Messages in this thread | | | Date | Fri, 20 Jul 2012 09:33:23 -0700 | Subject | Re: [PATCH 2/2] x86/mce: Add quirk for instruction recovery on Sandy Bridge processors | From | Tony Luck <> |
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> Maybe define a default empty quirk_no_way_out() on the remaining > families/vendors so that the compiler can optimize it away and we save > ourselves the if-test?
Perhaps I misunderstood your suggestion. I don't see how the compiler will manage to optimize it all away. I just tried defining
static void quirk_no_way_out_nop(int bank, struct mce *m, struct pt_regs *regs) { }
and providing that as an initial value for the quirk_no_way_out function pointer.
Then I deleted the "if (quirk_no_way_out)".
Looking at the assembly code produced, I now just have an unconditional call:
callq *0x9fe992(%rip) # ffffffff81a18668 <quirk_no_way_out>
I'd think that a call through a function pointer to an empty function is more expensive that testing whether that function pointer was NULL.
-Tony
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