Hi Harendra,
Would it be possible for you to provide a minimal example that compiles to such
assembly? It's hard to tell if this is an easy case.
Also, just to make sure, you're using -O, right? (I'm not sure if we have a
related transformation enabled with -O but just to make sure...)
2016-06-13 7:23 GMT-04:00 Harendra Kumar
Hi,
I noticed in the generated code (llvm as well as native) that in some cases the GC calls are in the straight path and the regular code is out of the straight line path. Like this:
=> 0x408fc0: lea 0x30(%r12),%rax => 0x408fc5: cmp 0x358(%r13),%rax => 0x408fcc: jbe 0x408fe9 # notice jbe instead of ja i.e. branch taken in normal case
I tried to count in how many cases its happening in my executable and found that its only a small percentage (4-6%) of cases but those cases include the code which runs 99% of the time in my benchmark. Though it does not make a whole lot of difference but the difference is perceptible and especially when it is in a tight loop.
Is it possible to somehow force all the GC calls out of the line during code generation? Has it been thought/discussed before?
-harendra
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