| Issue |
147733
|
| Summary |
[SLP] SLP ignores command line options and creates oversized vectors
|
| Labels |
llvm:SLPVectorizer
|
| Assignees |
|
| Reporter |
ashermancinelli
|
The SLP vectorizer is creating vectors that exceed the maximum register size specified by `-slp-max-reg-size`, the `"prefer-vector-width"="N"` metadata, and the `-force-vector-width=N` command line option.
https://godbolt.org/z/KMj67594P
I see a few checks like this in SLPVectorizer.cpp
```cpp
// Lines 1804-1809
if (MaxVectorRegSizeOption.getNumOccurrences())
MaxVecRegSize = MaxVectorRegSizeOption;
else
MaxVecRegSize =
TTI->getRegisterBitWidth(TargetTransformInfo::RGK_FixedWidthVector)
.getFixedValue();
// Line 2072
unsigned getMaximumVF(unsigned ElemWidth, unsigned Opcode) const {
unsigned MaxVF = MaxVFOption.getNumOccurrences() ?
MaxVFOption : TTI->getMaximumVF(ElemWidth, Opcode);
return MaxVF ? MaxVF : UINT_MAX;
}
```
Is this expected behavior? Is there another way to force slp to use a given max vector width?
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