Commit a50a59a9 authored by Ömer Sinan Ağacan's avatar Ömer Sinan Ağacan
Browse files

More efficient, non-allocating unsafeLookupStaticPtr

We now allocate the key to spt on C stack rather than in Haskell heap,
avoiding allocating in `unsafeLookupStaticPtr`. This should be slightly
more efficient.

Test Plan: Validated locally

Reviewers: simonmar, hvr, bgamari, erikd

Reviewed By: simonmar

Subscribers: rwbarton, carter

Differential Revision: https://phabricator.haskell.org/D5333
parent 4efd1b48
......@@ -126,7 +126,7 @@ extern void hs_free_stable_ptr_unsafe (HsStablePtr sp);
extern void hs_free_stable_ptr (HsStablePtr sp);
extern void hs_free_fun_ptr (HsFunPtr fp);
extern StgPtr hs_spt_lookup(StgWord64 key[2]);
extern StgPtr hs_spt_lookup(StgWord64 key1, StgWord64 key2);
extern int hs_spt_keys(StgPtr keys[], int szKeys);
extern int hs_spt_key_count (void);
......
......@@ -48,8 +48,7 @@ module GHC.StaticPtr
) where
import Foreign.C.Types (CInt(..))
import Foreign.Marshal (allocaArray, peekArray, withArray)
import Foreign.Ptr (castPtr)
import Foreign.Marshal (allocaArray, peekArray)
import GHC.Exts (addrToAny#)
import GHC.Ptr (Ptr(..), nullPtr)
import GHC.Fingerprint (Fingerprint(..))
......@@ -89,13 +88,13 @@ staticKey (StaticPtr w0 w1 _ _) = Fingerprint (W64# w0) (W64# w1)
--
unsafeLookupStaticPtr :: StaticKey -> IO (Maybe (StaticPtr a))
unsafeLookupStaticPtr (Fingerprint w1 w2) = do
ptr@(Ptr addr) <- withArray [w1,w2] (hs_spt_lookup . castPtr)
ptr@(Ptr addr) <- hs_spt_lookup w1 w2
if (ptr == nullPtr)
then return Nothing
else case addrToAny# addr of
(# spe #) -> return (Just spe)
foreign import ccall unsafe hs_spt_lookup :: Ptr () -> IO (Ptr a)
foreign import ccall unsafe hs_spt_lookup :: Word64 -> Word64 -> IO (Ptr a)
-- | A class for things buildable from static pointers.
class IsStatic p where
......
......@@ -76,9 +76,10 @@ void hs_spt_remove(StgWord64 key[2]) {
}
}
StgPtr hs_spt_lookup(StgWord64 key[2]) {
StgPtr hs_spt_lookup(StgWord64 key1, StgWord64 key2) {
if (spt) {
ACQUIRE_LOCK(&spt_lock);
StgWord64 key[2] = { key1, key2 };
const StgStablePtr * entry = lookupHashTable(spt, (StgWord)key);
const StgPtr ret = entry ? deRefStablePtr(*entry) : NULL;
RELEASE_LOCK(&spt_lock);
......
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