[PATCH] D19293: [profile] LLVM support for memory-mapping profile counters

[David Li via llvm-commits]

davidxl added inline comments.

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Comment at: lib/Transforms/Instrumentation/InstrProfiling.cpp:390
@@ -385,1 +389,3 @@
 
+void InstrProfiling::emitCounterPadding() {
+  auto PageSize = llvm::sys::Process::getPageSize();
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vsk wrote:
> Hm, I think I misunderstood your question.
> 
> To clarify, I'm not sure whether or not other linkers have the same behavior, so I thought it would be safer to always emit the padding.
Can you measure the size overhead (binary, .o files, and raw profile) with clang self build?

A couple of more questions:

1) getPageSize is on host -- not the target -- this is not intended, I think
2) do you assume padding bytes are tail paddings ?
3) With comdats, this may not work -- for instance, some of the comdat function's counters may be reclaimed by the linker thus leading to counter section size not rounded up to the page size.

This is why I think you need a driver level change.


http://reviews.llvm.org/D19293