================
@@ -359,9 +405,153 @@ ABIArgInfo
RISCVABIInfo::coerceAndExpandFPCCEligibleStruct(
return ABIArgInfo::getCoerceAndExpand(CoerceToType, UnpaddedCoerceToType);
}
+bool RISCVABIInfo::detectVLSCCEligibleStruct(QualType Ty, unsigned ABIVLen,
+ llvm::Type *&VLSType) const {
+ // No riscv_vls_cc attribute.
+ if (ABIVLen == 1)
+ return false;
+
+ // Legal struct for VLS calling convention should fulfill following rules:
+ // 1. Struct element should be either "homogeneous fixed-length vectors" or
"a
+ // fixed-length vector array".
+ // 2. Number of struct elements or array elements should be power of 2.
+ // 3. Total number of vector registers needed should not exceed 8.
+ //
+ // Examples: Assume ABI_VLEN = 128.
+ // These are legal structs:
+ // a. Structs with 1, 2, 4 or 8 "same" fixed-length vectors, e.g.
+ // struct {
+ // __attribute__((vector_size(16))) int a;
+ // __attribute__((vector_size(16))) int b;
+ // }
+ //
+ // b. Structs with "single" fixed-length vector array with lengh 1, 2, 4
+ // or 8, e.g.
+ // struct {
+ // __attribute__((vector_size(16))) int a[2];
+ // }
+ // These are illegal structs:
+ // a. Structs with 3 fixed-length vectors, e.g.
+ // struct {
+ // __attribute__((vector_size(16))) int a;
+ // __attribute__((vector_size(16))) int b;
+ // __attribute__((vector_size(16))) int c;
+ // }
+ //
+ // b. Structs with "multiple" fixed-length vector array, e.g.
+ // struct {
+ // __attribute__((vector_size(16))) int a[2];
+ // __attribute__((vector_size(16))) int b[2];
+ // }
+ //
+ // c. Vector registers needed exceeds 8, e.g.
+ // struct {
+ // // Registers needed for single fixed-length element:
+ // // 64 * 8 / ABI_VLEN = 4
+ // __attribute__((vector_size(64))) int a;
+ // __attribute__((vector_size(64))) int b;
+ // __attribute__((vector_size(64))) int c;
+ // __attribute__((vector_size(64))) int d;
+ // }
+ //
+ // Struct of 1 fixed-length vector is passed as a scalable vector.
+ // Struct of >1 fixed-length vectors are passed as vector tuple.
+ // Struct of 1 array of fixed-length vectors is passed as a scalable vector.
+ // Otherwise, pass the struct indirectly.
+
+ if (llvm::StructType *STy = dyn_cast<llvm::StructType>(CGT.ConvertType(Ty)))
{
+ int NumElts = STy->getStructNumElements();
+ if (NumElts > 8 || !llvm::isPowerOf2_32(NumElts))
+ return false;
+
+ auto *FirstEltTy = STy->getElementType(0);
+ if (!STy->containsHomogeneousTypes())
+ return false;
+
+ // Check structure of fixed-length vectors and turn them into vector tuple
+ // type if legal.
+ if (auto *FixedVecTy = dyn_cast<llvm::FixedVectorType>(FirstEltTy)) {
+ if (NumElts == 1) {
+ // Handle single fixed-length vector.
+ VLSType = llvm::ScalableVectorType::get(
+ FixedVecTy->getElementType(),
+ llvm::divideCeil(FixedVecTy->getNumElements() *
+ llvm::RISCV::RVVBitsPerBlock,
+ ABIVLen));
+ // Check registers needed <= 8.
+ return llvm::divideCeil(
+ FixedVecTy->getNumElements() *
+ FixedVecTy->getElementType()->getScalarSizeInBits(),
+ ABIVLen) <= 8;
+ }
+ // LMUL
+ // = fixed-length vector size / ABIVLen
+ // = 8 * I8EltCount / RVVBitsPerBlock
+ // =>
+ // I8EltCount
+ // = (fixed-length vector size * RVVBitsPerBlock) / (ABIVLen * 8)
+ unsigned I8EltCount = llvm::divideCeil(
+ FixedVecTy->getNumElements() *
+ FixedVecTy->getElementType()->getScalarSizeInBits() *
+ llvm::RISCV::RVVBitsPerBlock,
+ ABIVLen * 8);
+ VLSType = llvm::TargetExtType::get(
+ getVMContext(), "riscv.vector.tuple",
+ llvm::ScalableVectorType::get(llvm::Type::getInt8Ty(getVMContext()),
+ I8EltCount),
+ NumElts);
+ // Check registers needed <= 8.
+ return NumElts *
+ llvm::divideCeil(
+ FixedVecTy->getNumElements() *
+ FixedVecTy->getElementType()->getScalarSizeInBits(),
+ ABIVLen) <=
+ 8;
+ }
+
+ // If elements are not fixed-length vectors, it should be an array.
+ if (NumElts != 1)
+ return false;
+
+ // Check array of fixed-length vector and turn it into scalable vector type
+ // if legal.
+ if (auto *ArrTy = dyn_cast<llvm::ArrayType>(FirstEltTy)) {
+ int NumArrElt = ArrTy->getNumElements();
+ if (NumArrElt > 8 || !llvm::isPowerOf2_32(NumArrElt))
----------------
kito-cheng wrote:
```suggestion
if (NumArrElt > 8)
```
https://github.com/llvm/llvm-project/pull/100346
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