[cfe-dev] [PATCH] [OpenCL] Conversions for ternary operations between scalar and vector

[Sahasrabuddhe, Sameer]

On 12/4/2014 9:38 PM, Colin Riddell wrote:
> Working with the OpenCL 1.2 CTS I discovered one of the tests fails 
> with the tip revision of clang. Firstly, I wonder if anyone else 
> working with OpenCL has came across an assertion like this:
>
> Type.cpp:841: clang::Type::ScalarTypeKind 
> clang::Type::getScalarTypeKind() const: Assertion `isScalarType()' 
> failed.
>
> As far as I can tell, non scalar values are trying to be implicitly 
> casted where vector types should be allowed to be arithmetically 
> converted to the element type used by the vector operand as well.

I can see the crash too. The problem is that the call to 
checkConditionalConvertScalarsToVectors() has already implicitly casted 
LHS and RHS to the same vector type as CondTy, but the subsequent code 
still assumes scalar types. But I am confused about this conversion. The 
OpenCL 1.2 spec says on page 220 that "The second and third expressions 
can be any type, as long their types match, or there is a conversion ... 
<snip>". It further says that the type of the entire expression is 
derived from the second and third expression, and nowhere does it 
mention the type of the first expression. Then what is the type of the 
following expression?

float2 = char2 ? float2 : float2

I actually get an error for this: "error: initializing 'float2' (vector 
of 2 'float' values) with an expression of incompatible type 'char2' 
(vector of 2 'char' values)". It seems Clang decided that the ternary 
expression has type char2. But from my understanding of the spec, the 
type should be float2.

How about the following? Are they valid, and what is their return type?

char2 ? int : float
char2 ? int : unsigned
float2 ? char : unsigned

Sameer.