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Integrate OFront fix for unsigned DIV in heap.

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This commit is contained in:
David Brown 2016-12-28 12:33:34 +00:00
parent d292b4b2c9
commit 173c83f217
1 changed files with 25 additions and 17 deletions
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42
src/runtime/Heap.Mod
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@ -4,12 +4,13 @@ MODULE Heap;
before any other modules are initialized. *)
CONST
ModNameLen = 20;
CmdNameLen = 24;
SZA = SIZE(S.ADDRESS); (* Size of address *)
Unit = 4*SZA; (* smallest possible heap block *)
nofLists = 9; (* number of freelist entries excluding sentinel *)
heapSize0 = 8000*Unit; (* startup heap size *)
ModNameLen = 20;
CmdNameLen = 24;
SZA = SIZE(S.ADDRESS); (* Size of address *)
Unit = 4*SZA; (* Smallest possible heap block *)
nofLists = 9; (* Number of freelist entries excluding sentinel *)
heapSize0 = 8000*Unit; (* Startup heap size *)
heapMinExpand = 10000*Unit; (* minimum heap expansion size *)
(* all blocks look the same:
free blocks describe themselves: size = Unit
@ -78,6 +79,8 @@ MODULE Heap;
bigBlocks: S.ADDRESS;
allocated*: S.ADDRESS;
firstTry: BOOLEAN;
ldUnit: INTEGER; (* Unit = 2^ldUnit, for unsigned division expressed as logical shift right *)
(* extensible heap *)
heap-: S.ADDRESS; (* the sorted list of heap chunks *)
@ -210,8 +213,8 @@ MODULE Heap;
PROCEDURE ExtendHeap(blksz: S.ADDRESS);
VAR size, chnk, j, next: S.ADDRESS;
BEGIN
IF uLT(10000*Unit, blksz) THEN size := blksz
ELSE size := 10000*Unit (* additional heuristics *)
IF uLT(heapMinExpand, blksz) THEN size := blksz
ELSE size := heapMinExpand (* additional heuristics for avoiding many small heap expansions *)
END;
chnk := NewChunk(size);
IF chnk # 0 THEN
@ -239,15 +242,15 @@ MODULE Heap;
Lock();
S.GET(tag, blksz);
ASSERT((Unit = 16) OR (Unit = 32));
ASSERT(SIZE(S.PTR) = SIZE(S.ADDRESS));
ASSERT(blksz MOD Unit = 0);
i0 := blksz DIV Unit; i := i0;
IF uLT(i, nofLists) THEN adr := freeList[i];
i0 := S.LSH(blksz, -ldUnit); (*uDIV Unit*)
i := i0;
IF i < nofLists THEN adr := freeList[i];
WHILE adr = 0 DO INC(i); adr := freeList[i] END
END;
IF uLT(i, nofLists) THEN (* Unlink from freelist[i] *)
IF i < nofLists THEN (* Unlink from freelist[i] *)
S.GET(adr + nextOff, next);
freeList[i] := next;
IF i # i0 THEN (* Split *)
@ -266,11 +269,11 @@ MODULE Heap;
IF adr = 0 THEN (* Nothing free *)
IF firstTry THEN
GC(TRUE); INC(blksz, Unit);
(* Anti-thrashing heuristics: ensure 1/4 of the heap will not be allocated. *)
t := (allocated + blksz) DIV (3*Unit) * (4*Unit); (* Minimum required new heapsize *)
(* Anti-thrashing heuristics: ensure 1/5 of the heap will not be allocated. *)
t := S.LSH(allocated + blksz, -2) (*uDIV 4*) * 5 ; (* Minimum preferred heapsize *)
IF uLT(heapsize, t) THEN ExtendHeap(t - heapsize) END;
firstTry := FALSE; new := NEWREC(tag);
IF new = NIL THEN (* Fragmentation prevented allocation, heap is 1/4 free *)
IF new = NIL THEN (* Heap is 1/5 free but fragmentation prevented allocation *)
ExtendHeap(blksz);
new := NEWREC(tag) (* Will find a free block if heap has been expanded successfully *)
END;
@ -395,7 +398,8 @@ MODULE Heap;
S.PUT(start, start+SZA);
S.PUT(start+sizeOff, freesize);
S.PUT(start+sntlOff, NoPtrSntl);
i := freesize DIV Unit; freesize := 0;
i := S.LSH(freesize, -ldUnit) (*uDIV Unit*);
freesize := 0;
IF uLT(i, nofLists) THEN S.PUT(start + nextOff, freeList[i]); freeList[i] := start
ELSE S.PUT(start + nextOff, bigBlocks); bigBlocks := start
END
@ -416,7 +420,8 @@ MODULE Heap;
S.PUT(start, start+SZA);
S.PUT(start+sizeOff, freesize);
S.PUT(start+sntlOff, NoPtrSntl);
i := freesize DIV Unit; freesize := 0;
i := S.LSH(freesize, -ldUnit) (*uDIV Unit*);
freesize := 0;
IF uLT(i, nofLists) THEN S.PUT(start + nextOff, freeList[i]); freeList[i] := start
ELSE S.PUT(start + nextOff, bigBlocks); bigBlocks := start
END
@ -595,6 +600,9 @@ MODULE Heap;
heapMax := 0;
bigBlocks := 0;
ASSERT((Unit = 16) OR (Unit = 32));
IF Unit = 16 THEN ldUnit := 4 ELSE ldUnit := 5 END;
heap := NewChunk(heapSize0);
S.PUT(heap + nextChnkOff, AddressZero);