Enable Outlining of Inlined Standard Functions

[op2786]

Compilers sometimes makes standard functions (strlen, memcpy, strcat, memset, strcmp, memcmp etc) inline. I guess their code pattern can be recognized and replaced with pseudo call to function.

Example disassembly:

1800382a2  488dbda0120000     lea     rdi, [rbp+0x12a0 {Dst}]
1800382a9  33c0               xor     eax, eax  {0x0}
1800382ab  b90c010000         mov     ecx, 0x10c
1800382b0  f3aa               rep stosb byte [rdi]  {0x0}  {0x0}  {0x0}

Output in HLIL:

1800382a2          char (* rdi_1)[0x110] = &Dst
1800382b0          for (int64_t rcx_4 = 0x10c; rcx_4 != 0; rcx_4 = rcx_4 - 1) {
1800382b0              *rdi_1 = 0
1800382b0              rdi_1 = &(*rdi_1)[1]
1800382b0          }

Which can be replaced memset(Dst, 0, 0x10c). It may be related to #2185.

[fuzyll]

This is a subset of the functionality that would be required for #2185, so we're leaving this issue to track automatically resolving standard library calls that get inlined. The other issue tracks being able to make any HLIL code into an inlined function.

[plafosse]

Currently we have partial support for this feature. It is currently limited to "Constant Data" i.e. When a string or data is "usually" written to sequential stack locations. We recover these and display them as one of:

• __builtin_strcpy
• __builtin_strncpy
• __builtin_memcpy
• __builtin_wcscpy
• __builtin_memset

TODO:

• __builtin_ memcmp
• __builtin_ strcmp
• __builtin_ strcat

Recovery of non-"Constant Data" functions:

• strlen
• strcpy
• strncpy
• memcpy
• memcmp
• wcscpy
• strcmp

[0xdevalias]

Specific strcat related issue here:

• Add Outlining Support for strcat #5489

And a (potentially more complicated) issue for C++ things like std::string:

• Lift/abstract implementations like C++ std::string #5504

[xusheng6]

There are also other common routines like rdtsc that can be outlined. See #6265