Commit Graph

15 Commits

Author SHA1 Message Date
31413d8f1d Support: More BlockFrequencyTest => BranchProbabilityTest
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207554 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-29 16:44:59 +00:00
2c252dd576 Support: BlockFrequencyTest => BranchProbabilityTest
Move a detailed test of `BranchProbability::scale()` from
`BlockFrequencyTest` over to `BranchProbabilityTest`.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207552 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-29 16:40:17 +00:00
07f96126af blockfreq: Defer to BranchProbability::scale() (again)
Change `BlockFrequency` to defer to `BranchProbability::scale()` and
`BranchProbability::scaleByInverse()`.

This removes `BlockFrequency::scale()` from its API (and drops the
ability to see the remainder), but the only user was the unit tests.  If
some code in the future needs an API that exposes the remainder, we can
add something to `BranchProbability`, but I find that unlikely.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207550 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-29 16:31:29 +00:00
1b98ef1c19 [block-freq] Add a right shift to BlockFrequency that saturates at 1.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@197302 91177308-0d34-0410-b5e6-96231b3b80d8
2013-12-14 02:24:22 +00:00
e323506316 [block-freq] Update data in test case to be unsigned long long to fix mingw build.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@195411 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-22 05:00:51 +00:00
e7a1e3ee82 [block-freq] Add BlockFrequency::scale that returns a remainder from the division and make the private scale in BlockFrequency more performant.
This change is the first in a series of changes improving LLVM's Block
Frequency propogation implementation to not lose probability mass in
branchy code when propogating block frequency information from a basic
block to its successors. This patch is a simple infrastructure
improvement that does not actually modify the block frequency
algorithm. The specific changes are:

1. Changes the division algorithm used when scaling block frequencies by
branch probabilities to a short division algorithm. This gives us the
remainder for free as well as provides a nice speed boost. When I
benched the old routine and the new routine on a Sandy Bridge iMac with
disabled turbo mode performing 8192 iterations on an array of length
32768, I saw ~600% increase in speed in mean/median performance.

2. Exposes a scale method that returns a remainder. This is important so
we can ensure that when we scale a block frequency by some branch
probability BP = N/D, the remainder from the division by D can be
retrieved and propagated to other children to ensure no probability mass
is lost (more to come on this).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194950 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-17 03:25:24 +00:00
5d3257e37c Fix a bad overflow check pointed out by Ben.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@185226 91177308-0d34-0410-b5e6-96231b3b80d8
2013-06-28 21:51:18 +00:00
d7648ff20f Add a division operator to BlockFrequency.
Allow a BlockFrequency to be divided by a non-zero BranchProbability
with saturating arithmetic. This will be used to compute the frequency
of a loop header given the probability of leaving the loop.

Our long division algorithm already saturates on overflow, so that was a
freebie.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@185184 91177308-0d34-0410-b5e6-96231b3b80d8
2013-06-28 18:23:42 +00:00
b47aceaf06 Revert "BlockFrequency: Saturate at 1 instead of 0 when multiplying a frequency with a branch probability."
This reverts commit r184584. Breaks PPC selfhost.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@184590 91177308-0d34-0410-b5e6-96231b3b80d8
2013-06-21 20:20:27 +00:00
93702a3b07 BlockFrequency: Saturate at 1 instead of 0 when multiplying a frequency with a branch probability.
Zero is used by BlockFrequencyInfo as a special "don't know" value. It also
causes a sink for frequencies as you can't ever get off a zero frequency with
more multiplies.

This recovers a 10% regression on MultiSource/Benchmarks/7zip. A zero frequency
was propagated into an inner loop causing excessive spilling.

PR16402.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@184584 91177308-0d34-0410-b5e6-96231b3b80d8
2013-06-21 19:30:05 +00:00
5a88dda4be Sort the #include lines for unittest/...
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@169250 91177308-0d34-0410-b5e6-96231b3b80d8
2012-12-04 10:23:08 +00:00
3b6752eec5 For reasons I can't fathom MSVC supports ULL but not LLU suffixes on long long integer literals.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@158648 91177308-0d34-0410-b5e6-96231b3b80d8
2012-06-17 14:53:53 +00:00
13b10731ab Implement comparison operators for BranchProbability in a way that can't overflow INT64_MAX.
Add a test case for the edge case that triggers this. Thanks to Chandler for bringing this to my attention.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@142794 91177308-0d34-0410-b5e6-96231b3b80d8
2011-10-24 13:50:56 +00:00
341473c86d Add compare operators to BranchProbability and use it to determine if an edge is hot.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@142751 91177308-0d34-0410-b5e6-96231b3b80d8
2011-10-23 11:19:14 +00:00
0031b4f74e Add test cases for BlockFrequency.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@136244 91177308-0d34-0410-b5e6-96231b3b80d8
2011-07-27 18:57:40 +00:00