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Re: [testsuite] require arm_little_endian in two tests

On Thu, 13 Oct 2011, Richard Earnshaw wrote:

> 2) Change the compiler to make initializers of vectors assign elements
> of initializers to consecutive lanes in a vector, rather than the
> current behaviour of 'casting' an array of elements to a vector.
> While the second would be my preferred change, I suspect it's too hard
> to fix, and may well cause code written for other targets to break on
> big-endian (altivec for example).

Indeed, vector initializers are part of the target-independent GNU C 
language and have target-independent semantics that the elements go in 
memory order, corresponding to the target-independent semantics of lane 
numbers where they appear in GENERIC, GIMPLE and (non-UNSPEC) RTL and any 
target-independent built-in functions that use such numbers.  (The issue 
here being, as you saw, that the lane numbers used in ARM-specific NEON 
intrinsics are for big-endian not the same as those used in 
target-independent features of GNU C and target-independent internal 
representations in GCC - hence various code to translate them between the 
two conventions when processing intrinsics into non-UNSPEC RTL, and to 
translate back when generating assembly instructions that encode lane 
numbers with the ARM conventions, as expounded at greater length at 

Joseph S. Myers

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