Hex-Rays v7.2 vs. v7.1 Decompiler Comparison Page

Below you will find side-by-side comparisons of v7.1 and v7.2 decompilations. Please maximize the window too see both columns simultaneously.

The following examples are displayed on this page:

1. Magic divisions in 64-bit code

2. More aggressive 'if' to 'boolean' folding

3. Better type of 'this' argument

4. Improved union field selection

5. Improved recognition of 'for' loops

6. Added support for shifted pointers

7. Better recognition of inlined standard functions

8. Improved application of pre-increment and pre-decrement

9. Added support for RRX addressing mode in ARM

10. Improved constant propagation in global memory

11. Added support for Objective C blocks

12. Improved recognition of 64-bit comparisons

13. Merged common code in 'if' branches

14. Added forced stack variables

15. Added support for virtual calls

NOTE: these are just some selected examples that can be illustrated as side-by-side differences. There are many other improvements and new features that are not mentioned on this page.

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Magic divisions in 64-bit code

In the past the Decompiler was able to recognize magic divisions in 32-bit code. We now support magic divisions in 64-bit code too.

PSEUDOCODE V7.2

return 21600 * (t / 21600);

PSEUDOCODE V7.1

  return 21600
       * (((signed __int64)((unsigned __int128)(1749024623285053783LL
         * (signed __int128)t) >> 64) >> 11) - (t >> 63));

More aggressive 'if' to 'boolean' folding

More aggressive folding of if_one_else_zero constructs; the output is much shorter and easier to grasp.

PSEUDOCODE V7.2

return a1 << 28 != 0 && (a1 & (unsigned __int8)(a1 - 1)) == 0;

PSEUDOCODE V7.1

  v1 = 1;
  v2 = 1;
  if ( !(a1 << 28) )
    v2 = 0;
  if ( !((unsigned __int8)a1 & (unsigned __int8)(a1 - 1)) )
    v1 = 0;
  return v2 && !v1;

Better type of 'this' argument

The decompiler tries to guess the type of the first argument of a constructor. This leads to improved listing.

PSEUDOCODE V7.2

XImage *__fastcall XImage::setHotSpot(XImage *this, int a2, int a3)
{
  LOWORD(this->height) = a2;
  HIWORD(this->height) = a3;
  return this;
}

PSEUDOCODE V7.1

int __fastcall XImage::setHotSpot(int this, int a2, int a3)
{
  *(_WORD *)(this + 4) = a2;
  *(_WORD *)(this + 6) = a3;
  return this;
}

Improved union field selection

The decompiler has a better algorithm to find the correct union field. This reduces the number of casts in the output.

PSEUDOCODE V7.2

float __fastcall ret4f(__n128 a1)
{
  return a1.n128_f32[2];
}

PSEUDOCODE V7.1

float __fastcall ret4f(__n128 a1)
{
  return *(float *)&a1.n128_u32[2];
}

Improved recognition of 'for' loops

We improved recognition of 'for' loops, they are shorter and much easier to understand.

PSEUDOCODE V7.2

  for ( i = 0; i < 16; ++i )
  {
    printf("%x", *(unsigned __int8 *)(i + v2) >> 4);
    printf("%x", *(_BYTE *)(i + v2) & 0xF);
  }

PSEUDOCODE V7.1

v3 = 0;
do
{
  printf("%x", (unsigned int)*(unsigned __int8 *)(v3 + v2) >> 4);
  printf("%x", *(_BYTE *)(v3++ + v2) & 0xF);
}
while ( v3 < 16 );

Added support for shifted pointers

Please note that the code on the left is completely illegible; the assembler code is probably easier to work with in this case. However, the code on the right is very neat. JFYI, below is the class hierarchy for this example:

struct __cppobj B1
{
  B1_vtbl *__vftable /*VFT*/;
  char d1[4];
};
struct __cppobj B2
{
  B2_vtbl *__vftable /*VFT*/;
  char d2[4];
};