention doesn't mark main as a __thiscall, but your decompiled function lists sub_401000 as __thiscall. Why?
I don't own IDA so I can't reproduce with IDA.

What I do notice is that using i386-win32-tcc.exe (compiled with gcc or tcc) I get identical output to before my commit.
With tcc.exe (compiled with gcc or tcc, which in turns was built with build-tcc.bat -x), I get the situation that ecx is stored in the stack and then moved into eax. Very strange.
So the x86_64 build is affected. Before I start digging into the code (misplaced #ifdef somewhere?) I want to verify the byte code with you to make sure we are talking about the same issue. 
Can you post yours (objdump -D) ?

Compiled with version on branch mob after my commit:

00401000 <.text>:
  401000:       55                      push   %ebp
  401001:       89 e5                   mov    %esp,%ebp
  401003:       81 ec 04 00 00 00       sub    $0x4,%esp
  401009:       90                      nop
  40100a:       89 4d fc                mov    %ecx,-0x4(%ebp)
  40100d:       8b 45 fc                mov    -0x4(%ebp),%eax
  401010:       50                      push   %eax
  401011:       b8 00 20 40 00          mov    $0x402000,%eax
  401016:       50                      push   %eax
  401017:       e8 54 02 00 00          call   0x401270
  40101c:       83 c4 08                add    $0x8,%esp
  40101f:       b8 0b 20 40 00          mov    $0x40200b,%eax
  401024:       50                      push   %eax
  401025:       e8 4e 02 00 00          call   0x401278
  40102a:       83 c4 04                add    $0x4,%esp
  40102d:       b8 00 00 00 00          mov    $0x0,%eax
  401032:       c9                      leave
  401033:       c3                      ret

Compiled with version on branch mob before my commit:

00401000 <.text>:
  401000:       55                      push   %ebp
  401001:       89 e5                   mov    %esp,%ebp
  401003:       81 ec 00 00 00 00       sub    $0x0,%esp
  401009:       90                      nop
  40100a:       8b 45 08                mov    0x8(%ebp),%eax
  40100d:       50                      push   %eax
  40100e:       b8 00 20 40 00          mov    $0x402000,%eax
  401013:       50                      push   %eax
  401014:       e8 57 02 00 00          call   0x401270
  401019:       83 c4 08                add    $0x8,%esp
  40101c:       b8 0b 20 40 00          mov    $0x40200b,%eax
  401021:       50                      push   %eax
  401022:       e8 51 02 00 00          call   0x401278
  401027:       83 c4 04                add    $0x4,%esp
  40102a:       b8 00 00 00 00          mov    $0x0,%eax
  40102f:       c9                      leave
  401030:       c3                      ret




On Thu, Jun 6, 2024 at 5:30 PM HarukaMomono via Tinycc-devel <tinycc-devel@nongnu.org> wrote:
commit:3b943bec5de423e234b5f92d9a8f110ad66a85a1
author:Gynt <Gynt@users.noreply.github.com>
           Mon, 3 Jun 2024 19:52:34 +0800 (3 13:52 +0200)
committer:Gynt <Gynt@users.noreply.github.com>
                Mon, 3 Jun 2024 19:56:32 +0800 (3 13:56 +0200)
tree:3c7fd4f944e9417b6bf2c95c21c9e8c9ee671b11
parent:8cd21e91ccee3baf15ad2f8cba9cbc4b618695a0

envs: windows 10; gcc version 14.1.0 (MinGW-W64 x86_64-ucrt-posix-seh, built by Brecht Sanders, r1)

In this branch, I built it using gcc, the build command: build-tcc.bat -x

C file:
#include <stdio.h>
#include <stdlib.h>

int main(int argc, const char **argv, const char **envp) {
printf("argc = %d\n", argc);
system("pause");
return 0;
}

Compile Commands:
tcc.exe -std=c11 -m32 -o test.exe test.c

result:
argc = 9908136

Decompile using IDA:
int __thiscall sub_401000(void *this)
{
  printf("arg num = %d\n", this);
  system("pause");
  return 0;
}

There are missing parameters.


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