archived-llvm/bswap64.ll at testing - archived-llvm - Free-Git: DMCA Non-Compliant

RPCS3/archived-llvm

mirror of https://github.com/RPCS3/llvm.git synced 2026-01-31 01:25:19 +01:00

Files

Guozhi Wei 416cdcce39 [PPC] Use xxbrd to speed up bswap64

Power doesn't have bswap instructions, so llvm generates following code sequence for bswap64.

  rotldi   5, 3, 16
  rotldi   4, 3, 8
  rotldi   9, 3, 24
  rotldi   10, 3, 32
  rotldi   11, 3, 48
  rotldi   12, 3, 56
  rldimi 4, 5, 8, 48
  rldimi 4, 9, 16, 40
  rldimi 4, 10, 24, 32
  rldimi 4, 11, 40, 16
  rldimi 4, 12, 48, 8
  rldimi 4, 3, 56, 0

But Power9 has vector bswap instructions, they can also be used to speed up scalar bswap intrinsic. With this patch, bswap64 can be translated to:

  mtvsrdd 34, 3, 3
  xxbrd 34, 34
  mfvsrld 3, 34

Differential Revision: https://reviews.llvm.org/D39510



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@317499 91177308-0d34-0410-b5e6-96231b3b80d8

2017-11-06 19:09:38 +00:00

14 lines

259 B

LLVM

Raw Permalink Blame History

 ; RUN: llc -verify-machineinstrs < %s -mtriple=ppc64le-- -mcpu=pwr9 | FileCheck %s
 declare i64 @llvm.bswap.i64(i64)
 ; CHECK: mtvsrdd
 ; CHECK: xxbrd
 ; CHECK: mfvsrd
 define i64 @bswap64(i64 %x) {
 entry:
   %0 = call i64 @llvm.bswap.i64(i64 %x)
   ret i64 %0
 }