PE file: Debug directory of type IMAGE_DEBUG_TYPE_VC_FEATURE

Question

I compiled a vanilla exe using Visual Studio 2015. Besides the expected debug directory of type IMAGE_DEBUG_TYPE_CODEVIEW, I also found a second one of type IMAGE_DEBUG_TYPE_VC_FEATURE.

I could not find information regarding what data it contains and what it is used for. Could anybody explain or point me to a source explaining it?

Answer 1

when you compile with /GL or link time code generation compilers later than vc 2010 emits an extra debug directory that contains vcfeature these store some counts of pre-vc 110 /GS counts /sdl counts and guardN counts

dumpbin /headers will show the details of this feature 0xc

:\>dir /b
printf.cpp

:\>cat printf.cpp
#include <stdio.h>
void main (void) {
    printf("%x\n%d\n%u\n%f\n%g\n%s\n%c\n",256,100,-1,2.2,45.87,"hi",97);
}

:\>cl /Zi /W4 /GL /Ox /analyze /nologo printf.cpp
printf.cpp

Generating code
Finished generating code

:\>dumpbin /headers printf.exe | grep -A 10 "Debug Directories"
  Debug Directories

        Time Type        Size      RVA  Pointer
    -------- ------- -------- -------- --------
    5A7F2A78 cv            3C 0004529C    43E9C    Format: RSDS, xxx59}, 1, printf.pdb
    5A7F2A78 feat          14 000452D8    43ED8    Counts: Pre-VC++ 11.00=0, C/C++=194, /GS=194, /sd
l=0, guardN=193  <<<<<<<<<<<<<
    5A7F2A78 coffgrp      28C 000452EC    43EEC    4C544347 (LTCG)

for starters these are all defined in windows headers

13 id == coffgrp as already shown created by lint time code generation

14 is created if you do incremental linking /LINK /LTCG:INCREMENTAL

here is a dummy debug directory

Debug Directories(4)
Type       Size     Address  Pointer
cv           53       463cc    457cc    
(    12)      14       46420    45820
(    13)     29c       46434    45834
(    14)       0           0        0

dumpbin /headers pogo_vcfeature.exe | grep -A 8 "Debug Directories"

 Debug Directories

        Time Type        Size      RVA  Pointer
    -------- ------- -------- -------- --------
    5AD58258 cv            53 000463CC    457CC    
    5AD58258 feat          14 00046420    45820    
    Counts: Pre-VC++ 11.00=0, C/C++=202, /GS=202, /sdl=0, guardN=201
    5AD58258 coffgrp      29C 00046434    45834    
    4C544347 (LTCG)
    5AD58258 iltcg          0 00000000        0

windows headers

:\>echo %cd%
C:\Program Files\Windows Kits\10\Include\10.0.16299.0

:\>grep -ir -B 12 -A 4 IMAGE_DEBUG_TYPE_VC_FEATURE *
xxxxxxxxxxxxxx
km/ntimage.h:#define IMAGE_DEBUG_TYPE_VC_FEATURE       12
km/ntimage.h-#define IMAGE_DEBUG_TYPE_POGO             13
km/ntimage.h-#define IMAGE_DEBUG_TYPE_ILTCG            14
km/ntimage.h-#define IMAGE_DEBUG_TYPE_MPX              15
km/ntimage.h-#define IMAGE_DEBUG_TYPE_REPRO            16
--
xxxxxxxxxxxxxxxxx
um/winnt.h:#define IMAGE_DEBUG_TYPE_VC_FEATURE       12
um/winnt.h-#define IMAGE_DEBUG_TYPE_POGO             13
um/winnt.h-#define IMAGE_DEBUG_TYPE_ILTCG            14
um/winnt.h-#define IMAGE_DEBUG_TYPE_MPX              15
um/winnt.h-#define IMAGE_DEBUG_TYPE_REPRO            16

:\>