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This commit sets up the infrastructure for auto-generating <arm_mve.h> and doing clang-side code generation for the builtins it relies on, and demonstrates that it works by implementing a representative sample of the ACLE intrinsics, more or less matching the ones introduced in LLVM IR by D67158,D68699,D68700. Like NEON, that header file will provide a set of vector types like uint16x8_t and C functions with names like vaddq_u32(). Unlike NEON, the ACLE spec for <arm_mve.h> includes a polymorphism system, so that you can write plain vaddq() and disambiguate by the vector types you pass to it. Unlike the corresponding NEON code, I've arranged to make every user- facing ACLE intrinsic into a clang builtin, and implement all the code generation inside clang. So <arm_mve.h> itself contains nothing but typedefs and function declarations, with the latter all using the new `__attribute__((__clang_builtin))` system to arrange that the user- facing function names correspond to the right internal BuiltinIDs. So the new MveEmitter tablegen system specifies the full sequence of IRBuilder operations that each user-facing ACLE intrinsic should translate into. Where possible, the ACLE intrinsics map to standard IR operations such as vector-typed `add` and `fadd`; where no standard representation exists, I call down to the sample IR intrinsics introduced in an earlier commit. Doing it like this means that you get the polymorphism for free just by using __attribute__((overloadable)): the clang overload resolution decides which function declaration is the relevant one, and _then_ its BuiltinID is looked up, so by the time we're doing code generation, that's all been resolved by the standard system. It also means that you get really nice error messages if the user passes the wrong combination of types: clang will show the declarations from the header file and explain why each one doesn't match. (The obvious alternative approach would be to have wrapper functions in <arm_mve.h> which pass their arguments to the underlying builtins. But that doesn't work in the case where one of the arguments has to be a constant integer: the wrapper function can't pass the constantness through. So you'd have to do that case using a macro instead, and then use C11 `_Generic` to handle the polymorphism. Then you have to add horrible workarounds because `_Generic` requires even the untaken branches to type-check successfully, and //then// if the user gets the types wrong, the error message is totally unreadable!) Reviewers: dmgreen, miyuki, ostannard Subscribers: mgorny, javed.absar, kristof.beyls, cfe-commits Tags: #clang Differential Revision: https://reviews.llvm.org/D67161 |
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| .. | ||
| ABIInfo.h | ||
| Address.h | ||
| BackendUtil.cpp | ||
| CGAtomic.cpp | ||
| CGBlocks.cpp | ||
| CGBlocks.h | ||
| CGBuilder.h | ||
| CGBuiltin.cpp | ||
| CGCall.cpp | ||
| CGCall.h | ||
| CGClass.cpp | ||
| CGCleanup.cpp | ||
| CGCleanup.h | ||
| CGCoroutine.cpp | ||
| CGCUDANV.cpp | ||
| CGCUDARuntime.cpp | ||
| CGCUDARuntime.h | ||
| CGCXX.cpp | ||
| CGCXXABI.cpp | ||
| CGCXXABI.h | ||
| CGDebugInfo.cpp | ||
| CGDebugInfo.h | ||
| CGDecl.cpp | ||
| CGDeclCXX.cpp | ||
| CGException.cpp | ||
| CGExpr.cpp | ||
| CGExprAgg.cpp | ||
| CGExprComplex.cpp | ||
| CGExprConstant.cpp | ||
| CGExprCXX.cpp | ||
| CGExprScalar.cpp | ||
| CGGPUBuiltin.cpp | ||
| CGLoopInfo.cpp | ||
| CGLoopInfo.h | ||
| CGNonTrivialStruct.cpp | ||
| CGObjC.cpp | ||
| CGObjCGNU.cpp | ||
| CGObjCMac.cpp | ||
| CGObjCRuntime.cpp | ||
| CGObjCRuntime.h | ||
| CGOpenCLRuntime.cpp | ||
| CGOpenCLRuntime.h | ||
| CGOpenMPRuntime.cpp | ||
| CGOpenMPRuntime.h | ||
| CGOpenMPRuntimeNVPTX.cpp | ||
| CGOpenMPRuntimeNVPTX.h | ||
| CGRecordLayout.h | ||
| CGRecordLayoutBuilder.cpp | ||
| CGStmt.cpp | ||
| CGStmtOpenMP.cpp | ||
| CGValue.h | ||
| CGVTables.cpp | ||
| CGVTables.h | ||
| CGVTT.cpp | ||
| CMakeLists.txt | ||
| CodeGenABITypes.cpp | ||
| CodeGenAction.cpp | ||
| CodeGenFunction.cpp | ||
| CodeGenFunction.h | ||
| CodeGenModule.cpp | ||
| CodeGenModule.h | ||
| CodeGenPGO.cpp | ||
| CodeGenPGO.h | ||
| CodeGenTBAA.cpp | ||
| CodeGenTBAA.h | ||
| CodeGenTypeCache.h | ||
| CodeGenTypes.cpp | ||
| CodeGenTypes.h | ||
| ConstantEmitter.h | ||
| ConstantInitBuilder.cpp | ||
| CoverageMappingGen.cpp | ||
| CoverageMappingGen.h | ||
| EHScopeStack.h | ||
| ItaniumCXXABI.cpp | ||
| MacroPPCallbacks.cpp | ||
| MacroPPCallbacks.h | ||
| MicrosoftCXXABI.cpp | ||
| ModuleBuilder.cpp | ||
| ObjectFilePCHContainerOperations.cpp | ||
| PatternInit.cpp | ||
| PatternInit.h | ||
| README.txt | ||
| SanitizerMetadata.cpp | ||
| SanitizerMetadata.h | ||
| SwiftCallingConv.cpp | ||
| TargetInfo.cpp | ||
| TargetInfo.h | ||
| VarBypassDetector.cpp | ||
| VarBypassDetector.h | ||
IRgen optimization opportunities. //===---------------------------------------------------------------------===// The common pattern of -- short x; // or char, etc (x == 10) -- generates an zext/sext of x which can easily be avoided. //===---------------------------------------------------------------------===// Bitfields accesses can be shifted to simplify masking and sign extension. For example, if the bitfield width is 8 and it is appropriately aligned then is is a lot shorter to just load the char directly. //===---------------------------------------------------------------------===// It may be worth avoiding creation of alloca's for formal arguments for the common situation where the argument is never written to or has its address taken. The idea would be to begin generating code by using the argument directly and if its address is taken or it is stored to then generate the alloca and patch up the existing code. In theory, the same optimization could be a win for block local variables as long as the declaration dominates all statements in the block. NOTE: The main case we care about this for is for -O0 -g compile time performance, and in that scenario we will need to emit the alloca anyway currently to emit proper debug info. So this is blocked by being able to emit debug information which refers to an LLVM temporary, not an alloca. //===---------------------------------------------------------------------===// We should try and avoid generating basic blocks which only contain jumps. At -O0, this penalizes us all the way from IRgen (malloc & instruction overhead), all the way down through code generation and assembly time. On 176.gcc:expr.ll, it looks like over 12% of basic blocks are just direct branches! //===---------------------------------------------------------------------===//