>>> Andi Kleen <a...@firstfloor.org> 08/19/12 4:59 AM >>> >I verified this generates the same binary (on 64bit) as the original >register variable.
This isn't very surprising given that the modified code is inside a CONFIG_X86_32 conditional (as ought to be obvious from the code using %%esp). Given that it's being used as operand to a binary &, the resulting code - if the compiler handles this only half way sensibly - can hardly be expected to be identical. >-register unsigned long current_stack_pointer asm("esp") __used; >+#define current_stack_pointer ({ \ >+ unsigned long sp; \ >+ asm("mov %%esp,%0" : "=r" (sp)); \ >+ sp; \ >+}) It would get closer to the original if you used "=g" (I noticed in a few earlier patches already that you like to use "=r" in places where a register is not strictly required, thus reducing the flexibility the compiler has). Also, given that this is more a workaround for a compiler deficiency, shouldn't this be conditional upon use of LTO? Jan -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/