Multiple issues in fbranch

[rfalke]

Subject: https://github.com/rfalke/decompiler-subjects/blob/master/from_boomerang/fbranch/arm64_elf_clang_O0_from_rfalke/by_reko.c

Output:

void main()
{
	x0_17 = (uint64) __isoc99_scanf("%f", fp - 0x14);
	x0_32 = (uint64) printf("a is %f, b is %f\n", (real64) 7e-45F, (real64) dwLoc14);
	struct Eq_125 * sp_107 = fp - 0x48;
	if (dwLoc14 == 5.0F)
	{
		x0_42 = (uint64) printf("Equal\n");
		sp_107 = fp - 0x50;
	}

Issues:

• fp - 0x14 should be & dwLoc14
• 7e-45F should be 5.0f
• The return values of __isoc99_scanf and printf are unused, no extra variables needed

[uxmal]

The (non-)conversion fp - 0x14 to &dwLoc14 is a known issue, and is being investigated as part of the implementation of proper escape analysis (@ptomin and I are in discussions)

• Incorrect conversion of floating point constant (cause found, but preliminary fix causes massive regressions)
• dead return values should be removed.

[rfalke]

Output of version 0.11.4.0-931ca7d:

void main(Eq_91 s0)
{
	ptr64 fp;
	Eq_91 dwLoc1C;
	__isoc99_scanf("%f", fp + ~0x1B);
	printf("a is %f, b is %f\n", (real64) s0, (real64) dwLoc1C);
	if (s0 == dwLoc1C)
		printf("Equal\n");
...}

Issues:

• fp + ~0x1B should be & dwLoc1C
• s0 is not a parameter of main() but contains the constant of 5.0