[PowerPC] Improve BUILD_VECTOR of 4 i32s

Currently, for this node:
  vector int test(int a, int b, int c, int d) {
    return (vector int) { a, b, c, d };
  }

we get this on Power9:
  mtvsrdd 34, 5, 3
  mtvsrdd 35, 6, 4
  vmrgow 2, 3, 2

and this on Power8:
  mtvsrwz 0, 3
  mtvsrwz 1, 5
  mtvsrwz 2, 4
  mtvsrwz 3, 6
  xxmrghd 34, 1, 0
  xxmrghd 35, 3, 2
  vmrgow 2, 3, 2

This can be improved to this on LE Power9:
  rldimi 3, 4, 32, 0
  rldimi 5, 6, 32, 0
  mtvsrdd 34, 5, 3

and this on LE Power8
  rldimi 3, 4, 32, 0
  rldimi 5, 6, 32, 0
  mtvsrd 34, 3
  mtvsrd 35, 5
  xxpermdi 34, 35, 34, 0

This patch updates the TD pattern to generate the optimized sequence for both
Power8 and Power9 on LE and BE.

Differential Revision: https://reviews.llvm.org/D53494

llvm-svn: 345414

0 files changed, 0 insertions, 0 deletions