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First implementation of constant propagation
Local constant variables initialized with compile-time constants are optimized away from the code.
This commit is contained in:
Roberto Ierusalimschy
parent
be8445d7e4
commit
f6aab3ec1f
12 changed files with 249 additions and 119 deletions
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@ -7,6 +7,22 @@ if T==nil then
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end
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print "testing code generation and optimizations"
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-- to test constant propagation
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local <const> k0 = 0
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local <const> k1 = 1
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local <const> k3 = 3
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local <const> k6 = k3 + (k3 << k0)
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local <const> kFF0 = 0xFF0
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local <const> k3_78 = 3.78
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local <const> x, <const> k3_78_4 = 10, k3_78 / 4
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assert(x == 10)
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local <const> kx = "x"
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local <const> kTrue = true
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local <const> kFalse = false
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local <const> kNil = nil
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-- this code gave an error for the code checker
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do
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@ -27,12 +43,12 @@ end
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local function foo ()
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local a
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a = 3;
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a = k3;
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a = 0; a = 0.0; a = -7 + 7
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a = 3.78/4; a = 3.78/4
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a = -3.78/4; a = 3.78/4; a = -3.78/4
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a = k3_78/4; a = k3_78_4
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a = -k3_78/4; a = k3_78/4; a = -3.78/4
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a = -3.79/4; a = 0.0; a = -0;
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a = 3; a = 3.0; a = 3; a = 3.0
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a = k3; a = 3.0; a = 3; a = 3.0
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end
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checkKlist(foo, {3.78/4, -3.78/4, -3.79/4})
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@ -86,10 +102,11 @@ end, 'CLOSURE', 'NEWTABLE', 'GETTABUP', 'CALL', 'SETLIST', 'CALL', 'RETURN')
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-- sequence of LOADNILs
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check(function ()
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local <const> kNil = nil
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local a,b,c
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local d; local e;
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local f,g,h;
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d = nil; d=nil; b=nil; a=nil; c=nil;
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d = nil; d=nil; b=nil; a=kNil; c=nil;
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end, 'LOADNIL', 'RETURN0')
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check(function ()
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@ -109,7 +126,7 @@ check (function (a,b,c) return a end, 'RETURN1')
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-- infinite loops
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check(function () while true do local a = -1 end end,
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check(function () while kTrue do local a = -1 end end,
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'LOADI', 'JMP', 'RETURN0')
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check(function () while 1 do local a = -1 end end,
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@ -125,9 +142,9 @@ check(function (a,b,c,d) return a..b..c..d end,
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-- not
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check(function () return not not nil end, 'LOADBOOL', 'RETURN1')
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check(function () return not not false end, 'LOADBOOL', 'RETURN1')
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check(function () return not not kFalse end, 'LOADBOOL', 'RETURN1')
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check(function () return not not true end, 'LOADBOOL', 'RETURN1')
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check(function () return not not 1 end, 'LOADBOOL', 'RETURN1')
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check(function () return not not k3 end, 'LOADBOOL', 'RETURN1')
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-- direct access to locals
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check(function ()
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@ -144,7 +161,8 @@ end,
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-- direct access to constants
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check(function ()
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local a,b
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a.x = 3.2
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local c = kNil
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a[kx] = 3.2
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a.x = b
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a[b] = 'x'
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end,
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@ -152,8 +170,9 @@ end,
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-- "get/set table" with numeric indices
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check(function (a)
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local <const> k255 = 255
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a[1] = a[100]
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a[255] = a[256]
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a[k255] = a[256]
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a[256] = 5
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end,
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'GETI', 'SETI',
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@ -170,7 +189,7 @@ end,
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check(function ()
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local a,b
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a[true] = false
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a[kTrue] = false
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end,
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'LOADNIL', 'LOADBOOL', 'SETTABLE', 'RETURN0')
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@ -238,37 +257,39 @@ local function checkF (func, val)
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end
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checkF(function () return 0.0 end, 0.0)
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checkI(function () return 0 end, 0)
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checkI(function () return -0//1 end, 0)
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checkI(function () return k0 end, 0)
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checkI(function () return -k0//1 end, 0)
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checkK(function () return 3^-1 end, 1/3)
