https://github.com/4vtomat created https://github.com/llvm/llvm-project/pull/147173
Currently, struct of fixed-vector array is flattened and lowered to scalable vector. However only struct of 1-element-fixed-vector array should be lowered that way, struct of fixed-vector array of length >1 should be lowered to vector tuple type. https://github.com/riscv-non-isa/riscv-elf-psabi-doc/pull/418/files#diff-3a934f00cffdb3e509722753126a2cf6082a7648ab3b9ca8cbb0e84f8a6a12edR555-R558 >From 1934543b7ec215312eebefd152f7c9151c2d0e54 Mon Sep 17 00:00:00 2001 From: Brandon Wu <songwu0...@gmail.com> Date: Sat, 5 Jul 2025 21:32:28 -0700 Subject: [PATCH] [RISCV] Correct type lowering of struct of fixed-vector array in VLS Currently, struct of fixed-vector array is flattened and lowered to scalable vector. However only struct of 1-element-fixed-vector array should be lowered that way, struct of fixed-vector array of length >1 should be lowered to vector tuple type. https://github.com/riscv-non-isa/riscv-elf-psabi-doc/pull/418/files#diff-3a934f00cffdb3e509722753126a2cf6082a7648ab3b9ca8cbb0e84f8a6a12edR555-R558 --- clang/lib/CodeGen/Targets/RISCV.cpp | 144 ++++++++---------- .../RISCV/riscv-vector-callingconv-llvm-ir.c | 8 +- .../riscv-vector-callingconv-llvm-ir.cpp | 8 +- 3 files changed, 68 insertions(+), 92 deletions(-) diff --git a/clang/lib/CodeGen/Targets/RISCV.cpp b/clang/lib/CodeGen/Targets/RISCV.cpp index cc3d487da83b5..e1603d3095a04 100644 --- a/clang/lib/CodeGen/Targets/RISCV.cpp +++ b/clang/lib/CodeGen/Targets/RISCV.cpp @@ -441,98 +441,74 @@ bool RISCVABIInfo::detectVLSCCEligibleStruct(QualType Ty, unsigned ABIVLen, // __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))) { - unsigned NumElts = STy->getStructNumElements(); - if (NumElts > 8) - return false; + // 1. Struct of 1 fixed-length vector is passed as a scalable vector. + // 2. Struct of >1 fixed-length vectors are passed as vector tuple. + // 3. Struct of an array with 1 element of fixed-length vectors is passed as a + // scalable vector. + // 4. Struct of an array with >1 elements of fixed-length vectors is passed as + // vector tuple. + // 5. Otherwise, pass the struct indirectly. + + llvm::StructType *STy = dyn_cast<llvm::StructType>(CGT.ConvertType(Ty)); + if (!STy) + return false; - auto *FirstEltTy = STy->getElementType(0); - if (!STy->containsHomogeneousTypes()) - return false; + unsigned NumElts = STy->getStructNumElements(); + if (NumElts > 8) + 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; - } + auto *FirstEltTy = STy->getElementType(0); + if (!STy->containsHomogeneousTypes()) + return false; - // If elements are not fixed-length vectors, it should be an array. + if (auto *ArrayTy = dyn_cast<llvm::ArrayType>(FirstEltTy)) { + // Only struct of single array is accepted if (NumElts != 1) return false; + FirstEltTy = ArrayTy->getArrayElementType(); + NumElts = ArrayTy->getNumElements(); + } - // Check array of fixed-length vector and turn it into scalable vector type - // if legal. - if (auto *ArrTy = dyn_cast<llvm::ArrayType>(FirstEltTy)) { - unsigned NumArrElt = ArrTy->getNumElements(); - if (NumArrElt > 8) - return false; - - auto *ArrEltTy = dyn_cast<llvm::FixedVectorType>(ArrTy->getElementType()); - if (!ArrEltTy) - return false; + auto *FixedVecTy = dyn_cast<llvm::FixedVectorType>(FirstEltTy); + if (!FixedVecTy) + return false; - // LMUL - // = NumArrElt * fixed-length vector size / ABIVLen - // = fixed-length vector elt size * ScalVecNumElts / RVVBitsPerBlock - // => - // ScalVecNumElts - // = (NumArrElt * fixed-length vector size * RVVBitsPerBlock) / - // (ABIVLen * fixed-length vector elt size) - // = NumArrElt * num fixed-length vector elt * RVVBitsPerBlock / - // ABIVLen - unsigned ScalVecNumElts = llvm::divideCeil( - NumArrElt * ArrEltTy->getNumElements() * llvm::RISCV::RVVBitsPerBlock, - ABIVLen); - VLSType = llvm::ScalableVectorType::get(ArrEltTy->getElementType(), - ScalVecNumElts); - // Check registers needed <= 8. - return llvm::divideCeil( - ScalVecNumElts * - ArrEltTy->getElementType()->getScalarSizeInBits(), - llvm::RISCV::RVVBitsPerBlock) <= 8; - } + // Turn them into scalable vector type or vector tuple type if legal. + 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; } - return false; + // 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; } // Fixed-length