The `llvm-profdata order` command is used to compute a function order
using traces from the input profile. Add the `--num-test-traces` flag to
keep aside N traces to evalute this order. These test traces are assumed
to be the actual function execution order in some experiment. The output
is a number that represents how many page faults we got. Lower is
better.
I tested on a large profile I already had.
```
llvm-profdata order default.profdata --num-test-traces=30
# Ordered 149103 functions
# Total area under the page fault curve: 2.271827e+09
...
```
I also improved `TemporalProfTraceTy::createBPFunctionNodes()` in a few
ways:
* Simplified how `UN`s are computed
* Change how the initial `Node` order is computed
* Filter out rare and common `UN`s
* Output vector is an aliased argument instead of a return
These changes slightly improved the evaluation in my test.
```
llvm-profdata order default.profdata --num-test-traces=30
# Ordered 149103 functions
# Total area under the page fault curve: 2.268586e+09
...
```
Adding weights to utility nodes in BP so that we can give more
importance to
certain utilities. This is useful when we optimize several objectives
jointly.
When LargestTraceSize is a power of two, createBPFunctionNodes does not
allocate a group ID for Trace[LargestTraceSize-1] (as N is off by 1).
Fix
this and change floor+log2 to Log2_64.
BalancedPartitioning::bisect can use unstable sort because `Nodes`
contains distinct `InputOrderIndex`s.
BalancedPartitioning::runIterations: use one DenseMap and simplify the
node renumbering code.
In https://reviews.llvm.org/D147812 I created
`BalancedPartitioningTest.cpp` and inadvertently drastically increased the
number of files needed to compile `SupportTests`. Instead lets move the
`BPFunctionNode` test to `unittests/ProfileData` so we can remove the
extra dependency.
Reviewed By: thakis
Differential Revision: https://reviews.llvm.org/D152325
