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| author | Andreas Klebinger <klebinger.andreas@gmx.at> | 2018-03-13 13:54:53 -0400 |
|---|---|---|
| committer | Ben Gamari <ben@smart-cactus.org> | 2018-03-13 13:57:17 -0400 |
| commit | adc3415f14aa090c54c68149dcb1d99f19132a83 (patch) | |
| tree | ff40375cbd41de0d0087c73cea3de15f3843d592 /compiler/llvmGen/LlvmCodeGen/CodeGen.hs | |
| parent | abfe10487d2dba49bf511297f14575f9089cc5b1 (diff) | |
| download | haskell-wip/D4327.tar.gz | |
WIP: Add likelyhood to alternatives from stg onwardswip/D4327
Summary:
Adds a Freq value to Stg/Cmm cases/switches/conditionals.
Currently only generates these values by checking alternatives for
bottom expressions.
They are passed along to the backend where they affect conditional generation
slightly.
As it stands runtime improvements seem to be less than expected. This might only be worth merging once we have more branch weights available.
Reviewers: hvr, goldfire, bgamari, simonmar, simonpj, erikd
Reviewed By: simonpj
Subscribers: simonpj, rwbarton, thomie, carter
GHC Trac Issues: #14672
Differential Revision: https://phabricator.haskell.org/D4327
Diffstat (limited to 'compiler/llvmGen/LlvmCodeGen/CodeGen.hs')
| -rw-r--r-- | compiler/llvmGen/LlvmCodeGen/CodeGen.hs | 27 |
1 files changed, 21 insertions, 6 deletions
diff --git a/compiler/llvmGen/LlvmCodeGen/CodeGen.hs b/compiler/llvmGen/LlvmCodeGen/CodeGen.hs index e812dd445f..65f7d6652c 100644 --- a/compiler/llvmGen/LlvmCodeGen/CodeGen.hs +++ b/compiler/llvmGen/LlvmCodeGen/CodeGen.hs @@ -13,6 +13,7 @@ import Llvm import LlvmCodeGen.Base import LlvmCodeGen.Regs +import BasicTypes (BranchWeight, getWeight, neverFreq) import BlockId import CodeGen.Platform ( activeStgRegs, callerSaves ) import CLabel @@ -38,6 +39,7 @@ import Util import Control.Monad.Trans.Class import Control.Monad.Trans.Writer +import Data.Int (Int32) import Data.Semigroup ( Semigroup ) import qualified Data.Semigroup as Semigroup import Data.List ( nub ) @@ -1071,7 +1073,19 @@ For a real example of this, see ./rts/StgStdThunks.cmm -} - +switchMetaData :: BranchWeight -> [BranchWeight] -> MetaAnnot +switchMetaData defFreq altFreqs = + let values = map + -- LLVM branch weights are i32 typed so we cap it there. + (\w -> + min (fromIntegral (maxBound :: Int32)) + (fromIntegral . getWeight $ w)) + (defFreq:altFreqs) + types = repeat (LMInt $ fromIntegral 32) + lits = zipWith LMIntLit values types + weights = map (MetaVar . LMLitVar) lits + in + MetaAnnot (fsLit "branch_weights") $ MetaStruct weights -- | Switch branch genSwitch :: CmmExpr -> SwitchTargets -> LlvmM StmtData @@ -1079,13 +1093,14 @@ genSwitch cond ids = do (vc, stmts, top) <- exprToVar cond let ty = getVarType vc - let labels = [ (mkIntLit ty ix, blockIdToLlvm b) - | (ix, b) <- switchTargetsCases ids ] + let (labels,fs) = unzip [ ((mkIntLit ty ix, blockIdToLlvm b), f) + | (ix, (b,f)) <- switchTargetsCases ids ] -- out of range is undefined, so let's just branch to first label - let defLbl | Just l <- switchTargetsDefault ids = blockIdToLlvm l - | otherwise = snd (head labels) + let (defLbl,defFreq) + | Just (l,f) <- switchTargetsDefault ids = (blockIdToLlvm l,f) + | otherwise = (snd (head labels),neverFreq) - let s1 = Switch vc defLbl labels + let s1 = MetaStmt [switchMetaData defFreq fs ] (Switch vc defLbl labels) return $ (stmts `snocOL` s1, top) |