[Git][ghc/ghc][master] Revert "NCG: Fix a bug in jump shortcutting."

Marge Bot (@marge-bot) gitlab at gitlab.haskell.org
Wed Mar 27 01:18:08 UTC 2024



Marge Bot pushed to branch master at Glasgow Haskell Compiler / GHC


Commits:
cfeb70d3 by Rodrigo Mesquita at 2024-03-26T21:17:24-04:00
Revert "NCG: Fix a bug in jump shortcutting."

This reverts commit 5bd8ed53dcefe10b72acb5729789e19ceb22df66.

Fixes #24586

- - - - -


12 changed files:

- compiler/GHC/CmmToAsm/AArch64/Instr.hs
- compiler/GHC/CmmToAsm/BlockLayout.hs
- compiler/GHC/CmmToAsm/Instr.hs
- compiler/GHC/CmmToAsm/PPC/Instr.hs
- compiler/GHC/CmmToAsm/Reg/Graph/SpillClean.hs
- compiler/GHC/CmmToAsm/Reg/Linear/JoinToTargets.hs
- compiler/GHC/CmmToAsm/Reg/Liveness.hs
- compiler/GHC/CmmToAsm/X86/Instr.hs
- − testsuite/tests/codeGen/should_run/T24507.hs
- − testsuite/tests/codeGen/should_run/T24507.stdout
- − testsuite/tests/codeGen/should_run/T24507_cmm.cmm
- testsuite/tests/codeGen/should_run/all.T


Changes:

=====================================
compiler/GHC/CmmToAsm/AArch64/Instr.hs
=====================================
@@ -301,20 +301,15 @@ isJumpishInstr instr = case instr of
 -- | Checks whether this instruction is a jump/branch instruction.
 -- One that can change the flow of control in a way that the
 -- register allocator needs to worry about.
-jumpDestsOfInstr :: Instr -> [Maybe BlockId]
+jumpDestsOfInstr :: Instr -> [BlockId]
 jumpDestsOfInstr (ANN _ i) = jumpDestsOfInstr i
-jumpDestsOfInstr i = case i of
-    (CBZ _ t) -> [ mkDest t ]
-    (CBNZ _ t) -> [ mkDest t ]
-    (J t) -> [ mkDest t ]
-    (B t) -> [ mkDest t ]
-    (BL t _ _) -> [ mkDest t ]
-    (BCOND _ t) -> [ mkDest t ]
-    _ -> []
-  where
-    mkDest (TBlock id) = Just id
-    mkDest TLabel{} = Nothing
-    mkDest TReg{} = Nothing
+jumpDestsOfInstr (CBZ _ t) = [ id | TBlock id <- [t]]
+jumpDestsOfInstr (CBNZ _ t) = [ id | TBlock id <- [t]]
+jumpDestsOfInstr (J t) = [id | TBlock id <- [t]]
+jumpDestsOfInstr (B t) = [id | TBlock id <- [t]]
+jumpDestsOfInstr (BL t _ _) = [ id | TBlock id <- [t]]
+jumpDestsOfInstr (BCOND _ t) = [ id | TBlock id <- [t]]
+jumpDestsOfInstr _ = []
 
 -- | Change the destination of this jump instruction.
 -- Used in the linear allocator when adding fixup blocks for join


=====================================
compiler/GHC/CmmToAsm/BlockLayout.hs
=====================================
@@ -771,7 +771,7 @@ dropJumps :: forall a i. Instruction i => LabelMap a -> [GenBasicBlock i]
 dropJumps _    [] = []
 dropJumps info (BasicBlock lbl ins:todo)
     | Just ins <- nonEmpty ins --This can happen because of shortcutting
-    , [Just dest] <- jumpDestsOfInstr (NE.last ins)
+    , [dest] <- jumpDestsOfInstr (NE.last ins)
     , BasicBlock nextLbl _ : _ <- todo
     , not (mapMember dest info)
     , nextLbl == dest
@@ -870,7 +870,7 @@ mkNode edgeWeights block@(BasicBlock id instrs) =
               | length successors > 2 || edgeWeight info <= 0 -> []
               | otherwise -> [target]
           | Just instr <- lastMaybe instrs
-          , [one] <- jumpBlockDestsOfInstr instr
+          , [one] <- jumpDestsOfInstr instr
           = [one]
           | otherwise = []
 


=====================================
compiler/GHC/CmmToAsm/Instr.hs
=====================================
@@ -17,8 +17,6 @@ import GHC.Cmm.BlockId
 import GHC.CmmToAsm.Config
 import GHC.Data.FastString
 
-import Data.Maybe (catMaybes)
-
 -- | Holds a list of source and destination registers used by a
 --      particular instruction.
 --
@@ -75,17 +73,9 @@ class Instruction instr where
 
         -- | Give the possible destinations of this jump instruction.
         --      Must be defined for all jumpish instructions.
-        --      Returns Nothing for non BlockId destinations.
         jumpDestsOfInstr
-                :: instr -> [Maybe BlockId]
-
-        -- | Give the possible block destinations of this jump instruction.
-        --      Must be defined for all jumpish instructions.
-        jumpBlockDestsOfInstr
                 :: instr -> [BlockId]
 
-        jumpBlockDestsOfInstr = catMaybes . jumpDestsOfInstr
-
 
         -- | Change the destination of this jump instruction.
         --      Used in the linear allocator when adding fixup blocks for join


=====================================
compiler/GHC/CmmToAsm/PPC/Instr.hs
=====================================
@@ -513,15 +513,12 @@ isJumpishInstr instr
 -- | Checks whether this instruction is a jump/branch instruction.
 -- One that can change the flow of control in a way that the
 -- register allocator needs to worry about.
-jumpDestsOfInstr :: Instr -> [Maybe BlockId]
+jumpDestsOfInstr :: Instr -> [BlockId]
 jumpDestsOfInstr insn
   = case insn of
-        BCC _ id _       -> [Just id]
-        BCCFAR _ id _    -> [Just id]
-        BCTR targets _ _ -> targets
-        BCTRL{}          -> [Nothing]
-        BL{}             -> [Nothing]
-        JMP{}            -> [Nothing]
+        BCC _ id _       -> [id]
+        BCCFAR _ id _    -> [id]
+        BCTR targets _ _ -> [id | Just id <- targets]
         _                -> []
 
 


=====================================
compiler/GHC/CmmToAsm/Reg/Graph/SpillClean.hs
=====================================
@@ -207,7 +207,7 @@ cleanForward platform blockId assoc acc (li : instrs)
 
         -- Remember the association over a jump.
         | LiveInstr instr _     <- li
-        , targets               <- jumpBlockDestsOfInstr instr
+        , targets               <- jumpDestsOfInstr instr
         , not $ null targets
         = do    mapM_ (accJumpValid assoc) targets
                 cleanForward platform blockId assoc (li : acc) instrs
@@ -386,7 +386,7 @@ cleanBackward' liveSlotsOnEntry reloadedBy noReloads acc (li : instrs)
         --       it always does, but if those reloads are cleaned the slot
         --       liveness map doesn't get updated.
         | LiveInstr instr _     <- li
-        , targets               <- jumpBlockDestsOfInstr instr
+        , targets               <- jumpDestsOfInstr instr
         = do
                 let slotsReloadedByTargets
                         = IntSet.unions


=====================================
compiler/GHC/CmmToAsm/Reg/Linear/JoinToTargets.hs
=====================================
@@ -57,7 +57,7 @@ joinToTargets block_live id instr
         = return ([], instr)
 
         | otherwise
-        = joinToTargets' block_live [] id instr (jumpBlockDestsOfInstr instr)
+        = joinToTargets' block_live [] id instr (jumpDestsOfInstr instr)
 
 -----
 joinToTargets'


=====================================
compiler/GHC/CmmToAsm/Reg/Liveness.hs
=====================================
@@ -468,7 +468,7 @@ slurpReloadCoalesce live
 
                 -- if we hit a jump, remember the current slotMap
                 | LiveInstr (Instr instr) _     <- li
-                , targets                       <- jumpBlockDestsOfInstr instr
+                , targets                       <- jumpDestsOfInstr instr
                 , not $ null targets
                 = do    mapM_   (accSlotMap slotMap) targets
                         return  (slotMap, Nothing)
@@ -760,7 +760,7 @@ sccBlocks blocks entries mcfg = map (fmap node_payload) sccs
         sccs = stronglyConnCompG g2
 
         getOutEdges :: Instruction instr => [instr] -> [BlockId]
-        getOutEdges instrs = concatMap jumpBlockDestsOfInstr instrs
+        getOutEdges instrs = concatMap jumpDestsOfInstr instrs
 
