[PATCH] D123290: [LoongArch] Add support for selecting constant materializations.

[Ray Wang via Phabricator via llvm-commits]

wangleiat added inline comments.


================
Comment at: llvm/lib/Target/LoongArch/MCTargetDesc/LoongArchMatInt.cpp:23
+  //
+  int64_t Highest12 = Val >> 52 & 0xFFF;
+  int64_t Higher20 = Val >> 32 & 0xFFFFF;
----------------
MaskRay wrote:
> Add const if applicable
Thanks, I will add it.


================
Comment at: llvm/lib/Target/LoongArch/MCTargetDesc/LoongArchMatInt.cpp:44
+
+  if (SignExtend32<1>(Hi20 >> 19) != SignExtend32<20>(Higher20))
+    Insts.push_back(Inst(LoongArch::LU32I_D, SignExtend64<20>(Higher20)));
----------------
MaskRay wrote:
> The logic looks weird. What does it do?
It is to check whether `Higher20` is equal to the repetition of the 31st bit.
This judgment is made because these `LU12I_W` `ADDI_W` instructions will  writes `imm` into the general register after `sign extension`.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D123290/new/

https://reviews.llvm.org/D123290