gcc bug

Josh Huber huberj at wpi.edu
Sat Apr 1 00:27:07 EST 2000

Interesting gcc bug here...

in both cases this should print 0xDEADBEEF, but in the second case, garbage
is printed.

	unsigned long t1 = 32;
	unsigned long long t2 = 64;

	printf("%x\n", 1 ? 0xDEADBEEF : t1);
	printf("%x\n", 1 ? 0xDEADBEEF : t2);

as expected, the 1 ? ... operation is optimized away, but the compiler seems
to screw things up ...

working case:
	li 4,15
	crxor 6,6,6
	bl printf

failure case:
	li 5,0
	li 6,15
	crxor 6,6,6
	bl printf

in the failure case, r4 is not loaded with anything, so this is were the
garbage probably comes from.

This is a greatly simplified version of an actual piece of code (obviously,
as the code above is silly :)


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