[PATCH] D71370: [AArch64][SVE] Add integer arithmetic with immediate instructions.

[Danilo Carvalho Grael via Phabricator via llvm-commits]

dancgr marked 4 inline comments as done.
dancgr added inline comments.


================
Comment at: llvm/lib/Target/AArch64/AArch64ISelDAGToDAG.cpp:2828
+      Imm = CurDAG->getTargetConstant(ImmVal & 0xFF, DL, MVT::i32);
+      return true;
+    case MVT::i16:
----------------
efriedma wrote:
> dancgr wrote:
> > efriedma wrote:
> > > I'd prefer to reject immediates greater than 255 here, instead of masking off the bits.
> > In the immediate definition we have:
> > 
> > ```
> > def addsub_imm8_opt_lsl_i8  : imm8_opt_lsl<8,  "uint8_t",  SVEAddSubImmOperand8,  [{
> >   return AArch64_AM::isSVEAddSubImm<int8_t>(Imm);
> > }]>;
> > ```
> > This checks if the immediate is in the accepted range for AddSub. Would you say we should also add another check here?
> > 
> > I pasted the code of that function below, since it is not in the changed files from this patch:
> > 
> > ```
> > template <typename T>
> > static inline bool isSVEAddSubImm(int64_t Imm) {
> >   bool IsInt8t =
> >       std::is_same<int8_t, typename std::make_signed<T>::type>::value;
> >   return uint8_t(Imm) == Imm || (!IsInt8t && uint16_t(Imm & ~0xff) == Imm);
> > }
> > ```
> Not sure that TableGen code is actually getting called from isel in this situation?  If it is, fine, we don't need a redundant check.
I was able to reproduce some instances where invalid immediates would get past that check. I have added that extra check.


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CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D71370/new/

https://reviews.llvm.org/D71370