Commit Graph

4 Commits

Author SHA1 Message Date
Tim Northover 64ec0ff433 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
2013-05-30 13:19:42 +00:00
Preston Gurd 8b7ab4ba2b This patch adds the X86FixupLEAs pass, which will reduce instruction
latency for certain models of the Intel Atom family, by converting
instructions into their equivalent LEA instructions, when it is both
useful and possible to do so.

llvm-svn: 180573
2013-04-25 20:29:37 +00:00
Preston Gurd f2ea70ae4a Fix remaining lit tests which were failing when run on an Atom
processor.

Patches by Tyler Nowicki, Andy Zhang, and Preston Gurd!

llvm-svn: 160520
2012-07-19 18:53:21 +00:00
Dan Gohman c88fda477a Fix X86's isLegalAddressingMode to recognize that static addresses
need not be RIP-relative in small mode.

llvm-svn: 111917
2010-08-24 15:55:12 +00:00