Commit Graph

5 Commits

Author SHA1 Message Date
Sanjay Patel 610a2f6525 [x86][SSE/AVX] optimize pcmp results better (PR28484)
We know that pcmp produces all-ones/all-zeros bitmasks, so we can use that behavior to avoid unnecessary constant loading.

One could argue that load+and is actually a better solution for some CPUs (Intel big cores) because shifts don't have the
same throughput potential as load+and on those cores, but that should be handled as a CPU-specific later transformation if
it ever comes up. Removing the load is the more general x86 optimization. Note that the uneven usage of vpbroadcast in the
test cases is filed as PR28505:
https://llvm.org/bugs/show_bug.cgi?id=28505

Differential Revision: http://reviews.llvm.org/D22225

llvm-svn: 275276
2016-07-13 16:04:07 +00:00
Sanjay Patel b428951990 [x86] specify triple to avoid bot failures
llvm-svn: 275067
2016-07-11 14:17:54 +00:00
Sanjay Patel 0d38830aca [x86] update checks
llvm-svn: 275064
2016-07-11 14:07:31 +00:00
NAKAMURA Takumi 0607c15435 llvm/test/CodeGen/X86/shift-pcmp.ll: Tweak to appease FileCheck. "CHECK-LABEL" doesn't identify labels magically and CHECK-LABEL behaves free from other contexts.
For targeting pecoff, ".def foo" appears before ".short 32".

          .def    foo;
  ...
  .LCPI0_0:
          .short  32
  foo:

CHECK-LABEL seeks not from ".short 32" but from the top of the input.

llvm-svn: 201931
2014-02-22 07:27:04 +00:00
Quentin Colombet 4db08df18e [DAGCombiner] PCMP* sets its result to all ones or zeros so we can AND with the
shifted mask rather than masking and shifting separately.

The patch adds this transformation to the DAGCombiner:

  (shl (and (setcc:i8v16 ...) N01C) N1C) -> (and (setcc:i8v16 ...) N01C<<N1C)

<rdar://problem/16054492>

Patch by Adam Nemet <anemet@apple.com>

llvm-svn: 201906
2014-02-21 23:42:41 +00:00