Author: Nikita Popov Date: 2023-11-03T11:25:41+01:00 New Revision: c5a1d0ae6a69c7ba39a4386c30e49da0d2a3664e
URL: https://github.com/llvm/llvm-project/commit/c5a1d0ae6a69c7ba39a4386c30e49da0d2a3664e DIFF: https://github.com/llvm/llvm-project/commit/c5a1d0ae6a69c7ba39a4386c30e49da0d2a3664e.diff LOG: Revert "[ConstantFold] Remove unnecessary BitCastConstantVector() (NFCI)" This reverts commit 2182561b7ba675ca87356c02474eecb6ecfaa23f. The all-ones special case in this case isn't redundant. Will redo the change while preserving it. Added: Modified: llvm/lib/IR/ConstantFold.cpp Removed: ################################################################################ diff --git a/llvm/lib/IR/ConstantFold.cpp b/llvm/lib/IR/ConstantFold.cpp index d69665bd6c56ae6..a263cdcf4008a2a 100644 --- a/llvm/lib/IR/ConstantFold.cpp +++ b/llvm/lib/IR/ConstantFold.cpp @@ -37,6 +37,45 @@ using namespace llvm::PatternMatch; // ConstantFold*Instruction Implementations //===----------------------------------------------------------------------===// +/// Convert the specified vector Constant node to the specified vector type. +/// At this point, we know that the elements of the input vector constant are +/// all simple integer or FP values. +static Constant *BitCastConstantVector(Constant *CV, VectorType *DstTy) { + + if (CV->isAllOnesValue()) return Constant::getAllOnesValue(DstTy); + if (CV->isNullValue()) return Constant::getNullValue(DstTy); + + // Do not iterate on scalable vector. The num of elements is unknown at + // compile-time. + if (isa<ScalableVectorType>(DstTy)) + return nullptr; + + // If this cast changes element count then we can't handle it here: + // doing so requires endianness information. This should be handled by + // Analysis/ConstantFolding.cpp + unsigned NumElts = cast<FixedVectorType>(DstTy)->getNumElements(); + if (NumElts != cast<FixedVectorType>(CV->getType())->getNumElements()) + return nullptr; + + Type *DstEltTy = DstTy->getElementType(); + // Fast path for splatted constants. + if (Constant *Splat = CV->getSplatValue()) { + return ConstantVector::getSplat(DstTy->getElementCount(), + ConstantExpr::getBitCast(Splat, DstEltTy)); + } + + SmallVector<Constant*, 16> Result; + Type *Ty = IntegerType::get(CV->getContext(), 32); + for (unsigned i = 0; i != NumElts; ++i) { + Constant *C = + ConstantExpr::getExtractElement(CV, ConstantInt::get(Ty, i)); + C = ConstantExpr::getBitCast(C, DstEltTy); + Result.push_back(C); + } + + return ConstantVector::get(Result); +} + /// This function determines which opcode to use to fold two constant cast /// expressions together. It uses CastInst::isEliminableCastPair to determine /// the opcode. Consequently its just a wrapper around that function. @@ -75,12 +114,24 @@ static Constant *FoldBitCast(Constant *V, Type *DestTy) { // Handle casts from one vector constant to another. We know that the src // and dest type have the same size (otherwise its an illegal cast). if (VectorType *DestPTy = dyn_cast<VectorType>(DestTy)) { + if (VectorType *SrcTy = dyn_cast<VectorType>(V->getType())) { + assert(DestPTy->getPrimitiveSizeInBits() == + SrcTy->getPrimitiveSizeInBits() && + "Not cast between same sized vectors!"); + SrcTy = nullptr; + // First, check for null. Undef is already handled. + if (isa<ConstantAggregateZero>(V)) + return Constant::getNullValue(DestTy); + + // Handle ConstantVector and ConstantAggregateVector. + return BitCastConstantVector(V, DestPTy); + } + // Canonicalize scalar-to-vector bitcasts into vector-to-vector bitcasts // This allows for other simplifications (although some of them // can only be handled by Analysis/ConstantFolding.cpp). if (isa<ConstantInt>(V) || isa<ConstantFP>(V)) return ConstantExpr::getBitCast(ConstantVector::get(V), DestPTy); - return nullptr; } // Handle integral constant input. _______________________________________________ llvm-branch-commits mailing list llvm-branch-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits
