diff options
| -rw-r--r-- | libraries/base/GHC/Int.hs | 62 |
1 files changed, 44 insertions, 18 deletions
diff --git a/libraries/base/GHC/Int.hs b/libraries/base/GHC/Int.hs index 2fe7d6ce8c..6713130c14 100644 --- a/libraries/base/GHC/Int.hs +++ b/libraries/base/GHC/Int.hs @@ -136,6 +136,11 @@ instance Integral Int8 where | otherwise = I8# (intToInt8# ((int8ToInt# x#) `quotInt#` (int8ToInt# y#))) rem (I8# x#) y@(I8# y#) | y == 0 = divZeroError + -- The quotRem CPU instruction might fail for 'minBound + -- `quotRem` -1' if it is an instruction for exactly this + -- width of signed integer. But, 'minBound `rem` -1' is + -- well-defined (0). We therefore special-case it. + | y == (-1) = 0 | otherwise = I8# (intToInt8# ((int8ToInt# x#) `remInt#` (int8ToInt# y#))) div x@(I8# x#) y@(I8# y#) | y == 0 = divZeroError @@ -143,6 +148,11 @@ instance Integral Int8 where | otherwise = I8# (intToInt8# ((int8ToInt# x#) `divInt#` (int8ToInt# y#))) mod (I8# x#) y@(I8# y#) | y == 0 = divZeroError + -- The divMod CPU instruction might fail for 'minBound + -- `divMod` -1' if it is an instruction for exactly this + -- width of signed integer. But, 'minBound `mod` -1' is + -- well-defined (0). We therefore special-case it. + | y == (-1) = 0 | otherwise = I8# (intToInt8# ((int8ToInt# x#) `modInt#` (int8ToInt# y#))) quotRem x@(I8# x#) y@(I8# y#) | y == 0 = divZeroError @@ -343,6 +353,11 @@ instance Integral Int16 where | otherwise = I16# (intToInt16# ((int16ToInt# x#) `quotInt#` (int16ToInt# y#))) rem (I16# x#) y@(I16# y#) | y == 0 = divZeroError + -- The quotRem CPU instruction might fail for 'minBound + -- `quotRem` -1' if it is an instruction for exactly this + -- width of signed integer. But, 'minBound `rem` -1' is + -- well-defined (0). We therefore special-case it. + | y == (-1) = 0 | otherwise = I16# (intToInt16# ((int16ToInt# x#) `remInt#` (int16ToInt# y#))) div x@(I16# x#) y@(I16# y#) | y == 0 = divZeroError @@ -350,6 +365,11 @@ instance Integral Int16 where | otherwise = I16# (intToInt16# ((int16ToInt# x#) `divInt#` (int16ToInt# y#))) mod (I16# x#) y@(I16# y#) | y == 0 = divZeroError + -- The divMod CPU instruction might fail for 'minBound + -- `divMod` -1' if it is an instruction for exactly this + -- width of signed integer. But, 'minBound `mod` -1' is + -- well-defined (0). We therefore special-case it. + | y == (-1) = 0 | otherwise = I16# (intToInt16# ((int16ToInt# x#) `modInt#` (int16ToInt# y#))) quotRem x@(I16# x#) y@(I16# y#) | y == 0 = divZeroError @@ -555,9 +575,10 @@ instance Integral Int32 where | otherwise = I32# (intToInt32# ((int32ToInt# x#) `quotInt#` (int32ToInt# y#))) rem (I32# x#) y@(I32# y#) | y == 0 = divZeroError - -- The quotRem CPU instruction fails for minBound `quotRem` -1, - -- but minBound `rem` -1 is well-defined (0). We therefore - -- special-case it. + -- The quotRem CPU instruction might fail for 'minBound + -- `quotRem` -1' if it is an instruction for exactly this + -- width of signed integer. But, 'minBound `rem` -1' is + -- well-defined (0). We therefore special-case it. | y == (-1) = 0 | otherwise = I32# (intToInt32# ((int32ToInt# x#) `remInt#` (int32ToInt# y#))) div