[PATCH] D12052: [X86][SSE] Add _mm_undefined_* intrinsics

[Simon Pilgrim via cfe-commits]

RKSimon added a comment.

Yes using that uninitialized value has worried me as well. I originally set it to zero (and considered using __ LINE __ or __ COUNTER __) but both introduce defined behaviour that I could see causing all sorts of problems further down the line in debug vs release builds. How undefined do we want our undefined to be? ;-)

I can create __builtin_ia32_undef64mmx / __builtin_ia32_undef128 / __builtin_ia32_undef256 / __builtin_ia32_undef512 if nobody can think of a better alternative?


Repository:
  rL LLVM

http://reviews.llvm.org/D12052