         -- This is truly ugly, but I don't see a good alternative.
         -- Digraph just has the wrong API.  We want to identify nodes
@@ -837,7 +837,7 @@ checkIsReverseDependent sccs'
 
         slurpJumpDestsOfBlock (BasicBlock _ instrs)
                 = unionManyUniqSets
-                $ map (mkUniqSet . jumpBlockDestsOfInstr)
+                $ map (mkUniqSet . jumpDestsOfInstr)
                         [ i | LiveInstr i _ <- instrs]
 
 
@@ -1047,7 +1047,7 @@ liveness1 platform liveregs blockmap (LiveInstr instr _)
 
             -- union in the live regs from all the jump destinations of this
             -- instruction.
-            targets      = jumpBlockDestsOfInstr instr -- where we go from here
+            targets      = jumpDestsOfInstr instr -- where we go from here
             not_a_branch = null targets
 
             targetLiveRegs target


=====================================
compiler/GHC/CmmToAsm/X86/Instr.hs
=====================================
@@ -672,16 +672,13 @@ isJumpishInstr instr
 
 jumpDestsOfInstr
         :: Instr
-        -> [Maybe BlockId]
+        -> [BlockId]
 
 jumpDestsOfInstr insn
   = case insn of
-        JXX _ id        -> [Just id]
-        JMP_TBL _ ids _ _ -> [(mkDest dest) | Just dest <- ids]
+        JXX _ id        -> [id]
+        JMP_TBL _ ids _ _ -> [id | Just (DestBlockId id) <- ids]
         _               -> []
-    where
-      mkDest (DestBlockId id) = Just id
-      mkDest _ = Nothing
 
 
 patchJumpInstr


=====================================
testsuite/tests/codeGen/should_run/T24507.hs deleted
=====================================
@@ -1,15 +0,0 @@
-{-# LANGUAGE MagicHash #-}
-{-# LANGUAGE UnboxedTuples #-}
-{-# LANGUAGE GHCForeignImportPrim #-}
-{-# LANGUAGE UnliftedFFITypes #-}
-
-module Main where
-
-import GHC.Exts
-
-foreign import prim "foo" foo :: Int# -> Int#
-
-main = do
-
-    let f x = case x of I# x' -> case foo x' of x -> print (I# x)
-    mapM_ f [1..7]
\ No newline at end of file


=====================================
testsuite/tests/codeGen/should_run/T24507.stdout deleted
=====================================
@@ -1,7 +0,0 @@
-1
-2
-2
-2
-2
-2
-2


=====================================
testsuite/tests/codeGen/should_run/T24507_cmm.cmm deleted
=====================================
@@ -1,35 +0,0 @@
-#include "Cmm.h"
-
-bar() {
-    return (2);
-}
-
-foo(W_ x) {
-
-    switch(x) {
-        case 1: goto a;
-        case 2: goto b;
-        case 3: goto c;
-        case 4: goto d;
-        case 5: goto e;
-        case 6: goto f;
-        case 7: goto g;
-    }
-    return (1);
-
-    a:
-    return (1);
-    b:
-    jump bar();
-    c:
-    jump bar();
-    d:
-    jump bar();
-    e:
-    jump bar();
-    f:
-    jump bar();
-    g:
-    jump bar();
-
-}


=====================================
testsuite/tests/codeGen/should_run/all.T
=====================================
@@ -243,6 +243,3 @@ test('MulMayOflo_full',
 test('T24264run', normal, compile_and_run, [''])
 test('T24295a', normal, compile_and_run, ['-O -floopification'])
 test('T24295b', normal, compile_and_run, ['-O -floopification -fpedantic-bottoms'])
-
-test('T24507', [req_cmm], multi_compile_and_run,
-                 ['T24507', [('T24507_cmm.cmm', '')], '-O2'])



View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/cfeb70d3fed9c135295359296208bd800bab418f

-- 
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/cfeb70d3fed9c135295359296208bd800bab418f
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