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Commit 64ec0ff4 authored by Tim Northover's avatar Tim Northover
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X86: use sub-register sequences for MOV*r0 operations

Instead of having a bunch of separate MOV8r0, MOV16r0, ... pseudo-instructions,
it's better to use a single MOV32r0 (which will expand to "xorl %reg, %reg")
and obtain other sizes with EXTRACT_SUBREG and SUBREG_TO_REG. The encoding is
smaller and partial register updates can sometimes be avoided.

Until recently, this sequence was a barrier to rematerialization though. That
should now be fixed so it's an appropriate time to make the change.

llvm-svn: 182928
parent 6cb9a427
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