search for: always_poison

...d-out by the select. The next section will dive into this in greater detail. # Computation Involving Poison Values Poison in a computation results in poison if the result cannot be constrained by its non-poison operands. Examples of this rule which will result in poison: ``` %add = add i32 %x, %always_poison %sub = sub i32 %x, %always_poison %xor = xor i32 %x, %always_poison %mul = mul i32 %always_poison, 1 ``` Examples of this rule which do not result in poison: ``` %or = or i32 %always_poison, 2 %and = and i32 %always_poison, 2 %mul = mul i32 %always_poison, 0 ``` In fact, it would be...

On 01/28/2015 07:02 AM, Sean Silva wrote: > Could you maybe provide an example where replacing `%always_poison` > with `undef` will change the meaning? At least for me, the thing that > I'm most unclear about is how poison differs from undef. I will second this request for much the same reason. > > -- Sean Silva > > On Wed, Jan 28, 2015 at 2:50 AM, David Majnemer > <david.majn...

...gt; > > > # Computation Involving Poison Values > > Poison in a computation results in poison if the result cannot be > > constrained by its non-poison operands. > > > > Examples of this rule which will result in poison: > > ``` > > %add = add i32 %x, %always_poison > > %sub = sub i32 %x, %always_poison > > %xor = xor i32 %x, %always_poison > > %mul = mul i32 %always_poison, 1 > > ``` > > > > Examples of this rule which do not result in poison: > > ``` > > %or = or i32 %always_poison, 2 > > %and...

...il. > > > > # Computation Involving Poison Values > > Poison in a computation results in poison if the result cannot be > constrained by its non-poison operands. > > > > Examples of this rule which will result in poison: > > ``` > > %add = add i32 %x, %always_poison > > %sub = sub i32 %x, %always_poison > > %xor = xor i32 %x, %always_poison > > %mul = mul i32 %always_poison, 1 > > ``` > > > > Examples of this rule which do not result in poison: > > ``` > > %or = or i32 %always_poison, 2 > > %and...

On Wed, Jan 28, 2015 at 8:53 PM, Philip Reames <listmail at philipreames.com> wrote: > On 01/28/2015 07:02 AM, Sean Silva wrote: > > Could you maybe provide an example where replacing `%always_poison` with > `undef` will change the meaning? At least for me, the thing that I'm most > unclear about is how poison differs from undef. > > I will second this request for much the same reason. > undef isn't strong enough to perform the simplification "a + 1 > a -->...