Marge Bot pushed to branch master at Glasgow Haskell Compiler / GHC Commits: a46a1bb1 by Cheng Shao at 2026-03-09T04:50:30-04:00 compiler: add myCapabilityExpr to GHC.Cmm.Utils This commit adds `myCapabilityExpr` to `GHC.Cmm.Utils` which is computed from `BaseReg`. It's convenient for codegen logic where one needs to pass the current Capability's pointer. - - - - - 4afc65b1 by Cheng Shao at 2026-03-09T04:50:30-04:00 compiler: lower tryPutMVar# into a ccall directly This patch addresses an old TODO of `stg_tryPutMVarzh` by removing it completely and making the compiler lower `tryPutMVar#` into a ccall to `performTryPutMVar` directly, without landing into an intermediate C or Cmm function. `performTryPutMVar` is promoted to a public RTS function with default visibility, and the compiler lowering logic takes into account the C ABI of `performTryPutMVar` and converts from C Bool to primop's `Int#` result properly. - - - - - 8 changed files: - compiler/GHC/Cmm/Utils.hs - compiler/GHC/StgToCmm/Prim.hs - rts/PrimOps.cmm - rts/RtsSymbols.c - rts/Threads.c - rts/Threads.h - rts/include/rts/Threads.h - rts/include/stg/MiscClosures.h Changes: ===================================== compiler/GHC/Cmm/Utils.hs ===================================== @@ -37,6 +37,7 @@ module GHC.Cmm.Utils( baseExpr, spExpr, hpExpr, spLimExpr, hpLimExpr, currentTSOExpr, currentNurseryExpr, cccsExpr, + myCapabilityExpr, -- Tagging cmmTagMask, cmmPointerMask, cmmUntag, cmmIsTagged, cmmIsNotTagged, @@ -569,7 +570,7 @@ blockTicks b = reverse $ foldBlockNodesF goStmt b [] -- Access to common global registers baseExpr, spExpr, hpExpr, currentTSOExpr, currentNurseryExpr, - spLimExpr, hpLimExpr, cccsExpr :: Platform -> CmmExpr + spLimExpr, hpLimExpr, cccsExpr, myCapabilityExpr :: Platform -> CmmExpr baseExpr p = CmmReg $ baseReg p spExpr p = CmmReg $ spReg p spLimExpr p = CmmReg $ spLimReg p @@ -578,3 +579,5 @@ hpLimExpr p = CmmReg $ hpLimReg p currentTSOExpr p = CmmReg $ currentTSOReg p currentNurseryExpr p = CmmReg $ currentNurseryReg p cccsExpr p = CmmReg $ cccsReg p +myCapabilityExpr p = + cmmRegOff (baseReg p) $ negate $ pc_OFFSET_Capability_r $ platformConstants p ===================================== compiler/GHC/StgToCmm/Prim.hs ===================================== @@ -345,6 +345,25 @@ emitPrimOp cfg primop = emitPrimCall [res] (MO_Xchg (wordWidth platform)) [dst, val] emitDirtyMutVar mutv (CmmReg (CmmLocal res)) + TryPutMVarOp -> \[mvar, val] -> inlinePrimop $ \[res] -> do + cres <- newTemp b8 + emitCCall + [(cres, NoHint)] + ( CmmLit + ( CmmLabel + ( mkForeignLabel + (fsLit "performTryPutMVar") + ForeignLabelInExternalPackage + IsFunction + ) + ) + ) + [(myCapabilityExpr platform, AddrHint), (mvar, AddrHint), (val, AddrHint)] + emitAssign (CmmLocal res) $ + CmmMachOp + (MO_UU_Conv W8 (wordWidth platform)) + [CmmReg (CmmLocal cres)] + -- #define sizzeofByteArrayzh(r,a) \ -- r = ((StgArrBytes *)(a))->bytes SizeofByteArrayOp -> \[arg] -> inlinePrimop $ \[res] -> @@ -1777,7 +1796,6 @@ emitPrimOp cfg primop = TakeMVarOp -> alwaysExternal TryTakeMVarOp -> alwaysExternal PutMVarOp -> alwaysExternal - TryPutMVarOp -> alwaysExternal ReadMVarOp -> alwaysExternal TryReadMVarOp -> alwaysExternal IsEmptyMVarOp -> alwaysExternal ===================================== rts/PrimOps.cmm ===================================== @@ -1927,95 +1927,6 @@ loop: } -// NOTE: there is another implementation of this function in -// Threads.c:performTryPutMVar(). Keep them in sync! It was -// measurably slower to call the C function from here (70% for a -// tight loop doing tryPutMVar#). -// -// TODO: we could kill the duplication by making tryPutMVar# into an -// inline primop that expands into a C call to performTryPutMVar(). -stg_tryPutMVarzh ( P_ mvar, /* :: MVar a */ - P_ val, /* :: a */ ) -{ - W_ info, tso, q, qinfo; - - LOCK_CLOSURE(mvar, info); - - if (StgMVar_value(mvar) != stg_END_TSO_QUEUE_closure) { -#if defined(THREADED_RTS) - unlockClosure(mvar, info); -#endif - return (0); - } - - q = StgMVar_head(mvar); -loop: - if (q == stg_END_TSO_QUEUE_closure) { - /* No further takes, the MVar is now full. */ - if (info == stg_MVAR_CLEAN_info) { - ccall dirty_MVAR(BaseReg "ptr", mvar "ptr", StgMVar_value(mvar) "ptr"); - } - - StgMVar_value(mvar) = val; - unlockClosure(mvar, stg_MVAR_DIRTY_info); - return (1); - } - - qinfo = GET_INFO_ACQUIRE(q); - - if (qinfo == stg_IND_info || - qinfo == stg_MSG_NULL_info) { - q = %acquire StgInd_indirectee(q); - goto loop; - } - - // There are takeMVar(s) waiting: wake up the first one - - tso = StgMVarTSOQueue_tso(q); - q = StgMVarTSOQueue_link(q); - StgMVar_head(mvar) = q; - if (q == stg_END_TSO_QUEUE_closure) { - StgMVar_tail(mvar) = stg_END_TSO_QUEUE_closure; - } else { - if (info == stg_MVAR_CLEAN_info) { - // Resolve #18919. - ccall dirty_MVAR(BaseReg "ptr", mvar "ptr", - StgMVar_value(mvar) "ptr"); - info = stg_MVAR_DIRTY_info; - } - } - - // save why_blocked here, because waking up the thread destroys - // this information - W_ why_blocked; - why_blocked = TO_W_(StgTSO_why_blocked(tso)); // TODO: Missing barrier - ASSERT(StgTSO_block_info(tso) == mvar); - - // actually perform the takeMVar - W_ stack; - stack = StgTSO_stackobj(tso); - if (IS_STACK_CLEAN(stack)) { - ccall dirty_STACK(MyCapability() "ptr", stack "ptr"); - } - PerformTake(stack, val); - - // indicate that the MVar operation has now completed. - StgTSO__link(tso) = stg_END_TSO_QUEUE_closure; - - ccall tryWakeupThread(MyCapability() "ptr", tso); - - // If it was a readMVar, then we can still do work, - // so loop back. (XXX: This could take a while) - if (why_blocked == BlockedOnMVarRead) - goto loop; - - ASSERT(why_blocked == BlockedOnMVar); - - unlockClosure(mvar, info); - return (1); -} - - stg_readMVarzh ( P_ mvar, /* :: MVar a */ ) { W_ val, info, tso, q; ===================================== rts/RtsSymbols.c ===================================== @@ -678,6 +678,7 @@ extern char **environ; SymI_HasDataProto(stg_readTVarIOzh) \ SymI_HasProto(resumeThread) \ SymI_HasProto(setNumCapabilities) \ + SymI_HasProto(performTryPutMVar) \ SymI_HasProto(getNumberOfProcessors) \ SymI_HasProto(resolveObjs) \ SymI_HasDataProto(stg_retryzh) \ @@ -869,7 +870,6 @@ extern char **environ; SymI_HasDataProto(stg_takeMVarzh) \ SymI_HasDataProto(stg_readMVarzh) \ SymI_HasDataProto(stg_threadStatuszh) \ - SymI_HasDataProto(stg_tryPutMVarzh) \ SymI_HasDataProto(stg_tryTakeMVarzh) \ SymI_HasDataProto(stg_tryReadMVarzh) \ SymI_HasDataProto(stg_unmaskAsyncExceptionszh) \ ===================================== rts/Threads.c ===================================== @@ -795,8 +795,6 @@ threadStackUnderflow (Capability *cap, StgTSO *tso) /* ---------------------------------------------------------------------------- Implementation of tryPutMVar# - - NOTE: this should be kept in sync with stg_tryPutMVarzh in PrimOps.cmm ------------------------------------------------------------------------- */ bool performTryPutMVar(Capability *cap, StgMVar *mvar, StgClosure *value) ===================================== rts/Threads.h ===================================== @@ -24,7 +24,7 @@ void migrateThread (Capability *from, StgTSO *tso, Capability *to); // #if defined(THREADED_RTS) void wakeupThreadOnCapability (Capability *cap, - Capability *other_cap, + Capability *other_cap, StgTSO *tso); #endif @@ -40,8 +40,6 @@ StgBool isThreadBound (StgTSO* tso); void threadStackOverflow (Capability *cap, StgTSO *tso); W_ threadStackUnderflow (Capability *cap, StgTSO *tso); -bool performTryPutMVar(Capability *cap, StgMVar *mvar, StgClosure *value); - #if defined(DEBUG) void printThreadBlockage (StgTSO *tso); void printThreadStatus (StgTSO *t); ===================================== rts/include/rts/Threads.h ===================================== @@ -90,3 +90,5 @@ extern Capability MainCapability; // current value at the moment). // extern void setNumCapabilities (uint32_t new_); + +bool performTryPutMVar(Capability *cap, StgMVar *mvar, StgClosure *value); ===================================== rts/include/stg/MiscClosures.h ===================================== @@ -512,7 +512,6 @@ RTS_FUN_DECL(stg_takeMVarzh); RTS_FUN_DECL(stg_putMVarzh); RTS_FUN_DECL(stg_readMVarzh); RTS_FUN_DECL(stg_tryTakeMVarzh); -RTS_FUN_DECL(stg_tryPutMVarzh); RTS_FUN_DECL(stg_tryReadMVarzh); RTS_FUN_DECL(stg_waitReadzh); View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/689aafcd2e76283b6eee6659d0533f7... -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/689aafcd2e76283b6eee6659d0533f7... 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