llvm/lib/Transforms/IPO/ForceFunctionAttrs.cpp

   1 //===- ForceFunctionAttrs.cpp - Force function attrs for debugging --------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "llvm/Transforms/IPO/ForceFunctionAttrs.h"
  10 #include "llvm/IR/Function.h"
  11 #include "llvm/IR/LLVMContext.h"
  12 #include "llvm/IR/Module.h"
  13 #include "llvm/InitializePasses.h"
  14 #include "llvm/Support/CommandLine.h"
  15 #include "llvm/Support/Debug.h"
  16 #include "llvm/Support/raw_ostream.h"
  17 using namespace llvm;
  18
  19 #define DEBUG_TYPE "forceattrs"
  20
  21 static cl::list<std::string>
  22     ForceAttributes("force-attribute", cl::Hidden,
  23                     cl::desc("Add an attribute to a function. This should be a "
  24                              "pair of 'function-name:attribute-name', for "
  25                              "example -force-attribute=foo:noinline. This "
  26                              "option can be specified multiple times."));
  27
  28 static cl::list<std::string> ForceRemoveAttributes(
  29     "force-remove-attribute", cl::Hidden,
  30     cl::desc("Remove an attribute from a function. This should be a "
  31              "pair of 'function-name:attribute-name', for "
  32              "example -force-remove-attribute=foo:noinline. This "
  33              "option can be specified multiple times."));
  34
  35 /// If F has any forced attributes given on the command line, add them.
  36 /// If F has any forced remove attributes given on the command line, remove
  37 /// them. When both force and force-remove are given to a function, the latter
  38 /// takes precedence.
  39 static void forceAttributes(Function &F) {
  40   auto ParseFunctionAndAttr = [&](StringRef S) {
  41     auto Kind = Attribute::None;
  42     auto KV = StringRef(S).split(':');
  43     if (KV.first != F.getName())
  44       return Kind;
  45     Kind = Attribute::getAttrKindFromName(KV.second);
  46     if (Kind == Attribute::None || !Attribute::canUseAsFnAttr(Kind)) {
  47       LLVM_DEBUG(dbgs() << "ForcedAttribute: " << KV.second
  48                         << " unknown or not a function attribute!\n");
  49     }
  50     return Kind;
  51   };
  52
  53   for (auto &S : ForceAttributes) {
  54     auto Kind = ParseFunctionAndAttr(S);
  55     if (Kind == Attribute::None || F.hasFnAttribute(Kind))
  56       continue;
  57     F.addFnAttr(Kind);
  58   }
  59
  60   for (auto &S : ForceRemoveAttributes) {
  61     auto Kind = ParseFunctionAndAttr(S);
  62     if (Kind == Attribute::None || !F.hasFnAttribute(Kind))
  63       continue;
  64     F.removeFnAttr(Kind);
  65   }
  66 }
  67
  68 static bool hasForceAttributes() {
  69   return !ForceAttributes.empty() || !ForceRemoveAttributes.empty();
  70 }
  71
  72 PreservedAnalyses ForceFunctionAttrsPass::run(Module &M,
  73                                               ModuleAnalysisManager &) {
  74   if (!hasForceAttributes())
  75     return PreservedAnalyses::all();
  76
  77   for (Function &F : M.functions())
  78     forceAttributes(F);
  79
  80   // Just conservatively invalidate analyses, this isn't likely to be important.
  81   return PreservedAnalyses::none();
  82 }
  83
  84 namespace {
  85 struct ForceFunctionAttrsLegacyPass : public ModulePass {
  86   static char ID; // Pass identification, replacement for typeid
  87   ForceFunctionAttrsLegacyPass() : ModulePass(ID) {
  88     initializeForceFunctionAttrsLegacyPassPass(
  89         *PassRegistry::getPassRegistry());
  90   }
  91
  92   bool runOnModule(Module &M) override {
  93     if (!hasForceAttributes())
  94       return false;
  95
  96     for (Function &F : M.functions())
  97       forceAttributes(F);
  98
  99     // Conservatively assume we changed something.
 100     return true;
 101   }
 102 };
 103 }
 104
 105 char ForceFunctionAttrsLegacyPass::ID = 0;
 106 INITIALIZE_PASS(ForceFunctionAttrsLegacyPass, "forceattrs",
 107                 "Force set function attributes", false, false)
 108
 109 Pass *llvm::createForceFunctionAttrsLegacyPass() {
 110   return new ForceFunctionAttrsLegacyPass();
 111 }