RVV vectors are represented as scalable vectors in function diff --git a/clang/test/CodeGen/RISCV/riscv-vector-callingconv-llvm-ir.c b/clang/test/CodeGen/RISCV/riscv-vector-callingconv-llvm-ir.c index 3044d91f1c31c..82e43fff0c3aa 100644 --- a/clang/test/CodeGen/RISCV/riscv-vector-callingconv-llvm-ir.c +++ b/clang/test/CodeGen/RISCV/riscv-vector-callingconv-llvm-ir.c @@ -153,14 +153,14 @@ void __attribute__((riscv_vls_cc)) test_st_i32x4_arr1(struct st_i32x4_arr1 arg) // CHECK-LLVM: define dso_local riscv_vls_cc(256) void @test_st_i32x4_arr1_256(<vscale x 1 x i32> %arg) void __attribute__((riscv_vls_cc(256))) test_st_i32x4_arr1_256(struct st_i32x4_arr1 arg) {} -// CHECK-LLVM: define dso_local riscv_vls_cc(128) void @test_st_i32x4_arr4(<vscale x 8 x i32> %arg) +// CHECK-LLVM: define dso_local riscv_vls_cc(128) void @test_st_i32x4_arr4(target("riscv.vector.tuple", <vscale x 8 x i8>, 4) %arg) void __attribute__((riscv_vls_cc)) test_st_i32x4_arr4(struct st_i32x4_arr4 arg) {} -// CHECK-LLVM: define dso_local riscv_vls_cc(256) void @test_st_i32x4_arr4_256(<vscale x 4 x i32> %arg) +// CHECK-LLVM: define dso_local riscv_vls_cc(256) void @test_st_i32x4_arr4_256(target("riscv.vector.tuple", <vscale x 4 x i8>, 4) %arg) void __attribute__((riscv_vls_cc(256))) test_st_i32x4_arr4_256(struct st_i32x4_arr4 arg) {} -// CHECK-LLVM: define dso_local riscv_vls_cc(128) void @test_st_i32x4_arr8(<vscale x 16 x i32> %arg) +// CHECK-LLVM: define dso_local riscv_vls_cc(128) void @test_st_i32x4_arr8(target("riscv.vector.tuple", <vscale x 8 x i8>, 8) %arg) void __attribute__((riscv_vls_cc)) test_st_i32x4_arr8(struct st_i32x4_arr8 arg) {} -// CHECK-LLVM: define dso_local riscv_vls_cc(256) void @test_st_i32x4_arr8_256(<vscale x 8 x i32> %arg) +// CHECK-LLVM: define dso_local riscv_vls_cc(256) void @test_st_i32x4_arr8_256(target("riscv.vector.tuple", <vscale x 4 x i8>, 8) %arg) void __attribute__((riscv_vls_cc(256))) test_st_i32x4_arr8_256(struct st_i32x4_arr8 arg) {} // CHECK-LLVM: define dso_local riscv_vls_cc(128) void @test_st_i32x4x2(target("riscv.vector.tuple", <vscale x 8 x i8>, 2) %arg) diff --git a/clang/test/CodeGen/RISCV/riscv-vector-callingconv-llvm-ir.cpp b/clang/test/CodeGen/RISCV/riscv-vector-callingconv-llvm-ir.cpp index 594bfe159b28c..5f6539796c20d 100644 --- a/clang/test/CodeGen/RISCV/riscv-vector-callingconv-llvm-ir.cpp +++ b/clang/test/CodeGen/RISCV/riscv-vector-callingconv-llvm-ir.cpp @@ -133,14 +133,14 @@ typedef int __attribute__((vector_size(256))) int32x64_t; // CHECK-LLVM: define dso_local riscv_vls_cc(256) void @_Z22test_st_i32x4_arr1_25613st_i32x4_arr1(<vscale x 1 x i32> %arg) [[riscv::vls_cc(256)]] void test_st_i32x4_arr1_256(struct st_i32x4_arr1 arg) {} -// CHECK-LLVM: define dso_local riscv_vls_cc(128) void @_Z18test_st_i32x4_arr413st_i32x4_arr4(<vscale x 8 x i32> %arg) +// CHECK-LLVM: define dso_local riscv_vls_cc(128) void @_Z18test_st_i32x4_arr413st_i32x4_arr4(target("riscv.vector.tuple", <vscale x 8 x i8>, 4) %arg) [[riscv::vls_cc]] void test_st_i32x4_arr4(struct st_i32x4_arr4 arg) {} -// CHECK-LLVM: define dso_local riscv_vls_cc(256) void @_Z22test_st_i32x4_arr4_25613st_i32x4_arr4(<vscale x 4 x i32> %arg) +// CHECK-LLVM: define dso_local riscv_vls_cc(256) void @_Z22test_st_i32x4_arr4_25613st_i32x4_arr4(target("riscv.vector.tuple", <vscale x 4 x i8>, 4) %arg) [[riscv::vls_cc(256)]] void test_st_i32x4_arr4_256(struct st_i32x4_arr4 arg) {} -// CHECK-LLVM: define dso_local riscv_vls_cc(128) void @_Z18test_st_i32x4_arr813st_i32x4_arr8(<vscale x 16 x i32> %arg) +// CHECK-LLVM: define dso_local riscv_vls_cc(128) void @_Z18test_st_i32x4_arr813st_i32x4_arr8(target("riscv.vector.tuple", <vscale x 8 x i8>, 8) %arg) [[riscv::vls_cc]] void test_st_i32x4_arr8(struct st_i32x4_arr8 arg) {} -// CHECK-LLVM: define dso_local riscv_vls_cc(256) void @_Z22test_st_i32x4_arr8_25613st_i32x4_arr8(<vscale x 8 x i32> %arg) +// CHECK-LLVM: define dso_local riscv_vls_cc(256) void @_Z22test_st_i32x4_arr8_25613st_i32x4_arr8(target("riscv.vector.tuple", <vscale x 4 x i8>, 8) %arg) [[riscv::vls_cc(256)]] void test_st_i32x4_arr8_256(struct st_i32x4_arr8 arg) {} // CHECK-LLVM: define dso_local riscv_vls_cc(128) void @_Z15test_st_i32x4x210st_i32x4x2(target("riscv.vector.tuple", <vscale x 8 x i8>, 2) %arg) _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
