Janis Johnson writes: > On Wed, Apr 19, 2006 at 05:30:54PM +0200, Paolo Bonzini wrote: > > > > The C spec for Altivec (not the ISA) is a horrible spec that set a > > horrible de facto standard. To some extent, gcc already departed from > > Altivec, for example by disallowing the (vector int) (1, 2, 3, 4) syntax > > -- notice the parentheses instead of the braces -- because it was > > extremely hackish to implement in a Bison parser. > > The Motorola AltiVec PIM (sorry, I'm looking at a hard copy and don't > have the link handy) says: > > 2.4.2 Assignment > > If either the left hand side or right hand side of an expression has > a vector type, then both sides of the expression must be of the same > vector type. Thus, the expression a = b is valid and represents > assignment if a and b are of the same vector type (or if neither is > a vector type). Otherwise, the expression is invalid and must be > signaled as an error by the compiler. > > We can't blame this admittedly horrible spec for this one.
You seem to have missed "2.4.6 Type Casting "... None of the casts performs a conversion; the bit pattern of the result is the same as the bit pattern of the argument that is cast." Andrew.