Conditional Select Operators
For conditional select operands, the third and fourth operands determine the type returned. Third and fourth operands with same size, but different signedness, return the nearest common ancestor data type. For example:
- Return the nearest common ancestor data type if third and fourth operands are of the same size, but different signs:I16vec4 R = select_neq(Is16vec4, Is16vec4, Is16vec4, Iu16vec4);
- Conditional select for equality:R0 := (A0 == B0) ? C0 : D0; R1 := (A1 == B1) ? C1 : D1; R2 := (A2 == B2) ? C2 : D2; R3 := (A3 == B3) ? C3 : D3;
- Conditional select for inequality:R0 := (A0 != B0) ? C0 : D0; R1 := (A1 != B1) ? C1 : D1; R2 := (A2 != B2) ? C2 : D2; R3 := (A3 != B3) ? C3 : D3;
Conditional Select Symbols and Corresponding Intrinsics
The following table lists the conditional select symbols and their corresponding intrinsics:
Conditional Select
| Operators
| Syntax
| Corresponding Intrinsic
| Additional Intrinsic (Applies to All)
|
|---|---|---|---|---|
Equality
| select_eq | R = select_eq(A, B, C, D) | _mm_cmpeq_pi32 _mm_cmpeq_pi16 _mm_cmpeq_pi8 | _mm_and_si64 _mm_or_si64 _mm_andnot_si64 |
Inequality
| select_neq | R = select_neq(A, B, C, D) | _mm_cmpeq_pi32 _mm_cmpeq_pi16 _mm_cmpeq_pi8 | |
Greater Than
| select_gt | R = select_gt(A, B, C, D) | _mm_cmpgt_pi32 _mm_cmpgt_pi16 _mm_cmpgt_pi8 | |
Greater Thanor Equal To
| select_ge | R = select_gt(A, B, C, D) | _mm_cmpge_pi32 _mm_cmpge_pi16 _mm_cmpge_pi8 | |
Less Than
| select_lt | R = select_lt(A, B, C, D) | _mm_cmplt_pi32 _mm_cmplt_pi16 _mm_cmplt_pi8 | |
Less Thanor Equal To
| select_le | R = select_le(A, B, C, D) | _mm_cmple_pi32 _mm_cmple_pi16 _mm_cmple_pi8 |
Conditional Select Operator Overloading
All conditional select operands must be of the same size. The return data type is the nearest common ancestor of operands
C
and
D
. For conditional select operations using greater-than or less-than operations, the first and second operands must be signed as listed in the following table:
R
| Comparison
| A and B
| C
| D
|
|---|---|---|---|---|
I32vec2 R | select_eq select_ne | I[s|u]32vec2 | I[s|u]32vec2 | I[s|u]32vec2 |
I16vec4 R | I[s|u]16vec4 | I[s|u]16vec4 | ||
I8vec8 R | I[s|u]8vec8 | I[s|u]8vec8 | ||
I32vec2 R | select_gt select_ge select_lt select_le | Is32vec2 | Is32vec2 | Is32vec2 |
I16vec4 R | Is16vec4 | Is16vec4 | ||
I8vec8 R | Is8vec8 | Is8vec8 |
Conditional Select Operator Return Value Mapping
The following table lists the mapping of return values from
R0
to
R7
for any number of elements. The same return value mappings also apply when there are fewer than four return values.
Return Value
| A Operands
| Available Operators
| B Operands
| C and D Operands
| |||||
|---|---|---|---|---|---|---|---|---|---|
R0:=
| A0
| ==
| !=
| >
| >=
| <
| <=
| B0
| C0 : D0;
|
R1:=
| A0
| ==
| !=
| >
| >=
| <
| <=
| B0
| C1 : D1;
|
R2:=
| A0
| ==
| !=
| >
| >=
| <
| <=
| B0
| C2 : D2;
|
R3:=
| A0
| ==
| !=
| >
| >=
| <
| <=
| B0
| C3 : D3;
|
R4:=
| A0
| ==
| !=
| >
| >=
| <
| <=
| B0
| C4 : D4;
|
R5:=
| A0
| ==
| !=
| >
| >=
| <
| <=
| B0
| C5 : D5;
|
R6:=
| A0
| ==
| !=
| >
| >=
| <
| <=
| B0
| C6 : D6;
|
R7:=
| A0
| ==
| !=
| >
| >=
| <
| <=
| B0
| C7 : D7;
|