[PATCH] D105796: [RISCV] Optimize multiplication in the zba extension with SH*ADD

[Ben Shi via Phabricator via llvm-commits]

benshi001 added a comment.

I change the $rs2 in the Pat from non_imm12 to GPR as following

  def : Pat<(addshl GPR:$rs1, (XLenVT 1), (XLenVT 2), GPR:$rs2),
            (SH1ADD (SH1ADD GPR:$rs1, GPR:$rs1), GPR:$rs2)>;

Because for `a*6 + 10`, `non_imm12:$rs2` will lead to

  addi Rb, zero, 6
  mul Ra, Rb, Ra
  addi Ra, Ra, 6

while `GPR:$rs2` will lead to

  addi Rb, zero, 10
  sh1add Ra, Ra, Ra
  sh1add Ra, Ra, Rb

And I think the later one is better, so I changed `non_imm12:$rs2` to `GPR:$rs2`.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D105796/new/

https://reviews.llvm.org/D105796