x@(I32# x#) y@(I32# y#) @@ -566,9 +587,10 @@ instance Integral Int32 where | otherwise = I32# (intToInt32# ((int32ToInt# x#) `divInt#` (int32ToInt# y#))) mod (I32# x#) y@(I32# y#) | y == 0 = divZeroError - -- The divMod CPU instruction fails for minBound `divMod` -1, - -- but minBound `mod` -1 is well-defined (0). We therefore - -- special-case it. + -- The divMod CPU instruction might fail for 'minBound + -- `divMod` -1' if it is an instruction for exactly this + -- width of signed integer. But, 'minBound `mod` -1' is + -- well-defined (0). We therefore special-case it. | y == (-1) = 0 | otherwise = I32# (intToInt32# ((int32ToInt# x#) `modInt#` (int32ToInt# y#))) quotRem x@(I32# x#) y@(I32# y#) @@ -776,9 +798,10 @@ instance Integral Int64 where | otherwise = I64# (x# `quotInt64#` y#) rem (I64# x#) y@(I64# y#) | y == 0 = divZeroError - -- The quotRem CPU instruction fails for minBound `quotRem` -1, - -- but minBound `rem` -1 is well-defined (0). We therefore - -- special-case it. + -- The quotRem CPU instruction might fail for 'minBound + -- `quotRem` -1' if it is an instruction for exactly this + -- width of signed integer. But, 'minBound `rem` -1' is + -- well-defined (0). We therefore special-case it. | y == (-1) = 0 | otherwise = I64# (x# `remInt64#` y#) div x@(I64# x#) y@(I64# y#) @@ -787,9 +810,10 @@ instance Integral Int64 where | otherwise = I64# (x# `divInt64#` y#) mod (I64# x#) y@(I64# y#) | y == 0 = divZeroError - -- The divMod CPU instruction fails for minBound `divMod` -1, - -- but minBound `mod` -1 is well-defined (0). We therefore - -- special-case it. + -- The divMod CPU instruction might fail for 'minBound + -- `divMod` -1' if it is an instruction for exactly this + -- width of signed integer. But, 'minBound `mod` -1' is + -- well-defined (0). We therefore special-case it. | y == (-1) = 0 | otherwise = I64# (x# `modInt64#` y#) quotRem x@(I64# x#) y@(I64# y#) @@ -976,9 +1000,10 @@ instance Integral Int64 where | otherwise = I64# (x# `quotInt#` y#) rem (I64# x#) y@(I64# y#) | y == 0 = divZeroError - -- The quotRem CPU instruction fails for minBound `quotRem` -1, - -- but minBound `rem` -1 is well-defined (0). We therefore - -- special-case it. + -- The quotRem CPU instruction might fail for 'minBound + -- `quotRem` -1' if it is an instruction for exactly this + -- width of signed integer. But, 'minBound `rem` -1' is + -- well-defined (0). We therefore special-case it. | y == (-1) = 0 | otherwise = I64# (x# `remInt#` y#) div x@(I64# x#) y@(I64# y#) @@ -987,9 +1012,10 @@ instance Integral Int64 where | otherwise = I64# (x# `divInt#` y#) mod (I64# x#) y@(I64# y#) | y == 0 = divZeroError - -- The divMod CPU instruction fails for minBound `divMod` -1, - -- but minBound `mod` -1 is well-defined (0). We therefore - -- special-case it. + -- The divMod CPU instruction might fail for 'minBound + -- `divMod` -1' if it is an instruction for exactly this + -- width of signed integer. But, 'minBound `mod` -1' is + -- well-defined (0). We therefore special-case it. | y == (-1) = 0 | otherwise = I64# (x# `modInt#` y#) quotRem x@(I64# x#) y@(I64# y#) |