ext_vector_type is not compatible with constexpr

[llvmbot]

Bugzilla Link	20157
Version	trunk
OS	All
Blocks	#30794
Reporter	LLVM Bugzilla Contributor
CC	@hfinkel,@RKSimon,@zygoloid
Fixed by commit(s)	b30c166

Extended Description

It seems many uses of a type based on ext_vector_type are not suitable for use in a constexpr, for example:

typedef float attribute((ext_vector_type(4))) float4;

constexpr float4 MultiplyByTwo(float4 x)
{
return x * 2.0f;
}

main.cpp:3:18: error: constexpr function never produces a constant expression [-Winvalid-constexpr]

constexpr float4 MultiplyByTwo(float4 x)
^
main.cpp:5:12: note: subexpression not valid in a constant expression

return x * 2.0f;
^
1 error generated.

[RKSimon]

typedef float attribute((ext_vector_type(4))) float4;

constexpr float4 MultiplyByTwo(float4 x)
{
return x * 2.0f;
}

Vector/ExtVector binary operator support was added by D79755 / rGb30c16670e42

[gnzlbg]

mentioned in issue #30794

[yronglin]

Vector/ExtVector binary operator was already supported (https://godbolt.org/z/qd1fvMxMb).