support of MSVC __asm {} statement

[Bertk]

Microsoft C++ uses a proprietary __asm keyword which is not handled by cxx-squid. The analysis of the source file will fail and no workaround is known so far.

Syntax:
__asm assembly-instruction [ ; ]
__asm { assembly-instruction-list } [ ; ]

The lexer shall support this Microsoft specific statement.
See also: http://jira.sonarsource.com/browse/CPP-648

[Bertk]

sample file:

// http://msdn.microsoft.com/en-us/library/45yd4tzz.aspx
// Microsoft C++ support for the Standard C++ asm keyword is limited to the fact that the compiler
// will not generate an error on the keyword. However, an asm block will not generate any meaningful code.
// Use __asm instead of asm.

#define __asm asm

//  Microsoft specific asm
// Syntax:
//  __asm assembly-instruction [ ; ]
//  __asm { assembly-instruction-list } [ ; ]

// see http://msdn.microsoft.com/en-us/library/ydwz5zc6.aspx

// Power2_inline_asm.c
// compile with: /EHsc
// processor: x86

#include <stdio.h>

int power2( int num, int power );

int main( void )
{
    printf_s( "3 times 2 to the power of 5 is %d\n", power2( 3, 5) );
}
int power2( int num, int power )
{
// Microsoft specific asm

   __asm
   {
      mov eax, num
      mov ecx, power
      shl eax, cl
   }

   __asm
   {
      mov eax, num    ; Get first argument
      mov ecx, power  ; Get second argument
      shl eax, cl     ; EAX = EAX * ( 2 to the power of CL )
   }

   // Return with result in EAX
}

int alt_1 (void)
{
    int array[10];

    __asm mov array[6], bx ;
    __asm mov array[6], bx ;  Store BX at array+6 (not scaled)

    array[6] = 0;         /* Store 0 at array+24 (scaled) */
}

int alt_2 (void)
{
    __asm push ebp   __asm mov  ebp, esp   __asm sub  esp, __LOCAL_SIZE
}

[guwirth]

Hi,

Some hints below:

Mock compiler specific keywords with:
#define _asm asm
#define __asm asm

ISO standard defines:
asm("assembler code");

Many compiler are supporting:
//C++ Code
asm {
//Assembler Code
}
//more C++ Code

VS: http://msdn.microsoft.com/en-us/library/45yd4tzz.aspx
__asm assembly-instruction ; opt
__asm { assembly-instruction-list }; opt

GCC:
asm("assembler code");
_ asm _("assembler code");

Current parser implementation:
b.rule(asmDefinition).is(CxxKeyword.ASM, "(", STRING, ")", ";");

So yes, VS syntax is not supported. Would add support, but only with keyword asm. Others could be simulated with preprocessor.

Regards

[Bertk]

An additional keyword '__asm' is not necessary and the '#define __asm asm' directive should do the job. The important part is anyway to support 'asm { assembly-instruction-list }' and 'asm assembly-instruction' syntax.

[guwirth]

This two cases seems to be easy to support:
__asm assembly-instruction ;
__asm { assembly-instruction-list }; opt

Interesting is this case (without semicolon at the end). How to parse for EOL?
__asm assembly-instruction

[guwirth]

Solved except syntax
__asm assembly-instruction // without ; at eol

@Bertk please test

[Bertk]

Works fine with this preprocessor settings:

#define _asm asm
#define __asm asm

Thank you.

[guwirth]

Docu: https://github.com/wenns/sonar-cxx/wiki/Supported-compiler-specific-extensions