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First implementation of constant propagation

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Local constant variables initialized with compile-time constants
are optimized away from the code.
This commit is contained in:
Roberto Ierusalimschy
2019-07-12 11:38:42 -03:00
parent be8445d7e4
commit f6aab3ec1f
12 changed files with 249 additions and 119 deletions
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89
testes/code.lua
View File

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

24
testes/constructs.lua
View File

@@ -287,7 +287,7 @@ a,b = F(nil)==nil; assert(a == true and b == nil)
------------------------------------------------------------------
-- sometimes will be 0, sometimes will not...
_ENV.GLOB1 = math.floor(os.time()) % 2
_ENV.GLOB1 = math.random(0, 1)
-- basic expressions with their respective values
local basiccases = {
@@ -298,6 +298,26 @@ local basiccases = {
{"(0==_ENV.GLOB1)", 0 == _ENV.GLOB1},
}
local prog
if _ENV.GLOB1 == 0 then
basiccases[2][1] = "F" -- constant false
prog = [[
local <const> F = false
if %s then IX = true end
return %s
]]
else
basiccases[4][1] = "k10" -- constant 10
prog = [[
local <const> k10 = 10
if %s then IX = true end
return %s
]]
end
print('testing short-circuit optimizations (' .. _ENV.GLOB1 .. ')')
@@ -337,8 +357,6 @@ cases[1] = basiccases
for i = 2, level do cases[i] = createcases(i) end
print("+")
local prog = [[if %s then IX = true end; return %s]]
local i = 0
for n = 1, level do
for _, v in pairs(cases[n]) do

2
testes/locals.lua
View File

@@ -324,7 +324,7 @@ do
-- errors due to non-closable values
local function foo ()
local <toclose> x = 34
local <toclose> x = {}
end
local stat, msg = pcall(foo)
assert(not stat and string.find(msg, "variable 'x'"))

16
testes/math.lua
View File

@@ -270,7 +270,7 @@ else
end
do
local NaN = 0/0
local <const> NaN = 0/0
assert(not (NaN < 0))
assert(not (NaN > minint))
assert(not (NaN <= -9))
@@ -767,7 +767,8 @@ assert(a == '10' and b == '20')
do
print("testing -0 and NaN")
local mz, z = -0.0, 0.0
local <const> mz = -0.0
local <const> z = 0.0
assert(mz == z)
assert(1/mz < 0 and 0 < 1/z)
local a = {[mz] = 1}
@@ -775,17 +776,18 @@ do
a[z] = 2
assert(a[z] == 2 and a[mz] == 2)
local inf = math.huge * 2 + 1
mz, z = -1/inf, 1/inf
local <const> mz = -1/inf
local <const> z = 1/inf
assert(mz == z)
assert(1/mz < 0 and 0 < 1/z)
local NaN = inf - inf
local <const> NaN = inf - inf
assert(NaN ~= NaN)
assert(not (NaN < NaN))
assert(not (NaN <= NaN))
assert(not (NaN > NaN))
assert(not (NaN >= NaN))
assert(not (0 < NaN) and not (NaN < 0))
local NaN1 = 0/0
local <const> NaN1 = 0/0
assert(NaN ~= NaN1 and not (NaN <= NaN1) and not (NaN1 <= NaN))
local a = {}
assert(not pcall(rawset, a, NaN, 1))
@@ -814,8 +816,8 @@ end
-- the first call after seed 1007 should return 0x7a7040a5a323c9d6
do
-- all computations assume at most 32-bit integers
local h = 0x7a7040a5 -- higher half
local l = 0xa323c9d6 -- lower half
local <const> h = 0x7a7040a5 -- higher half
local <const> l = 0xa323c9d6 -- lower half
math.randomseed(1007)
-- get the low 'intbits' of the 64-bit expected result