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| author | Pawel Wodnicki <pawel@32bitmicro.com> | 2012-12-19 09:57:57 +0000 |
|---|---|---|
| committer | Pawel Wodnicki <pawel@32bitmicro.com> | 2012-12-19 09:57:57 +0000 |
| commit | eb8eaa89a589e0a63f4053a401668d1fd916e4cd (patch) | |
| tree | 8987f03f32b9fe0b0da40a19dde81a62040f9230 | |
| parent | 2691635b5771df4624f4af1a6242020aaaabd9d7 (diff) | |
Sync-up SROA notes
git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_32@170521 91177308-0d34-0410-b5e6-96231b3b80d8
| -rw-r--r-- | docs/ReleaseNotes.html | 17 |
1 files changed, 14 insertions, 3 deletions
diff --git a/docs/ReleaseNotes.html b/docs/ReleaseNotes.html index fbcafc3f00..1fc16a36d7 100644 --- a/docs/ReleaseNotes.html +++ b/docs/ReleaseNotes.html @@ -579,12 +579,23 @@ </p> -<p>SROA - We've re-written SROA to be significantly more powerful. -<!-- FIXME: Add more text here... --></p> +<p>SROA - We’ve re-written SROA to be significantly more powerful and generate +code which is much more friendly to the rest of the optimization pipeline. +Previously this pass had scaling problems that required it to only operate on +relatively small aggregates, and at times it would mistakenly replace a large +aggregate with a single very large integer in order to make it a scalar SSA +value. The result was a large number of i1024 and i2048 values representing any +small stack buffer. These in turn slowed down many subsequent optimization +paths.</p> +<p>The new SROA pass uses a different algorithm that allows it to only promote to +scalars the pieces of the aggregate actively in use. Because of this it doesn’t +require any thresholds. It also always deduces the scalar values from the uses +of the aggregate rather than the specific LLVM type of the aggregate. These +features combine to both optimize more code with the pass but to improve the +compile time of many functions dramatically.</p> <ul> <li>Branch weight metadata is preseved through more of the optimizer.</li> - <li>...</li> </ul> </div> |