[PATCH] D28965: [PGO] Value profile for size of memory intrinsic calls

[Rong Xu via llvm-commits]

On Tue, Mar 7, 2017 at 2:00 PM, David Li via Phabricator <
reviews at reviews.llvm.org> wrote:

> davidxl added a comment.
>
> The profile annotation part of another patch should be merged in here.
>
>
>
> ================
> Comment at: include/llvm/Transforms/InstrProfiling.h:63
> +  // The start value of precise value profile range for memory intrinsic
> sizes.
> +  const int64_t DefaultMemOPSizeRangeStart = 0;
> +  int64_t MemOPSizeRangeStart;
> ----------------
> xur wrote:
> > davidxl wrote:
> > > should it be 1?
> > there are calls to memory intrinsics with size 0.  There are quite many
> actually.
> The value transformation patch does not seem to handle it .  Do you see
> cases where value 0 is a frequent value in hot stringop sites?
>

I think the transformation patch handles size 0. It just transforms the
dominant size values (it does not check the values).
value 0 is one of the top size values. The absolute value is not large. But
it's frequent in various call sites.


>
>
> ================
> Comment at: lib/Transforms/Instrumentation/InstrProfiling.cpp:83
> +    cl::desc("Set the range of size in memory intrinsic calls to be
> profiled "
> +             "precisely, in a format of <start_val>:<end_val>"),
> +    cl::init(""));
> ----------------
> document the case when some value is missing in the option.
>
>
> https://reviews.llvm.org/D28965
>
>
>
>
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