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fix #15704 #15597 wrong VM register was freed (#15705)

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* fix #15704 #15597 wrong VM register was freed

* same treatment for nkCheckedFieldExpr

* note concerning HighRegisterPressure

* bump NimPatch

* Update lib/system.nim

Co-authored-by: Andreas Rumpf <rumpf_a@web.de>
This commit is contained in:
Timothee Cour 2020-10-26 10:13:37 +02:00 • committed by GitHub
commit d4c2e2c53f
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2 changed files with 134 additions and 2 deletions
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compiler/vmgen.nim
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@ -247,6 +247,8 @@ proc freeTemp(c: PCtx; r: TRegister) =
proc getTempRange(cc: PCtx; n: int; kind: TSlotKind): TRegister =
# if register pressure is high, we re-use more aggressively:
let c = cc.prc
# we could also customize via the following (with proper caching in ConfigRef):
# let highRegisterPressure = cc.config.getConfigVar("vm.highRegisterPressure", "40").parseInt
if c.maxSlots >= HighRegisterPressure or c.maxSlots+n >= high(TRegister):
for i in 0..c.maxSlots-n:
if not c.slots[i].inUse:
@ -1508,14 +1510,14 @@ proc genAsgn(c: PCtx; le, ri: PNode; requiresCopy: bool) =
let tmp = c.genx(ri)
c.preventFalseAlias(le[0], opcWrObj, objR, idx, tmp)
c.freeTemp(tmp)
c.freeTemp(idx)
# c.freeTemp(idx) # BUGFIX, see nkDotExpr
c.freeTemp(objR)
of nkDotExpr:
let dest = c.genx(le[0], {gfNode})
let idx = genField(c, le[1])
let tmp = c.genx(ri)
c.preventFalseAlias(le, opcWrObj, dest, idx, tmp)
c.freeTemp(idx)
# c.freeTemp(idx) # BUGFIX: idx is an immediate (field position), not a register
c.freeTemp(tmp)
c.freeTemp(dest)
of nkDerefExpr, nkHiddenDeref: