the goal is to test if an integer value can fit in a 61bits Small Integer or not. The way to do it, is as in `isIntegerValue:`

We check that most significant 4 bits are all 0 or all 1. This is achieved by shifting `>> 60`. we should then have `xxxx0000 `or `xxxx1111` then we add `1` we should have `xxxx0001 `or `xxxx0000` we thus test: `& 0b1111 <= 1 `=> SmallInteger `& 0b1111 > 1` => NotSmallInteger

Unfortunately, the JIT have it right once:

genJumpIsSmallIntegerValue: aRegister scratch: scratchReg "Generate a test for aRegister containing an integer value in the SmallInteger range, and a jump if so, answering the jump. c.f. Spur64BitMemoryManager>>isIntegerValue:" <returnTypeC: #'AbstractInstruction *'> ^cogit MoveR: aRegister R: scratchReg; ArithmeticShiftRightCq: 63 - objectMemory numTagBits R: scratchReg; AddCq: 1 R: scratchReg; AndCq: 1 << (objectMemory numTagBits + 1) - 1 R: scratchReg; "sign and top numTags bits must be the same" CmpCq: 1 R: scratchReg; JumpLessOrEqual: 0

but wrong once:

genJumpNotSmallIntegerValue: aRegister scratch: scratchReg "Generate a test for aRegister containing an integer value outside the SmallInteger range, and a jump if so, answering the jump. c.f. Spur64BitMemoryManager>>isIntegerValue:" <returnTypeC: #'AbstractInstruction *'> ^cogit MoveR: aRegister R: scratchReg; ArithmeticShiftRightCq: 64 - objectMemory numTagBits R: scratchReg; AddCq: 1 R: scratchReg; AndCq: 1 << (objectMemory numTagBits + 1) - 1 R: scratchReg; "sign and top numTags bits must be the same" CmpCq: 1 R: scratchReg; JumpGreater: 0

64 should be 63, or we only test highest 3 bits...

Fortunately, this is only used in genPrimitiveDivide... Unfortunately, this triggers the `(self deny: SmallInteger minVal / -1 = SmallInteger minVal)` bug...

That's not the first time that this bug happens, I already reported it in the past, but it seems that we did not capitalize this test case (or it is not jitted?). If you accept a short method in Object:

testDiv | si | si := -1152921504606846976. ^si / -1

then force the jitter with a bench:

[self assert: 0 testDiv isLarge] bench

then you'll trigger it...