gchatelet added a comment. In D61634#1493350 <https://reviews.llvm.org/D61634#1493350>, @theraven wrote:
> I wonder if a list of comma-separated names is the right approach. Would it > make more sense to add a new attribute for each of the helpers, such as > `#no-runtime-for-memcpy`? That should make querying simpler (one lookup in > the table, rather than a lookup and a string scan) and also make it easier to > add and remove attributes (merging is now just a matter of trying to add all > of them, with the existing logic to deduplicate repeated attributes working). So I decided to go that route for two reasons: - The `no_runtime_for` attribute will be used almost exclusively by runtime implementers, on average lookup will return false and the parsing part should be marginal (famous last words?) - We need to support every function in TargetLibraryInfo <https://github.com/llvm/llvm-project/blob/master/llvm/include/llvm/Analysis/TargetLibraryInfo.def> (I count 434 of them) and I'm not sure adding one attribute per function will scale or can stay in sync. Now I haven't thought about merging indeed, we may be able to reuse or clone the approach used for `target-features`? For instance some backend disable specific functions and we may warn the user if it happens. e.g. `setLibcallName(RTLIB::SHL_I128, nullptr);` in X86ISelLowering.cpp <https://raw.githubusercontent.com/llvm/llvm-project/master/llvm/lib/Target/X86/X86ISelLowering.cpp> I'm not saying one attribute per helper is not feasible but I'd like to put it into perspective with other constraints. > We probably need to also carefully audit all of the transform passes to find > ones that insert calls. Last time I looked, there were four places in LLVM > where memcpy could be expanded, I wonder if there are a similar number where > it can be synthesised... Yes indeed, it's going to be long and painful, here are the functions calling `CallLoweringInfo::setLibCallee` : **llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp** - ExpandLibCall(LC, Node, isSigned) - ExpandChainLibCall(LC, Node, isSigned) - ExpandDivRemLibCall(Node, Results) - ExpandSinCosLibCall(Node, Results) - ConvertNodeToLibcall(Node) - ConvertNodeToLibcall(Node) **llvm/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp** - ExpandIntRes_XMULO(N, Lo, Hi) **llvm/lib/CodeGen/SelectionDAG/LegalizeTypes.cpp** - ExpandChainLibCall(LC, Node, isSigned) **llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp** - getMemcpy(Chain, dl, Dst, Src, Size, Align, isVol, AlwaysInline, isTailCall, DstPtrInfo, SrcPtrInfo) - getAtomicMemcpy(Chain, dl, Dst, DstAlign, Src, SrcAlign, Size, SizeTy, ElemSz, isTailCall, DstPtrInfo, SrcPtrInfo) - getMemmove(Chain, dl, Dst, Src, Size, Align, isVol, isTailCall, DstPtrInfo, SrcPtrInfo) - getAtomicMemmove(Chain, dl, Dst, DstAlign, Src, SrcAlign, Size, SizeTy, ElemSz, isTailCall, DstPtrInfo, SrcPtrInfo) - getMemset(Chain, dl, Dst, Src, Size, Align, isVol, isTailCall, DstPtrInfo) - getAtomicMemset(Chain, dl, Dst, DstAlign, Value, Size, SizeTy, ElemSz, isTailCall, DstPtrInfo) **llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp** - visitIntrinsicCall(I, Intrinsic) **llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp** - makeLibCall(DAG, LC, RetVT, Ops, isSigned, dl, doesNotReturn, isReturnValueUsed, isPostTypeLegalization) - LowerToTLSEmulatedModel(GA, DAG) **llvm/lib/Target/AArch64/AArch64ISelLowering.cpp** - LowerFSINCOS(Op, DAG) **llvm/lib/Target/AArch64/AArch64SelectionDAGInfo.cpp** - EmitTargetCodeForMemset(DAG, dl, Chain, Dst, Src, Size, Align, isVolatile, DstPtrInfo) **llvm/lib/Target/ARM/ARMISelLowering.cpp** - LowerToTLSGeneralDynamicModel(GA, DAG) **llvm/lib/Target/ARM/ARMSelectionDAGInfo.cpp** - EmitSpecializedLibcall(DAG, dl, Chain, Dst, Src, Size, Align, LC) **llvm/lib/Target/Hexagon/HexagonSelectionDAGInfo.cpp** - EmitTargetCodeForMemcpy(DAG, dl, Chain, Dst, Src, Size, Align, isVolatile, AlwaysInline, DstPtrInfo, SrcPtrInfo) **llvm/lib/Target/PowerPC/PPCISelLowering.cpp** - LowerINIT_TRAMPOLINE(Op, DAG) **llvm/lib/Target/X86/X86ISelLowering.cpp** - LowerWin64_i128OP(Op, DAG) - LowerFSINCOS(Op, Subtarget, DAG) **llvm/lib/Target/X86/X86SelectionDAGInfo.cpp** - EmitTargetCodeForMemset(DAG, dl, Chain, Dst, Val, Size, Align, isVolatile, DstPtrInfo) Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D61634/new/ https://reviews.llvm.org/D61634 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