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checkK(function () return (1 + 1)^(50 + 50) end, 2^100)
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checkK(function () return (-2)^(31 - 2) end, -0x20000000 + 0.0)
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checkF(function () return (-3^0 + 5) // 3.0 end, 1.0)
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checkI(function () return -3 % 5 end, 2)
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checkF(function () return (-k3^0 + 5) // 3.0 end, 1.0)
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checkI(function () return -k3 % 5 end, 2)
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checkF(function () return -((2.0^8 + -(-1)) % 8)/2 * 4 - 3 end, -5.0)
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checkF(function () return -((2^8 + -(-1)) % 8)//2 * 4 - 3 end, -7.0)
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checkI(function () return 0xF0.0 | 0xCC.0 ~ 0xAA & 0xFD end, 0xF4)
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checkI(function () return ~(~0xFF0 | 0xFF0) end, 0)
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checkI(function () return ~(~kFF0 | kFF0) end, 0)
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checkI(function () return ~~-1024.0 end, -1024)
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checkI(function () return ((100 << 6) << -4) >> 2 end, 100)
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checkI(function () return ((100 << k6) << -4) >> 2 end, 100)
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-- borders around MAXARG_sBx ((((1 << 17) - 1) >> 1) == 65535)
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local a = 17; local sbx = ((1 << a) - 1) >> 1 -- avoid folding
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checkI(function () return 65535 end, sbx)
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checkI(function () return -65535 end, -sbx)
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checkI(function () return 65536 end, sbx + 1)
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checkK(function () return 65537 end, sbx + 2)
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checkK(function () return -65536 end, -(sbx + 1))
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local <const> border = 65535
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checkI(function () return border end, sbx)
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checkI(function () return -border end, -sbx)
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checkI(function () return border + 1 end, sbx + 1)
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checkK(function () return border + 2 end, sbx + 2)
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checkK(function () return -(border + 1) end, -(sbx + 1))
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checkF(function () return 65535.0 end, sbx + 0.0)
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checkF(function () return -65535.0 end, -sbx + 0.0)
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checkF(function () return 65536.0 end, (sbx + 1.0))
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checkK(function () return 65537.0 end, (sbx + 2.0))
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checkK(function () return -65536.0 end, -(sbx + 1.0))
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local <const> border = 65535.0
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checkF(function () return border end, sbx + 0.0)
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checkF(function () return -border end, -sbx + 0.0)
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checkF(function () return border + 1 end, (sbx + 1.0))
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checkK(function () return border + 2 end, (sbx + 2.0))
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checkK(function () return -(border + 1) end, -(sbx + 1.0))
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-- immediate operands
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checkR(function (x) return x + 1 end, 10, 11, 'ADDI', 'RETURN1')
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checkR(function (x) return x + k1 end, 10, 11, 'ADDI', 'RETURN1')
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checkR(function (x) return 128 + x end, 0.0, 128.0, 'ADDI', 'RETURN1')
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checkR(function (x) return x * -127 end, -1.0, 127.0, 'MULI', 'RETURN1')
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checkR(function (x) return 20 * x end, 2, 40, 'MULI', 'RETURN1')
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@ -276,7 +297,7 @@ checkR(function (x) return x ^ -2 end, 2, 0.25, 'POWI', 'RETURN1')
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checkR(function (x) return x / 40 end, 40, 1.0, 'DIVI', 'RETURN1')
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checkR(function (x) return x // 1 end, 10.0, 10.0, 'IDIVI', 'RETURN1')
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checkR(function (x) return x % (100 - 10) end, 91, 1, 'MODI', 'RETURN1')
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checkR(function (x) return 1 << x end, 3, 8, 'SHLI', 'RETURN1')
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checkR(function (x) return k1 << x end, 3, 8, 'SHLI', 'RETURN1')
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checkR(function (x) return x << 2 end, 10, 40, 'SHRI', 'RETURN1')
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checkR(function (x) return x >> 2 end, 8, 2, 'SHRI', 'RETURN1')
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checkR(function (x) return x & 1 end, 9, 1, 'BANDK', 'RETURN1')
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@ -295,7 +316,7 @@ checkR(function (x) return x % (100.0 - 10) end, 91, 1.0, 'MODK', 'RETURN1')
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-- no foldings (and immediate operands)
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check(function () return -0.0 end, 'LOADF', 'UNM', 'RETURN1')
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check(function () return 3/0 end, 'LOADI', 'DIVI', 'RETURN1')
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check(function () return k3/0 end, 'LOADI', 'DIVI', 'RETURN1')
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check(function () return 0%0 end, 'LOADI', 'MODI', 'RETURN1')
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check(function () return -4//0 end, 'LOADI', 'IDIVI', 'RETURN1')
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check(function (x) return x >> 2.0 end, 'LOADF', 'SHR', 'RETURN1')
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@ -335,7 +356,7 @@ end,
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do -- tests for table access in upvalues
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local t
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check(function () t.x = t.y end, 'GETTABUP', 'SETTABUP')
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check(function () t[kx] = t.y end, 'GETTABUP', 'SETTABUP')
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check(function (a) t[a()] = t[a()] end,
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'MOVE', 'CALL', 'GETUPVAL', 'MOVE', 'CALL',
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'GETUPVAL', 'GETTABLE', 'SETTABLE')
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@ -379,6 +400,12 @@ function (a)
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end
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)
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checkequal(function () return 6 or true or nil end,
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function () return k6 or kTrue or kNil end)
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checkequal(function () return 6 and true or nil end,
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function () return k6 and kTrue or kNil end)
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print 'OK'
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