Created attachment 1452 [details]
test case source code

I get a segmentation fault with -O -release for the read of *src in the following partial function:

--------8<--------
ubyte* src = …;
uint c;
final switch (pixelSize)
{
	case 16:
		foreach (w; 0 .. count)
		{
			c = *src & 0b000_11111;
			c |= (*src++ & 0b111_00000) << (8-5);
			src++;
			c |= (*src & 0b0_00000_11) << (8+3);
			c |= (*src & 0b0_11111_00) << (16-2);
			src++;                          // *** problematic instruction
			(dst++).color = 0xFF000000 | (c << 3);
		}
		break;
	case 24:
		foreach (w; 0 .. count)
		{
			c = 0xFF000000 | *(src++) | (*(src++) << 8) | (*(src++) << 16);
			(dst++).color = c;
		}
		break;
	case 32:
		foreach (w; 0 .. count)
		{
			c = 0xFF000000 | *(src++) | (*(src++) << 8) | (*(src++) << 16);
			src++;
			(dst++).color = c;
		}
		break;
}
-------->8--------

If I change the location of the problematic instruction from:

	c |= (*src & 0b0_11111_00) << (16-2);
	src++;

to:

	c |= (*src++ & 0b0_11111_00) << (16-2);

I get no crash and the function completes. I was also able to fix it with a function call right before the snippet, so it is likely to be affected by CPU register allocation(?)

When I created a test case and removed some files the crash with the -O -release switches disappeared but could be  reproduced again with `dmd -O -release -inline main.d && ./main`. The test case requires the .tga file to work.