1 //===- FunctionAttrs.h - Compute function attributes ------------*- C++ -*-===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 /// \file 11 /// Provides passes for computing function attributes based on interprocedural 12 /// analyses. 13 // 14 //===----------------------------------------------------------------------===// 15 16 #ifndef LLVM_TRANSFORMS_IPO_FUNCTIONATTRS_H 17 #define LLVM_TRANSFORMS_IPO_FUNCTIONATTRS_H 18 19 #include "llvm/Analysis/CGSCCPassManager.h" 20 #include "llvm/Analysis/LazyCallGraph.h" 21 #include "llvm/IR/PassManager.h" 22 23 namespace llvm { 24 25 class AAResults; 26 class Function; 27 class Module; 28 class Pass; 29 30 /// The three kinds of memory access relevant to 'readonly' and 31 /// 'readnone' attributes. 32 enum MemoryAccessKind { 33 MAK_ReadNone = 0, 34 MAK_ReadOnly = 1, 35 MAK_MayWrite = 2 36 }; 37 38 /// Returns the memory access properties of this copy of the function. 39 MemoryAccessKind computeFunctionBodyMemoryAccess(Function &F, AAResults &AAR); 40 41 /// Computes function attributes in post-order over the call graph. 42 /// 43 /// By operating in post-order, this pass computes precise attributes for 44 /// called functions prior to processsing their callers. This "bottom-up" 45 /// approach allows powerful interprocedural inference of function attributes 46 /// like memory access patterns, etc. It can discover functions that do not 47 /// access memory, or only read memory, and give them the readnone/readonly 48 /// attribute. It also discovers function arguments that are not captured by 49 /// the function and marks them with the nocapture attribute. 50 struct PostOrderFunctionAttrsPass : PassInfoMixin<PostOrderFunctionAttrsPass> { 51 PreservedAnalyses run(LazyCallGraph::SCC &C, CGSCCAnalysisManager &AM, 52 LazyCallGraph &CG, CGSCCUpdateResult &UR); 53 }; 54 55 /// Create a legacy pass manager instance of a pass to compute function attrs 56 /// in post-order. 57 Pass *createPostOrderFunctionAttrsLegacyPass(); 58 59 /// A pass to do RPO deduction and propagation of function attributes. 60 /// 61 /// This pass provides a general RPO or "top down" propagation of 62 /// function attributes. For a few (rare) cases, we can deduce significantly 63 /// more about function attributes by working in RPO, so this pass 64 /// provides the complement to the post-order pass above where the majority of 65 /// deduction is performed. 66 // FIXME: Currently there is no RPO CGSCC pass structure to slide into and so 67 // this is a boring module pass, but eventually it should be an RPO CGSCC pass 68 // when such infrastructure is available. 69 class ReversePostOrderFunctionAttrsPass 70 : public PassInfoMixin<ReversePostOrderFunctionAttrsPass> { 71 public: 72 PreservedAnalyses run(Module &M, ModuleAnalysisManager &AM); 73 }; 74 75 } // end namespace llvm 76 77 #endif // LLVM_TRANSFORMS_IPO_FUNCTIONATTRS_H 78
