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fixes #72, simplify SDIV implementation

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andri lim 2019-08-12 17:39:29 +07:00 committed by zah
parent 63afc9fd36
commit 74d68ea425
2 changed files with 90 additions and 7 deletions
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8
nimbus/vm/interpreter/opcodes_impl.nim
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@ -49,17 +49,13 @@ op sdiv, inline = true, lhs, rhs:
## 0x05, Signed division
var r: UInt256
if rhs != 0:
const min = (1.u256 shl 255) - 1.u256
var a = lhs
var b = rhs
var signA, signB: bool
extractSign(a, signA)
extractSign(b, signB)
if a == min and b == not zero(UInt256):
r = min
else:
r = a div b
setSign(r, signA xor signB)
r = a div b
setSign(r, signA xor signB)
push(r)
op modulo, inline = true, lhs, rhs:

89
tests/test_op_arith.nim
View File

@ -195,7 +195,7 @@ suite "Arithmetic Opcodes":
SDIV
stack: "0x0000000000000000000000000000000000000000000000000000000000000001"
assembler: # SDIV OP
assembler: # SDIV OP, SDIV by zero should be zero
title: "SDIV_3"
code:
PUSH1 "0x00"
@ -211,6 +211,93 @@ suite "Arithmetic Opcodes":
success: false
stack: "0xFF"
assembler: # -2^255 SDIV -1 = -2^255 (special case in yellow paper)
title: "SDIV_5"
code:
PUSH32 "0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF" # -1
PUSH32 "0x8000000000000000000000000000000000000000000000000000000000000000" # -2^255 == low(int256)
SDIV
stack: "0x8000000000000000000000000000000000000000000000000000000000000000" # -2^255 == low(int256)
assembler: # -2^255 SDIV 1 = -2^255
title: "SDIV_6"
code:
PUSH32 "0x0000000000000000000000000000000000000000000000000000000000000001" # 1
PUSH32 "0x8000000000000000000000000000000000000000000000000000000000000000" # -2^255 == low(int256)
SDIV
stack: "0x8000000000000000000000000000000000000000000000000000000000000000" # -2^255 == low(int256)
assembler: # -2 SDIV 2 = -1
title: "SDIV_7"
code:
PUSH32 "0x0000000000000000000000000000000000000000000000000000000000000002" # 2
PUSH32 "0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFE" # -2
SDIV
stack: "0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF" # -1
assembler: # 4 SDIV -2 = -2
title: "SDIV_8"
code:
PUSH32 "0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFE" # -2
PUSH32 "0x0000000000000000000000000000000000000000000000000000000000000004" # 4
SDIV
stack: "0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFE" # -2
assembler: # -4 SDIV 2 = -2
title: "SDIV_9"
code:
PUSH32 "0x0000000000000000000000000000000000000000000000000000000000000002" # -4
PUSH32 "0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFC" # 2
SDIV
stack: "0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFE" # -2
assembler: # -1 SDIV 2 = 0
title: "SDIV_10"
code:
PUSH32 "0x0000000000000000000000000000000000000000000000000000000000000002" # 2
PUSH32 "0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF" # -1
SDIV
stack: "0x00" # 0
assembler: # low(int256) SDIV low(int256) = 1
title: "SDIV_11"
code:
PUSH32 "0x8000000000000000000000000000000000000000000000000000000000000000" # low(int256)
PUSH32 "0x8000000000000000000000000000000000000000000000000000000000000000" # low(int256)
SDIV
stack: "0x01" # 1
assembler: # low(int256) SDIV 2
title: "SDIV_12"
code:
PUSH32 "0x0000000000000000000000000000000000000000000000000000000000000002" # 2
PUSH32 "0x8000000000000000000000000000000000000000000000000000000000000000" # low(int256)
SDIV
stack: "0xC000000000000000000000000000000000000000000000000000000000000000" # negative half low(int256)
assembler: # low(int256) SDIV -2
title: "SDIV_13"
code:
PUSH32 "0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFE" # -2
PUSH32 "0x8000000000000000000000000000000000000000000000000000000000000000" # low(int256)
SDIV
stack: "0x4000000000000000000000000000000000000000000000000000000000000000" # positive version of SDIV_12
assembler:
title: "SDIV_14"
code:
PUSH1 "0x01" # 1
PUSH1 "0x7F" # 127
SHL # 1 shl 127 (move the bit to the center or 128th position)
PUSH1 "0x01" # 1
PUSH1 "0xFF" # 255
SHL # 1 shl 255 (create low(int256))
SDIV
stack: "0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF00000000000000000000000000000000" # half of the hi bits are set
fork: constantinople
assembler: # SUB OP
title: "SUB_1"
code: