Displaying 2 results from an estimated 2 matches for "poisonvalu".
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poison_val
2017 Nov 29
3
RFC: Adding 'no-overflow' keyword to 'sdiv'\'udiv' instructions
...Division by zero is undefined behavior. For vectors, if any element
of the divisor is zero, the operation has undefined behavior.
See the description of the ``nof`` keyword below for division by zero.
If the ``exact`` keyword is present, the result value of the ``udiv`` is
a :ref:`poison value <poisonvalues>` if %op1 is not a multiple of %op2 (as
such, "((a udiv exact b) mul b) == a").
``nof``stands for "No Overflow". If the ``nof`` keyword is present, the result is undefined behavior for division by zero.
If the ``nof`` keyword is not present, division by zero results in poi...
2015 Aug 11
2
NSW and ExtLdPromotion()
Hi, All:
I have a testcase which produced incorrect result, it's caused by the
combination of nsw flag and ExtLdPromotion, I am leaning to say Clang set
nsw flag incorrectly, but please let me know if I was wrong.
Here is the reduced testcase:
long long foo(int *a)
{
long long c;
c = *a * 1405;
return c;
}
Clang emitted the following IR (It is done by EmitMUL() in