Too liberal array access simplification

[psifertex]

From a user report:

Here is one sample that BN might having trouble to understand.

Binary Ninja 5.3:

9b02fe74    char const (*)[0x5] mcp_xorshift_prng_core()
9b02fe74    {
9b02fe74        int32_t r0 = sub_9b032194();
9b02fe90        char const (* result)[0x5] = 0xbec1b ^ r0 << 0xd ^ r0 >> 9;
9b02fe94        data_10000ac8 = result;
9b02fe96        return result;
9b02fe74    }

IDA:

unsigned int sub_9B02FE74()
{
  unsigned int v0; // r0
  unsigned int result; // r0

  v0 = sub_9B032194();
  result = (dword_10000AC8 << 7) & 0x3F807F80 ^ ((unsigned int)dword_10000AC8 >> 8) & 0xF80FF ^ (v0 << 13) ^ (v0 >> 9);
  dword_10000AC8 = result;
  return result;
}

Reference code:

static int _freertos_arc4random(void)
{
#if defined(CONFIG_PLATFORM_8721D)
	int value = (int)Rand();
	return value;

#else
	u32 res = xTaskGetTickCount();
	static unsigned long seed = 0xDEADB00B;

#if defined(CONFIG_PLATFORM_8711B)
	if(random_seed){
		seed = random_seed;
		random_seed = 0;
	}
#endif

	seed = ((seed & 0x007F00FF) << 7) ^
	    ((seed & 0x0F80FF00) >> 8) ^ // be sure to stir those low bits
	    (res << 13) ^ (res >> 9);    // using the clock too!
	return (int)seed;
#endif
}

Version and Platform (required):

• Binary Ninja Version: 5.3.9434, f7cf98e7
• OS: macos
• OS Version: 15.7.5
• CPU Architecture: arm64

File: thermal ice switches helpfully