[PATCH] D139301: [X86] Add scheduling info of CodeGenOnly but encodable instructions for AlderlakeP model

[Andrea Di Biagio via Phabricator via llvm-commits]

andreadb added inline comments.


================
Comment at: llvm/lib/Target/X86/X86SchedAlderlakeP.td:812-814
+def : InstRW<[ADLPWriteResGroup38, ReadInt2Fpu], (instrs CVTSI642SSrr)>;
+def : InstRW<[ADLPWriteResGroup38, ReadDefault, ReadInt2Fpu], (instregex "^(V?)CVTSI642SSrr_Int$")>;
+def : InstRW<[ADLPWriteResGroup38, ReadDefault, ReadInt2Fpu], (instrs VCVTSI642SSrr)>;
----------------
HaohaiWen wrote:
> RKSimon wrote:
> > HaohaiWen wrote:
> > > CVTSI642SSrr has different schedreadwrite with CVTSI642SSrr_Int?
> > > I think they should be same.
> > Difference between sse12_cvt_s and sse12_vcvt_avx that are getting interpreted differently for some reason?
> Hi @andreadb, could you please answer RKSimon's question? I noticed you edited it in D57148.
It has been a while since I looked at that .td file. However, I think that the main difference is that some variants accept two operands, while other variants use three-operands forms.

More specifically, _Int variants tend to use three operands. CVTSI642SS is a codegen only instance of multiclass sse12_cvt_s, which assumes two input operands:

```
  def rr : SI<opc, MRMSrcReg, (outs DstRC:$dst), (ins SrcRC:$src),
              !strconcat(asm,"\t{$src, $dst|$dst, $src}"),
              [(set DstRC:$dst, (OpNode SrcRC:$src))]>,
              Sched<[sched, Int2Fpu]>;
```

That's why we don't need to skip the first use by introducing an "extra" ReadDefault.

If you look at the tablegen'd definitions, you see this:
```
  { 909,        2,      1,      0,      613,    0|(1ULL<<MCID::MayRaiseFPException), 0x1508023029ULL, ImplicitList18, nullptr, OperandInfo205 },  // Inst #909 = CVTSI642SSrr
  { 910,        3,      1,      0,      614,    0|(1ULL<<MCID::MayRaiseFPException), 0x1508023029ULL, ImplicitList18, nullptr, OperandInfo204 },  // Inst #910 = CVTSI642SSrr_Int
```

Note how CVTSI642SSrr takes 2 operands (second field), but the _Int variant takes 3 operands.


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https://reviews.llvm.org/D139301