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Constant folding for integer casts (#8095)

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This commit is contained in:
LemonBoy
2018-08-31 13:45:42 +02:00
committed by Andreas Rumpf
parent b74faf354e
commit 2c8361bd39
3 changed files with 86 additions and 8 deletions
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32
compiler/semfold.nim
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@@ -450,21 +450,38 @@ proc rangeCheck(n: PNode, value: BiggestInt; g: ModuleGraph) =
localError(g.config, n.info, "cannot convert " & $value &
" to " & typeToString(n.typ))
proc foldConv*(n, a: PNode; g: ModuleGraph; check = false): PNode =
proc foldConv(n, a: PNode; g: ModuleGraph; check = false): PNode =
let dstTyp = skipTypes(n.typ, abstractRange)
let srcTyp = skipTypes(a.typ, abstractRange)
# XXX range checks?
case skipTypes(n.typ, abstractRange).kind
of tyInt..tyInt64, tyUInt..tyUInt64:
case skipTypes(a.typ, abstractRange).kind
case dstTyp.kind
of tyInt..tyInt64, tyUint..tyUInt64:
case srcTyp.kind
of tyFloat..tyFloat64:
result = newIntNodeT(int(getFloat(a)), n, g)
of tyChar: result = newIntNodeT(getOrdValue(a), n, g)
of tyChar:
result = newIntNodeT(getOrdValue(a), n, g)
of tyUInt8..tyUInt32, tyInt8..tyInt32:
let fromSigned = srcTyp.kind in tyInt..tyInt64
let toSigned = dstTyp.kind in tyInt..tyInt64
let mask = lastOrd(g.config, dstTyp, fixedUnsigned=true)
var val =
if toSigned:
a.getOrdValue mod mask
else:
a.getOrdValue and mask
result = newIntNodeT(val, n, g)
else:
result = a
result.typ = n.typ
if check and result.kind in {nkCharLit..nkUInt64Lit}:
rangeCheck(n, result.intVal, g)
of tyFloat..tyFloat64:
case skipTypes(a.typ, abstractRange).kind
case srcTyp.kind
of tyInt..tyInt64, tyEnum, tyBool, tyChar:
result = newFloatNodeT(toBiggestFloat(getOrdValue(a)), n, g)
else:
@@ -742,7 +759,8 @@ proc getConstExpr(m: PSym, n: PNode; g: ModuleGraph): PNode =
of nkHiddenStdConv, nkHiddenSubConv, nkConv:
var a = getConstExpr(m, n.sons[1], g)
if a == nil: return
result = foldConv(n, a, g, check=n.kind == nkHiddenStdConv)
# XXX: we should enable `check` for other conversion types too
result = foldConv(n, a, g, check=n.kind == nkHiddenSubConv)
of nkCast:
var a = getConstExpr(m, n.sons[1], g)
if a == nil: return

2
lib/posix/posix_linux_amd64_consts.nim
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@@ -300,7 +300,7 @@ const IPPROTO_TCP* = cint(6)
const IPPROTO_UDP* = cint(17)
const INADDR_ANY* = InAddrScalar(0)
const INADDR_LOOPBACK* = InAddrScalar(2130706433)
const INADDR_BROADCAST* = InAddrScalar(-1)
const INADDR_BROADCAST* = InAddrScalar(4294967295)
const INET_ADDRSTRLEN* = cint(16)
const INET6_ADDRSTRLEN* = cint(46)
const IPV6_JOIN_GROUP* = cint(20)

60
tests/arithm/tcast.nim Normal file
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@@ -0,0 +1,60 @@
discard """
output: '''
B0
B1
B2
B3
'''
"""
template crossCheck(ty: untyped, exp: untyped) =
let rt = ty(exp)
const ct = ty(exp)
if $rt != $ct:
echo "Got ", ct
echo "Expected ", rt
block:
when true:
echo "B0"
crossCheck(int8, 0'i16 - 5'i16)
crossCheck(int16, 0'i32 - 5'i32)
crossCheck(int32, 0'i64 - 5'i64)
echo "B1"
crossCheck(uint8, 0'u8 - 5'u8)
crossCheck(uint16, 0'u16 - 5'u16)
crossCheck(uint32, 0'u32 - 5'u32)
crossCheck(uint64, 0'u64 - 5'u64)
echo "B2"
crossCheck(uint8, uint8.high + 5'u8)
crossCheck(uint16, uint16.high + 5'u16)
crossCheck(uint32, uint32.high + 5'u32)
crossCheck(uint64, (-1).uint64 + 5'u64)
echo "B3"
crossCheck(int8, 0'u8 - 5'u8)
crossCheck(int16, 0'u16 - 5'u16)
crossCheck(int32, 0'u32 - 5'u32)
crossCheck(int64, 0'u64 - 5'u64)
# crossCheck(int8, 0'u16 - 129'u16)
# crossCheck(uint8, 0'i16 + 257'i16)
# Signed integer {under,over}flow is guarded against
# crossCheck(int8, int8.high + 5'i8)
# crossCheck(int16, int16.high + 5'i16)
# crossCheck(int32, int32.high + 5'i32)
# crossCheck(int64, int64.high + 5'i64)
# crossCheck(int8, int8.low - 5'i8)
# crossCheck(int16, int16.low - 5'i16)
# crossCheck(int32, int32.low - 5'i32)
# crossCheck(int64, int64.low - 5'i64)
# crossCheck(uint8, 0'i8 - 5'i8)
# crossCheck(uint16, 0'i16 - 5'i16)
# crossCheck(uint32, 0'i32 - 5'i32)
# crossCheck(uint64, 0'i64 - 5'i64)