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Negation in constant folding of '>>' may overflow

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This commit is contained in:
Roberto Ierusalimschy
2022-09-23 11:08:10 -03:00
parent cfbe378f90
commit 26be27459b
4 changed files with 19 additions and 4 deletions
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12
testes/bitwise.lua
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@@ -38,6 +38,18 @@ d = d << 32
assert(a | b ~ c & d == 0xF4000000 << 32)
assert(~~a == a and ~a == -1 ~ a and -d == ~d + 1)
do -- constant folding
local code = string.format("return -1 >> %d", math.maxinteger)
assert(load(code)() == 0)
local code = string.format("return -1 >> %d", math.mininteger)
assert(load(code)() == 0)
local code = string.format("return -1 << %d", math.maxinteger)
assert(load(code)() == 0)
local code = string.format("return -1 << %d", math.mininteger)
assert(load(code)() == 0)
end
assert(-1 >> 1 == (1 << (numbits - 1)) - 1 and 1 << 31 == 0x80000000)
assert(-1 >> (numbits - 1) == 1)
assert(-1 >> numbits == 0 and